import { createHash } from 'node:crypto';
import type { Pool, PoolClient, QueryResult } from 'pg';
import { describe, expect, it, vi } from 'vitest';
import { runDatabaseMigrations } from '../../server/postgres/migration-runner';

function result(rows: unknown[] = []): QueryResult {
  return { command: '', rowCount: rows.length, oid: 0, fields: [], rows } as QueryResult;
}

function fakePool(existing: Array<{ version: string; checksum: string }> = []) {
  const query = vi.fn(async (text: string) => text.includes('SELECT version, checksum') ? result(existing) : result());
  const release = vi.fn();
  const client = { query, release } as unknown as PoolClient;
  const pool = { connect: vi.fn(async () => client) } as unknown as Pool;
  return { pool, query, release };
}

describe('PostgreSQL migration runner', () => {
  it('serializes, applies and records a pending migration transactionally', async () => {
    const runtime = fakePool();
    const applied = await runDatabaseMigrations(runtime.pool, [{ version: '900', name: 'test', sql: 'SELECT 900' }]);

    expect(applied).toEqual([{ version: '900', name: 'test', checksum: createHash('sha256').update('SELECT 900').digest('hex') }]);
    const statements = runtime.query.mock.calls.map(call => call[0]);
    expect(statements).toContain('BEGIN');
    expect(statements).toContain('SELECT 900');
    expect(statements).toContain('COMMIT');
    expect(statements.some(statement => statement.includes('INSERT INTO assessor_schema_migrations'))).toBe(true);
    expect(statements.some(statement => statement.includes('pg_advisory_lock'))).toBe(true);
    expect(statements.some(statement => statement.includes('pg_advisory_unlock'))).toBe(true);
    expect(runtime.release).toHaveBeenCalledOnce();
  });

  it('rejects a changed migration checksum without executing its SQL', async () => {
    const runtime = fakePool([{ version: '900', checksum: 'different' }]);
    await expect(runDatabaseMigrations(runtime.pool, [{ version: '900', name: 'test', sql: 'SELECT 900' }]))
      .rejects.toThrow('nach ihrer Anwendung verändert');
    expect(runtime.query.mock.calls.map(call => call[0])).not.toContain('SELECT 900');
    expect(runtime.release).toHaveBeenCalledOnce();
  });
});