import { describe, it, expect, vi, beforeEach } from 'vitest'

const mockFetch = vi.fn()
vi.stubGlobal('fetch', mockFetch)

function okResponse(data: unknown): Response {
  return {
    ok: true,
    status: 200,
    json: async () => data,
  } as unknown as Response
}

function errorResponse(status: number): Response {
  return { ok: false, status, json: async () => ({}) } as unknown as Response
}

// Reset module cache between tests so tariffsCache is cleared
let getTariffs: () => Promise<unknown>
let createPayment: (
  email: string,
  items: Array<{ tariff: string; count: string }>
) => Promise<{ url: string }>

beforeEach(async () => {
  vi.resetModules()
  mockFetch.mockReset()
  vi.stubEnv('EZY_ACTIVITY', 'test-activity')
  vi.stubEnv('EZY_PARTNER_KEY', 'test-partner-key')
  const mod = await import('@/lib/ezy')
  getTariffs = mod.getTariffs
  createPayment = mod.createPayment
})

const sampleTariffs = [
  { id: 1, name: 'Adult', price: 250 },
  { id: 2, name: 'Child', price: 150 },
]

describe('getTariffs', () => {
  it('fetches and returns tariffs on success', async () => {
    mockFetch.mockResolvedValueOnce(okResponse(sampleTariffs))
    const result = await getTariffs()
    expect(result).toEqual(sampleTariffs)
    expect(mockFetch).toHaveBeenCalledOnce()
  })

  it('returns cached data on second call within 5 minutes', async () => {
    mockFetch.mockResolvedValueOnce(okResponse(sampleTariffs))
    await getTariffs()
    await getTariffs() // should hit cache
    expect(mockFetch).toHaveBeenCalledOnce()
  })

  it('throws when EZY_ACTIVITY env var is missing', async () => {
    vi.stubEnv('EZY_ACTIVITY', '')
    vi.resetModules()
    const mod = await import('@/lib/ezy')
    await expect(mod.getTariffs()).rejects.toThrow('EZY_ACTIVITY')
  })

  it('throws when the API returns a non-ok status', async () => {
    mockFetch.mockResolvedValueOnce(errorResponse(503))
    await expect(getTariffs()).rejects.toThrow('503')
  })

  it('throws when the API response fails Zod validation', async () => {
    // Missing required `price` field
    mockFetch.mockResolvedValueOnce(okResponse([{ id: 1, name: 'Bad' }]))
    await expect(getTariffs()).rejects.toThrow()
  })

  it('retries up to 2 times on network failure, then throws', async () => {
    const err = new Error('network error')
    mockFetch.mockRejectedValue(err)
    await expect(getTariffs()).rejects.toThrow('network error')
    // 1 initial + 2 retries = 3 calls
    expect(mockFetch).toHaveBeenCalledTimes(3)
  })

  it('re-fetches from API after the 5-minute cache TTL has expired', async () => {
    vi.useFakeTimers()
    mockFetch.mockResolvedValue(okResponse(sampleTariffs))

    await getTariffs() // populates cache
    expect(mockFetch).toHaveBeenCalledTimes(1)

    vi.advanceTimersByTime(5 * 60 * 1_000 + 1) // expire cache
    await getTariffs()
    expect(mockFetch).toHaveBeenCalledTimes(2)

    vi.useRealTimers()
  })
})

describe('createPayment', () => {
  it('returns the payment URL on success', async () => {
    mockFetch.mockResolvedValueOnce(okResponse({ url: 'https://pay.example.com/order/123' }))
    const result = await createPayment('user@example.com', [{ tariff: 't1', count: '2' }])
    expect(result.url).toBe('https://pay.example.com/order/123')
  })

  it('throws when EZY_PARTNER_KEY env var is missing', async () => {
    vi.stubEnv('EZY_PARTNER_KEY', '')
    vi.resetModules()
    const mod = await import('@/lib/ezy')
    await expect(
      mod.createPayment('user@example.com', [{ tariff: 't1', count: '1' }])
    ).rejects.toThrow('EZY_PARTNER_KEY')
  })

  it('throws when the API returns a non-ok status', async () => {
    mockFetch.mockResolvedValueOnce(errorResponse(400))
    await expect(createPayment('user@example.com', [{ tariff: 't1', count: '1' }])).rejects.toThrow(
      '400'
    )
  })

  it('throws when the API response fails Zod validation (missing url)', async () => {
    mockFetch.mockResolvedValueOnce(okResponse({ form: null }))
    await expect(
      createPayment('user@example.com', [{ tariff: 't1', count: '1' }])
    ).rejects.toThrow()
  })

  it('includes email and items in the POST body', async () => {
    mockFetch.mockResolvedValueOnce(okResponse({ url: 'https://pay.example.com/1' }))
    await createPayment('buyer@example.com', [{ tariff: 'vip', count: '3' }])

    const [, init] = mockFetch.mock.calls[0] as [string, RequestInit & { body: FormData }]
    const body = init.body as FormData
    expect(body.get('email')).toBe('buyer@example.com')
    expect(body.get('partner_key')).toBe('test-partner-key')
  })

  it('retries up to 2 times on network failure, then throws', async () => {
    mockFetch.mockRejectedValue(new Error('network error'))
    await expect(
      createPayment('user@example.com', [{ tariff: 't1', count: '1' }])
    ).rejects.toThrow('network error')
    expect(mockFetch).toHaveBeenCalledTimes(3)
  })

  it('serializes items as JSON in the order FormData field', async () => {
    mockFetch.mockResolvedValueOnce(okResponse({ url: 'https://pay.example.com/2' }))
    await createPayment('buyer@example.com', [
      { tariff: 'adult', count: '2' },
      { tariff: 'child', count: '1' },
    ])

    const [, init] = mockFetch.mock.calls[0] as [string, RequestInit & { body: FormData }]
    const order = JSON.parse((init.body as FormData).get('order') as string)
    expect(order).toEqual([
      { tariff: 'adult', count: '2' },
      { tariff: 'child', count: '1' },
    ])
  })
})