#!/usr/bin/env bun
// Generates src/apps/officer-web/index.gen.html from index.html, substituting __PUBLIC_URL__ with
// PUBLIC_URL from .env.
//
// The OpenGraph tags need absolute URLs — crawlers fetch the page standalone and cannot resolve
// relative ones — but hardcoding the domain forces every deployment to carry its own edit of
// index.html. Bun's HTML import offers no substitution hook, so the swap happens here and the server
// imports the generated file. index.gen.html is gitignored; index.html is the tracked template and
// is identical on every instance.

import { existsSync } from 'node:fs';
import { dirname, join, resolve } from 'node:path';
import { fileURLToPath } from 'node:url';

const root = resolve(dirname(fileURLToPath(import.meta.url)), '..');
const template = join(root, 'src/apps/officer-web/index.html');
const output = join(root, 'src/apps/officer-web/index.gen.html');

// Where the URL comes from, most specific first:
//
//   1. the first argument   `bun gen:index https://officer.example.com`
//   2. PUBLIC_URL in the environment
//   3. PUBLIC_URL in .env    (this script runs standalone; the server gets it via --env-file)
//
// The argument exists so changing the public address is one command rather than an edit plus a
// regenerate — and so a second address can be generated for without touching the install's own .env.
const argUrl = process.argv[2]?.trim();

const envPath = join(root, '.env');
if (!argUrl && !process.env.PUBLIC_URL && existsSync(envPath)) {
  for (const line of (await Bun.file(envPath).text()).split('\n')) {
    const match = line.match(/^\s*PUBLIC_URL\s*=\s*(.*)$/);
    if (match) process.env.PUBLIC_URL = match[1]!.trim().replace(/^["']|["']$/g, '');
  }
}

const publicUrl = (argUrl || process.env.PUBLIC_URL || '').replace(/\/+$/, '');
if (!publicUrl) {
  console.error('[gen-index] no public URL. Pass one — `bun gen:index https://officer.example.com` —');
  console.error('[gen-index] or set PUBLIC_URL in .env.');
  process.exit(1);
}

// Caught here rather than left to a crawler: a relative or scheme-less value substitutes without
// complaint and produces OpenGraph tags nothing can resolve, which is invisible until someone shares a
// link and the preview is blank.
try {
  const parsed = new URL(publicUrl);
  if (parsed.protocol !== 'http:' && parsed.protocol !== 'https:') throw new Error('not http(s)');
} catch {
  console.error(`[gen-index] "${publicUrl}" is not an absolute http(s) URL — OpenGraph tags need one.`);
  process.exit(1);
}

const html = await Bun.file(template).text();
const generated = html.replaceAll('__PUBLIC_URL__', publicUrl);

if (generated.includes('__PUBLIC_URL__')) {
  console.error('[gen-index] substitution left placeholders behind');
  process.exit(1);
}

// Only write when the content actually changes, so `bun --watch` does not restart in a loop.
if (existsSync(output) && (await Bun.file(output).text()) === generated) {
  console.log(`[gen-index] up to date (${publicUrl})`);
} else {
  await Bun.write(output, generated);
  console.log(`[gen-index] wrote index.gen.html (${publicUrl})`);
}
