#!/usr/bin/env node
// 將各書頁圖片整理到 pages/005/img_0_.jpg，避免全書共用 3 張圖被覆寫。
import crypto from 'node:crypto';
import fs from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const ROOT = path.resolve(__dirname, '..', '..');
const PATTERNS_DIR = path.join(ROOT, 'content', 'raw', 'patterns');
const META_PATH = path.join(PATTERNS_DIR, 'metadata.json');

function fileMd5(filePath) {
  return crypto.createHash('md5').update(fs.readFileSync(filePath)).digest('hex');
}

function loadSharedHashes() {
  const flatDir = path.join(PATTERNS_DIR, 'images');
  const hashes = new Map();
  if (!fs.existsSync(flatDir)) return hashes;
  for (const fname of fs.readdirSync(flatDir)) {
    if (!/\.(jpe?g|png|webp)$/i.test(fname)) continue;
    hashes.set(fname, fileMd5(path.join(flatDir, fname)));
  }
  return hashes;
}

function copyIfExists(src, dest, { allowShared = false, sharedHashes = null } = {}) {
  if (!fs.existsSync(src)) return false;
  const fname = path.basename(dest);
  if (!allowShared && sharedHashes?.has(fname) && fileMd5(src) === sharedHashes.get(fname)) {
    return false;
  }
  fs.mkdirSync(path.dirname(dest), { recursive: true });
  fs.copyFileSync(src, dest);
  return true;
}

function candidateSourceDirs() {
  const dirs = [];
  if (fs.existsSync(META_PATH)) {
    try {
      const meta = JSON.parse(fs.readFileSync(META_PATH, 'utf8'));
      if (meta.output_dir) {
        dirs.push(path.resolve(PATTERNS_DIR, meta.output_dir));
        dirs.push(path.resolve(ROOT, meta.output_dir));
      }
    } catch { /* ignore */ }
  }
  dirs.push(path.join(PATTERNS_DIR, 'output'));
  dirs.push(path.join(ROOT, '短線交易日線圖大全'));
  return [...new Set(dirs)].filter((d) => fs.existsSync(d));
}

function imagesFromMd(mdPath) {
  const raw = fs.readFileSync(mdPath, 'utf8');
  return [...raw.matchAll(/!\[\]\((images\/[^)]+)\)/g)].map((m) => path.basename(m[1]));
}

function main() {
  const force = process.argv.includes('--force');
  const sources = candidateSourceDirs();
  const sharedHashes = loadSharedHashes();
  let copied = 0;
  let missing = 0;
  let skippedShared = 0;

  for (let i = 1; i <= 72; i++) {
    const pageId = String(i).padStart(3, '0');
    const mdPath = path.join(PATTERNS_DIR, `${pageId}.md`);
    if (!fs.existsSync(mdPath)) continue;
    const names = imagesFromMd(mdPath);
    if (!names.length) continue;

    const destDir = path.join(PATTERNS_DIR, 'pages', pageId);
    fs.mkdirSync(destDir, { recursive: true });

    for (const name of names) {
      const dest = path.join(destDir, name);
      if (fs.existsSync(dest)) {
        const isSharedArtifact = sharedHashes.get(name) === fileMd5(dest);
        if (isSharedArtifact) fs.unlinkSync(dest);
        else if (!force) continue;
      }

      let hit = false;
      for (const srcRoot of sources) {
        const tries = [
          path.join(srcRoot, pageId, 'images', name),
          path.join(srcRoot, `${pageId}.images`, name),
          path.join(srcRoot, 'images', pageId, name),
          path.join(srcRoot, pageId, name),
        ];
        for (const src of tries) {
          if (copyIfExists(src, dest, { sharedHashes })) {
            copied += 1;
            hit = true;
            break;
          }
        }
        if (hit) break;
      }

      if (!hit) {
        // flat images/ 是擷取器跨頁共用的檔案，不能當成該頁教材圖。
        skippedShared += 1;
        missing += 1;
      }
    }
  }

  console.log(`[repack-pattern-images] copied=${copied} missing=${missing} shared_fallback=${skippedShared}`);
  if (sources.length) console.log(`來源目錄：${sources.join(', ')}`);
  if (missing > 0 || skippedShared > 0) {
    console.log('缺少各頁專屬圖片；已略過擷取器產生的全書共用圖，避免教材顯示錯圖。');
  }
}

main();