// The web reader's own block list for EPUBs, from the real app code (static/js/app/40-epub.js
// parseEpub + the reader's block selector) in headless Chromium. Reference for compare_blocks.py.
//
//   node web_blocks.cjs <diora-web checkout> <out.json> book.epub [more.epub ...]
//
// Needs playwright-core (e.g. NODE_PATH=<diora-web>/node_modules) and a Chromium
// (PLAYWRIGHT_BROWSERS_PATH as for the e2e tests).
const fs = require('fs');
const path = require('path');
const { chromium } = require('playwright-core');

(async () => {
  const [web, out, ...books] = process.argv.slice(2);
  const browser = await chromium.launch();
  const page = await browser.newPage();
  await page.goto('about:blank');
  await page.addScriptTag({ path: path.join(web, 'static/js/jszip.min.js') });
  await page.addScriptTag({ path: path.join(web, 'static/js/app/40-epub.js') });
  const result = {};
  for (const file of books) {
    const b64 = fs.readFileSync(file).toString('base64');
    result[file] = await page.evaluate(async (b64) => {
      const bin = Uint8Array.from(atob(b64), (c) => c.charCodeAt(0));
      const book = await parseEpub(bin.buffer);
      const el = document.createElement('div');
      el.innerHTML = book.chapters.join('');
      document.body.appendChild(el);
      const SEL = 'p, h1, h2, h3, h4, h5, h6, li, blockquote, dt, dd, figcaption, div:not(:has(*))'; // EPUB_BLOCK_SELECTOR, 44-books.js
      const blocks = Array.from(el.querySelectorAll(SEL));
      const chapters = Array.from(el.querySelectorAll('[data-epub-src]'));
      // _bookCharIndex (44-books.js): offset of each block's first text node among all text nodes
      const offsets = new Map();
      let pos = 0;
      const walker = document.createTreeWalker(el, NodeFilter.SHOW_TEXT);
      for (let n; (n = walker.nextNode());) { offsets.set(n, pos); pos += n.nodeValue.length; }
      const starts = [];
      blocks.forEach((b, i) => {
        const first = document.createTreeWalker(b, NodeFilter.SHOW_TEXT).nextNode();
        starts[i] = first ? offsets.get(first) : (i ? starts[i - 1] + blocks[i - 1].textContent.length : 0);
      });
      const res = blocks.map((b, i) => ({
        start: starts[i],
        tag: b.tagName.toLowerCase(),
        text: b.textContent.replace(/\s+/g, ' ').trim(),
        len: b.textContent.length,
        ch: chapters.findIndex((c) => c.contains(b)),
      }));
      el.remove();
      return { title: book.title, chapters: chapters.length, total: pos || 1, blocks: res };
    }, b64);
    console.error(path.basename(file), result[file].blocks.length, 'blocks');
  }
  fs.writeFileSync(out, JSON.stringify(result));
  await browser.close();
})().catch((e) => { console.error(e); process.exit(1); });