import { Pool } from "pg";

const TEST_DATABASE_HOST = "127.0.0.1";
const TEST_DATABASE_PORT = "55432";
const TEST_DATABASE_NAME = "mike_test";

let pool: Pool | null = null;
let activeConnectionString: string | null = null;

function isIntegrationTestMode() {
  return (
    process.env.MIKE_INTEGRATION_TEST === "1" || process.env.NODE_ENV === "test"
  );
}

export function validateTestDatabaseUrl(connectionString: string) {
  if (!connectionString) {
    throw new Error("TEST_DATABASE_URL is required");
  }

  let parsed: URL;
  try {
    parsed = new URL(connectionString);
  } catch {
    throw new Error("Invalid TEST_DATABASE_URL");
  }

  if (parsed.protocol !== "postgres:") {
    throw new Error("Invalid protocol, must be postgres:");
  }
  if (parsed.hostname !== TEST_DATABASE_HOST) {
    throw new Error(`Invalid hostname, must be ${TEST_DATABASE_HOST}`);
  }
  if (parsed.port !== TEST_DATABASE_PORT) {
    throw new Error(`Invalid port, must be ${TEST_DATABASE_PORT}`);
  }
  if (parsed.pathname !== `/${TEST_DATABASE_NAME}`) {
    throw new Error(`Invalid database name, must be ${TEST_DATABASE_NAME}`);
  }
}

export function resolveDatabaseUrl() {
  const explicitTestUrl = process.env.TEST_DATABASE_URL;
  if (explicitTestUrl) {
    validateTestDatabaseUrl(explicitTestUrl);
    return explicitTestUrl;
  }

  if (isIntegrationTestMode()) {
    throw new Error(
      "TEST_DATABASE_URL is required during integration tests and must target the disposable mike_test database",
    );
  }

  return (
    process.env.DATABASE_URL || "postgres://mike:mike123@127.0.0.1:5432/mike"
  );
}

export function getDatabasePool() {
  const connectionString = resolveDatabaseUrl();

  if (!pool || activeConnectionString !== connectionString) {
    pool = new Pool({ connectionString });
    activeConnectionString = connectionString;
  }

  return pool;
}

export async function closeDatabasePool() {
  if (!pool) {
    return;
  }

  const currentPool = pool;
  pool = null;
  activeConnectionString = null;
  await currentPool.end();
}

export const TEST_DATABASE_TARGET = {
  host: TEST_DATABASE_HOST,
  port: TEST_DATABASE_PORT,
  databaseName: TEST_DATABASE_NAME,
};