import { Pool } from 'pg';

import type { DatabaseProbe } from './health.js';

/**
 * A small connection pool to the same PostgreSQL the api uses (ADR 0002). The
 * collab skeleton (issue #33) only needs it for the health probe; the document
 * persistence hooks (issue #35) will reuse this pool for load/store.
 */
export function createPool(connectionString: string): Pool {
  return new Pool({
    connectionString,
    max: 4,
    // Fail fast on health probes instead of hanging when the db is unreachable.
    connectionTimeoutMillis: 5000,
    query_timeout: 5000,
  });
}

/** Probe database reachability for the health endpoint. Never throws. */
export async function pingDatabase(pool: Pool): Promise<DatabaseProbe> {
  try {
    await pool.query('SELECT 1');
    return { ok: true };
  } catch (error) {
    return { ok: false, detail: shortMessage(error) };
  }
}

function shortMessage(error: unknown): string {
  const message = error instanceof Error ? error.message : String(error);
  // Keep the health output single-line and free of any connection string.
  return message.split('\n').filter(Boolean).slice(-1)[0]?.slice(0, 200) ?? 'unknown error';
}