import pg from 'pg';

const { Pool, types } = pg;

function parseNumericDatabaseValue(value) {
  if (value == null) return value;
  const parsed = Number(value);
  return Number.isFinite(parsed) ? parsed : value;
}

// Mobile/frontend routes expect numeric JSON values for database aggregates.
types.setTypeParser(types.builtins.INT8, parseNumericDatabaseValue);
types.setTypeParser(types.builtins.NUMERIC, parseNumericDatabaseValue);

let pool;

function parseIntOrDefault(value, fallback) {
  const parsed = Number.parseInt(`${value || fallback}`, 10);
  return Number.isFinite(parsed) ? parsed : fallback;
}

function resolveDatabasePoolConfig() {
  if (process.env.DATABASE_URL) {
    return {
      connectionString: process.env.DATABASE_URL,
      max: parseIntOrDefault(process.env.DB_POOL_MAX, 10),
      idleTimeoutMillis: parseIntOrDefault(process.env.DB_IDLE_TIMEOUT_MS, 30000),
    };
  }

  const user = process.env.DB_USER;
  const password = process.env.DB_PASSWORD;
  const database = process.env.DB_NAME;
  const host = process.env.DB_HOST || (
    process.env.INSTANCE_CONNECTION_NAME
      ? `/cloudsql/${process.env.INSTANCE_CONNECTION_NAME}`
      : ''
  );

  if (!user || password == null || !database || !host) {
    return null;
  }

  return {
    host,
    port: parseIntOrDefault(process.env.DB_PORT, 5432),
    user,
    password,
    database,
    max: parseIntOrDefault(process.env.DB_POOL_MAX, 10),
    idleTimeoutMillis: parseIntOrDefault(process.env.DB_IDLE_TIMEOUT_MS, 30000),
  };
}

export function isDatabaseConfigured() {
  return Boolean(resolveDatabasePoolConfig());
}

function getPool() {
  if (!pool) {
    const resolved = resolveDatabasePoolConfig();
    if (!resolved) {
      throw new Error('Database connection settings are required');
    }
    pool = new Pool(resolved);
  }
  return pool;
}

export async function query(text, params = []) {
  return getPool().query(text, params);
}

export async function checkDatabaseHealth() {
  const result = await query('SELECT 1 AS ok');
  return result.rows[0]?.ok === 1;
}

export async function closePool() {
  if (pool) {
    await pool.end();
    pool = null;
  }
}