import { describe, it, expect, vi, beforeEach } from 'vitest';
import { NextRequest } from 'next/server';

vi.mock('@/lib/db/queries', () => ({
  getReviewCheckpoints: vi.fn(),
  getNextReviewAt: vi.fn().mockResolvedValue(null),
}));

import { GET } from '../route';
import { getReviewCheckpoints } from '@/lib/db/queries';

const mockGet = vi.mocked(getReviewCheckpoints);

const REVIEW_ITEMS = [
  {
    conceptId: 'c1',
    conceptName: 'Closures',
    score: 0.65,
    checkpointId: 'cp1',
    checkpointPrompt: 'Explain what a closure is.',
    checkpointKind: 'explain' as const,
  },
];

function makeRequest(userId?: string) {
  const url = userId
    ? `http://localhost:3000/api/review?userId=${userId}`
    : 'http://localhost:3000/api/review';
  return new NextRequest(url);
}

describe('GET /api/review', () => {
  beforeEach(() => vi.clearAllMocks());

  it('returns 400 when userId is missing', async () => {
    const res = await GET(makeRequest());
    expect(res.status).toBe(400);
  });

  it('returns 200 with empty list when nothing due', async () => {
    mockGet.mockResolvedValue([]);
    const res = await GET(makeRequest('user-1'));
    expect(res.status).toBe(200);
    const body = await res.json();
    expect(body.checkpoints).toHaveLength(0);
  });

  it('returns 200 with due checkpoints', async () => {
    mockGet.mockResolvedValue(REVIEW_ITEMS);
    const res = await GET(makeRequest('user-1'));
    expect(res.status).toBe(200);
    const body = await res.json();
    expect(body.checkpoints).toHaveLength(1);
    expect(body.checkpoints[0].conceptName).toBe('Closures');
    expect(body.checkpoints[0].score).toBe(0.65);
  });

  it('passes userId to getReviewCheckpoints', async () => {
    mockGet.mockResolvedValue([]);
    await GET(makeRequest('user-abc'));
    expect(mockGet).toHaveBeenCalledWith('user-abc');
  });
});