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

const TAR_GZ_PATH = 'C:/Users/Carlos/Downloads/u858407019.almeiraproducciones-com.20260607074508.tar.gz';
const WP_DATA_PATH = path.join(__dirname, 'wp_extracted_data.json');
const OUT_DIR = 'C:/tmp/wp_images';

if (!fs.existsSync(OUT_DIR)) {
  fs.mkdirSync(OUT_DIR, { recursive: true });
}

function safeFileKey(relPath) {
  return relPath.replace(/[^a-zA-Z0-9._-]/g, '_');
}

async function run() {
  const wpData = JSON.parse(fs.readFileSync(WP_DATA_PATH, 'utf8'));
  const neededRelPaths = new Map(); // normalized lower relPath -> original relPath
  const neededBasenames = new Map(); // lower basename -> original relPath

  for (const post of wpData.posts) {
    if (post.imageRelPath) {
      const clean = post.imageRelPath.replace(/^\/+/, '');
      neededRelPaths.set(clean.toLowerCase(), clean);
      neededBasenames.set(path.posix.basename(clean).toLowerCase(), clean);
    }
  }

  console.log(`Total imágenes destacadas únicas requeridas por los ${wpData.posts.length} posts: ${neededRelPaths.size}`);

  let extractedCount = 0;
  let scannedFiles = 0;
  let nextLongName = null;
  let nextPaxPath = null;

  // Streaming tar reader using a growable/ring buffer list
  let chunks = [];
  let totalBuffered = 0;

  function consumeBytes(n) {
    const out = Buffer.allocUnsafe(n);
    let offset = 0;
    while (offset < n) {
      const first = chunks[0];
      const toCopy = Math.min(first.length, n - offset);
      first.copy(out, offset, 0, toCopy);
      offset += toCopy;
      if (toCopy === first.length) {
        chunks.shift();
      } else {
        chunks[0] = first.subarray(toCopy);
      }
    }
    totalBuffered -= n;
    return out;
  }

  function skipBytes(n) {
    let remaining = n;
    while (remaining > 0) {
      const first = chunks[0];
      if (first.length <= remaining) {
        remaining -= first.length;
        chunks.shift();
      } else {
        chunks[0] = first.subarray(remaining);
        remaining = 0;
      }
    }
    totalBuffered -= n;
  }

  let state = 'HEADER'; // 'HEADER' | 'DATA' | 'SKIP'
  let currentEntrySize = 0;
  let currentEntryPadded = 0;
  let currentEntryType = '0';
  let currentMatchedRel = null;

  const pendingSharpPromises = [];

  const gunzip = zlib.createGunzip({ chunkSize: 1024 * 1024 });
  const readStream = fs.createReadStream(TAR_GZ_PATH, { highWaterMark: 1024 * 1024 });
  const stream = readStream.pipe(gunzip);

  for await (const chunk of stream) {
    chunks.push(chunk);
    totalBuffered += chunk.length;

    while (true) {
      if (state === 'HEADER') {
        if (totalBuffered < 512) break;
        const header = consumeBytes(512);

        // Check empty block (end of archive)
        let allZero = true;
        for (let i = 0; i < 512; i++) {
          if (header[i] !== 0) {
            allZero = false;
            break;
          }
        }
        if (allZero) continue;

        const nameRaw = header.toString('utf8', 0, 100).replace(/\0.*$/, '');
        const sizeOctal = header.toString('ascii', 124, 136).replace(/\0.*$/, '').trim();
        const typeFlag = String.fromCharCode(header[156] || 48);
        const prefixRaw = header.toString('utf8', 345, 500).replace(/\0.*$/, '');

        let fullPath = prefixRaw ? `${prefixRaw}/${nameRaw}` : nameRaw;
        if (nextLongName) {
          fullPath = nextLongName;
          nextLongName = null;
        }
        if (nextPaxPath) {
          fullPath = nextPaxPath;
          nextPaxPath = null;
        }

        currentEntrySize = parseInt(sizeOctal, 8) || 0;
        currentEntryPadded = Math.ceil(currentEntrySize / 512) * 512;
        currentEntryType = typeFlag;

        if (typeFlag === 'L' || typeFlag === 'x') {
          state = 'DATA';
          continue;
        }

        if (typeFlag === '0' || typeFlag === '\0') {
          scannedFiles++;
          if (scannedFiles % 10000 === 0) {
            console.log(`... escaneados ${scannedFiles} archivos en tar.gz | extraídas: ${extractedCount}/${neededRelPaths.size}`);
          }

          const uploadsIdx = fullPath.indexOf('wp-content/uploads/');
          if (uploadsIdx !== -1 && currentEntrySize > 0) {
            const relInUploads = fullPath.slice(uploadsIdx + 'wp-content/uploads/'.length);
            const lowerRel = relInUploads.toLowerCase();
            const lowerBase = path.posix.basename(relInUploads).toLowerCase();

            let matched = neededRelPaths.get(lowerRel) || neededBasenames.get(lowerBase) || null;
            if (matched) {
              const outFile = path.join(OUT_DIR, safeFileKey(matched) + '.jpg');
              if (!fs.existsSync(outFile)) {
                currentMatchedRel = matched;
                state = 'DATA';
                continue;
              }
            }
          }
        }

        state = 'SKIP';
      } else if (state === 'SKIP') {
        if (totalBuffered < currentEntryPadded) break;
        if (currentEntryPadded > 0) skipBytes(currentEntryPadded);
        state = 'HEADER';
      } else if (state === 'DATA') {
        if (totalBuffered < currentEntryPadded) break;
        const dataBlock = consumeBytes(currentEntryPadded);
        const fileData = dataBlock.subarray(0, currentEntrySize);

        if (currentEntryType === 'L') {
          nextLongName = fileData.toString('utf8').replace(/\0.*$/, '');
        } else if (currentEntryType === 'x') {
          const paxStr = fileData.toString('utf8');
          const m = paxStr.match(/\d+ path=([^\n]+)\n/);
          if (m) nextPaxPath = m[1];
        } else if (currentMatchedRel) {
          const targetRel = currentMatchedRel;
          currentMatchedRel = null;
          const outFile = path.join(OUT_DIR, safeFileKey(targetRel) + '.jpg');
          extractedCount++;

          const p = sharp(fileData)
            .resize(800, 500, { fit: 'inside', withoutEnlargement: true })
            .jpeg({ quality: 80 })
            .toFile(outFile)
            .catch(() => {
              // Fallback: write raw buffer if sharp fails on an unusual image
              try { fs.writeFileSync(outFile, fileData); } catch (_) {}
            });
          pendingSharpPromises.push(p);

          if (pendingSharpPromises.length >= 50) {
            await Promise.all(pendingSharpPromises.splice(0, pendingSharpPromises.length));
          }
        }

        state = 'HEADER';
      }
    }
  }

  await Promise.all(pendingSharpPromises);
  console.log(`\n✅ Extracción de imágenes de WordPress finalizada: ${extractedCount} imágenes listas en ${OUT_DIR}`);
}

run().catch((e) => {
  console.error('Error:', e);
  process.exit(1);
});