/**
 * One-time split of legacy Gallery → gallery_prod + gallery_dev on TrueNAS PostgreSQL.
 *
 * Usage:
 *   PGPASSWORD=... PGHOST=192.168.10.122 PGUSER=postgres npm run infra:db:split-dev-prod
 *
 * Options:
 *   --copy       pg_dump legacy → gallery_prod instead of rename
 *   --skip-dev   Do not create gallery_dev
 */
const { execFileSync } = require('child_process');
const pg = require('pg');
const {
  DEV_DB_NAME,
  LEGACY_DB_NAMES,
  PROD_DB_NAME,
} = require('./db-env');

const { Client } = pg;

const args = new Set(process.argv.slice(2));
const useCopy = args.has('--copy');
const skipDev = args.has('--skip-dev');

const host = process.env.PGHOST ?? process.env.DB_HOST ?? '192.168.10.122';
const port = Number(process.env.PGPORT ?? process.env.DB_PORT ?? 5432);
const user = process.env.PGUSER ?? process.env.DB_USER ?? 'postgres';
const password = process.env.PGPASSWORD ?? process.env.DB_PASSWORD;

if (!password) {
  console.error('PGPASSWORD (or DB_PASSWORD) is required');
  process.exit(1);
}

function quoteIdent(ident) {
  return `"${ident.replace(/"/g, '""')}"`;
}

async function databaseExists(client, name) {
  const res = await client.query(
    'SELECT 1 FROM pg_database WHERE datname = $1',
    [name],
  );
  return res.rowCount > 0;
}

async function findLegacyName(client) {
  for (const name of LEGACY_DB_NAMES) {
    if (await databaseExists(client, name)) return name;
  }
  return null;
}

async function createDatabaseIfMissing(admin, name) {
  if (await databaseExists(admin, name)) {
    console.log(`Database "${name}" already exists`);
    return false;
  }
  await admin.query(`CREATE DATABASE ${quoteIdent(name)}`);
  console.log(`Created database "${name}"`);
  return true;
}

async function terminateConnections(admin, dbName) {
  await admin.query(
    `SELECT pg_terminate_backend(pid)
     FROM pg_stat_activity
     WHERE datname = $1 AND pid <> pg_backend_pid()`,
    [dbName],
  );
}

async function cloneDevFromProd(admin) {
  if (await databaseExists(admin, DEV_DB_NAME)) {
    console.log(`"${DEV_DB_NAME}" already exists — skipping dev clone`);
    return;
  }

  await terminateConnections(admin, PROD_DB_NAME);
  console.log(`Creating "${DEV_DB_NAME}" from TEMPLATE "${PROD_DB_NAME}"...`);
  await admin.query(
    `CREATE DATABASE ${quoteIdent(DEV_DB_NAME)} WITH TEMPLATE ${quoteIdent(PROD_DB_NAME)} OWNER ${quoteIdent(user)}`,
  );
  console.log(`Created "${DEV_DB_NAME}" as a full copy of "${PROD_DB_NAME}"`);
}

async function main() {
  const admin = new Client({ host, port, user, password, database: 'postgres' });
  await admin.connect();

  const legacyName = await findLegacyName(admin);
  const hasProd = await databaseExists(admin, PROD_DB_NAME);

  if (hasProd) {
    console.log(`"${PROD_DB_NAME}" already exists — skipping prod migration`);
  } else if (legacyName) {
    if (useCopy) {
      await createDatabaseIfMissing(admin, PROD_DB_NAME);
      console.log(`Copying ${legacyName} → ${PROD_DB_NAME} via pg_dump...`);
      const dump = execFileSync(
        'pg_dump',
        ['-h', host, '-p', String(port), '-U', user, '-d', legacyName, '--no-owner', '--no-acl'],
        { env: { ...process.env, PGPASSWORD: password }, encoding: 'buffer' },
      );
      execFileSync(
        'psql',
        ['-h', host, '-p', String(port), '-U', user, '-d', PROD_DB_NAME, '-v', 'ON_ERROR_STOP=1'],
        { env: { ...process.env, PGPASSWORD: password }, input: dump, stdio: ['pipe', 'inherit', 'inherit'] },
      );
      console.log(`Copied ${legacyName} → ${PROD_DB_NAME}`);
    } else {
      await terminateConnections(admin, legacyName);
      await admin.query(`ALTER DATABASE ${quoteIdent(legacyName)} RENAME TO ${quoteIdent(PROD_DB_NAME)}`);
      console.log(`Renamed ${legacyName} → ${PROD_DB_NAME}`);
    }
  } else {
    console.warn(`No legacy database (${LEGACY_DB_NAMES.join(' / ')}) or "${PROD_DB_NAME}" found`);
    await createDatabaseIfMissing(admin, PROD_DB_NAME);
    console.log('Run npm run dev:migrate against gallery_prod to apply schema');
  }

  if (!skipDev) {
    await cloneDevFromProd(admin);
    console.log(`Next on dev PC: set .env DB_NAME=${DEV_DB_NAME}, then npm run dev:migrate`);
  }

  await admin.end();
  console.log('Done. TrueNAS compose.truenas.yaml should use DB_NAME=gallery_prod.');
}

main().catch((error) => {
  if (error.code === '42501') {
    console.error(
      'Permission denied — the gallery user cannot rename databases.\n'
      + 'Use pgAdmin on the dev PC (recommended):\n'
      + '  Open db/split-dev-prod-pgadmin.sql → connect as postgres → run each STEP (F5)\n'
      + 'Or: PGUSER=postgres PGPASSWORD=... npm run infra:db:split-dev-prod\n'
      + 'Or: psql -h 192.168.10.122 -U postgres -d postgres -f db/split-dev-prod.sql',
    );
  }
  console.error(error.message || error);
  process.exit(1);
});