const { paginate } = require('../utils/pagination')

describe('paginate', () => {
  // 模拟 queryFn
  const createMockQueryFn = (totalCount, dataRows) => {
    return jest.fn((sql, params) => {
      if (sql.includes('COUNT(*)')) {
        return Promise.resolve([{ total: totalCount }])
      }
      return Promise.resolve(dataRows)
    })
  }

  it('应返回正确的分页结构', async () => {
    const mockFn = createMockQueryFn(50, [{ id: 1 }])
    const result = await paginate(mockFn, 'SELECT * FROM users', [], 1, 10)

    expect(result).toHaveProperty('data')
    expect(result).toHaveProperty('total', 50)
    expect(result).toHaveProperty('page', 1)
    expect(result).toHaveProperty('pageSize', 10)
    expect(result).toHaveProperty('totalPages', 5)
  })

  it('应计算正确的 totalPages', async () => {
    // 50 条数据，每页 20 条 → 3 页
    const mockFn = createMockQueryFn(50, [])
    const result = await paginate(mockFn, 'SELECT * FROM t', [], 1, 20)
    expect(result.totalPages).toBe(3)
  })

  it('应在无数据时 totalPages 为 0', async () => {
    const mockFn = createMockQueryFn(0, [])
    const result = await paginate(mockFn, 'SELECT * FROM t', [], 1, 20)
    expect(result.totalPages).toBe(0)
    expect(result.total).toBe(0)
  })

  it('应将 page 限制为最小值 1', async () => {
    const mockFn = createMockQueryFn(10, [])
    const result = await paginate(mockFn, 'SELECT * FROM t', [], -5, 10)
    expect(result.page).toBe(1)
  })

  it('应将 page 设为 1 当输入无法解析时', async () => {
    const mockFn = createMockQueryFn(10, [])
    const result = await paginate(mockFn, 'SELECT * FROM t', [], 'abc', 10)
    expect(result.page).toBe(1)
  })

  it('应将 pageSize 限制在 1-100 之间', async () => {
    // pageSize=0 时 parseInt(0)||20 = 20（0 是 falsy），所以回退到默认值
    const mockFn1 = createMockQueryFn(10, [])
    const result1 = await paginate(mockFn1, 'SELECT * FROM t', [], 1, -5)
    expect(result1.pageSize).toBe(1)

    const mockFn2 = createMockQueryFn(10, [])
    const result2 = await paginate(mockFn2, 'SELECT * FROM t', [], 1, 200)
    expect(result2.pageSize).toBe(100)
  })

  it('应使用默认 page=1 和 pageSize=20', async () => {
    const mockFn = createMockQueryFn(100, [])
    const result = await paginate(mockFn, 'SELECT * FROM t', [])
    expect(result.page).toBe(1)
    expect(result.pageSize).toBe(20)
  })

  it('应传递正确的 SQL 和参数给 queryFn', async () => {
    const mockFn = createMockQueryFn(10, [])
    await paginate(mockFn, 'SELECT * FROM users WHERE status = ?', ['active'], 2, 10)

    // 第一次调用：count 查询
    expect(mockFn).toHaveBeenNthCalledWith(
      1,
      'SELECT COUNT(*) as total FROM (SELECT * FROM users WHERE status = ?) AS _paged',
      ['active']
    )
    // 第二次调用：数据查询
    expect(mockFn).toHaveBeenNthCalledWith(
      2,
      'SELECT * FROM users WHERE status = ? LIMIT 10 OFFSET 10',
      ['active']
    )
  })

  it('应计算正确的 offset', async () => {
    const mockFn = createMockQueryFn(100, [])
    await paginate(mockFn, 'SELECT * FROM t', [], 3, 15)

    // page=3, pageSize=15 → offset = (3-1)*15 = 30
    expect(mockFn).toHaveBeenNthCalledWith(
      2,
      'SELECT * FROM t LIMIT 15 OFFSET 30',
      []
    )
  })

  it('应返回 queryFn 返回的数据', async () => {
    const rows = [{ id: 1, name: 'Alice' }, { id: 2, name: 'Bob' }]
    const mockFn = createMockQueryFn(2, rows)
    const result = await paginate(mockFn, 'SELECT * FROM t', [], 1, 10)
    expect(result.data).toEqual(rows)
  })

  it('应处理字符串形式的 page 和 pageSize', async () => {
    const mockFn = createMockQueryFn(50, [])
    const result = await paginate(mockFn, 'SELECT * FROM t', [], '2', '25')
    expect(result.page).toBe(2)
    expect(result.pageSize).toBe(25)
  })
})