const fs = require('fs');
const path = require('path');

function walk(dir, cb) {
  fs.readdirSync(dir, { withFileTypes: true }).forEach(d => {
    const full = path.join(dir, d.name);
    if (d.isDirectory()) walk(full, cb);
    else cb(full);
  });
}

function removeAtRuleBlocks(css, atRule) {
  // Remove occurrences like @atRule ... { ... } with brace matching
  let out = '';
  let i = 0;
  while (i < css.length) {
    const idx = css.indexOf('@' + atRule, i);
    if (idx === -1) {
      out += css.slice(i);
      break;
    }
    out += css.slice(i, idx);
    let j = idx;
    // advance past @atRule
    while (j < css.length && css[j] !== '{' && css[j] !== ';') j++;
    if (css[j] === ';') {
      // simple at-rule with semicolon, skip it
      i = j + 1;
      continue;
    }
    if (css[j] !== '{') {
      // can't find block start, bail out
      i = j;
      continue;
    }
    // now find matching closing brace
    let brace = 0;
    let k = j;
    do {
      if (css[k] === '{') brace++;
      else if (css[k] === '}') brace--;
      k++;
    } while (k < css.length && brace > 0);
    i = k; // skip whole block
  }
  return out;
}

function removeAtRuleLine(css, atRule) {
  // remove simple at-rule lines like @layer name;
  return css.replace(new RegExp('^\\s*@' + atRule + "\\s+[^;{]+;\\s*", 'gmi'), '');
}

function transformMediaRanges(css) {
  // (width >= 40rem) -> (min-width: 40rem)
  css = css.replace(/\(\s*width\s*>=\s*([^\)]+)\)/g, '(min-width: $1)');
  css = css.replace(/\(\s*width\s*<=\s*([^\)]+)\)/g, '(max-width: $1)');
  css = css.replace(/@media\s*\(\s*width\s*>\s*([^\)]+)\)/g, '@media (min-width: $1)');
  css = css.replace(/@media\s*\(\s*width\s*<\s*([^\)]+)\)/g, '@media (max-width: $1)');
  return css;
}

function processFile(file) {
  if (!file.endsWith('.wxss')) return;
  const orig = fs.readFileSync(file, 'utf8');
  let css = orig;
  // remove @supports blocks entirely (unsupported in WXSS)
  css = removeAtRuleBlocks(css, 'supports');
  // remove @layer lines and blocks
  css = removeAtRuleLine(css, 'layer');
  css = removeAtRuleBlocks(css, 'layer');
  // convert range media queries to min/max equivalents
  css = transformMediaRanges(css);
  // remove @container blocks (not supported)
  css = removeAtRuleBlocks(css, 'container');

  if (css !== orig) {
    fs.writeFileSync(file, css, 'utf8');
    console.log('Fixed', file);
  }
}

const target = path.join(__dirname, '..', 'unpackage', 'dist', 'dev', 'mp-weixin');
if (!fs.existsSync(target)) {
  console.error('Target directory not found:', target);
  process.exit(1);
}
walk(target, processFile);
console.log('Done');