import crypto from 'node:crypto';
import fs from 'node:fs';
import path from 'node:path';
import process from 'node:process';
import { execFileSync } from 'node:child_process';
import { fileURLToPath } from 'node:url';
import postcss from 'postcss';

const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '../..');

export function analyzeCss(css) {
  const ast = postcss.parse(css);
  const result = { rules: 0, selectors: 0, declarations: 0, important: 0, selectorList: [] };
  ast.walkRules((rule) => {
    result.rules += 1;
    const selectors = rule.selectors ?? [rule.selector];
    result.selectors += selectors.length;
    result.selectorList.push(...selectors);
  });
  ast.walkDecls((declaration) => {
    result.declarations += 1;
    if (declaration.important) result.important += 1;
  });
  return result;
}

export function broadBusinessSelectors(css) {
  const findings = [];
  postcss.parse(css).walkRules((rule) => {
    for (const selector of rule.selectors ?? [rule.selector]) {
      if (/^(?:div|section|article|button|table|input|select|textarea)(?:\b|[ >+~:[.#])/.test(selector.trim())) {
        findings.push(selector);
      }
    }
  });
  return findings;
}

export function verifyGlobalCssAbsent(repoRoot) {
  const legacy = path.join(repoRoot, 'src/styles/global.css');
  if (fs.existsSync(legacy)) throw new Error('src/styles/global.css 已完成迁移，禁止重新创建');
}

function read(relativePath) {
  return fs.readFileSync(path.join(root, relativePath), 'utf8');
}

function currentCssFiles(directory) {
  return fs.readdirSync(directory, { withFileTypes: true }).flatMap((entry) => {
    const target = path.join(directory, entry.name);
    return entry.isDirectory() ? currentCssFiles(target) : entry.name.endsWith('.css') ? [target] : [];
  });
}

function changedCssFiles() {
  if (!fs.existsSync(path.join(root, '.git'))) return { base: 'archive', files: [] };
  const configuredBase = process.env.QUALITY_BASE_REF;
  let base = configuredBase || 'HEAD';
  if (!configuredBase) {
    try {
      base =
        execFileSync('git', ['merge-base', 'origin/main', 'HEAD'], { cwd: root, encoding: 'utf8' }).trim() || 'HEAD';
    } catch {
      base = 'HEAD';
    }
  }
  const tracked = execFileSync('git', ['diff', '--name-only', '--diff-filter=ACMR', base, '--', '*.css'], {
    cwd: root,
    encoding: 'utf8',
  });
  const untracked = execFileSync('git', ['ls-files', '--others', '--exclude-standard', '--', '*.css'], {
    cwd: root,
    encoding: 'utf8',
  });
  return { base, files: [...new Set(`${tracked}\n${untracked}`.split(/\r?\n/).filter(Boolean))] };
}

function baseCss(base, file) {
  try {
    return execFileSync('git', ['show', `${base}:${file}`], {
      cwd: root,
      encoding: 'utf8',
      stdio: ['ignore', 'pipe', 'ignore'],
    });
  } catch {
    return '';
  }
}

function verify() {
  verifyGlobalCssAbsent(root);
  const baseline = JSON.parse(read('tools/quality/css-governance-baseline.json'));
  const entry = read(baseline.entry);
  const imports = [...entry.matchAll(/@import\s+['"](.+?)['"]/g)].map((match) =>
    path.posix.join(path.posix.dirname(baseline.entry), match[1]).replace(/\\/g, '/'),
  );
  if (JSON.stringify(imports) !== JSON.stringify(baseline.importOrder)) {
    throw new Error('业务样式入口顺序与治理基线不一致，可能改变级联结果');
  }

  const totals = { rules: 0, selectors: 0, declarations: 0, important: 0 };
  const selectorList = [];
  for (const module of baseline.modules) {
    const css = read(module.file);
    const metrics = analyzeCss(css);
    for (const key of Object.keys(totals)) totals[key] += metrics[key];
    selectorList.push(...metrics.selectorList);
    if (metrics.important > module.important) {
      throw new Error(`${module.file} 新增了未登记的 !important`);
    }
  }
  for (const key of Object.keys(totals)) {
    if (totals[key] !== baseline.legacySource[key]) {
      throw new Error(`迁移后 CSS ${key}=${totals[key]}，与原 global.css 基线 ${baseline.legacySource[key]} 不一致`);
    }
  }
  if (JSON.stringify(selectorList) !== JSON.stringify(baseline.legacySource.selectorList)) {
    throw new Error('迁移后选择器及顺序与原 global.css 基线不一致');
  }

  const changes = changedCssFiles();
  const migratedFiles = new Set(baseline.modules.map((item) => item.file));
  for (const file of changes.files) {
    if (migratedFiles.has(file) || !fs.existsSync(path.join(root, file))) continue;
    const current = read(file);
    const previous = baseCss(changes.base, file);
    const oldBroad = new Set(broadBusinessSelectors(previous));
    const newBroad = broadBusinessSelectors(current).filter((selector) => !oldBroad.has(selector));
    if (newBroad.length) throw new Error(`${file} 新增宽泛业务标签选择器：${newBroad.join(', ')}`);
    if (analyzeCss(current).important > analyzeCss(previous).important) {
      throw new Error(`${file} 新增了未登记的 !important`);
    }
  }

  const sourceText = currentCssFiles(path.join(root, 'src'))
    .map((file) => fs.readFileSync(file, 'utf8'))
    .join('\n');
  const codeText = fs
    .readdirSync(path.join(root, 'src'), { recursive: true })
    .filter((name) => /\.(?:ts|tsx)$/.test(String(name)))
    .map((name) => fs.readFileSync(path.join(root, 'src', String(name)), 'utf8'))
    .join('\n');
  for (const file of currentCssFiles(path.join(root, 'src'))) {
    const relative = path.relative(path.join(root, 'src'), file).replace(/\\/g, '/');
    if (relative === 'styles/tokens.css' || relative === 'styles/reset.css') continue;
    if (!sourceText.includes(path.basename(file)) && !codeText.includes(path.basename(file))) {
      throw new Error(`${relative} 没有明确 import 所有者`);
    }
  }

  const duplicateCount = selectorList.length - new Set(selectorList).size;
  const digest = crypto.createHash('sha256').update(selectorList.join('\n')).digest('hex').slice(0, 12);
  console.log(
    `CSS governance verified: ${totals.rules} rules, ${totals.selectors} selectors, ${totals.declarations} declarations, ${duplicateCount} duplicate selector occurrences, order ${digest}; ${changes.files.length} changed CSS files checked from ${changes.base}.`,
  );
}

if (process.argv[1] && path.resolve(process.argv[1]) === fileURLToPath(import.meta.url)) verify();