path: root/src/resolver/resolver.zig

usingnamespace @import("../global.zig");
const ast = @import("../import_record.zig");
const logger = @import("../logger.zig");
const options = @import("../options.zig");
const Fs = @import("../fs.zig");
const std = @import("std");
const cache = @import("../cache.zig");
const sync = @import("../sync.zig");
const TSConfigJSON = @import("./tsconfig_json.zig").TSConfigJSON;
const PackageJSON = @import("./package_json.zig").PackageJSON;
const MacroRemap = @import("./package_json.zig").MacroMap;
const ESModule = @import("./package_json.zig").ESModule;
const BrowserMap = @import("./package_json.zig").BrowserMap;
const CacheSet = cache.Set;
usingnamespace @import("./data_url.zig");
pub const DirInfo = @import("./dir_info.zig");
const HTTPWatcher = @import("../http.zig").Watcher;
const Wyhash = std.hash.Wyhash;
const ResolvePath = @import("./resolve_path.zig");
const NodeFallbackModules = @import("../node_fallbacks.zig");

const Mutex = @import("../lock.zig").Lock;
const StringBoolMap = std.StringHashMap(bool);

const allocators = @import("../allocators.zig");

const Path = Fs.Path;
const NodeModuleBundle = @import("../node_module_bundle.zig").NodeModuleBundle;

const FileSystem = Fs.FileSystem;
const File = Fs.File;

pub fn isPackagePath(path: string) bool {
    // this could probably be flattened into something more optimized
    return path[0] != '/' and !strings.startsWith(path, "./") and !strings.startsWith(path, "../") and !strings.eql(path, ".") and !strings.eql(path, "..");
}

pub const SideEffectsData = struct {
    source: *logger.Source,
    range: logger.Range,

    // If true, "sideEffects" was an array. If false, "sideEffects" was false.
    is_side_effects_array_in_json: bool = false,
};

pub const TemporaryBuffer = struct {
    pub threadlocal var ExtensionPathBuf: [512]u8 = undefined;
    pub threadlocal var TSConfigMatchStarBuf: [512]u8 = undefined;
    pub threadlocal var TSConfigMatchPathBuf: [512]u8 = undefined;
    pub threadlocal var TSConfigMatchFullBuf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
    pub threadlocal var TSConfigMatchFullBuf2: [std.fs.MAX_PATH_BYTES]u8 = undefined;
};

pub const PathPair = struct {
    primary: Path,
    secondary: ?Path = null,

    pub const Iter = struct {
        index: u2,
        ctx: *PathPair,
        pub fn next(i: *Iter) ?*Path {
            const ind = i.index;
            i.index += 1;

            switch (ind) {
                0 => return &i.ctx.primary,
                1 => return if (i.ctx.secondary) |*sec| sec else null,
                else => return null,
            }
        }
    };

    pub fn iter(p: *PathPair) Iter {
        return Iter{ .ctx = p, .index = 0 };
    }
};

pub const Result = struct {
    path_pair: PathPair,

    jsx: options.JSX.Pragma = options.JSX.Pragma{},

    package_json: ?*PackageJSON = null,

    is_external: bool = false,

    // This is true when the package was loaded from within the node_modules directory.
    is_from_node_modules: bool = false,

    diff_case: ?Fs.Entry.Lookup.DifferentCase = null,

    // If present, any ES6 imports to this file can be considered to have no side
    // effects. This means they should be removed if unused.
    primary_side_effects_data: ?SideEffectsData = null,

    // If true, the class field transform should use Object.defineProperty().
    use_define_for_class_fields_ts: ?bool = null,

    // If true, unused imports are retained in TypeScript code. This matches the
    // behavior of the "importsNotUsedAsValues" field in "tsconfig.json" when the
    // value is not "remove".
    preserve_unused_imports_ts: bool = false,

    // This is the "type" field from "package.json"
    module_type: options.ModuleType = options.ModuleType.unknown,

    debug_meta: ?DebugMeta = null,

    dirname_fd: StoredFileDescriptorType = 0,
    file_fd: StoredFileDescriptorType = 0,
    import_kind: ast.ImportKind = undefined,

    pub fn getMacroRemappings(this: *const Result) MacroRemap {
        const pkg = this.package_json orelse return MacroRemap{};

        return pkg.macros;
    }

    pub fn path(this: *Result) ?*Path {
        if (!this.path_pair.primary.is_disabled)
            return &this.path_pair.primary;

        if (this.path_pair.secondary) |*second| {
            if (!second.is_disabled) return second;
        }

        return null;
    }

    pub fn pathConst(this: *const Result) ?*const Path {
        if (!this.path_pair.primary.is_disabled)
            return &this.path_pair.primary;

        if (this.path_pair.secondary) |*second| {
            if (!second.is_disabled) return second;
        }

        return null;
    }

    // remember: non-node_modules can have package.json
    // checking package.json may not be relevant
    pub fn isLikelyNodeModule(this: *const Result) bool {
        const path_ = this.pathConst() orelse return false;
        return this.is_from_node_modules or strings.indexOf(path_.text, "/node_modules/") != null;
    }

    // Most NPM modules are CommonJS
    // If unspecified, assume CommonJS.
    // If internal app code, assume ESM.
    pub fn shouldAssumeCommonJS(r: *const Result, import_record: *const ast.ImportRecord) bool {
        if (import_record.kind == .require or import_record.kind == .require_resolve or r.module_type == .cjs) {
            return true;
        }

        if (r.module_type == .esm) {
            return false;
        }

        // If we rely just on isPackagePath, we mess up tsconfig.json baseUrl paths.
        return r.isLikelyNodeModule();
    }

    pub const DebugMeta = struct {
        notes: std.ArrayList(logger.Data),
        suggestion_text: string = "",
        suggestion_message: string = "",

        pub fn init(allocator: *std.mem.Allocator) DebugMeta {
            return DebugMeta{ .notes = std.ArrayList(logger.Data).init(allocator) };
        }

        pub fn logErrorMsg(m: *DebugMeta, log: *logger.Log, _source: ?*const logger.Source, r: logger.Range, comptime fmt: string, args: anytype) !void {
            if (_source != null and m.suggestion_message.len > 0) {
                const data = logger.rangeData(_source.?, r, m.suggestion_message);
                data.location.?.suggestion = m.suggestion_text;
                try m.notes.append(data);
            }

            try log.addMsg(Msg{
                .kind = .err,
                .data = logger.rangeData(_source, r, std.fmt.allocPrint(m.notes.allocator, fmt, args)),
                .notes = m.toOwnedSlice(),
            });
        }
    };

    pub fn hash(this: *const Result, root_dir: string, loader: options.Loader) u32 {
        const module = this.path_pair.primary.text;
        const node_module_root = std.fs.path.sep_str ++ "node_modules" ++ std.fs.path.sep_str;
        if (strings.lastIndexOf(module, node_module_root)) |end_| {
            var end: usize = end_ + node_module_root.len;

            return @truncate(u32, std.hash.Wyhash.hash(0, module[end..]));
        }

        return @truncate(u32, std.hash.Wyhash.hash(0, this.path_pair.primary.text));
    }
};

pub const DirEntryResolveQueueItem = struct {
    result: allocators.Result,
    unsafe_path: string,
    safe_path: string = "",
    fd: StoredFileDescriptorType = 0,
};

threadlocal var _dir_entry_paths_to_resolve: [256]DirEntryResolveQueueItem = undefined;
threadlocal var _open_dirs: [256]Fs.Dir = undefined;
threadlocal var resolve_without_remapping_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var index_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var dir_info_uncached_filename_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var dir_info_uncached_path_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var tsconfig_base_url_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var relative_abs_path_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var load_as_file_or_directory_via_tsconfig_base_path: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var node_modules_check_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var field_abs_path_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var tsconfig_path_abs_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var check_browser_map_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var remap_path_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var load_as_file_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;
threadlocal var remap_path_trailing_slash: [std.fs.MAX_PATH_BYTES]u8 = undefined;

pub const DebugLogs = struct {
    what: string = "",
    indent: MutableString,
    notes: std.ArrayList(logger.Data),

    pub const FlushMode = enum { fail, success };

    pub fn init(allocator: *std.mem.Allocator) !DebugLogs {
        var mutable = try MutableString.init(allocator, 0);
        return DebugLogs{
            .indent = mutable,
            .notes = std.ArrayList(logger.Data).init(allocator),
        };
    }

    pub fn deinit(d: DebugLogs) void {
        var allocator = d.notes.allocator;
        d.notes.deinit();
        // d.indent.deinit();
    }

    pub fn increaseIndent(d: *DebugLogs) !void {
        @setCold(true);
        try d.indent.append(" ");
    }

    pub fn decreaseIndent(d: *DebugLogs) !void {
        @setCold(true);
        d.indent.list.shrinkRetainingCapacity(d.indent.list.items.len - 1);
    }

    pub fn addNote(d: *DebugLogs, _text: string) !void {
        @setCold(true);
        var text = _text;
        const len = d.indent.len();
        if (len > 0) {
            var __text = try d.notes.allocator.alloc(u8, text.len + len);
            std.mem.copy(u8, __text, d.indent.list.items);
            std.mem.copy(u8, __text[len..__text.len], _text);
            d.notes.allocator.free(_text);
        }

        try d.notes.append(logger.rangeData(null, logger.Range.None, text));
    }

    pub fn addNoteFmt(d: *DebugLogs, comptime fmt: string, args: anytype) !void {
        @setCold(true);
        return try d.addNote(try std.fmt.allocPrint(d.notes.allocator, fmt, args));
    }
};

pub const TSConfigExtender = struct {
    visited: *StringBoolMap,
    file_dir: string,
    r: *ThisResolver,

    pub fn extends(ctx: *TSConfigExtender, ext: String, range: logger.Range) ?*TSConfigJSON {
        unreachable;
        // if (isPackagePath(extends)) {
        //     // // If this is a package path, try to resolve it to a "node_modules"
        //     // // folder. This doesn't use the normal node module resolution algorithm
        //     // // both because it's different (e.g. we don't want to match a directory)
        //     // // and because it would deadlock since we're currently in the middle of
        //     // // populating the directory info cache.
        //     // var current = ctx.file_dir;
        //     // while (true) {
        //     //     // Skip "node_modules" folders
        //     //     if (!strings.eql(std.fs.path.basename(current), "node_modules")) {
        //     //         var paths1 = [_]string{ current, "node_modules", extends };
        //     //         var join1 = FileSystem.instance.absAlloc(ctx.r.allocator, &paths1) catch unreachable;
        //     //         const res = ctx.r.parseTSConfig(join1, ctx.1) catch |err| {
        //     //             if (err == error.ENOENT) {
        //     //                 continue;
        //     //             } else if (err == error.ParseErrorImportCycle) {} else if (err != error.ParseErrorAlreadyLogged) {}
        //     //             return null;
        //     //         };
        //     //         return res;

        //     //     }
        //     // }
        // }
    }
};

pub const MatchResult = struct {
    path_pair: PathPair,
    dirname_fd: StoredFileDescriptorType = 0,
    file_fd: StoredFileDescriptorType = 0,
    is_node_module: bool = false,
    package_json: ?*PackageJSON = null,
    diff_case: ?Fs.Entry.Lookup.DifferentCase = null,
    dir_info: ?*DirInfo = null,
};

pub const LoadResult = struct {
    path: string,
    diff_case: ?Fs.Entry.Lookup.DifferentCase,
    dirname_fd: StoredFileDescriptorType = 0,
    file_fd: StoredFileDescriptorType = 0,
    dir_info: ?*DirInfo = null,
};

// This is a global so even if multiple resolvers are created, the mutex will still work
var resolver_Mutex: Mutex = undefined;
var resolver_Mutex_loaded: bool = false;
// TODO:
// - Fix "browser" field mapping
// - Consider removing the string list abstraction?
pub const Resolver = struct {
    const ThisResolver = @This();
    opts: options.BundleOptions,
    fs: *Fs.FileSystem,
    log: *logger.Log,
    allocator: *std.mem.Allocator,
    node_module_bundle: ?*NodeModuleBundle,
    extension_order: []const string = undefined,

    debug_logs: ?DebugLogs = null,
    elapsed: i128 = 0, // tracing

    onStartWatchingDirectory: ?fn (*HTTPWatcher, dir_path: string, dir_fd: StoredFileDescriptorType) void = null,
    onStartWatchingDirectoryCtx: ?*HTTPWatcher = null,

    caches: CacheSet,

    // These are sets that represent various conditions for the "exports" field
    // in package.json.
    // esm_conditions_default: std.StringHashMap(bool),
    // esm_conditions_import: std.StringHashMap(bool),
    // esm_conditions_require: std.StringHashMap(bool),

    // A special filtered import order for CSS "@import" imports.
    //
    // The "resolve extensions" setting determines the order of implicit
    // extensions to try when resolving imports with the extension omitted.
    // Sometimes people create a JavaScript/TypeScript file and a CSS file with
    // the same name when they create a component. At a high level, users expect
    // implicit extensions to resolve to the JS file when being imported from JS
    // and to resolve to the CSS file when being imported from CSS.
    //
    // Different bundlers handle this in different ways. Parcel handles this by
    // having the resolver prefer the same extension as the importing file in
    // front of the configured "resolve extensions" order. Webpack's "css-loader"
    // plugin just explicitly configures a special "resolve extensions" order
    // consisting of only ".css" for CSS files.
    //
    // It's unclear what behavior is best here. What we currently do is to create
    // a special filtered version of the configured "resolve extensions" order
    // for CSS files that filters out any extension that has been explicitly
    // configured with a non-CSS loader. This still gives users control over the
    // order but avoids the scenario where we match an import in a CSS file to a
    // JavaScript-related file. It's probably not perfect with plugins in the
    // picture but it's better than some alternatives and probably pretty good.
    // atImportExtensionOrder []string

    // This mutex serves two purposes. First of all, it guards access to "dirCache"
    // which is potentially mutated during path resolution. But this mutex is also
    // necessary for performance. The "React admin" benchmark mysteriously runs
    // twice as fast when this mutex is locked around the whole resolve operation
    // instead of around individual accesses to "dirCache". For some reason,
    // reducing parallelism in the resolver helps the rest of the bundler go
    // faster. I'm not sure why this is but please don't change this unless you
    // do a lot of testing with various benchmarks and there aren't any regressions.
    mutex: *Mutex,

    // This cache maps a directory path to information about that directory and
    // all parent directories
    dir_cache: *DirInfo.HashMap,

    pub fn init1(
        allocator: *std.mem.Allocator,
        log: *logger.Log,
        _fs: *Fs.FileSystem,
        opts: options.BundleOptions,
    ) ThisResolver {
        if (!resolver_Mutex_loaded) {
            resolver_Mutex = Mutex.init();
            resolver_Mutex_loaded = true;
        }

        return ThisResolver{
            .allocator = allocator,
            .dir_cache = DirInfo.HashMap.init(allocator),
            .mutex = &resolver_Mutex,
            .caches = CacheSet.init(allocator),
            .opts = opts,
            .fs = _fs,
            .node_module_bundle = opts.node_modules_bundle,
            .log = log,
            .extension_order = opts.extension_order,
        };
    }

    pub fn isExternalPattern(r: *ThisResolver, import_path: string) bool {
        for (r.opts.external.patterns) |pattern| {
            if (import_path.len >= pattern.prefix.len + pattern.suffix.len and (strings.startsWith(
                import_path,
                pattern.prefix,
            ) and strings.endsWith(
                import_path,
                pattern.suffix,
            ))) {
                return true;
            }
        }
        return false;
    }

    pub fn flushDebugLogs(r: *ThisResolver, flush_mode: DebugLogs.FlushMode) !void {
        if (r.debug_logs) |*debug| {
            if (flush_mode == DebugLogs.FlushMode.fail) {
                try r.log.addRangeDebugWithNotes(null, logger.Range{ .loc = logger.Loc{} }, debug.what, debug.notes.toOwnedSlice());
            } else if (@enumToInt(r.log.level) <= @enumToInt(logger.Log.Level.verbose)) {
                try r.log.addVerboseWithNotes(null, logger.Loc.Empty, debug.what, debug.notes.toOwnedSlice());
            }
        }
    }
    var tracing_start: i128 = if (FeatureFlags.tracing) 0 else undefined;

    pub const bunFrameworkPackagePrefix = "bun-framework-";
    pub fn resolveFramework(
        r: *ThisResolver,
        package: string,
        pair: *PackageJSON.FrameworkRouterPair,
        comptime preference: PackageJSON.LoadFramework,
        comptime load_defines: bool,
    ) !void {

        // We want to enable developers to integrate frameworks without waiting on official support.
        // But, we still want the command to do the actual framework integration to be succint
        // This lets users type "--use next" instead of "--use bun-framework-next"
        // If they're using a local file path, we skip this.
        if (isPackagePath(package)) {
            var prefixed_package_buf: [512]u8 = undefined;
            // Prevent the extra lookup if the package is already prefixed, i.e. avoid "bun-framework-next-bun-framework-next"
            if (strings.startsWith(package, bunFrameworkPackagePrefix) or package.len + bunFrameworkPackagePrefix.len >= prefixed_package_buf.len) {
                return r._resolveFramework(package, pair, preference, load_defines) catch |err| {
                    switch (err) {
                        error.ModuleNotFound => {
                            Output.prettyErrorln("<r><red>ResolveError<r> can't find framework: <b>\"{s}\"<r>.\n\nMaybe it's not installed? Try running this:\n\n   <b>npm install -D {s}<r>\n   <b>bun bun --use {s}<r>", .{ package, package, package });
                            Output.flush();
                            std.os.exit(1);
                        },
                        else => {
                            return err;
                        },
                    }
                };
            }

            prefixed_package_buf[0..bunFrameworkPackagePrefix.len].* = bunFrameworkPackagePrefix.*;
            std.mem.copy(u8, prefixed_package_buf[bunFrameworkPackagePrefix.len..], package);
            const prefixed_name = prefixed_package_buf[0 .. bunFrameworkPackagePrefix.len + package.len];
            return r._resolveFramework(prefixed_name, pair, preference, load_defines) catch |err| {
                switch (err) {
                    error.ModuleNotFound => {
                        return r._resolveFramework(package, pair, preference, load_defines) catch |err2| {
                            switch (err2) {
                                error.ModuleNotFound => {
                                    Output.prettyErrorln("<r><red>ResolveError<r> can't find framework: <b>\"{s}\"<r>.\n\nMaybe it's not installed? Try running this:\n\n   <b>npm install -D {s}\n   <b>bun bun --use {s}<r>", .{ package, prefixed_name, package });
                                    Output.flush();
                                    std.os.exit(1);
                                },
                                else => {
                                    return err;
                                },
                            }
                        };
                    },
                    else => {
                        return err;
                    },
                }
            };
        }

        return r._resolveFramework(package, pair, preference, load_defines) catch |err| {
            switch (err) {
                error.ModuleNotFound => {
                    Output.prettyError("<r><red>ResolveError<r> can't find local framework: <b>\"{s}\"<r>.", .{package});

                    Output.flush();
                    std.os.exit(1);
                },
                else => {
                    return err;
                },
            }
        };
    }

    fn _resolveFramework(
        r: *ThisResolver,
        package: string,
        pair: *PackageJSON.FrameworkRouterPair,
        comptime preference: PackageJSON.LoadFramework,
        comptime load_defines: bool,
    ) !void {

        // TODO: make this only parse package.json once
        var result = try r.resolve(FileSystem.instance.top_level_dir, package, .internal);
        // support passing a package.json or path to a package
        const pkg: *const PackageJSON = result.package_json orelse r.packageJSONForResolvedNodeModuleWithIgnoreMissingName(&result, true) orelse return error.MissingPackageJSON;

        const json = (try r.caches.json.parseJSON(r.log, pkg.source, r.allocator)) orelse return error.JSONParseError;

        pkg.loadFrameworkWithPreference(pair, json, r.allocator, load_defines, preference);
        const dir = pkg.source.path.sourceDir();

        var buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;

        pair.framework.resolved_dir = pkg.source.path.sourceDir();

        if (pair.framework.client.isEnabled()) {
            var parts = [_]string{ dir, pair.framework.client.path };
            const abs = FileSystem.instance.abs(&parts);
            pair.framework.client.path = try r.allocator.dupe(u8, abs);
            pair.framework.resolved = true;
        }

        if (pair.framework.server.isEnabled()) {
            var parts = [_]string{ dir, pair.framework.server.path };
            const abs = FileSystem.instance.abs(&parts);
            pair.framework.server.path = try r.allocator.dupe(u8, abs);
            pair.framework.resolved = true;
        }

        if (pair.framework.fallback.isEnabled()) {
            var parts = [_]string{ dir, pair.framework.fallback.path };
            const abs = FileSystem.instance.abs(&parts);
            pair.framework.fallback.path = try r.allocator.dupe(u8, abs);
            pair.framework.resolved = true;
        }

        if (pair.loaded_routes) {
            const chosen_dir: string = brk: {
                if (pair.router.possible_dirs.len > 0) {
                    for (pair.router.possible_dirs) |route_dir| {
                        var parts = [_]string{ FileSystem.instance.top_level_dir, std.fs.path.sep_str, route_dir };
                        const abs = FileSystem.instance.join(&parts);
                        // must end in trailing slash
                        break :brk (File.realpath(abs, &buf) catch continue);
                    }
                    return error.MissingRouteDir;
                } else {
                    var parts = [_]string{ FileSystem.instance.top_level_dir, std.fs.path.sep_str, pair.router.dir };
                    const abs = FileSystem.instance.join(&parts);
                    // must end in trailing slash
                    break :brk File.realpath(abs, &buf) catch return error.MissingRouteDir;
                }
            };

            var out = try r.allocator.alloc(u8, chosen_dir.len + 1);
            std.mem.copy(u8, out, chosen_dir);
            out[out.len - 1] = '/';
            pair.router.dir = out;
            pair.router.routes_enabled = true;
        }
    }

    pub fn resolve(r: *ThisResolver, source_dir: string, import_path: string, kind: ast.ImportKind) !Result {
        r.extension_order = if (kind.isFromCSS()) std.mem.span(&options.BundleOptions.Defaults.CSSExtensionOrder) else r.opts.extension_order;

        if (FeatureFlags.tracing) {
            tracing_start = std.time.nanoTimestamp();
        }
        defer {
            if (FeatureFlags.tracing) {
                r.elapsed += std.time.nanoTimestamp() - tracing_start;
            }
        }
        if (r.log.level == .verbose) {
            if (r.debug_logs != null) {
                r.debug_logs.?.deinit();
            }

            r.debug_logs = try DebugLogs.init(r.allocator);
        }

        if (import_path.len == 0) return error.ModuleNotFound;

        // Certain types of URLs default to being external for convenience
        if (r.isExternalPattern(import_path) or
            // "fill: url(#filter);"
            (kind.isFromCSS() and strings.startsWith(import_path, "#")) or

            // "background: url(http://example.com/images/image.png);"
            strings.startsWith(import_path, "http://") or

            // "background: url(https://example.com/images/image.png);"
            strings.startsWith(import_path, "https://") or

            // "background: url(//example.com/images/image.png);"
            strings.startsWith(import_path, "//"))
        {
            if (r.debug_logs) |*debug| {
                try debug.addNote("Marking this path as implicitly external");
                r.flushDebugLogs(.success) catch {};
            }

            return Result{
                .import_kind = kind,
                .path_pair = PathPair{
                    .primary = Path.init(import_path),
                },
                .is_external = true,
                .module_type = .esm,
            };
        }

        if (DataURL.parse(import_path)) |_data_url| {
            const data_url: DataURL = _data_url;
            // "import 'data:text/javascript,console.log(123)';"
            // "@import 'data:text/css,body{background:white}';"
            if (data_url.decode_mime_type() != .Unsupported) {
                if (r.debug_logs) |*debug| {
                    debug.addNote("Putting this path in the \"dataurl\" namespace") catch {};
                    r.flushDebugLogs(.success) catch {};
                }

                return Result{ .path_pair = PathPair{ .primary = Path.initWithNamespace(import_path, "dataurl") } };
            }

            // "background: url(data:image/png;base64,iVBORw0KGgo=);"
            if (r.debug_logs) |*debug| {
                debug.addNote("Marking this \"dataurl\" as external") catch {};
                r.flushDebugLogs(.success) catch {};
            }

            return Result{
                .path_pair = PathPair{ .primary = Path.initWithNamespace(import_path, "dataurl") },
                .is_external = true,
            };
        }

        // Fail now if there is no directory to resolve in. This can happen for
        // virtual modules (e.g. stdin) if a resolve directory is not specified.
        if (source_dir.len == 0) {
            if (r.debug_logs) |*debug| {
                debug.addNote("Cannot resolve this path without a directory") catch {};
                r.flushDebugLogs(.fail) catch {};
            }

            return error.MissingResolveDir;
        }

        // r.mutex.lock();
        // defer r.mutex.unlock();
        errdefer (r.flushDebugLogs(.fail) catch {});
        var result = (try r.resolveWithoutSymlinks(source_dir, import_path, kind)) orelse {
            r.flushDebugLogs(.fail) catch {};
            return error.ModuleNotFound;
        };

        if (!strings.eqlComptime(result.path_pair.primary.namespace, "node"))
            try r.finalizeResult(&result);

        r.flushDebugLogs(.success) catch {};
        result.import_kind = kind;
        return result;
    }

    pub fn finalizeResult(r: *ThisResolver, result: *Result) !void {
        if (result.is_external) return;

        var iter = result.path_pair.iter();
        while (iter.next()) |path| {
            var dir: *DirInfo = (r.readDirInfo(path.name.dir) catch continue) orelse continue;
            result.package_json = result.package_json orelse dir.enclosing_package_json;

            if (dir.enclosing_tsconfig_json) |tsconfig| {
                result.jsx = tsconfig.mergeJSX(result.jsx);
            }

            if (dir.getEntries()) |entries| {
                if (entries.get(path.name.filename)) |query| {
                    const symlink_path = query.entry.symlink(&FileSystem.instance.fs);
                    if (symlink_path.len > 0) {
                        path.setRealpath(symlink_path);
                        if (result.file_fd == 0) result.file_fd = query.entry.cache.fd;

                        if (r.debug_logs) |*debug| {
                            debug.addNoteFmt("Resolved symlink \"{s}\" to \"{s}\"", .{ path.text, symlink_path }) catch {};
                        }
                    } else if (dir.abs_real_path.len > 0) {
                        var parts = [_]string{ dir.abs_real_path, query.entry.base() };
                        var buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;

                        var out = FileSystem.instance.absBuf(&parts, &buf);

                        if (query.entry.cache.fd == 0) {
                            buf[out.len] = 0;
                            const span = buf[0..out.len :0];
                            var file = try FileSystem.openFileZ(span, .{ .read = true });

                            if (comptime !FeatureFlags.store_file_descriptors) {
                                out = try std.os.getFdPath(query.entry.cache.fd, &buf);
                                file.close();
                            } else {
                                query.entry.cache.fd = file.handle;
                                Fs.FileSystem.setMaxFd(file.handle);
                            }
                        }

                        defer {
                            if (FileSystem.instance.needToCloseFiles()) {
                                if (query.entry.cache.fd != 0) {
                                    Fs.FileSystem.close(query.entry.cache.fd);
                                    query.entry.cache.fd = 0;
                                }
                            }
                        }

                        if (comptime FeatureFlags.store_file_descriptors) {
                            out = try std.os.getFdPath(query.entry.cache.fd, &buf);
                        }

                        const symlink = try Fs.FileSystem.FilenameStore.instance.append(@TypeOf(out), out);
                        if (r.debug_logs) |*debug| {
                            debug.addNoteFmt("Resolved symlink \"{s}\" to \"{s}\"", .{ symlink, path.text }) catch {};
                        }
                        query.entry.cache.symlink = PathString.init(symlink);
                        if (result.file_fd == 0) result.file_fd = query.entry.cache.fd;

                        path.setRealpath(symlink);
                    }
                }
            }
        }

        if (result.package_json) |package_json| {
            result.module_type = switch (package_json.module_type) {
                .esm, .cjs => package_json.module_type,
                .unknown => result.module_type,
            };
        }
    }

    pub fn resolveWithoutSymlinks(r: *ThisResolver, source_dir: string, import_path: string, kind: ast.ImportKind) !?Result {

        // This implements the module resolution algorithm from node.js, which is
        // described here: https://nodejs.org/api/modules.html#modules_all_together
        var result: Result = Result{
            .path_pair = PathPair{
                .primary = Path.empty,
            },
            .jsx = r.opts.jsx,
        };

        // Return early if this is already an absolute path. In addition to asking
        // the file system whether this is an absolute path, we also explicitly check
        // whether it starts with a "/" and consider that an absolute path too. This
        // is because relative paths can technically start with a "/" on Windows
        // because it's not an absolute path on Windows. Then people might write code
        // with imports that start with a "/" that works fine on Windows only to
        // experience unexpected build failures later on other operating systems.
        // Treating these paths as absolute paths on all platforms means Windows
        // users will not be able to accidentally make use of these paths.
        if (strings.startsWith(import_path, "/") or std.fs.path.isAbsolutePosix(import_path)) {
            if (r.debug_logs) |*debug| {
                debug.addNoteFmt("The import \"{s}\" is being treated as an absolute path", .{import_path}) catch {};
            }

            // First, check path overrides from the nearest enclosing TypeScript "tsconfig.json" file
            if ((r.dirInfoCached(source_dir) catch null)) |_dir_info| {
                const dir_info: *DirInfo = _dir_info;
                if (dir_info.enclosing_tsconfig_json) |tsconfig| {
                    if (tsconfig.paths.count() > 0) {
                        if (r.matchTSConfigPaths(tsconfig, import_path, kind)) |res| {

                            // We don't set the directory fd here because it might remap an entirely different directory
                            return Result{
                                .path_pair = res.path_pair,
                                .diff_case = res.diff_case,
                                .package_json = res.package_json,
                                .dirname_fd = res.dirname_fd,
                                .file_fd = res.file_fd,
                                .jsx = tsconfig.mergeJSX(result.jsx),
                            };
                        }
                    }
                }
            }

            if (r.opts.external.abs_paths.count() > 0 and r.opts.external.abs_paths.contains(import_path)) {
                // If the string literal in the source text is an absolute path and has
                // been marked as an external module, mark it as *not* an absolute path.
                // That way we preserve the literal text in the output and don't generate
                // a relative path from the output directory to that path.
                if (r.debug_logs) |*debug| {
                    debug.addNoteFmt("The path \"{s}\" is marked as external by the user", .{import_path}) catch {};
                }

                return Result{
                    .path_pair = .{ .primary = Path.init(import_path) },
                    .is_external = true,
                };
            }

            // Run node's resolution rules (e.g. adding ".js")
            if (r.loadAsFileOrDirectory(import_path, kind)) |entry| {
                return Result{
                    .dirname_fd = entry.dirname_fd,
                    .path_pair = entry.path_pair,
                    .diff_case = entry.diff_case,
                    .package_json = entry.package_json,
                    .file_fd = entry.file_fd,
                };
            }

            return null;
        }

        // Check both relative and package paths for CSS URL tokens, with relative
        // paths taking precedence over package paths to match Webpack behavior.
        const is_package_path = isPackagePath(import_path);
        var check_relative = !is_package_path or kind == .url;
        var check_package = is_package_path;

        if (check_relative) {
            const parts = [_]string{ source_dir, import_path };
            const abs_path = FileSystem.instance.absBuf(&parts, &relative_abs_path_buf);

            if (r.opts.external.abs_paths.count() > 0 and r.opts.external.abs_paths.contains(abs_path)) {
                // If the string literal in the source text is an absolute path and has
                // been marked as an external module, mark it as *not* an absolute path.
                // That way we preserve the literal text in the output and don't generate
                // a relative path from the output directory to that path.
                if (r.debug_logs) |*debug| {
                    debug.addNoteFmt("The path \"{s}\" is marked as external by the user", .{abs_path}) catch {};
                }

                return Result{
                    .path_pair = .{ .primary = Path.init(FileSystem.instance.dirname_store.append(@TypeOf(abs_path), abs_path) catch unreachable) },
                    .is_external = true,
                };
            }

            // Check the "browser" map
            if (r.dirInfoCached(std.fs.path.dirname(abs_path) orelse unreachable) catch null) |_import_dir_info| {
                if (_import_dir_info.getEnclosingBrowserScope()) |import_dir_info| {
                    const pkg = import_dir_info.package_json.?;
                    if (r.checkBrowserMap(
                        import_dir_info,
                        abs_path,
                        .AbsolutePath,
                    )) |remap| {

                        // Is the path disabled?
                        if (remap.len == 0) {
                            var _path = Path.init(FileSystem.instance.dirname_store.append(string, abs_path) catch unreachable);
                            _path.is_disabled = true;
                            return Result{
                                .path_pair = PathPair{
                                    .primary = _path,
                                },
                            };
                        }

                        if (r.resolveWithoutRemapping(import_dir_info, remap, kind)) |_result| {
                            result = Result{
                                .path_pair = _result.path_pair,
                                .diff_case = _result.diff_case,
                                .module_type = pkg.module_type,
                                .dirname_fd = _result.dirname_fd,
                                .package_json = pkg,
                            };
                            check_relative = false;
                            check_package = false;
                        }
                    }
                }
            }

            if (check_relative) {
                if (r.loadAsFileOrDirectory(abs_path, kind)) |res| {
                    check_package = false;
                    result = Result{
                        .path_pair = res.path_pair,
                        .diff_case = res.diff_case,
                        .dirname_fd = res.dirname_fd,
                        .package_json = res.package_json,
                    };
                } else if (!check_package) {
                    return null;
                }
            }
        }

        if (check_package) {
            if (r.opts.polyfill_node_globals) {
                var import_path_without_node_prefix = import_path;
                const had_node_prefix = import_path_without_node_prefix.len > "node:".len and
                    strings.eqlComptime(import_path_without_node_prefix[0.."node:".len], "node:");

                import_path_without_node_prefix = if (had_node_prefix)
                    import_path_without_node_prefix["node:".len..]
                else
                    import_path_without_node_prefix;

                if (NodeFallbackModules.Map.get(import_path_without_node_prefix)) |*fallback_module| {
                    result.path_pair.primary = fallback_module.path;
                    result.module_type = .cjs;
                    result.package_json = @intToPtr(*PackageJSON, @ptrToInt(fallback_module.package_json));
                    result.is_from_node_modules = true;
                    return result;
                    // "node:*
                    // "fs"
                    // "fs/*"
                    // These are disabled!
                } else if (had_node_prefix or
                    (import_path_without_node_prefix.len >= 2 and strings.eqlComptimeIgnoreLen(import_path_without_node_prefix[0..2], "fs") and
                    (import_path_without_node_prefix.len == 2 or
                    import_path_without_node_prefix[3] == '/')))
                {
                    result.path_pair.primary.namespace = "node";
                    result.path_pair.primary.text = import_path_without_node_prefix;
                    result.path_pair.primary.name = Fs.PathName.init(import_path_without_node_prefix);
                    result.module_type = .cjs;
                    result.path_pair.primary.is_disabled = true;
                    result.is_from_node_modules = true;
                    return result;
                }
            }

            // Check for external packages first
            if (r.opts.external.node_modules.count() > 0) {
                var query = import_path;
                while (true) {
                    if (r.opts.external.node_modules.contains(query)) {
                        if (r.debug_logs) |*debug| {
                            debug.addNoteFmt("The path \"{s}\" was marked as external by the user", .{query}) catch {};
                        }
                        return Result{
                            .path_pair = .{ .primary = Path.init(query) },
                            .is_external = true,
                        };
                    }

                    // If the module "foo" has been marked as external, we also want to treat
                    // paths into that module such as "foo/bar" as external too.
                    var slash = strings.lastIndexOfChar(query, '/') orelse break;
                    query = query[0..slash];
                }
            }

            const source_dir_info = (r.dirInfoCached(source_dir) catch null) orelse return null;

            // Support remapping one package path to another via the "browser" field
            if (source_dir_info.getEnclosingBrowserScope()) |browser_scope| {
                if (browser_scope.package_json) |package_json| {
                    if (r.checkBrowserMap(
                        browser_scope,
                        import_path,
                        .PackagePath,
                    )) |remapped| {
                        if (remapped.len == 0) {
                            // "browser": {"module": false}
                            if (r.loadNodeModules(import_path, kind, source_dir_info)) |node_module| {
                                var pair = node_module.path_pair;
                                pair.primary.is_disabled = true;
                                if (pair.secondary != null) {
                                    pair.secondary.?.is_disabled = true;
                                }
                                return Result{
                                    .path_pair = pair,
                                    .dirname_fd = node_module.dirname_fd,
                                    .diff_case = node_module.diff_case,
                                    .package_json = package_json,
                                };
                            }
                        } else {
                            var primary = Path.init(import_path);
                            primary.is_disabled = true;
                            return Result{
                                .path_pair = PathPair{ .primary = primary },
                                // this might not be null? i think it is
                                .diff_case = null,
                            };
                        }
                    }
                }
            }

            if (r.resolveWithoutRemapping(source_dir_info, import_path, kind)) |res| {
                result.path_pair = res.path_pair;
                result.dirname_fd = res.dirname_fd;
                result.file_fd = res.file_fd;
                result.package_json = res.package_json;
                result.diff_case = res.diff_case;
                result.is_from_node_modules = result.is_from_node_modules or res.is_node_module;

                if (res.path_pair.primary.is_disabled and res.path_pair.secondary == null) {
                    return result;
                }

                if (res.package_json) |pkg| {
                    var base_dir_info = res.dir_info orelse (r.readDirInfo(res.path_pair.primary.name.dir) catch null) orelse return result;
                    if (base_dir_info.getEnclosingBrowserScope()) |browser_scope| {
                        if (r.checkBrowserMap(
                            browser_scope,
                            res.path_pair.primary.text,
                            .AbsolutePath,
                        )) |remap| {
                            if (remap.len == 0) {
                                result.path_pair.primary.is_disabled = true;
                                result.path_pair.primary = Fs.Path.initWithNamespace(remap, "file");
                            } else {
                                if (r.resolveWithoutRemapping(browser_scope, remap, kind)) |remapped| {
                                    result.path_pair = remapped.path_pair;
                                    result.dirname_fd = remapped.dirname_fd;
                                    result.file_fd = remapped.file_fd;
                                    result.package_json = remapped.package_json;
                                    result.diff_case = remapped.diff_case;
                                    result.is_from_node_modules = result.is_from_node_modules or remapped.is_node_module;
                                    return result;
                                }
                            }
                        }
                    }
                }

                return result;
            } else {
                // Note: node's "self references" are not currently supported
                return null;
            }
        }

        return result;
    }

    pub fn packageJSONForResolvedNodeModule(
        r: *ThisResolver,
        result: *const Result,
    ) ?*const PackageJSON {
        return @call(.{ .modifier = .always_inline }, packageJSONForResolvedNodeModuleWithIgnoreMissingName, .{ r, result, true });
    }

    // This is a fallback, hopefully not called often. It should be relatively quick because everything should be in the cache.
    fn packageJSONForResolvedNodeModuleWithIgnoreMissingName(
        r: *ThisResolver,
        result: *const Result,
        comptime ignore_missing_name: bool,
    ) ?*const PackageJSON {
        var dir_info = (r.dirInfoCached(result.path_pair.primary.name.dir) catch null) orelse return null;
        while (true) {
            if (dir_info.package_json) |pkg| {
                // if it doesn't have a name, assume it's something just for adjusting the main fields (react-bootstrap does this)
                // In that case, we really would like the top-level package that you download from NPM
                // so we ignore any unnamed packages
                if (comptime !ignore_missing_name) {
                    if (pkg.name.len > 0) {
                        return pkg;
                    }
                } else {
                    return pkg;
                }
            }

            dir_info = dir_info.getParent() orelse return null;
        }

        unreachable;
    }
    const node_module_root_string = std.fs.path.sep_str ++ "node_modules" ++ std.fs.path.sep_str;

    pub fn rootNodeModulePackageJSON(
        r: *ThisResolver,
        result: *const Result,
    ) ?RootPathPair {
        const path = (result.pathConst() orelse return null);
        var absolute = path.text;
        // /foo/node_modules/@babel/standalone/index.js
        //     ^------------^
        var end = strings.lastIndexOf(absolute, node_module_root_string) orelse brk: {
            // try non-symlinked version
            if (path.pretty.len != absolute.len) {
                absolute = path.pretty;
                break :brk strings.lastIndexOf(absolute, node_module_root_string);
            }

            break :brk null;
        } orelse return null;
        end += node_module_root_string.len;

        const is_scoped_package = absolute[end] == '@';
        end += strings.indexOfChar(absolute[end..], std.fs.path.sep) orelse return null;

        // /foo/node_modules/@babel/standalone/index.js
        //                   ^
        if (is_scoped_package) {
            end += 1;
            end += strings.indexOfChar(absolute[end..], std.fs.path.sep) orelse return null;
        }

        end += 1;

        // /foo/node_modules/@babel/standalone/index.js
        //                                    ^
        const slice = absolute[0..end];

        // Try to avoid the hash table lookup whenever possible
        // That can cause filesystem lookups in parent directories and it requires a lock
        if (result.package_json) |pkg| {
            if (strings.eql(slice, pkg.source.path.name.dirWithTrailingSlash())) {
                return RootPathPair{
                    .package_json = pkg,
                    .base_path = slice,
                };
            }
        }

        {
            var dir_info = (r.dirInfoCached(slice) catch null) orelse return null;
            return RootPathPair{
                .base_path = slice,
                .package_json = dir_info.package_json.?,
            };
        }
    }

    threadlocal var esm_subpath_buf: [512]u8 = undefined;
    threadlocal var esm_absolute_package_path: [std.fs.MAX_PATH_BYTES]u8 = undefined;
    threadlocal var esm_absolute_package_path_joined: [std.fs.MAX_PATH_BYTES]u8 = undefined;
    pub fn loadNodeModules(r: *ThisResolver, import_path: string, kind: ast.ImportKind, _dir_info: *DirInfo) ?MatchResult {
        var dir_info = _dir_info;
        if (r.debug_logs) |*debug| {
            debug.addNoteFmt("Searching for {s} in \"node_modules\" directories starting from \"{s}\"", .{ import_path, dir_info.abs_path }) catch {};
            debug.increaseIndent() catch {};
        }

        defer {
            if (r.debug_logs) |*debug| {
                debug.decreaseIndent() catch {};
            }
        }

        // First, check path overrides from the nearest enclosing TypeScript "tsconfig.json" file

        if (dir_info.enclosing_tsconfig_json) |tsconfig| {
            // Try path substitutions first
            if (tsconfig.paths.count() > 0) {
                if (r.matchTSConfigPaths(tsconfig, import_path, kind)) |res| {
                    return res;
                }
            }

            // Try looking up the path relative to the base URL
            if (tsconfig.hasBaseURL()) {
                const base = tsconfig.base_url;
                const paths = [_]string{ base, import_path };
                const abs = FileSystem.instance.absBuf(&paths, &load_as_file_or_directory_via_tsconfig_base_path);

                if (r.loadAsFileOrDirectory(abs, kind)) |res| {
                    return res;
                }
                // r.allocator.free(abs);
            }
        }

        const esm_ = ESModule.Package.parse(import_path, &esm_subpath_buf);

        // Then check for the package in any enclosing "node_modules" directories
        while (true) {
            // Skip directories that are themselves called "node_modules", since we
            // don't ever want to search for "node_modules/node_modules"
            if (dir_info.has_node_modules) {
                var _paths = [_]string{ dir_info.abs_path, "node_modules", import_path };
                const abs_path = FileSystem.instance.absBuf(&_paths, &node_modules_check_buf);
                if (r.debug_logs) |*debug| {
                    debug.addNoteFmt("Checking for a package in the directory \"{s}\"", .{abs_path}) catch {};
                }

                if (esm_) |esm| {
                    const abs_package_path = brk: {
                        var parts = [_]string{ dir_info.abs_path, "node_modules", esm.name };
                        break :brk FileSystem.instance.absBuf(&parts, &esm_absolute_package_path);
                    };

                    if (r.dirInfoCached(abs_package_path) catch null) |pkg_dir_info| {
                        if (pkg_dir_info.package_json) |package_json| {
                            if (package_json.exports) |exports_map| {

                                // The condition set is determined by the kind of import

                                const esmodule = ESModule{
                                    .conditions = switch (kind) {
                                        ast.ImportKind.stmt, ast.ImportKind.dynamic => r.opts.conditions.import,
                                        ast.ImportKind.require, ast.ImportKind.require_resolve => r.opts.conditions.require,
                                        else => r.opts.conditions.default,
                                    },
                                    .allocator = r.allocator,
                                    .debug_logs = if (r.debug_logs) |*debug| debug else null,
                                };

                                // Resolve against the path "/", then join it with the absolute
                                // directory path. This is done because ESM package resolution uses
                                // URLs while our path resolution uses file system paths. We don't
                                // want problems due to Windows paths, which are very unlike URL
                                // paths. We also want to avoid any "%" characters in the absolute
                                // directory path accidentally being interpreted as URL escapes.
                                var esm_resolution = esmodule.resolve("/", esm.subpath, exports_map.root);

                                if ((esm_resolution.status == .Inexact or esm_resolution.status == .Exact) and strings.startsWith(esm_resolution.path, "/")) {
                                    const abs_esm_path: string = brk: {
                                        var parts = [_]string{
                                            abs_package_path,
                                            esm_resolution.path[1..],
                                        };
                                        break :brk FileSystem.instance.absBuf(&parts, &esm_absolute_package_path_joined);
                                    };

                                    switch (esm_resolution.status) {
                                        .Exact => {
                                            const resolved_dir_info = (r.dirInfoCached(std.fs.path.dirname(abs_esm_path).?) catch null) orelse {
                                                esm_resolution.status = .ModuleNotFound;
                                                return null;
                                            };
                                            const entries = resolved_dir_info.getEntries() orelse {
                                                esm_resolution.status = .ModuleNotFound;
                                                return null;
                                            };
                                            const entry_query = entries.get(std.fs.path.basename(abs_esm_path)) orelse {
                                                esm_resolution.status = .ModuleNotFound;
                                                return null;
                                            };

                                            if (entry_query.entry.kind(&FileSystem.instance.fs) == .dir) {
                                                esm_resolution.status = .UnsupportedDirectoryImport;
                                                return null;
                                            }

                                            const absolute_out_path = brk: {
                                                if (entry_query.entry.abs_path.isEmpty()) {
                                                    entry_query.entry.abs_path =
                                                        PathString.init(FileSystem.instance.dirname_store.append(@TypeOf(abs_esm_path), abs_esm_path) catch unreachable);
                                                }
                                                break :brk entry_query.entry.abs_path.slice();
                                            };

                                            return MatchResult{
                                                .path_pair = PathPair{
                                                    .primary = Path.initWithNamespace(absolute_out_path, "file"),
                                                },
                                                .dirname_fd = entries.fd,
                                                .file_fd = entry_query.entry.cache.fd,
                                                .dir_info = resolved_dir_info,
                                                .diff_case = entry_query.diff_case,
                                                .is_node_module = true,
                                                .package_json = resolved_dir_info.package_json orelse package_json,
                                            };
                                        },
                                        .Inexact => {
                                            // If this was resolved against an expansion key ending in a "/"
                                            // instead of a "*", we need to try CommonJS-style implicit
                                            // extension and/or directory detection.
                                            if (r.loadAsFileOrDirectory(abs_esm_path, kind)) |*res| {
                                                res.is_node_module = true;
                                                res.package_json = res.package_json orelse package_json;
                                                return res.*;
                                            }
                                            esm_resolution.status = .ModuleNotFound;
                                            return null;
                                        },
                                        else => unreachable,
                                    }
                                }
                            }
                        }
                    }
                }

                if (r.loadAsFileOrDirectory(abs_path, kind)) |res| {
                    return res;
                }
                // r.allocator.free(abs_path);
            }

            dir_info = dir_info.getParent() orelse break;
        }

        // Mostly to cut scope, we don't resolve `NODE_PATH` environment variable.
        // But also: https://github.com/nodejs/node/issues/38128#issuecomment-814969356

        return null;
    }

    pub fn resolveWithoutRemapping(r: *ThisResolver, source_dir_info: *DirInfo, import_path: string, kind: ast.ImportKind) ?MatchResult {
        if (isPackagePath(import_path)) {
            return r.loadNodeModules(import_path, kind, source_dir_info);
        } else {
            const paths = [_]string{ source_dir_info.abs_path, import_path };
            var resolved = FileSystem.instance.absBuf(&paths, &resolve_without_remapping_buf);
            return r.loadAsFileOrDirectory(resolved, kind);
        }
    }

    pub fn parseTSConfig(
        r: *ThisResolver,
        file: string,
        dirname_fd: StoredFileDescriptorType,
    ) !?*TSConfigJSON {
        const entry = try r.caches.fs.readFile(
            &FileSystem.instance,
            file,
            dirname_fd,
            false,
            null,
        );
        const key_path = Path.init(file);

        const source = logger.Source.initPathString(key_path.text, entry.contents);
        const file_dir = source.path.sourceDir();

        var result = (try TSConfigJSON.parse(r.allocator, r.log, source, &r.caches.json, r.opts.jsx.development)) orelse return null;

        if (result.hasBaseURL()) {
            // this might leak
            if (!std.fs.path.isAbsolute(result.base_url)) {
                const paths = [_]string{ file_dir, result.base_url };
                result.base_url = FileSystem.instance.dirname_store.append(string, FileSystem.instance.absBuf(&paths, &tsconfig_base_url_buf)) catch unreachable;
            }
        }

        if (result.paths.count() > 0 and (result.base_url_for_paths.len == 0 or !std.fs.path.isAbsolute(result.base_url_for_paths))) {
            // this might leak
            const paths = [_]string{ file_dir, result.base_url };
            result.base_url_for_paths = FileSystem.instance.dirname_store.append(string, FileSystem.instance.absBuf(&paths, &tsconfig_base_url_buf)) catch unreachable;
        }

        return result;
    }

    // TODO:
    pub fn prettyPath(r: *ThisResolver, path: Path) string {
        return path.text;
    }

    pub fn parsePackageJSON(r: *ThisResolver, file: string, dirname_fd: StoredFileDescriptorType) !?*PackageJSON {
        const pkg = PackageJSON.parse(ThisResolver, r, file, dirname_fd, true) orelse return null;
        var _pkg = try r.allocator.create(PackageJSON);
        _pkg.* = pkg;
        return _pkg;
    }

    fn dirInfoCached(
        r: *ThisResolver,
        path: string,
    ) !?*DirInfo {
        return try r.dirInfoCachedMaybeLog(path, true, true);
    }

    pub fn readDirInfo(
        r: *ThisResolver,
        path: string,
    ) !?*DirInfo {
        return try r.dirInfoCachedMaybeLog(path, false, true);
    }

    pub fn readDirInfoIgnoreError(
        r: *ThisResolver,
        path: string,
    ) ?*const DirInfo {
        return r.dirInfoCachedMaybeLog(path, false, true) catch null;
    }

    pub inline fn readDirInfoCacheOnly(
        r: *ThisResolver,
        path: string,
    ) ?*DirInfo {
        return r.dir_cache.get(path);
    }

    inline fn dirInfoCachedMaybeLog(r: *ThisResolver, __path: string, comptime enable_logging: bool, comptime follow_symlinks: bool) !?*DirInfo {
        r.mutex.lock();
        defer r.mutex.unlock();
        var _path = __path;
        if (strings.eqlComptime(_path, "./") or strings.eqlComptime(_path, "."))
            _path = FileSystem.instance.top_level_dir;

        const top_result = try r.dir_cache.getOrPut(_path);
        if (top_result.status != .unknown) {
            return r.dir_cache.atIndex(top_result.index);
        }

        var i: i32 = 1;
        std.mem.copy(u8, &dir_info_uncached_path_buf, _path);
        var path = dir_info_uncached_path_buf[0.._path.len];

        _dir_entry_paths_to_resolve[0] = (DirEntryResolveQueueItem{ .result = top_result, .unsafe_path = path, .safe_path = "" });
        var top = Dirname.dirname(path);

        var top_parent: allocators.Result = allocators.Result{
            .index = allocators.NotFound,
            .hash = 0,
            .status = .not_found,
        };
        const root_path = if (comptime isWindows)
            std.fs.path.diskDesignator(path)
        else
            // we cannot just use "/"
            // we will write to the buffer past the ptr len so it must be a non-const buffer
            path[0..1];
        var rfs = &FileSystem.instance;

        rfs.entries_mutex.lock();
        defer rfs.entries_mutex.unlock();

        while (!strings.eql(top, root_path)) : (top = Dirname.dirname(top)) {
            var result = try r.dir_cache.getOrPut(top);
            if (result.status != .unknown) {
                top_parent = result;
                break;
            }
            _dir_entry_paths_to_resolve[@intCast(usize, i)] = DirEntryResolveQueueItem{
                .unsafe_path = top,
                .result = result,
                .fd = 0,
            };

            if (rfs.entries.get(top)) |top_entry| {
                _dir_entry_paths_to_resolve[@intCast(usize, i)].safe_path = top_entry.entries.dir;
                _dir_entry_paths_to_resolve[@intCast(usize, i)].fd = top_entry.entries.fd;
            }
            i += 1;
        }

        if (strings.eql(top, root_path)) {
            var result = try r.dir_cache.getOrPut(root_path);
            if (result.status != .unknown) {
                top_parent = result;
            } else {
                _dir_entry_paths_to_resolve[@intCast(usize, i)] = DirEntryResolveQueueItem{
                    .unsafe_path = root_path,
                    .result = result,
                    .fd = 0,
                };
                if (rfs.entries.get(top)) |top_entry| {
                    _dir_entry_paths_to_resolve[@intCast(usize, i)].safe_path = top_entry.entries.dir;
                    _dir_entry_paths_to_resolve[@intCast(usize, i)].fd = top_entry.entries.fd;
                }

                i += 1;
            }
        }

        var queue_slice: []DirEntryResolveQueueItem = _dir_entry_paths_to_resolve[0..@intCast(usize, i)];
        std.debug.assert(queue_slice.len > 0);
        var open_dir_count: usize = 0;

        // When this function halts, any item not processed means it's not found.
        defer {

            // Anything
            if (open_dir_count > 0 and FileSystem.instance.fs.needToCloseFiles()) {
                var open_dirs: []Fs.Dir = _open_dirs[0..open_dir_count];
                for (open_dirs) |*open_dir| {
                    open_dir.close();
                }
            }
        }

        // We want to walk in a straight line from the topmost directory to the desired directory
        // For each directory we visit, we get the entries, but not traverse into child directories
        // (unless those child directores are in the queue)
        // We go top-down instead of bottom-up to increase odds of reusing previously open file handles
        // "/home/jarred/Code/node_modules/react/cjs/react.development.js"
        //       ^
        // If we start there, we will traverse all of /home/jarred, including e.g. /home/jarred/Downloads
        // which is completely irrelevant.

        // After much experimentation...
        // - fts_open is not the fastest way to read directories. fts actually just uses readdir!!
        // - remember
        var _safe_path: ?string = null;

        // Start at the top.
        while (queue_slice.len > 0) {
            var queue_top = queue_slice[queue_slice.len - 1];
            defer top_parent = queue_top.result;
            queue_slice.len -= 1;

            var _open_dir: anyerror!Fs.Dir = undefined;
            if (queue_top.fd == 0) {

                // This saves us N copies of .toPosixPath
                // which was likely the perf gain from resolving directories relative to the parent directory, anyway.
                const prev_char = path.ptr[queue_top.unsafe_path.len];
                path.ptr[queue_top.unsafe_path.len] = 0;
                defer path.ptr[queue_top.unsafe_path.len] = prev_char;
                var sentinel = path.ptr[0..queue_top.unsafe_path.len :0];
                _open_dir = FileSystem.openDirectory(
                    sentinel,
                    .{
                        .iterate = true,
                        .no_follow = !follow_symlinks,
                    },
                );
                // }
            }

            const open_dir = if (queue_top.fd != 0) Fs.Dir{ .fd = queue_top.fd } else (_open_dir catch |err| {
                switch (err) {
                    error.EACCESS => {},

                    // Ignore "ENOTDIR" here so that calling "ReadDirectory" on a file behaves
                    // as if there is nothing there at all instead of causing an error due to
                    // the directory actually being a file. This is a workaround for situations
                    // where people try to import from a path containing a file as a parent
                    // directory. The "pnpm" package manager generates a faulty "NODE_PATH"
                    // list which contains such paths and treating them as missing means we just
                    // ignore them during path resolution.
                    error.ENOENT,
                    error.ENOTDIR,
                    error.IsDir,
                    error.NotDir,
                    error.FileNotFound,
                    => {
                        return null;
                    },

                    else => {
                        var cached_dir_entry_result = rfs.entries.getOrPut(queue_top.unsafe_path) catch unreachable;
                        r.dir_cache.markNotFound(queue_top.result);
                        rfs.entries.markNotFound(cached_dir_entry_result);
                        if (comptime enable_logging) {
                            const pretty = r.prettyPath(Path.init(queue_top.unsafe_path));

                            r.log.addErrorFmt(
                                null,
                                logger.Loc{},
                                r.allocator,
                                "Cannot read directory \"{s}\": {s}",
                                .{
                                    pretty,
                                    @errorName(err),
                                },
                            ) catch {};
                        }
                    },
                }

                return null;
            });

            if (queue_top.fd == 0) {
                Fs.FileSystem.setMaxFd(open_dir.fd);
                // these objects mostly just wrap the file descriptor, so it's fine to keep it.
                _open_dirs[open_dir_count] = open_dir;
                open_dir_count += 1;
            }

            const dir_path = if (queue_top.safe_path.len > 0) queue_top.safe_path else brk: {

                // ensure trailing slash
                if (_safe_path == null) {
                    // Now that we've opened the topmost directory successfully, it's reasonable to store the slice.
                    if (path[path.len - 1] != std.fs.path.sep) {
                        var parts = [_]string{ path, std.fs.path.sep_str };
                        _safe_path = try FileSystem.instance.dirname_store.append(@TypeOf(parts), parts);
                    } else {
                        _safe_path = try FileSystem.instance.dirname_store.append(string, path);
                    }
                }

                const safe_path = _safe_path.?;

                var dir_path_i = std.mem.indexOf(u8, safe_path, queue_top.unsafe_path) orelse unreachable;
                var end = dir_path_i +
                    queue_top.unsafe_path.len;

                // Directories must always end in a trailing slash or else various bugs can occur.
                // This covers "what happens when the trailing"
                end += @intCast(usize, @boolToInt(safe_path.len > end and end > 0 and safe_path[end - 1] != std.fs.path.sep and safe_path[end] == std.fs.path.sep));
                break :brk safe_path[dir_path_i..end];
            };

            var cached_dir_entry_result = rfs.entries.getOrPut(dir_path) catch unreachable;

            var dir_entries_option: *Fs.EntriesOption = undefined;
            var needs_iter: bool = true;

            if (rfs.entries.atIndex(cached_dir_entry_result.index)) |cached_entry| {
                if (cached_entry.* == .entries) {
                    dir_entries_option = cached_entry;
                    needs_iter = false;
                }
            }

            if (needs_iter) {
                dir_entries_option = try rfs.entries.put(&cached_dir_entry_result, .{
                    .entries = Fs.DirEntry.init(dir_path, FileSystem.instance.allocator),
                });

                if (FeatureFlags.store_file_descriptors) {
                    Fs.FileSystem.setMaxFd(open_dir.fd);
                    dir_entries_option.entries.fd = open_dir.fd;
                }
                var dir_iterator = open_dir.iterate();
                while (try dir_iterator.next()) |_value| {
                    dir_entries_option.entries.addEntry(_value) catch unreachable;
                }
            }

            // We must initialize it as empty so that the result index is correct.
            // This is important so that browser_scope has a valid index.
            var dir_info_ptr = try r.dir_cache.put(&queue_top.result, DirInfo{});

            try r.dirInfoUncached(
                dir_info_ptr,
                dir_path,
                dir_entries_option,
                queue_top.result,
                cached_dir_entry_result.index,
                r.dir_cache.atIndex(top_parent.index),
                top_parent.index,
                open_dir.fd,
            );

            if (queue_slice.len == 0) {
                return dir_info_ptr;

                // Is the directory we're searching for actually a file?
            } else if (queue_slice.len == 1) {
                // const next_in_queue = queue_slice[0];
                // const next_basename = std.fs.path.basename(next_in_queue.unsafe_path);
                // if (dir_info_ptr.getEntries()) |entries| {
                //     if (entries.get(next_basename) != null) {
                //         return null;
                //     }
                // }
            }
        }

        unreachable;
    }

    // This closely follows the behavior of "tryLoadModuleUsingPaths()" in the
    // official TypeScript compiler
    pub fn matchTSConfigPaths(r: *ThisResolver, tsconfig: *const TSConfigJSON, path: string, kind: ast.ImportKind) ?MatchResult {
        if (r.debug_logs) |*debug| {
            debug.addNoteFmt("Matching \"{s}\" against \"paths\" in \"{s}\"", .{ path, tsconfig.abs_path }) catch unreachable;
        }

        var abs_base_url = tsconfig.base_url_for_paths;

        // The explicit base URL should take precedence over the implicit base URL
        // if present. This matters when a tsconfig.json file overrides "baseUrl"
        // from another extended tsconfig.json file but doesn't override "paths".
        if (tsconfig.hasBaseURL()) {
            abs_base_url = tsconfig.base_url;
        }

        if (r.debug_logs) |*debug| {
            debug.addNoteFmt("Using \"{s}\" as \"baseURL\"", .{abs_base_url}) catch unreachable;
        }

        // Check for exact matches first
        {
            var iter = tsconfig.paths.iterator();
            while (iter.next()) |entry| {
                const key = entry.key_ptr.*;

                if (strings.eql(key, path)) {
                    for (entry.value_ptr.*) |original_path| {
                        var absolute_original_path = original_path;
                        var was_alloc = false;

                        if (!std.fs.path.isAbsolute(absolute_original_path)) {
                            const parts = [_]string{ abs_base_url, original_path };
                            absolute_original_path = FileSystem.instance.absBuf(&parts, &tsconfig_path_abs_buf);
                        }

                        if (r.loadAsFileOrDirectory(absolute_original_path, kind)) |res| {
                            return res;
                        }
                    }
                }
            }
        }

        const TSConfigMatch = struct {
            prefix: string,
            suffix: string,
            original_paths: []string,
        };

        var longest_match: TSConfigMatch = undefined;
        var longest_match_prefix_length: i32 = -1;
        var longest_match_suffix_length: i32 = -1;

        var iter = tsconfig.paths.iterator();
        while (iter.next()) |entry| {
            const key = entry.key_ptr.*;
            const original_paths = entry.value_ptr.*;

            if (strings.indexOfChar(key, '*')) |star| {
                const prefix = key[0 .. star - 1];
                const suffix = key[star + 1 ..];

                // Find the match with the longest prefix. If two matches have the same
                // prefix length, pick the one with the longest suffix. This second edge
                // case isn't handled by the TypeScript compiler, but we handle it
                // because we want the output to always be deterministic
                if (strings.startsWith(path, prefix) and
                    strings.endsWith(path, suffix) and
                    (prefix.len >= longest_match_prefix_length and
                    suffix.len > longest_match_suffix_length))
                {
                    longest_match_prefix_length = @intCast(i32, prefix.len);
                    longest_match_suffix_length = @intCast(i32, suffix.len);
                    longest_match = TSConfigMatch{ .prefix = prefix, .suffix = suffix, .original_paths = original_paths };
                }
            }
        }

        // If there is at least one match, only consider the one with the longest
        // prefix. This matches the behavior of the TypeScript compiler.
        if (longest_match_prefix_length > -1) {
            if (r.debug_logs) |*debug| {
                debug.addNoteFmt("Found a fuzzy match for \"{s}*{s}\" in \"paths\"", .{ longest_match.prefix, longest_match.suffix }) catch unreachable;
            }

            for (longest_match.original_paths) |original_path| {
                // Swap out the "*" in the original path for whatever the "*" matched
                const matched_text = path[longest_match.prefix.len .. path.len - longest_match.suffix.len];

                const total_length = std.mem.indexOfScalar(u8, original_path, '*') orelse unreachable;
                var prefix_parts = [_]string{ abs_base_url, original_path[0..total_length] };

                // 1. Normalize the base path
                // so that "/Users/foo/project/", "../components/*" => "/Users/foo/components/""
                var prefix = FileSystem.instance.absBuf(&prefix_parts, &TemporaryBuffer.TSConfigMatchFullBuf2);

                // 2. Join the new base path with the matched result
                // so that "/Users/foo/components/", "/foo/bar" => /Users/foo/components/foo/bar
                var parts = [_]string{ prefix, std.mem.trimLeft(u8, matched_text, "/"), std.mem.trimLeft(u8, longest_match.suffix, "/") };
                var absolute_original_path = FileSystem.instance.absBuf(
                    &parts,
                    &TemporaryBuffer.TSConfigMatchFullBuf,
                );

                if (r.loadAsFileOrDirectory(absolute_original_path, kind)) |res| {
                    return res;
                }
            }
        }

        return null;
    }

    const BrowserMapPath = struct {
        remapped: string = "",
        cleaned: string = "",
        input_path: string = "",
        extension_order: []const string,
        map: BrowserMap,

        pub threadlocal var abs_to_rel_buf: [std.fs.MAX_PATH_BYTES]u8 = undefined;

        pub const Kind = enum { PackagePath, AbsolutePath };

        pub fn checkPath(
            this: *BrowserMapPath,
            path_to_check: string,
        ) bool {
            const map = this.map;

            const cleaned = this.cleaned;
            // Check for equality
            if (this.map.get(path_to_check)) |result| {
                this.remapped = result;
                this.input_path = path_to_check;
                return true;
            }

            std.mem.copy(u8, &TemporaryBuffer.ExtensionPathBuf, cleaned);

            // If that failed, try adding implicit extensions
            for (this.extension_order) |ext| {
                std.mem.copy(u8, TemporaryBuffer.ExtensionPathBuf[cleaned.len .. cleaned.len + ext.len], ext);
                const new_path = TemporaryBuffer.ExtensionPathBuf[0 .. cleaned.len + ext.len];
                // if (r.debug_logs) |*debug| {
                //     debug.addNoteFmt("Checking for \"{s}\" ", .{new_path}) catch {};
                // }
                if (map.get(new_path)) |_remapped| {
                    this.remapped = _remapped;
                    this.cleaned = new_path;
                    this.input_path = new_path;
                    return true;
                }
            }

            // If that failed, try assuming this is a directory and looking for an "index" file

            var index_path: string = "";
            {
                var parts = [_]string{ std.mem.trimRight(u8, path_to_check, std.fs.path.sep_str), std.fs.path.sep_str ++ "index" };
                index_path = ResolvePath.joinStringBuf(&tsconfig_base_url_buf, &parts, .auto);
            }

            if (map.get(index_path)) |_remapped| {
                this.remapped = _remapped;
                this.input_path = index_path;
                return true;
            }

            std.mem.copy(u8, &TemporaryBuffer.ExtensionPathBuf, index_path);

            for (this.extension_order) |ext| {
                std.mem.copy(u8, TemporaryBuffer.ExtensionPathBuf[index_path.len .. index_path.len + ext.len], ext);
                const new_path = TemporaryBuffer.ExtensionPathBuf[0 .. index_path.len + ext.len];
                // if (r.debug_logs) |*debug| {
                //     debug.addNoteFmt("Checking for \"{s}\" ", .{new_path}) catch {};
                // }
                if (map.get(new_path)) |_remapped| {
                    this.remapped = _remapped;
                    this.cleaned = new_path;
                    this.input_path = new_path;
                    return true;
                }
            }

            return false;
        }
    };

    pub fn checkBrowserMap(
        r: *ThisResolver,
        dir_info: *const DirInfo,
        input_path_: string,
        comptime kind: BrowserMapPath.Kind,
    ) ?string {
        const package_json = dir_info.package_json orelse return null;
        const browser_map = package_json.browser_map;

        if (browser_map.count() == 0) return null;

        var input_path = input_path_;

        if (comptime kind == .AbsolutePath) {
            const abs_path = dir_info.abs_path;
            // Turn absolute paths into paths relative to the "browser" map location
            if (!strings.startsWith(input_path, abs_path)) {
                return null;
            }

            input_path = input_path[abs_path.len..];
        }

        if (input_path.len == 0 or (input_path.len == 1 and (input_path[0] == '.' or input_path[0] == std.fs.path.sep))) {
            // No bundler supports remapping ".", so we don't either
            return null;
        }

        // Normalize the path so we can compare against it without getting confused by "./"
        var cleaned = FileSystem.instance.normalizeBuf(&check_browser_map_buf, input_path);

        if (cleaned.len == 1 and cleaned[0] == '.') {
            // No bundler supports remapping ".", so we don't either
            return null;
        }

        var checker = BrowserMapPath{
            .remapped = "",
            .cleaned = cleaned,
            .input_path = input_path,
            .extension_order = r.extension_order,
            .map = package_json.browser_map,
        };

        if (checker.checkPath(input_path)) {
            return checker.remapped;
        }

        // First try the import path as a package path
        if (isPackagePath(checker.input_path)) {
            switch (comptime kind) {
                .AbsolutePath => {
                    BrowserMapPath.abs_to_rel_buf[0..2].* = "./".*;
                    std.mem.copy(u8, BrowserMapPath.abs_to_rel_buf[2..], checker.input_path);
                    if (checker.checkPath(BrowserMapPath.abs_to_rel_buf[0 .. checker.input_path.len + 2])) {
                        return checker.remapped;
                    }
                },
                .PackagePath => {
                    // Browserify allows a browser map entry of "./pkg" to override a package
                    // path of "require('pkg')". This is weird, and arguably a bug. But we
                    // replicate this bug for compatibility. However, Browserify only allows
                    // this within the same package. It does not allow such an entry in a
                    // parent package to override this in a child package. So this behavior
                    // is disallowed if there is a "node_modules" folder in between the child
                    // package and the parent package.
                    const isInSamePackage = brk: {
                        const parent = dir_info.getParent() orelse break :brk true;
                        break :brk !parent.is_node_modules;
                    };

                    if (isInSamePackage) {
                        BrowserMapPath.abs_to_rel_buf[0..2].* = "./".*;
                        std.mem.copy(u8, BrowserMapPath.abs_to_rel_buf[2..], checker.input_path);

                        if (checker.checkPath(BrowserMapPath.abs_to_rel_buf[0 .. checker.input_path.len + 2])) {
                            return checker.remapped;
                        }
                    }
                },
            }
        }

        return null;
    }

    pub fn loadFromMainField(r: *ThisResolver, path: string, dir_info: *DirInfo, _field_rel_path: string, field: string, extension_order: []const string) ?MatchResult {
        var field_rel_path = _field_rel_path;
        // Is this a directory?
        if (r.debug_logs) |*debug| {
            debug.addNoteFmt("Found main field \"{s}\" with path \"{s}\"", .{ field, field_rel_path }) catch {};
            debug.increaseIndent() catch {};
        }

        defer {
            if (r.debug_logs) |*debug| {
                debug.decreaseIndent() catch {};
            }
        }

        // Potentially remap using the "browser" field
        if (dir_info.getEnclosingBrowserScope()) |browser_scope| {
            if (browser_scope.package_json) |browser_json| {
                if (r.checkBrowserMap(
                    browser_scope,
                    field_rel_path,
                    .AbsolutePath,
                )) |remap| {
                    // Is the path disabled?
                    if (remap.len == 0) {
                        const paths = [_]string{ path, field_rel_path };
                        const new_path = FileSystem.instance.absAlloc(r.allocator, &paths) catch unreachable;
                        var _path = Path.init(new_path);
                        _path.is_disabled = true;
                        return MatchResult{
                            .path_pair = PathPair{
                                .primary = _path,
                            },
                            .package_json = browser_json,
                        };
                    }

                    field_rel_path = remap;
                }
            }
        }
        const _paths = [_]string{ path, field_rel_path };
        const field_abs_path = FileSystem.instance.absBuf(&_paths, &field_abs_path_buf);

        // Is this a file?
        if (r.loadAsFile(field_abs_path, extension_order)) |result| {
            if (dir_info.package_json) |package_json| {
                return MatchResult{
                    .path_pair = PathPair{ .primary = Fs.Path.init(result.path) },
                    .package_json = package_json,
                    .dirname_fd = result.dirname_fd,
                };
            }

            return MatchResult{
                .path_pair = PathPair{ .primary = Fs.Path.init(result.path) },
                .dirname_fd = result.dirname_fd,
                .diff_case = result.diff_case,
            };
        }

        // Is it a directory with an index?
        const field_dir_info = (r.dirInfoCached(field_abs_path) catch null) orelse {
            return null;
        };

        return r.loadAsIndexWithBrowserRemapping(field_dir_info, field_abs_path, extension_order) orelse {
            return null;
        };
    }

    pub fn loadAsIndex(r: *ThisResolver, dir_info: *DirInfo, path: string, extension_order: []const string) ?MatchResult {
        var rfs = &FileSystem.instance.fs;
        // Try the "index" file with extensions
        for (extension_order) |ext| {
            var base = TemporaryBuffer.ExtensionPathBuf[0 .. "index".len + ext.len];
            base[0.."index".len].* = "index".*;
            std.mem.copy(u8, base["index".len..base.len], ext);

            if (dir_info.getEntries()) |entries| {
                if (entries.get(base)) |lookup| {
                    if (lookup.entry.kind(rfs) == .file) {
                        const out_buf = brk: {
                            if (lookup.entry.abs_path.isEmpty()) {
                                const parts = [_]string{ path, base };
                                const out_buf_ = FileSystem.instance.absBuf(&parts, &index_buf);
                                lookup.entry.abs_path =
                                    PathString.init(FileSystem.instance.dirname_store.append(@TypeOf(out_buf_), out_buf_) catch unreachable);
                            }
                            break :brk lookup.entry.abs_path.slice();
                        };

                        if (r.debug_logs) |*debug| {
                            debug.addNoteFmt("Found file: \"{s}\"", .{out_buf}) catch unreachable;
                        }

                        if (dir_info.package_json) |package_json| {
                            return MatchResult{
                                .path_pair = .{ .primary = Path.init(out_buf) },
                                .diff_case = lookup.diff_case,
                                .package_json = package_json,
                                .dirname_fd = dir_info.getFileDescriptor(),
                            };
                        }

                        return MatchResult{
                            .path_pair = .{ .primary = Path.init(out_buf) },
                            .diff_case = lookup.diff_case,

                            .dirname_fd = dir_info.getFileDescriptor(),
                        };
                    }
                }
            }

            if (r.debug_logs) |*debug| {
                debug.addNoteFmt("Failed to find file: \"{s}/{s}\"", .{ path, base }) catch unreachable;
            }
        }

        return null;
    }

    pub fn loadAsIndexWithBrowserRemapping(r: *ThisResolver, dir_info: *DirInfo, path_: string, extension_order: []const string) ?MatchResult {
        // In order for our path handling logic to be correct, it must end with a trailing slash.
        var path = path_;
        if (!strings.endsWithChar(path_, std.fs.path.sep)) {
            std.mem.copy(u8, &remap_path_trailing_slash, path);
            remap_path_trailing_slash[path.len] = std.fs.path.sep;
            remap_path_trailing_slash[path.len + 1] = 0;
            path = remap_path_trailing_slash[0 .. path.len + 1];
        }

        if (dir_info.getEnclosingBrowserScope()) |browser_scope| {
            const field_rel_path = comptime "index";

            if (browser_scope.package_json) |browser_json| {
                if (r.checkBrowserMap(
                    browser_scope,
                    field_rel_path,
                    .AbsolutePath,
                )) |remap| {

                    // Is the path disabled?
                    if (remap.len == 0) {
                        const paths = [_]string{ path, field_rel_path };
                        const new_path = FileSystem.instance.absBuf(&paths, &remap_path_buf);
                        var _path = Path.init(new_path);
                        _path.is_disabled = true;
                        return MatchResult{
                            .path_pair = PathPair{
                                .primary = _path,
                            },
                            .package_json = browser_json,
                        };
                    }

                    const new_paths = [_]string{ path, remap };
                    const remapped_abs = FileSystem.instance.absBuf(&new_paths, &remap_path_buf);

                    // Is this a file
                    if (r.loadAsFile(remapped_abs, extension_order)) |file_result| {
                        return MatchResult{ .dirname_fd = file_result.dirname_fd, .path_pair = .{ .primary = Path.init(file_result.path) }, .diff_case = file_result.diff_case };
                    }

                    // Is it a directory with an index?
                    if (r.dirInfoCached(remapped_abs) catch null) |new_dir| {
                        if (r.loadAsIndex(new_dir, remapped_abs, extension_order)) |absolute| {
                            return absolute;
                        }
                    }

                    return null;
                }
            }
        }

        return r.loadAsIndex(dir_info, path_, extension_order);
    }

    pub fn loadAsFileOrDirectory(r: *ThisResolver, path: string, kind: ast.ImportKind) ?MatchResult {
        const extension_order = r.extension_order;

        // Is this a file?
        if (r.loadAsFile(path, extension_order)) |file| {

            // Determine the package folder by looking at the last node_modules/ folder in the path
            if (strings.lastIndexOf(file.path, "node_modules" ++ std.fs.path.sep_str)) |last_node_modules_folder| {
                const node_modules_folder_offset = last_node_modules_folder + ("node_modules" ++ std.fs.path.sep_str).len;
                // Determine the package name by looking at the next separator
                if (strings.indexOfChar(file.path[node_modules_folder_offset..], std.fs.path.sep)) |package_name_length| {
                    if ((r.dirInfoCached(file.path[0 .. node_modules_folder_offset + package_name_length]) catch null)) |package_dir_info| {
                        if (package_dir_info.package_json) |package_json| {
                            return MatchResult{
                                .path_pair = .{ .primary = Path.init(file.path) },
                                .diff_case = file.diff_case,
                                .dirname_fd = file.dirname_fd,
                                .package_json = package_json,
                                .file_fd = file.file_fd,
                            };
                        }
                    }
                }
            }

            return MatchResult{
                .path_pair = .{ .primary = Path.init(file.path) },
                .diff_case = file.diff_case,
                .dirname_fd = file.dirname_fd,
                .file_fd = file.file_fd,
            };
        }

        // Is this a directory?
        if (r.debug_logs) |*debug| {
            debug.addNoteFmt("Attempting to load \"{s}\" as a directory", .{path}) catch {};
            debug.increaseIndent() catch {};
        }

        defer {
            if (r.debug_logs) |*debug| {
                debug.decreaseIndent() catch {};
            }
        }

        const dir_info = (r.dirInfoCached(path) catch |err| {
            if (comptime isDebug) Output.prettyErrorln("err: {s} reading {s}", .{ @errorName(err), path });
            return null;
        }) orelse return null;
        var package_json: ?*PackageJSON = null;

        // Try using the main field(s) from "package.json"
        if (dir_info.package_json) |pkg_json| {
            package_json = pkg_json;
            if (pkg_json.main_fields.count() > 0) {
                const main_field_values = pkg_json.main_fields;
                const main_field_keys = r.opts.main_fields;
                // TODO: check this works right. Not sure this will really work.
                const auto_main = r.opts.main_fields.ptr == options.Platform.DefaultMainFields.get(r.opts.platform).ptr;

                if (r.debug_logs) |*debug| {
                    debug.addNoteFmt("Searching for main fields in \"{s}\"", .{pkg_json.source.path.text}) catch {};
                }

                for (main_field_keys) |key| {
                    const field_rel_path = (main_field_values.get(key)) orelse {
                        if (r.debug_logs) |*debug| {
                            debug.addNoteFmt("Did not find main field \"{s}\"", .{key}) catch {};
                        }
                        continue;
                    };

                    var _result = r.loadFromMainField(path, dir_info, field_rel_path, key, extension_order) orelse continue;

                    // If the user did not manually configure a "main" field order, then
                    // use a special per-module automatic algorithm to decide whether to
                    // use "module" or "main" based on whether the package is imported
                    // using "import" or "require".
                    if (auto_main and strings.eqlComptime(key, "module")) {
                        var absolute_result: ?MatchResult = null;

                        if (main_field_values.get("main")) |main_rel_path| {
                            if (main_rel_path.len > 0) {
                                absolute_result = r.loadFromMainField(path, dir_info, main_rel_path, "main", extension_order);
                            }
                        } else {
                            // Some packages have a "module" field without a "main" field but
                            // still have an implicit "index.js" file. In that case, treat that
                            // as the value for "main".
                            absolute_result = r.loadAsIndexWithBrowserRemapping(dir_info, path, extension_order);
                        }

                        if (absolute_result) |auto_main_result| {
                            // If both the "main" and "module" fields exist, use "main" if the
                            // path is for "require" and "module" if the path is for "import".
                            // If we're using "module", return enough information to be able to
                            // fall back to "main" later if something ended up using "require()"
                            // with this same path. The goal of this code is to avoid having
                            // both the "module" file and the "main" file in the bundle at the
                            // same time.
                            if (kind != ast.ImportKind.require) {
                                if (r.debug_logs) |*debug| {
                                    debug.addNoteFmt("Resolved to \"{s}\" using the \"module\" field in \"{s}\"", .{ auto_main_result.path_pair.primary.text, pkg_json.source.key_path.text }) catch {};

                                    debug.addNoteFmt("The fallback path in case of \"require\" is {s}", .{auto_main_result.path_pair.primary.text}) catch {};
                                }

                                return MatchResult{
                                    .path_pair = .{
                                        .primary = _result.path_pair.primary,
                                        .secondary = auto_main_result.path_pair.primary,
                                    },
                                    .diff_case = _result.diff_case,
                                    .dirname_fd = _result.dirname_fd,
                                    .package_json = package_json,
                                    .file_fd = auto_main_result.file_fd,
                                };
                            } else {
                                if (r.debug_logs) |*debug| {
                                    debug.addNoteFmt("Resolved to \"{s}\" using the \"{s}\" field in \"{s}\"", .{
                                        auto_main_result.path_pair.primary.text,
                                        key,
                                        pkg_json.source.key_path.text,
                                    }) catch {};
                                }
                                var _auto_main_result = auto_main_result;
                                _auto_main_result.package_json = package_json;
                                return _auto_main_result;
                            }
                        }
                    }

                    _result.package_json = _result.package_json orelse package_json;
                    return _result;
                }
            }
        }

        // Look for an "index" file with known extensions
        if (r.loadAsIndexWithBrowserRemapping(dir_info, path, extension_order)) |*res| {
            res.package_json = res.package_json orelse package_json;
            return res.*;
        }

        return null;
    }

    pub fn loadAsFile(r: *ThisResolver, path: string, extension_order: []const string) ?LoadResult {
        var rfs: *Fs.RealFS = &FileSystem.instance.fs;

        if (r.debug_logs) |*debug| {
            debug.addNoteFmt("Attempting to load \"{s}\" as a file", .{path}) catch {};
            debug.increaseIndent() catch {};
        }
        defer {
            if (r.debug_logs) |*debug| {
                debug.decreaseIndent() catch {};
            }
        }

        const dir_path = Dirname.dirname(path);

        const dir_entry: *Fs.EntriesOption = FileSystem.instance.readDirectory(
            dir_path,
            null,
        ) catch {
            return null;
        };

        if (@as(Fs.EntriesOption.Tag, dir_entry.*) == .err) {
            if (dir_entry.err.original_err != error.ENOENT) {
                r.log.addErrorFmt(
                    null,
                    logger.Loc.Empty,
                    r.allocator,
                    "Cannot read directory \"{s}\": {s}",
                    .{
                        r.prettyPath(Path.init(dir_path)),
                        @errorName(dir_entry.err.original_err),
                    },
                ) catch {};
            }
            return null;
        }

        const entries = dir_entry.entries;

        const base = std.fs.path.basename(path);

        // Try the plain path without any extensions
        if (r.debug_logs) |*debug| {
            debug.addNoteFmt("Checking for file \"{s}\" ", .{base}) catch {};
        }

        if (entries.get(base)) |query| {
            if (query.entry.kind(rfs) == .file) {
                if (r.debug_logs) |*debug| {
                    debug.addNoteFmt("Found file \"{s}\" ", .{base}) catch {};
                }

                const abs_path = brk: {
                    if (query.entry.abs_path.isEmpty()) {
                        const abs_path_parts = [_]string{ query.entry.dir, query.entry.base() };
                        query.entry.abs_path = PathString.init(FileSystem.instance.dirname_store.append(string, FileSystem.instance.absBuf(&abs_path_parts, &load_as_file_buf)) catch unreachable);
                    }

                    break :brk query.entry.abs_path.slice();
                };

                return LoadResult{
                    .path = abs_path,
                    .diff_case = query.diff_case,
                    .dirname_fd = entries.fd,
                    .file_fd = query.entry.cache.fd,
                };
            }
        }

        // Try the path with extensions
        std.mem.copy(u8, &load_as_file_buf, path);
        for (r.extension_order) |ext| {
            var buffer = load_as_file_buf[0 .. path.len + ext.len];
            std.mem.copy(u8, buffer[path.len..buffer.len], ext);
            const file_name = buffer[path.len - base.len .. buffer.len];

            if (r.debug_logs) |*debug| {
                debug.addNoteFmt("Checking for file \"{s}\" ", .{buffer}) catch {};
            }

            if (entries.get(file_name)) |query| {
                if (query.entry.kind(rfs) == .file) {
                    if (r.debug_logs) |*debug| {
                        debug.addNoteFmt("Found file \"{s}\" ", .{buffer}) catch {};
                    }

                    // now that we've found it, we allocate it.
                    return LoadResult{
                        .path = brk: {
                            query.entry.abs_path = if (query.entry.abs_path.isEmpty())
                                PathString.init(FileSystem.instance.dirname_store.append(@TypeOf(buffer), buffer) catch unreachable)
                            else
                                query.entry.abs_path;

                            break :brk query.entry.abs_path.slice();
                        },
                        .diff_case = query.diff_case,
                        .dirname_fd = entries.fd,
                        .file_fd = query.entry.cache.fd,
                    };
                }
            }
        }

        // TypeScript-specific behavior: if the extension is ".js" or ".jsx", try
        // replacing it with ".ts" or ".tsx". At the time of writing this specific
        // behavior comes from the function "loadModuleFromFile()" in the file
        // "moduleNameThisResolver.ts" in the TypeScript compiler source code. It
        // contains this comment:
        //
        //   If that didn't work, try stripping a ".js" or ".jsx" extension and
        //   replacing it with a TypeScript one; e.g. "./foo.js" can be matched
        //   by "./foo.ts" or "./foo.d.ts"
        //
        // We don't care about ".d.ts" files because we can't do anything with
        // those, so we ignore that part of the behavior.
        //
        // See the discussion here for more historical context:
        // https://github.com/microsoft/TypeScript/issues/4595
        if (strings.lastIndexOfChar(base, '.')) |last_dot| {
            const ext = base[last_dot..base.len];
            if (strings.eqlComptime(ext, ".js") or strings.eqlComptime(ext, ".jsx")) {
                const segment = base[0..last_dot];
                var tail = load_as_file_buf[path.len - base.len ..];
                std.mem.copy(u8, tail, segment);

                const exts = comptime [_]string{ ".ts", ".tsx" };

                inline for (exts) |ext_to_replace| {
                    var buffer = tail[0 .. segment.len + ext_to_replace.len];
                    std.mem.copy(u8, buffer[segment.len..buffer.len], ext_to_replace);

                    if (entries.get(buffer)) |query| {
                        if (query.entry.kind(rfs) == .file) {
                            if (r.debug_logs) |*debug| {
                                debug.addNoteFmt("Rewrote to \"{s}\" ", .{buffer}) catch {};
                            }

                            return LoadResult{
                                .path = brk: {
                                    if (query.entry.abs_path.isEmpty()) {
                                        // Should already have a trailing slash so we shouldn't need to worry.
                                        var parts = [_]string{ query.entry.dir, buffer };
                                        query.entry.abs_path = PathString.init(FileSystem.instance.filename_store.append(@TypeOf(parts), parts) catch unreachable);
                                    }

                                    break :brk query.entry.abs_path.slice();
                                },
                                .diff_case = query.diff_case,
                                .dirname_fd = entries.fd,
                                .file_fd = query.entry.cache.fd,
                            };
                        }
                    }
                    if (r.debug_logs) |*debug| {
                        debug.addNoteFmt("Failed to rewrite \"{s}\" ", .{base}) catch {};
                    }
                }
            }
        }

        if (r.debug_logs) |*debug| {
            debug.addNoteFmt("Failed to find \"{s}\" ", .{path}) catch {};
        }

        if (comptime FeatureFlags.watch_directories) {
            // For existent directories which don't find a match
            // Start watching it automatically,
            // onStartWatchingDirectory fn decides whether to actually watch.
            if (r.onStartWatchingDirectoryCtx) |ctx| {
                r.onStartWatchingDirectory.?(ctx, entries.dir, entries.fd);
            }
        }
        return null;
    }

    fn dirInfoUncached(
        r: *ThisResolver,
        info: *DirInfo,
        path: string,
        _entries: *Fs.EntriesOption,
        _result: allocators.Result,
        dir_entry_index: allocators.IndexType,
        parent: ?*DirInfo,
        parent_index: allocators.IndexType,
        fd: FileDescriptorType,
    ) anyerror!void {
        var result = _result;

        var rfs: *Fs.RealFS = &FileSystem.instance.fs;
        var entries = _entries.entries;

        info.* = DirInfo{
            .abs_path = path,
            // .abs_real_path = path,
            .parent = parent_index,
            .entries = dir_entry_index,
        };

        // A "node_modules" directory isn't allowed to directly contain another "node_modules" directory
        var base = std.fs.path.basename(path);

        // base must
        if (base.len > 1 and base[base.len - 1] == std.fs.path.sep) base = base[0 .. base.len - 1];

        info.is_node_modules = strings.eqlComptime(base, "node_modules");

        // if (entries != null) {
        if (!info.is_node_modules) {
            if (entries.getComptimeQuery("node_modules")) |entry| {
                info.has_node_modules = (entry.entry.kind(rfs)) == .dir;
            }
        }
        // }

        if (parent != null) {

            // Propagate the browser scope into child directories
            info.enclosing_browser_scope = parent.?.enclosing_browser_scope;
            info.package_json_for_browser_field = parent.?.package_json_for_browser_field;
            info.enclosing_tsconfig_json = parent.?.enclosing_tsconfig_json;
            info.enclosing_package_json = parent.?.package_json orelse parent.?.enclosing_package_json;

            // Make sure "absRealPath" is the real path of the directory (resolving any symlinks)
            if (!r.opts.preserve_symlinks) {
                if (parent.?.getEntries()) |parent_entries| {
                    if (parent_entries.get(base)) |lookup| {
                        if (entries.fd != 0 and lookup.entry.cache.fd == 0) lookup.entry.cache.fd = entries.fd;
                        const entry = lookup.entry;

                        var symlink = entry.symlink(rfs);
                        if (symlink.len > 0) {
                            if (r.debug_logs) |*logs| {
                                try logs.addNote(std.fmt.allocPrint(r.allocator, "Resolved symlink \"{s}\" to \"{s}\"", .{ path, symlink }) catch unreachable);
                            }
                            info.abs_real_path = symlink;
                        } else if (parent.?.abs_real_path.len > 0) {
                            // this might leak a little i'm not sure
                            const parts = [_]string{ parent.?.abs_real_path, base };
                            symlink = FileSystem.instance.dirname_store.append(string, FileSystem.instance.absBuf(&parts, &dir_info_uncached_filename_buf)) catch unreachable;

                            if (r.debug_logs) |*logs| {
                                try logs.addNote(std.fmt.allocPrint(r.allocator, "Resolved symlink \"{s}\" to \"{s}\"", .{ path, symlink }) catch unreachable);
                            }
                            lookup.entry.cache.symlink = PathString.init(symlink);
                            info.abs_real_path = symlink;
                        }
                    }
                }
            }
        }

        // Record if this directory has a package.json file
        if (entries.getComptimeQuery("package.json")) |lookup| {
            const entry = lookup.entry;
            if (entry.kind(rfs) == .file) {
                info.package_json = r.parsePackageJSON(path, if (FeatureFlags.store_file_descriptors) fd else 0) catch null;

                if (info.package_json) |pkg| {
                    if (pkg.browser_map.count() > 0) {
                        info.enclosing_browser_scope = result.index;
                        info.package_json_for_browser_field = pkg;
                    }
                    info.enclosing_package_json = pkg;

                    if (r.debug_logs) |*logs| {
                        logs.addNoteFmt("Resolved package.json in \"{s}\"", .{
                            path,
                        }) catch unreachable;
                    }
                }
            }
        }

        // Record if this directory has a tsconfig.json or jsconfig.json file
        {
            var tsconfig_path: ?string = null;
            if (r.opts.tsconfig_override == null) {
                if (entries.getComptimeQuery("tsconfig.json")) |lookup| {
                    const entry = lookup.entry;
                    if (entry.kind(rfs) == .file) {
                        const parts = [_]string{ path, "tsconfig.json" };

                        tsconfig_path = FileSystem.instance.absBuf(&parts, &dir_info_uncached_filename_buf);
                    }
                }
                if (tsconfig_path == null) {
                    if (entries.getComptimeQuery("jsconfig.json")) |lookup| {
                        const entry = lookup.entry;
                        if (entry.kind(rfs) == .file) {
                            const parts = [_]string{ path, "jsconfig.json" };
                            tsconfig_path = FileSystem.instance.absBuf(&parts, &dir_info_uncached_filename_buf);
                        }
                    }
                }
            } else if (parent == null) {
                tsconfig_path = r.opts.tsconfig_override.?;
            }

            if (tsconfig_path) |tsconfigpath| {
                info.tsconfig_json = r.parseTSConfig(
                    tsconfigpath,
                    if (FeatureFlags.store_file_descriptors) fd else 0,
                ) catch |err| brk: {
                    const pretty = r.prettyPath(Path.init(tsconfigpath));

                    if (err == error.ENOENT) {
                        r.log.addErrorFmt(null, logger.Loc.Empty, r.allocator, "Cannot find tsconfig file \"{s}\"", .{pretty}) catch unreachable;
                    } else if (err != error.ParseErrorAlreadyLogged and err != error.IsDir) {
                        r.log.addErrorFmt(null, logger.Loc.Empty, r.allocator, "Cannot read file \"{s}\": {s}", .{ pretty, @errorName(err) }) catch unreachable;
                    }
                    break :brk null;
                };
                info.enclosing_tsconfig_json = info.tsconfig_json;
            }
        }
    }
};

pub const Dirname = struct {
    pub fn dirname(path: string) string {
        if (path.len == 0)
            return "/";

        var end_index: usize = path.len - 1;
        while (path[end_index] == '/') {
            if (end_index == 0)
                return "/";
            end_index -= 1;
        }

        while (path[end_index] != '/') {
            if (end_index == 0)
                return "/";
            end_index -= 1;
        }

        if (end_index == 0 and path[0] == '/')
            return path[0..1];

        if (end_index == 0)
            return "/";

        return path[0 .. end_index + 1];
    }
};

test "murmur" {
    var str = try std.heap.c_allocator.alloc(u8, "swiper@6.8.2swiper.cjs.js".len);
    var str2 = try std.heap.c_allocator.alloc(u8, "swiper@6.8.2swiper.cjs.js".len);
    std.mem.copy(u8, str, "swiper@6.8.2swiper.cjs.js");
    std.mem.copy(u8, str2, "swiper@6.8.2swiper.cjs.js");

    try std.testing.expectEqual(
        std.hash.murmur.Murmur3_32.hash(str),
        std.hash.murmur.Murmur3_32.hash(str2),
    );
}

pub const RootPathPair = struct {
    base_path: string,
    package_json: *const PackageJSON,
};