// App version + «what changed» notes, baked into each front-end at build time.
//
// Version: the build number is the commit count of HEAD, so it only ever goes
// up and needs no file to bump. It is compiled into the bundle (__APP_BUILD__)
// and written to dist/version.json; the running app polls that file and, when
// the server's build is newer than its own, shows the update modal.
//
// Notes come from commit messages. Technical text is never shown: only lines
// that start with a Persian tag, written for the person using that part:
//
//   اپ: …      the customer app
//   اپ۱: …     user-app (alias of اپ)
//   پنل: …     the admin panel
//
// A commit may carry several such lines. Each app shows only its own.

import { execFileSync } from 'node:child_process';

const TAGS = {
  'user-app': ['اپ', 'اپ۱', 'اپ1'],
  'admin-panel': ['پنل'],
};

/** How many released builds with notes the file keeps. */
const HISTORY = 30;

function git(args, cwd) {
  return execFileSync('git', args, { cwd, encoding: 'utf8', stdio: ['ignore', 'pipe', 'ignore'] });
}

/** Pure, for testing: the note lines in one commit message that belong to `app`. */
export function notesFor(app, message) {
  const tags = TAGS[app] ?? [];
  const out = [];
  for (const raw of message.split(/\r?\n/)) {
    const m = /^\s*([^\s:：]+)\s*[:：]\s*(.+?)\s*$/.exec(raw);
    // The note must be Persian: a wrapped English line that happens to begin
    // with a tag (e.g. in a commit body explaining the tags) is not a note.
    if (m && tags.includes(m[1]) && /[؀-ۿ]/.test(m[2])) out.push(m[2]);
  }
  return out;
}

export function computeAppVersion(app, cwd = process.cwd()) {
  const builtAt = new Date().toISOString();
  try {
    const build = Number(git(['rev-list', '--count', 'HEAD'], cwd).trim());
    const commit = git(['rev-parse', '--short', 'HEAD'], cwd).trim();
    // Newest first; a record separator between commits, unit separator between fields.
    const log = git(['log', '-n', '400', '--format=%ct%x1f%B%x1e'], cwd);
    const history = [];
    log.split('\x1e').forEach((rec, i) => {
      const [ts, body] = rec.replace(/^\s+/, '').split('\x1f');
      if (!body) return;
      const notes = notesFor(app, body);
      if (!notes.length) return;
      history.push({ build: build - i, date: new Date(Number(ts) * 1000).toISOString(), notes });
    });
    return { app, build, version: `1.${build}`, commit, builtAt, history: history.slice(0, HISTORY) };
  } catch {
    // Not a git checkout (e.g. a copied tree): still a valid, if note-less, build.
    const build = Math.floor(Date.now() / 1000);
    return { app, build, version: `1.${build}`, commit: null, builtAt, history: [] };
  }
}

/**
 * Vite plugin: defines __APP_BUILD__ / __APP_VERSION__ and emits version.json.
 * The dev server has no version.json, so the update check stays quiet there.
 */
export function appVersion(app) {
  const info = computeAppVersion(app);
  return {
    name: 'app-version',
    config() {
      return {
        define: {
          __APP_BUILD__: JSON.stringify(info.build),
          __APP_VERSION__: JSON.stringify(info.version),
        },
      };
    },
    generateBundle() {
      this.emitFile({ type: 'asset', fileName: 'version.json', source: JSON.stringify(info, null, 2) });
    },
  };
}