#include "ZigSourceProvider.h"
#include "helpers.h"
#include "root.h"
#include <JavaScriptCore/BytecodeCacheError.h>
#include <JavaScriptCore/CodeCache.h>

#include <JavaScriptCore/Completion.h>
#include <sys/stat.h>
#include <wtf/FileSystem.h>
#include <wtf/Scope.h>
#include <wtf/text/StringHash.h>

namespace Zig {

using Base = JSC::SourceProvider;
using BytecodeCacheGenerator = JSC::BytecodeCacheGenerator;
using UnlinkedFunctionExecutable = JSC::UnlinkedFunctionExecutable;
using CachedBytecode = JSC::CachedBytecode;
using UnlinkedFunctionCodeBlock = JSC::UnlinkedFunctionCodeBlock;
using SourceCode = JSC::SourceCode;
using CodeSpecializationKind = JSC::CodeSpecializationKind;
using SourceOrigin = JSC::SourceOrigin;
using String = WTF::String;
using SourceProviderSourceType = JSC::SourceProviderSourceType;

Ref<SourceProvider> SourceProvider::create(ResolvedSource resolvedSource)
{
    void* allocator = resolvedSource.allocator;

    WTF::StringImpl* stringImpl = nullptr;
    if (allocator) {
        Ref<WTF::ExternalStringImpl> stringImpl_ = WTF::ExternalStringImpl::create(
            resolvedSource.source_code.ptr, resolvedSource.source_code.len,
            [allocator](WTF::ExternalStringImpl* str, void* ptr, unsigned int len) {
                ZigString__free((const unsigned char*)ptr, len, allocator);
            });
        return adoptRef(*new SourceProvider(
            resolvedSource, reinterpret_cast<WTF::StringImpl*>(stringImpl_.ptr()),
            JSC::SourceOrigin(WTF::URL::fileURLWithFileSystemPath(toString(resolvedSource.source_url))),
            toStringNotConst(resolvedSource.source_url), TextPosition(),
            JSC::SourceProviderSourceType::Module));

    } else {
        Ref<WTF::ExternalStringImpl> stringImpl_ = WTF::ExternalStringImpl::createStatic(
            resolvedSource.source_code.ptr, resolvedSource.source_code.len);
        return adoptRef(*new SourceProvider(
            resolvedSource, reinterpret_cast<WTF::StringImpl*>(stringImpl_.ptr()),
            JSC::SourceOrigin(WTF::URL::fileURLWithFileSystemPath(toString(resolvedSource.source_url))),
            toStringNotConst(resolvedSource.source_url), TextPosition(),
            JSC::SourceProviderSourceType::Module));
    }
}

unsigned SourceProvider::getHash()
{
    if (m_hash) {
        return m_hash;
    }

    m_hash = WTF::StringHash::hash(m_source.get());
    return m_hash;
}

void SourceProvider::freeSourceCode()
{
    if (did_free_source_code) {
        return;
    }
    did_free_source_code = true;
    if (m_resolvedSource.allocator != 0) { // // WTF::ExternalStringImpl::destroy(m_source.ptr());
        this->m_source = WTF::StringImpl::empty()->isolatedCopy();
        this->m_hash = 0;
        m_resolvedSource.allocator = 0;
    }
    // if (m_resolvedSource.allocator != 0) {
    //   ZigString__free(m_resolvedSource.source_code.ptr, m_resolvedSource.source_code.len,
    //                   m_resolvedSource.allocator);
    // }
}

void SourceProvider::updateCache(const UnlinkedFunctionExecutable* executable, const SourceCode&,
    CodeSpecializationKind kind,
    const UnlinkedFunctionCodeBlock* codeBlock)
{
    if (!m_resolvedSource.bytecodecache_fd || !m_cachedBytecode)
        return;

    JSC::BytecodeCacheError error;
    RefPtr<JSC::CachedBytecode> cachedBytecode = JSC::encodeFunctionCodeBlock(executable->vm(), codeBlock, error);
    if (cachedBytecode && !error.isValid())
        m_cachedBytecode->addFunctionUpdate(executable, kind, *cachedBytecode);
}

void SourceProvider::cacheBytecode(const BytecodeCacheGenerator& generator)
{
    if (!m_resolvedSource.bytecodecache_fd)
        return;

    if (!m_cachedBytecode)
        m_cachedBytecode = JSC::CachedBytecode::create();
    auto update = generator();
    if (update)
        m_cachedBytecode->addGlobalUpdate(*update);
}
void SourceProvider::commitCachedBytecode()
{
    if (!m_resolvedSource.bytecodecache_fd || !m_cachedBytecode || !m_cachedBytecode->hasUpdates())
        return;

    auto clearBytecode = WTF::makeScopeExit([&] { m_cachedBytecode = nullptr; });
    const auto fd = m_resolvedSource.bytecodecache_fd;

    auto fileSize = FileSystem::fileSize(fd);
    if (!fileSize)
        return;

    size_t cacheFileSize;
    if (!WTF::convertSafely(*fileSize, cacheFileSize) || cacheFileSize != m_cachedBytecode->size()) {
        // The bytecode cache has already been updated
        return;
    }

    if (!FileSystem::truncateFile(fd, m_cachedBytecode->sizeForUpdate()))
        return;

    m_cachedBytecode->commitUpdates([&](off_t offset, const void* data, size_t size) {
        long long result = FileSystem::seekFile(fd, offset, FileSystem::FileSeekOrigin::Beginning);
        ASSERT_UNUSED(result, result != -1);
        size_t bytesWritten = static_cast<size_t>(FileSystem::writeToFile(fd, data, size));
        ASSERT_UNUSED(bytesWritten, bytesWritten == size);
    });
}

bool SourceProvider::isBytecodeCacheEnabled() const
{
    return m_resolvedSource.bytecodecache_fd > 0;
}

void SourceProvider::readOrGenerateByteCodeCache(JSC::VM& vm, const JSC::SourceCode& sourceCode)
{
    auto status = this->readCache(vm, sourceCode);
    switch (status) {
    case -1: {
        m_resolvedSource.bytecodecache_fd = 0;
        break;
    }
    case 0: {
        JSC::BytecodeCacheError err;
        m_cachedBytecode = JSC::generateModuleBytecode(vm, sourceCode, m_resolvedSource.bytecodecache_fd, err);

        if (err.isValid()) {
            m_resolvedSource.bytecodecache_fd = 0;
            m_cachedBytecode = JSC::CachedBytecode::create();
        }
    }
    // TODO: read the bytecode into a JSC::SourceCode object here
    case 1: {
    }
    }
}
int SourceProvider::readCache(JSC::VM& vm, const JSC::SourceCode& sourceCode)
{
    if (m_resolvedSource.bytecodecache_fd == 0)
        return -1;
    if (!FileSystem::isHandleValid(m_resolvedSource.bytecodecache_fd))
        return -1;
    const auto fd = m_resolvedSource.bytecodecache_fd;

    bool success;
    FileSystem::MappedFileData mappedFile(fd, FileSystem::MappedFileMode::Shared, success);
    if (!success)
        return -1;

    const uint8_t* fileData = reinterpret_cast<const uint8_t*>(mappedFile.data());
    unsigned fileTotalSize = mappedFile.size();
    if (fileTotalSize == 0)
        return 0;

    Ref<JSC::CachedBytecode> cachedBytecode = JSC::CachedBytecode::create(WTFMove(mappedFile));
    // auto key = JSC::sourceCodeKeyForSerializedModule(vm, sourceCode);
    // if (isCachedBytecodeStillValid(vm, cachedBytecode.copyRef(), key,
    //                                JSC::SourceCodeType::ModuleType)) {
    m_cachedBytecode = WTFMove(cachedBytecode);
    return 1;
    // } else {
    //   FileSystem::truncateFile(fd, 0);
    //   return 0;
    // }
}
}; // namespace Zig