import * as dotenv from 'dotenv';
import mysql from 'mysql2';
import {Kysely, MysqlDialect} from 'kysely';
import {AdminDatabase} from './admin.schema.js';
import logger from '../../middleware/logger.js';

dotenv.config();

/**
 * The admin module is the one place in this API that does not use the
 * `mariadb` driver: better-auth talks to the database through Kysely, whose
 * MySQL dialect expects a mysql2 pool. The other domains keep their own
 * `mariadb` pools (see Feedback.db.ts) - this is an addition, not a migration.
 *
 * The pool is the callback-style `mysql2` one, NOT `mysql2/promise`: Kysely's
 * MysqlDialect calls `pool.getConnection((err, conn) => ...)`. The promise
 * wrapper ignores that callback and returns a Promise instead, so every query
 * through Kysely would hang forever with no error - which is exactly what it
 * did until the integration tests caught it.
 *
 * timezone 'Z' matters: better-auth computes session and token expiry in UTC.
 * Without it mysql2 would write and read those DATETIMEs in the process's local
 * zone, so sessions would expire an hour early or late depending on DST.
 */

export namespace NachklangAdminDB {
	export const pool = mysql.createPool({
		host: process.env.DB_HOST,
		user: process.env.DB_USER,
		password: process.env.DB_PASSWORD,
		database: process.env.ADMIN_DB,
		// The other modules' pools default to 3306. This one is configurable so
		// the integration tests can point at a throwaway container on another
		// port without touching a developer's real .env.
		port: parseInt(process.env.DB_PORT || '3306', 10),
		connectionLimit: 5,
		timezone: 'Z'
	});

	// mysql2 emits connection trouble as an event on the pool, not only as a
	// rejected query. Without a listener Node turns that into an
	// uncaughtException, so a database restart would take the whole API - and
	// with it the calendar, feedback and tickets domains - down with it.
	// Individual queries still reject, and their callers still answer 500.
	pool.on('error', (err: unknown) => {
		logger.error('Admin database pool error', {detail: (err as any)?.message});
	});

	// Handed to better-auth as `database: {dialect, type: 'mysql'}`.
	export const dialect = new MysqlDialect({pool});

	// Used by this module's own services for the two custom tables and for
	// permission lookups that join better-auth's `user`.
	export const db = new Kysely<AdminDatabase>({dialect});
}