clean up config loading and flag merging (#2469)

3 files changed, 79 insertions, 71 deletions

diff --git a/packages/astro/src/@types/astro.ts b/packages/astro/src/@types/astro.ts
index 805317dfc..abe62b13a 100644
--- a/packages/astro/src/@types/astro.ts
+++ b/packages/astro/src/@types/astro.ts
@@ -19,6 +19,18 @@ export interface AstroComponentMetadata {
 	componentExport?: { value: string; namespace?: boolean };
 }
 
+/** The flags supported by the Astro CLI */
+export interface CLIFlags {
+	projectRoot?: string;
+	site?: string;
+	sitemap?: boolean;
+	hostname?: string;
+	port?: number;
+	config?: string;
+	experimentalStaticBuild?: boolean;
+	drafts?: boolean;
+}
+
 /**
  * Astro.* available in all components
  * Docs: https://docs.astro.build/reference/api-reference/#astro-global
@@ -115,6 +127,11 @@ export interface AstroUserConfig {
 		 * Default: false
 		 */
 		drafts?: boolean;
+		/**
+		 * Experimental: Enables "static build mode" for faster builds.
+		 * Default: false
+		 */
+		experimentalStaticBuild?: boolean;
 	};
 	/** Options for the development server run with `astro dev`. */
 	devOptions?: {
diff --git a/packages/astro/src/cli/index.ts b/packages/astro/src/cli/index.ts
index 0031a08ae..e764e96b7 100644
--- a/packages/astro/src/cli/index.ts
+++ b/packages/astro/src/cli/index.ts
@@ -15,54 +15,7 @@ import { check } from './check.js';
 import { formatConfigError, loadConfig } from '../core/config.js';
 
 type Arguments = yargs.Arguments;
-type cliCommand = 'help' | 'version' | 'dev' | 'build' | 'preview' | 'reload' | 'check';
-interface CLIState {
-	cmd: cliCommand;
-	options: {
-		projectRoot?: string;
-		site?: string;
-		sitemap?: boolean;
-		hostname?: string;
-		port?: number;
-		config?: string;
-		experimentalStaticBuild?: boolean;
-		drafts?: boolean;
-	};
-}
-
-/** Determine which action the user requested */
-function resolveArgs(flags: Arguments): CLIState {
-	const options: CLIState['options'] = {
-		projectRoot: typeof flags.projectRoot === 'string' ? flags.projectRoot : undefined,
-		site: typeof flags.site === 'string' ? flags.site : undefined,
-		sitemap: typeof flags.sitemap === 'boolean' ? flags.sitemap : undefined,
-		port: typeof flags.port === 'number' ? flags.port : undefined,
-		config: typeof flags.config === 'string' ? flags.config : undefined,
-		hostname: typeof flags.hostname === 'string' ? flags.hostname : undefined,
-		experimentalStaticBuild: typeof flags.experimentalStaticBuild === 'boolean' ? flags.experimentalStaticBuild : false,
-		drafts: typeof flags.drafts === 'boolean' ? flags.drafts : false,
-	};
-
-	if (flags.version) {
-		return { cmd: 'version', options };
-	} else if (flags.help) {
-		return { cmd: 'help', options };
-	}
-
-	const cmd = flags._[2];
-	switch (cmd) {
-		case 'dev':
-			return { cmd: 'dev', options };
-		case 'build':
-			return { cmd: 'build', options };
-		case 'preview':
-			return { cmd: 'preview', options };
-		case 'check':
-			return { cmd: 'check', options };
-		default:
-			return { cmd: 'help', options };
-	}
-}
+type CLICommand = 'help' | 'version' | 'dev' | 'build' | 'preview' | 'reload' | 'check';
 
 /** Display --help flag */
 function printHelp() {
@@ -95,24 +48,28 @@ async function printVersion() {
 	console.log(pkgVersion);
 }
 
-/** Merge CLI flags & config options (CLI flags take priority) */
-function mergeCLIFlags(astroConfig: AstroConfig, flags: CLIState['options']) {
-	if (typeof flags.sitemap === 'boolean') astroConfig.buildOptions.sitemap = flags.sitemap;
-	if (typeof flags.site === 'string') astroConfig.buildOptions.site = flags.site;
-	if (typeof flags.port === 'number') astroConfig.devOptions.port = flags.port;
-	if (typeof flags.hostname === 'string') astroConfig.devOptions.hostname = flags.hostname;
-	if (typeof flags.experimentalStaticBuild === 'boolean') astroConfig.buildOptions.experimentalStaticBuild = flags.experimentalStaticBuild;
-	if (typeof flags.drafts === 'boolean') astroConfig.buildOptions.drafts = flags.drafts;
+/** Determine which command the user requested */
+function resolveCommand(flags: Arguments): CLICommand {
+	if (flags.version) {
+		return 'version';
+	} else if (flags.help) {
+		return 'help';
+	}
+	const cmd = flags._[2];
+	const supportedCommands = new Set(['dev', 'build', 'preview', 'check']);
+	if (supportedCommands.has(cmd)) {
+		return cmd as 'dev' | 'build' | 'preview' | 'check';
+	}
+	return 'help';
 }
 
 /** The primary CLI action */
 export async function cli(args: string[]) {
 	const flags = yargs(args);
-	const state = resolveArgs(flags);
-	const options = { ...state.options };
-	const projectRoot = options.projectRoot || flags._[3];
+	const cmd = resolveCommand(flags);
+	const projectRoot = flags.projectRoot || flags._[3];
 
-	switch (state.cmd) {
+	switch (cmd) {
 		case 'help':
 			printHelp();
 			return process.exit(0);
@@ -131,8 +88,7 @@ export async function cli(args: string[]) {
 	if (flags.silent) logging.level = 'silent';
 	let config: AstroConfig;
 	try {
-		config = await loadConfig({ cwd: projectRoot, filename: options.config });
-		mergeCLIFlags(config, options);
+		config = await loadConfig({ cwd: projectRoot, flags });
 	} catch (err) {
 		if (err instanceof z.ZodError) {
 			console.error(formatConfigError(err));
@@ -142,7 +98,7 @@ export async function cli(args: string[]) {
 		process.exit(1);
 	}
 
-	switch (state.cmd) {
+	switch (cmd) {
 		case 'dev': {
 			try {
 				await devServer(config, { logging });
@@ -154,6 +110,7 @@ export async function cli(args: string[]) {
 
 			return;
 		}
+
 		case 'build': {
 			try {
 				await build(config, { logging });
@@ -163,10 +120,12 @@ export async function cli(args: string[]) {
 			}
 			return;
 		}
+
 		case 'check': {
 			const ret = await check(config);
 			return process.exit(ret);
 		}
+
 		case 'preview': {
 			try {
 				await preview(config, { logging }); // this will keep running
@@ -175,8 +134,9 @@ export async function cli(args: string[]) {
 			}
 			return;
 		}
+
 		default: {
-			throw new Error(`Error running ${state.cmd}`);
+			throw new Error(`Error running ${cmd}`);
 		}
 	}
 }
diff --git a/packages/astro/src/core/config.ts b/packages/astro/src/core/config.ts
index 6d5fd9a72..4c0b75449 100644
--- a/packages/astro/src/core/config.ts
+++ b/packages/astro/src/core/config.ts
@@ -1,4 +1,5 @@
-import type { AstroConfig, AstroUserConfig } from '../@types/astro';
+import type { AstroConfig, AstroUserConfig, CLIFlags } from '../@types/astro';
+import type { Arguments as Flags } from 'yargs-parser';
 
 import * as colors from 'kleur/colors';
 import path from 'path';
@@ -116,19 +117,47 @@ function addTrailingSlash(str: string): string {
 	return str.replace(/\/*$/, '/');
 }
 
+/** Convert the generic "yargs" flag object into our own, custom TypeScript object. */
+function resolveFlags(flags: Partial<Flags>): CLIFlags {
+	return {
+		projectRoot: typeof flags.projectRoot === 'string' ? flags.projectRoot : undefined,
+		site: typeof flags.site === 'string' ? flags.site : undefined,
+		sitemap: typeof flags.sitemap === 'boolean' ? flags.sitemap : undefined,
+		port: typeof flags.port === 'number' ? flags.port : undefined,
+		config: typeof flags.config === 'string' ? flags.config : undefined,
+		hostname: typeof flags.hostname === 'string' ? flags.hostname : undefined,
+		experimentalStaticBuild: typeof flags.experimentalStaticBuild === 'boolean' ? flags.experimentalStaticBuild : false,
+		drafts: typeof flags.drafts === 'boolean' ? flags.drafts : false,
+	};
+}
+
+/** Merge CLI flags & user config object (CLI flags take priority) */
+function mergeCLIFlags(astroConfig: AstroUserConfig, flags: CLIFlags) {
+	astroConfig.buildOptions = astroConfig.buildOptions || {};
+	astroConfig.devOptions = astroConfig.devOptions || {};
+	if (typeof flags.sitemap === 'boolean') astroConfig.buildOptions.sitemap = flags.sitemap;
+	if (typeof flags.site === 'string') astroConfig.buildOptions.site = flags.site;
+	if (typeof flags.port === 'number') astroConfig.devOptions.port = flags.port;
+	if (typeof flags.hostname === 'string') astroConfig.devOptions.hostname = flags.hostname;
+	if (typeof flags.experimentalStaticBuild === 'boolean') astroConfig.buildOptions.experimentalStaticBuild = flags.experimentalStaticBuild;
+	if (typeof flags.drafts === 'boolean') astroConfig.buildOptions.drafts = flags.drafts;
+	return astroConfig;
+}
+
 interface LoadConfigOptions {
 	cwd?: string;
-	filename?: string;
+	flags?: Flags;
 }
 
 /** Attempt to load an `astro.config.mjs` file */
-export async function loadConfig(options: LoadConfigOptions): Promise<AstroConfig> {
-	const root = options.cwd ? path.resolve(options.cwd) : process.cwd();
+export async function loadConfig(configOptions: LoadConfigOptions): Promise<AstroConfig> {
+	const root = configOptions.cwd ? path.resolve(configOptions.cwd) : process.cwd();
+	const flags = resolveFlags(configOptions.flags || {});
 	let userConfig: AstroUserConfig = {};
 	let userConfigPath: string | undefined;
 
-	if (options.filename) {
-		userConfigPath = /^\.*\//.test(options.filename) ? options.filename : `./${options.filename}`;
+	if (flags?.config) {
+		userConfigPath = /^\.*\//.test(flags.config) ? flags.config : `./${flags.config}`;
 		userConfigPath = fileURLToPath(new URL(userConfigPath, `file://${root}/`));
 	}
 	// Automatically load config file using Proload
@@ -138,7 +167,9 @@ export async function loadConfig(options: LoadConfigOptions): Promise<AstroConfi
 		userConfig = config.value;
 	}
 	// normalize, validate, and return
-	return validateConfig(userConfig, root);
+	const mergedConfig = mergeCLIFlags(userConfig, flags);
+	const validatedConfig = await validateConfig(mergedConfig, root);
+	return validatedConfig;
 }
 
 export function formatConfigError(err: z.ZodError) {