import esbuild from 'esbuild';
import { cpSync, mkdirSync, readFileSync, writeFileSync, existsSync, rmSync, readdirSync, statSync } from 'fs';
import { join, relative } from 'path';
import { createHash } from 'crypto';
import { execSync } from 'child_process';

const webDir = import.meta.dirname;
const repoDir = join(webDir, '..');
const srcDir = join(webDir, 'src');
const distDir = join(webDir, 'dist');
const isDev = process.argv.includes('--dev');

// Clean dist/
if (existsSync(distDir)) rmSync(distDir, { recursive: true });
mkdirSync(distDir, { recursive: true });

// Build JS bundle
await esbuild.build({
    entryPoints: [join(srcDir, 'js', 'app.js')],
    bundle: true,
    format: 'iife',
    target: ['es2020'],
    outfile: join(distDir, 'bundle.js'),
    minify: !isDev,
    sourcemap: isDev,
    logLevel: 'warning',
});

// Copy all of src/ to dist/, skipping js/ (bundled separately), css/ (minified), and index.html (generated)
function copyDir(src, dst, skip = new Set()) {
    mkdirSync(dst, { recursive: true });
    for (const entry of readdirSync(src)) {
        if (skip.has(entry)) continue;
        const srcPath = join(src, entry);
        const dstPath = join(dst, entry);
        if (statSync(srcPath).isDirectory()) {
            copyDir(srcPath, dstPath);
        } else {
            cpSync(srcPath, dstPath);
        }
    }
}
copyDir(srcDir, distDir, new Set(['js', 'css', 'index.html']));

// Minify CSS
mkdirSync(join(distDir, 'css'), { recursive: true });
const cssSrc = readFileSync(join(srcDir, 'css', 'style.css'), 'utf-8');
const { code: cssMinified } = await esbuild.transform(cssSrc, {
    loader: 'css',
    minify: !isDev,
});
writeFileSync(join(distDir, 'css', 'style.css'), cssMinified);

// Copy worker files from src/js/ (not bundled, served separately)
mkdirSync(join(distDir, 'js'), { recursive: true });

// Copy wasm_exec.js as-is
const wasmExecSrc = join(srcDir, 'js', 'wasm_exec.js');
if (existsSync(wasmExecSrc)) {
    cpSync(wasmExecSrc, join(distDir, 'js', 'wasm_exec.js'));
}

// Copy patch-worker.js with WASM hash injected
const workerSrc = join(srcDir, 'js', 'patch-worker.js');
if (existsSync(workerSrc)) {
    let workerContent = readFileSync(workerSrc, 'utf-8');
    const wasmFile = join(distDir, 'wasm', 'kobopatch.wasm');
    if (existsSync(wasmFile)) {
        const wasmHash = createHash('md5').update(readFileSync(wasmFile)).digest('hex').slice(0, 8);
        workerContent = workerContent.replace(
            "kobopatch.wasm'",
            `kobopatch.wasm?h=${wasmHash}'`
        );
    }
    writeFileSync(join(distDir, 'js', 'patch-worker.js'), workerContent);
}

// Get git version string
let versionStr = 'unknown';
let versionHash = 'unknown';
try {
    const hash = String(execSync('git rev-parse --short HEAD', { cwd: repoDir })).trim();
    versionHash = hash;

    let tag = '';
    try {
        tag = String(execSync('git describe --tags --exact-match', { cwd: repoDir, stdio: 'ignore' })).trim();
    } catch {}
    if (tag) {
        versionStr = tag;
    } else {
        const dirty = String(execSync('git status --porcelain', { cwd: repoDir })).trim();
        versionStr = dirty ? `${hash} (D)` : hash;
    }
} catch {}

// Generate cache-busted index.html
const bundleContent = readFileSync(join(distDir, 'bundle.js'));
const bundleHash = createHash('md5').update(bundleContent).digest('hex').slice(0, 8);

const cssContent = readFileSync(join(distDir, 'css/style.css'));
const cssHash = createHash('md5').update(cssContent).digest('hex').slice(0, 8);

let html = readFileSync(join(srcDir, 'index.html'), 'utf-8');

// Remove all <script src="js/..."> tags
html = html.replace(/\s*<script src="js\/[^"]*"><\/script>\n/g, '');
// Add the bundle script before </body>
html = html.replace(
    '</body>',
    `    <script src="/bundle.js?h=${bundleHash}"></script>\n</body>`
);

// Update CSS cache bust
html = html.replace(
    /css\/style\.css\?[^"]*/,
    `css/style.css?h=${cssHash}`
);

// Inject version string and link
html = html.replace('<span id="commit-hash"></span>', `<span id="commit-hash">${versionStr}</span>`);
html = html.replace(
    'href="https://github.com/nicoverbruggen/kobopatch-webui"',
    `href="https://github.com/nicoverbruggen/kobopatch-webui/commit/${versionHash}"`
);

writeFileSync(join(distDir, 'index.html'), html);

console.log(`Built to ${distDir} (bundle: ${bundleHash}, css: ${cssHash}, version: ${versionStr})`);

// Dev server mode
if (isDev) {
    const ctx = await esbuild.context({
        entryPoints: [join(srcDir, 'js', 'app.js')],
        bundle: true,
        format: 'iife',
        target: ['es2020'],
        outfile: join(distDir, 'bundle.js'),
        minify: false,
        sourcemap: true,
        logLevel: 'warning',
    });

    await ctx.watch();

    const { host, port } = await ctx.serve({
        servedir: distDir,
        port: 8889,
    });

    console.log(`Dev server running at http://${host}:${port}`);
}