'use strict';
const fs   = require('fs');
const path = require('path');
const db   = require('./db');

const MIGRATIONS_DIR = path.join(__dirname, 'migrations');

function init() {
  db.exec(`
    CREATE TABLE IF NOT EXISTS _migrations (
      filename   TEXT PRIMARY KEY,
      applied_at TEXT NOT NULL DEFAULT (datetime('now'))
    );
  `);
}

function listFiles() {
  if (!fs.existsSync(MIGRATIONS_DIR)) return [];
  return fs.readdirSync(MIGRATIONS_DIR)
    .filter(f => f.endsWith('.sql'))
    .sort();
}

function applied() {
  return new Set(db.prepare('SELECT filename FROM _migrations').all().map(r => r.filename));
}

function run() {
  init();
  const done    = applied();
  const files   = listFiles();
  const pending = files.filter(f => !done.has(f));

  if (pending.length === 0) {
    console.log('[migrate] Nothing to apply — schema is up to date');
    return;
  }

  for (const file of pending) {
    const sql = fs.readFileSync(path.join(MIGRATIONS_DIR, file), 'utf8');
    console.log(`[migrate] Applying ${file}...`);
    try {
      db.exec('BEGIN');
      db.exec(sql);
      db.prepare('INSERT INTO _migrations (filename) VALUES (?)').run(file);
      db.exec('COMMIT');
      console.log(`[migrate] OK: ${file}`);
    } catch (e) {
      db.exec('ROLLBACK');
      console.error(`[migrate] FAILED at ${file}: ${e.message}`);
      process.exit(1);
    }
  }

  console.log(`[migrate] Applied ${pending.length} migration(s)`);
}

/* Mark 000_baseline.sql as applied on existing DBs without running it.
   Run once per environment after first deploy of this system. */
function markBaseline() {
  init();
  const hasUsers = db.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='users'").get();
  if (hasUsers) {
    const done = applied();
    if (!done.has('000_baseline.sql')) {
      db.prepare('INSERT INTO _migrations (filename) VALUES (?)').run('000_baseline.sql');
      console.log('[migrate] Marked 000_baseline.sql as applied (existing DB — not re-run)');
    } else {
      console.log('[migrate] 000_baseline.sql already marked as applied');
    }
  } else {
    console.log('[migrate] No users table found — run `npm run migrate` first to initialize schema');
    process.exit(1);
  }
}

if (require.main === module) {
  const cmd = process.argv[2];
  if (cmd === 'bootstrap') markBaseline();
  else run();
}

module.exports = { run, markBaseline };