import { mkdir, readFile, writeFile } from 'node:fs/promises';
import { createRequire } from 'node:module';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
const require = createRequire(path.join(repoRoot, 'assets/admin/package.json'));
const { transform } = require('esbuild');
const cssBuildDir = path.join(repoRoot, 'assets/css/build');
const jsBuildDir = path.join(repoRoot, 'assets/js/build');

const cssBundles = {
  // bootstrap / fontawesome5 / main.min.css 由 PHP 单独入队，不在此重复打包。
  'public.css': [
    'style.css',
    'assets/css/core/tokens.css',
    'assets/css/core/reset.css',
    'assets/css/core/typography.css',
    'assets/css/core/buttons.css',
    'assets/css/core/forms.css',
    'assets/css/core/alerts.css',
    'assets/css/core/animations.css',
    'assets/css/core/components-ext.css',
    'assets/css/core/color-utilities.css',
    'assets/css/frontend/base.css',
    'assets/css/frontend/header-userbox.css',
    'assets/css/frontend/card-primitives.css',
    'assets/css/frontend/overlay-primitives.css',
    'assets/css/frontend/layout.css',
    'assets/css/frontend/footer.css',
    'assets/css/frontend/floating-buttons.css',
    'assets/css/frontend/enhancements.css',
    'assets/css/frontend/empty-state.css',
    'assets/css/frontend/pagination.css',
    'assets/css/frontend/modal-runtime.css',
    'assets/css/frontend/notyf.css',
    'assets/css/shared/captcha.css',
    'assets/css/frontend/single-post/rewards.css',
  ],
  'homepage.css': [
    'assets/css/frontend/post-card.css',
    'assets/css/frontend/sidebar.css',
    'assets/css/frontend/breadcrumb.css',
    'assets/css/frontend/homepage-fixed/base.css',
  ],
  'single.css': [
    'assets/css/frontend/legacy-utilities.css',
    'assets/css/frontend/single-post/shell.css',
    'assets/css/frontend/single-post/content.css',
    'assets/css/frontend/single-post/author-actions.css',
  ],
  'comments.css': [
    'assets/css/frontend/comments/layout.css',
    'assets/css/frontend/comments/shell.css',
    'assets/css/frontend/comments/mobile-item.css',
  ],
};

const runtimePreludeScripts = [
  'assets/js/notyf.js',
  'assets/js/core/modal-telemetry.js',
  'assets/js/core/request.js',
  'assets/js/core/modal-cache.js',
  'assets/js/core/modal-state.js',
  'assets/js/core/modal-runtime.js',
  'assets/js/core/modal-triggers.js',
  'assets/js/core/article.js',
  'assets/js/core/comments.js',
  'assets/js/core/comment-fixed-input.js',
  'assets/js/core/comment-move-form.js',
  'assets/js/core/ajax-list.js',
  'assets/js/core/pagination.js',
  'assets/js/core/archive.js',
  'assets/js/core/footer-tabbar.js',
  'assets/js/core/misc.js',
  'assets/js/core/theme.js',
  'assets/js/follow.js',
  'assets/js/enhancements.js',
  'assets/js/enhancements2.js',
  'assets/js/color-extract.js',
  'assets/js/effects.js',
  'assets/js/captcha-front.js',
  'assets/js/instant-page.js',
];

const imgboxScripts = [
  'assets/js/runtime/imgbox.js',
];

function normalizePath(filePath) {
  return filePath.split(path.sep).join('/');
}

function rewriteCssUrls(css, sourcePath, outputPath) {
  const outputDir = path.dirname(outputPath);
  return css.replace(/url\(\s*(['"]?)([^)'"\s]+)\1\s*\)/gi, (match, quote, rawUrl) => {
    if (/^(?:data:|https?:|\/\/|\/|#|var\()/i.test(rawUrl)) {
      return match;
    }

    const suffixIndex = rawUrl.search(/[?#]/);
    const pathname = suffixIndex === -1 ? rawUrl : rawUrl.slice(0, suffixIndex);
    const suffix = suffixIndex === -1 ? '' : rawUrl.slice(suffixIndex);
    const absoluteAsset = path.resolve(path.dirname(sourcePath), pathname);
    let relativeAsset = normalizePath(path.relative(outputDir, absoluteAsset));
    if (!relativeAsset.startsWith('.')) {
      relativeAsset = `./${relativeAsset}`;
    }
    const wrapper = quote || '"';
    return `url(${wrapper}${relativeAsset}${suffix}${wrapper})`;
  });
}

async function expandCss(sourcePath, outputPath, stack = []) {
  const absoluteSource = path.resolve(sourcePath);
  if (stack.includes(absoluteSource)) {
    throw new Error(`Circular CSS import: ${normalizePath(path.relative(repoRoot, absoluteSource))}`);
  }

  const source = await readFile(absoluteSource, 'utf8');
  const importPattern = /@import\s+(?:url\(\s*)?['"]([^'"]+\.css)['"]\s*\)?\s*;/gi;
  let expanded = '';
  let cursor = 0;
  let match;

  while ((match = importPattern.exec(source)) !== null) {
    expanded += rewriteCssUrls(source.slice(cursor, match.index), absoluteSource, outputPath);
    const importedPath = path.resolve(path.dirname(absoluteSource), match[1]);
    expanded += await expandCss(importedPath, outputPath, [...stack, absoluteSource]);
    cursor = importPattern.lastIndex;
  }

  expanded += rewriteCssUrls(source.slice(cursor), absoluteSource, outputPath);
  return expanded.trimEnd();
}

async function buildCssBundle(outputName, sources) {
  const outputPath = path.join(cssBuildDir, outputName);
  const sections = [];
  for (const source of sources) {
    const sourcePath = path.join(repoRoot, source);
    sections.push(`/* source: ${source} */\n${await expandCss(sourcePath, outputPath)}`);
  }
  const bundle = `${sections.join('\n\n')}\n`;
  const minified = await transform(bundle, {
    charset: 'utf8',
    legalComments: 'inline',
    loader: 'css',
    minify: true,
    sourcefile: outputName,
  });
  const minifiedPath = outputPath.replace(/\.css$/, '.min.css');

  await Promise.all([
    writeFile(outputPath, bundle, 'utf8'),
    writeFile(minifiedPath, minified.code, 'utf8'),
  ]);
}

async function buildScriptBundle(sources, outputName) {
  const sections = [];
  for (const source of sources) {
    const content = (await readFile(path.join(repoRoot, source), 'utf8')).trimEnd();
    sections.push(`/* source: ${source} */\n${content}\n;`);
  }
  const bundle = `${sections.join('\n\n')}\n`;
  const minified = await transform(bundle, {
    charset: 'utf8',
    legalComments: 'inline',
    loader: 'js',
    // 保留原始标识符：压缩产生的 `$` 局部变量会破坏「禁用美元别名」契约。
    minifyIdentifiers: false,
    minifySyntax: true,
    minifyWhitespace: true,
    sourcefile: outputName,
  });
  await writeFile(path.join(repoRoot, outputName), minified.code, 'utf8');
}
// 评论区硬切换后 main.min.css 由 main.css 重新生成，保持两者同步。
async function buildMainMin() {
  const sourcePath = path.join(repoRoot, 'assets/css/main.css');
  const outputPath = path.join(repoRoot, 'assets/css/main.min.css');
  const source = await readFile(sourcePath, 'utf8');
  const minified = await transform(source, {
    charset: 'utf8',
    legalComments: 'inline',
    loader: 'css',
    minify: true,
    sourcefile: 'main.css',
  });
  await writeFile(outputPath, minified.code, 'utf8');
}

await mkdir(cssBuildDir, { recursive: true });
await mkdir(jsBuildDir, { recursive: true });
// 先刷新 main.min.css，public.css 打包时才能读到最新内容。
await buildMainMin();
for (const [outputName, sources] of Object.entries(cssBundles)) {
  await buildCssBundle(outputName, sources);
}
await buildScriptBundle([...runtimePreludeScripts, 'assets/js/runtime/main.js'], 'assets/js/runtime/main.min.js');
await buildScriptBundle(imgboxScripts, 'assets/js/runtime/imgbox.min.js');

console.log('Built public CSS and runtime JS bundles.');