// Builds the pages ipx serves: each page's TypeScript from web/src, types stripped and minified
// by swc into a script of its own (app.js, login.js), and the page minified, its
// <script data-src> pointing at that script. build.rs runs it into OUT_DIR, where web.rs
// include_str!s the results, so the binary still carries everything and nothing is served
// from disk.
//
// The page names its script with a hash of the script's contents, /app.js?v=<hash>, and the
// server lets a browser keep that for a year without asking again. A changed script is a new
// URL, and the page, which the browser checks on every visit, is what carries it.
//
//   node web/build.mjs [out-dir]      default out-dir: web/dist
import crypto from 'node:crypto';
import fs from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import swc from '@swc/core';
import html from '@swc/html';

const here = path.dirname(fileURLToPath(import.meta.url));

// The files are one script, concatenated in this order, not modules: they share one top-level
// scope, as the single inline script did, and code that runs at load needs what came before it.
const PAGES = {
  'index.html': { script: 'app.js', src: ['util', 'theme', 'feeds', 'feedpage', 'items', 'player', 'dialogs', 'gestures', 'events'] },
  'login.html': { script: 'login.js', src: ['login'] },
};

/// The page and its script, built: { html, js, script }, where script is the file's name.
export function buildPage(name, { minify = true } = {}) {
  const { script, src: files } = PAGES[name];
  const src = files.map(f => fs.readFileSync(path.join(here, 'src', f + '.ts'), 'utf8')).join('\n');
  const js = swc.transformSync(src, {
    filename: name + '.ts',
    jsc: {
      parser: { syntax: 'typescript' },
      target: 'es2022',
      // Top-level names stay as they are: markup calls some of them by name (onclick="closeModal()")
      // and the browser tests reach others (player, savePos) through page.evaluate.
      minify: minify ? { compress: { toplevel: false }, mangle: { toplevel: false } } : undefined,
    },
    isModule: false,
    minify,
  }).code;
  const page = fs.readFileSync(path.join(here, name), 'utf8');
  const marker = /<script data-src="[^"]*"><\/script>/;
  if (!marker.test(page)) throw new Error(`${name} has no <script data-src> to put its script in`);
  const v = crypto.createHash('sha256').update(js).digest('hex').slice(0, 12);
  // Where the inline script was, and a plain <script src>, so it still runs in the same place:
  // after the markup it wires up, before anything else.
  const out = page.replace(marker, `<script src="/${script}?v=${v}"></script>`);
  if (!minify) return { html: out, js, script };
  const r = html.minifySync(out, { minifyJs: false, minifyCss: true, removeComments: true });
  const bad = (r.errors || []).filter(e => e.level === 'Error');
  if (bad.length) throw new Error(`${name}: ${bad.map(e => e.message).join('; ')}`);
  return { html: r.code, js, script };
}

if (process.argv[1] === fileURLToPath(import.meta.url)) {
  const out = process.argv[2] || path.join(here, 'dist');
  fs.mkdirSync(out, { recursive: true });
  for (const name of Object.keys(PAGES)) {
    const { html, js, script } = buildPage(name);
    fs.writeFileSync(path.join(out, name), html);
    fs.writeFileSync(path.join(out, script), js);
  }
}