// Render the corporate identity band used by the delivery package.
//
// The band is the same assets/header.html the PDF is printed with, captured as
// an image so its ribbon geometry survives into Word, where it is placed in a
// real page header instead of being reconstructed in the body.
import fs from 'node:fs/promises';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import { chromium } from 'playwright';

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

export const BAND_MM = { width: 210, height: 27 };
const SCALE = 3;   // the band is drawn at 3x so it stays crisp in print

const applyTemplate = (template, values) => template.replace(/{{(\w+)}}/g, (_, key) => values[key] ?? '');
const slug = (title) => title.replace(/[^\w-]+/g, '-').replace(/^-|-$/g, '').toLowerCase() || 'band';

async function markdownFiles(directory) {
  const entries = await fs.readdir(directory, { withFileTypes: true });
  const results = await Promise.all(entries.map(async (entry) => {
    const target = path.join(directory, entry.name);
    if (entry.isDirectory()) return markdownFiles(target);
    return entry.isFile() && entry.name.endsWith('.md') ? [target] : [];
  }));
  return results.flat();
}

async function main() {
  const [sourceRoot, outputRoot] = process.argv.slice(2);
  if (!sourceRoot || !outputRoot) throw new Error('Usage: render-ci-band.mjs SOURCE_DIRECTORY OUTPUT_DIRECTORY');

  const [template, logo] = await Promise.all([
    fs.readFile(path.join(assets, 'header.html'), 'utf8'),
    fs.readFile(path.join(root, 'app/assets/images/logo.svg'))
  ]);
  const values = {
    logoPath: `data:image/svg+xml;base64,${logo.toString('base64')}`,
    ciBlue: '#0797d5',
    ciGrey: '#8e8e8e'   // ribbon grey measured from the audited reference documents
  };

  await fs.mkdir(outputRoot, { recursive: true });
  const sources = (await markdownFiles(sourceRoot)).sort();
  const bands = {};
  const rendered = new Map();

  const browser = await chromium.launch({ headless: true });
  try {
    const page = await browser.newPage({ deviceScaleFactor: SCALE });
    for (const source of sources) {
      const markdown = await fs.readFile(source, 'utf8');
      const title = markdown.match(/^#\s+(.+)$/m)?.[1]?.trim() ?? 'BRN WMS';
      const footer = markdown.match(/^<!--\s*footer:\s*(.+?)\s*-->\s*$/m)?.[1] ?? '';

      if (!rendered.has(title)) {
        const file = path.join(outputRoot, `${slug(title)}.png`);
        await page.setContent(
          '<!doctype html><meta charset="utf-8"><body style="margin:0;background:#fff">' +
          `<div id="band" style="width:${BAND_MM.width}mm;height:${BAND_MM.height}mm;overflow:hidden;position:relative">` +
          `${applyTemplate(template, { ...values, documentTitle: title })}</div></body>`,
          { waitUntil: 'networkidle' }
        );
        await page.locator('#band').screenshot({ type: 'png', path: file });
        rendered.set(title, file);
      }

      bands[path.relative(sourceRoot, source)] = { title, footer, band: rendered.get(title) };
    }
  } finally {
    await browser.close();
  }

  await fs.writeFile(path.join(outputRoot, 'bands.json'), `${JSON.stringify(bands, null, 2)}\n`);
  console.log(`${rendered.size} band${rendered.size === 1 ? '' : 's'} rendered for ${sources.length} documents`);
}

main().catch((error) => { console.error(error); process.exit(1); });