/** @jest-environment node */

import { readFile } from 'node:fs/promises'
import { join } from 'node:path'
import { NextRequest } from 'next/server'
import { GET } from '@/app/api/favicon/route'
import { prisma } from '@/lib/prisma'

jest.mock('@/lib/prisma', () => ({
  prisma: {
    systemSettings: {
      findFirst: jest.fn(),
    },
  },
}))

jest.mock('@/lib/url-rewrite', () => ({
  rewriteStorageUrlForClient: jest.fn((url: string) => url),
}))

const request = new NextRequest('https://sc.jiansun.vip/api/favicon')
let remoteLogoSequence = 0

function mockFetchResponse({
  ok,
  contentType,
  body = Buffer.alloc(0),
  chunks = [body],
  contentLength = String(body.length),
  cancel = jest.fn(),
}: {
  ok: boolean
  contentType: string
  body?: Buffer
  chunks?: Buffer[]
  contentLength?: string | null
  cancel?: jest.Mock
}) {
  let index = 0
  const stream = new ReadableStream<Uint8Array>({
    pull(controller) {
      if (index >= chunks.length) {
        controller.close()
        return
      }
      controller.enqueue(chunks[index])
      index += 1
    },
    cancel,
  })
  const arrayBuffer = jest.fn().mockRejectedValue(
    new Error('favicon route must not buffer the unbounded response'),
  )

  ;(global.fetch as jest.Mock).mockResolvedValue({
    ok,
    headers: {
      get: jest.fn((name: string) => {
        if (name.toLowerCase() === 'content-type') return contentType
        if (name.toLowerCase() === 'content-length') return contentLength
        return null
      }),
    },
    body: stream,
    arrayBuffer,
  })

  return { arrayBuffer, cancel }
}

describe('/api/favicon', () => {
  let localFavicon: Buffer

  beforeAll(async () => {
    localFavicon = await readFile(join(process.cwd(), 'public', 'brand', 'favicon.png'))
  })

  beforeEach(() => {
    jest.clearAllMocks()
    global.fetch = jest.fn()
    remoteLogoSequence += 1
    ;(prisma.systemSettings.findFirst as jest.Mock).mockResolvedValue({
      headerLogoUrl: `https://s3.jiansun.vip/gongxiangpan/brand/header-${remoteLogoSequence}.png`,
    })
  })

  test.each([
    { name: '404', ok: false, contentType: 'text/html' },
    { name: '返回 HTML', ok: true, contentType: 'text/html; charset=utf-8' },
  ])('上游 $name 时返回真实本地图标', async ({ ok, contentType }) => {
    const upstream = mockFetchResponse({
      ok,
      contentType,
      body: Buffer.from('<html>bad gateway</html>'),
    })

    const response = await GET(request)
    const bytes = Buffer.from(await response.arrayBuffer())

    expect(upstream.cancel).toHaveBeenCalledTimes(1)
    expect(response.status).toBe(200)
    expect(response.headers.get('content-type')).toBe('image/png')
    expect(bytes.equals(localFavicon)).toBe(true)
  })

  test('Content-Length 声明超过 favicon 的 1MB 上限时不读取正文并立即取消', async () => {
    const upstream = mockFetchResponse({
      ok: true,
      contentType: 'image/png',
      body: localFavicon,
      contentLength: String(1024 * 1024 + 1),
    })

    const response = await GET(request)
    const bytes = Buffer.from(await response.arrayBuffer())

    expect(upstream.arrayBuffer).not.toHaveBeenCalled()
    expect(upstream.cancel).toHaveBeenCalledTimes(1)
    expect(bytes.equals(localFavicon)).toBe(true)
  })

  test('无 Content-Length 的流超过 favicon 的 1MB 上限时停止读取、取消上游并回退', async () => {
    const upstream = mockFetchResponse({
      ok: true,
      contentType: 'image/png',
      // 第三个分片让流保持打开，可确认超限时确实主动 cancel，而不是自然结束。
      chunks: [
        Buffer.alloc(768 * 1024),
        Buffer.alloc(512 * 1024),
        Buffer.alloc(1),
      ],
      contentLength: null,
    })

    const response = await GET(request)
    const bytes = Buffer.from(await response.arrayBuffer())

    expect(upstream.arrayBuffer).not.toHaveBeenCalled()
    expect(upstream.cancel).toHaveBeenCalledTimes(1)
    expect(bytes.equals(localFavicon)).toBe(true)
  })

  test('Content-Length 撒谎时仍由流式硬上限拦截', async () => {
    const upstream = mockFetchResponse({
      ok: true,
      contentType: 'image/png',
      chunks: [
        Buffer.alloc(768 * 1024),
        Buffer.alloc(512 * 1024),
        Buffer.alloc(1),
      ],
      contentLength: '1024',
    })

    const response = await GET(request)
    const bytes = Buffer.from(await response.arrayBuffer())

    expect(upstream.cancel).toHaveBeenCalledTimes(1)
    expect(bytes.equals(localFavicon)).toBe(true)
  })

  test('无 Content-Length 的正常分片图片可以完成解码并返回', async () => {
    const splitAt = Math.floor(localFavicon.length / 2)
    const upstream = mockFetchResponse({
      ok: true,
      contentType: 'image/png',
      chunks: [localFavicon.subarray(0, splitAt), localFavicon.subarray(splitAt)],
      contentLength: null,
    })

    const response = await GET(request)
    const bytes = Buffer.from(await response.arrayBuffer())

    expect(upstream.arrayBuffer).not.toHaveBeenCalled()
    expect(upstream.cancel).not.toHaveBeenCalled()
    expect(response.headers.get('content-type')).toBe('image/png')
    expect(bytes.equals(localFavicon)).toBe(true)
  })

  test('上游请求超时或网络失败时返回真实本地图标', async () => {
    ;(global.fetch as jest.Mock).mockRejectedValue(new Error('request timeout'))

    const response = await GET(request)
    const bytes = Buffer.from(await response.arrayBuffer())

    expect(response.status).toBe(200)
    expect(bytes.equals(localFavicon)).toBe(true)
  })

  test('数据库是本地品牌地址时不发起网络请求', async () => {
    ;(prisma.systemSettings.findFirst as jest.Mock).mockResolvedValue({
      headerLogoUrl: '/brand/header-logo.png',
    })

    const response = await GET(request)
    const bytes = Buffer.from(await response.arrayBuffer())

    expect(global.fetch).not.toHaveBeenCalled()
    expect(bytes.equals(localFavicon)).toBe(true)
  })

  test('只透传真正能够完整解码的受控上游图片', async () => {
    mockFetchResponse({ ok: true, contentType: 'image/png', body: localFavicon })

    const response = await GET(request)
    const bytes = Buffer.from(await response.arrayBuffer())

    expect(response.headers.get('content-type')).toBe('image/png')
    expect(bytes.equals(localFavicon)).toBe(true)
  })

  test('同一 Logo 的并发和后续请求只下载并解码一次', async () => {
    mockFetchResponse({ ok: true, contentType: 'image/png', body: localFavicon })

    const [first, second] = await Promise.all([GET(request), GET(request)])
    const third = await GET(request)
    const bodies = await Promise.all(
      [first, second, third].map(async response => Buffer.from(await response.arrayBuffer())),
    )

    expect(global.fetch).toHaveBeenCalledTimes(1)
    expect(bodies.every(bytes => bytes.equals(localFavicon))).toBe(true)
  })

  test('只有图片文件头的截断响应会回退本地图标', async () => {
    const truncatedPng = Buffer.from([
      0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a, 1, 2, 3,
    ])
    mockFetchResponse({ ok: true, contentType: 'image/png', body: truncatedPng })

    const response = await GET(request)
    const bytes = Buffer.from(await response.arrayBuffer())

    expect(response.headers.get('content-type')).toBe('image/png')
    expect(bytes.equals(localFavicon)).toBe(true)
    expect(bytes.equals(truncatedPng)).toBe(false)
  })
})