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

import { triggerDownload } from './triggerDownload'

describe('triggerDownload', () => {
  const fetchMock = vi.fn()
  const openMock = vi.fn()
  const createObjectURLMock = vi.fn()
  const revokeObjectURLMock = vi.fn()
  const clickMock = vi
    .spyOn(HTMLAnchorElement.prototype, 'click')
    .mockImplementation(() => undefined)

  beforeEach(() => {
    vi.stubGlobal('fetch', fetchMock)
    vi.spyOn(window, 'open').mockImplementation(openMock)
    Object.defineProperty(URL, 'createObjectURL', {
      configurable: true,
      value: createObjectURLMock,
    })
    Object.defineProperty(URL, 'revokeObjectURL', {
      configurable: true,
      value: revokeObjectURLMock,
    })
    fetchMock.mockReset()
    openMock.mockReset()
    createObjectURLMock.mockReset()
    revokeObjectURLMock.mockReset()
    clickMock.mockClear()
  })

  it('downloads a successful response with the supplied filename', async () => {
    const blob = new Blob(['file'])
    fetchMock.mockResolvedValue({
      ok: true,
      blob: () => Promise.resolve(blob),
    })
    createObjectURLMock.mockReturnValue('blob:attachment')
    const appendSpy = vi.spyOn(document.body, 'appendChild')
    const removeSpy = vi.spyOn(document.body, 'removeChild')

    await expect(
      triggerDownload('https://cdn.example.com/file.pdf', 'report.pdf')
    ).resolves.toBeUndefined()

    expect(fetchMock).toHaveBeenCalledWith('https://cdn.example.com/file.pdf', {
      mode: 'cors',
    })
    expect(createObjectURLMock).toHaveBeenCalledWith(blob)
    expect(clickMock).toHaveBeenCalledOnce()
    expect(revokeObjectURLMock).toHaveBeenCalledWith('blob:attachment')
    const anchor = appendSpy.mock.calls.at(-1)?.[0] as HTMLAnchorElement
    expect(anchor.href).toBe('blob:attachment')
    expect(anchor.download).toBe('report.pdf')
    expect(anchor.style.display).toBe('none')
    expect(removeSpy).toHaveBeenCalledWith(anchor)
  })

  it('uses the URL filename when no filename is supplied', async () => {
    fetchMock.mockResolvedValue({
      ok: true,
      blob: () => Promise.resolve(new Blob()),
    })
    createObjectURLMock.mockReturnValue('blob:attachment')
    const appendSpy = vi.spyOn(document.body, 'appendChild')

    await triggerDownload('https://cdn.example.com/a/My%20file.pdf')

    expect(
      (appendSpy.mock.calls.at(-1)?.[0] as HTMLAnchorElement).download
    ).toBe('My file.pdf')
  })

  it.each(['a non-ok response', 'a rejected fetch'])(
    'falls back to a new window for %s',
    async (label) => {
      if (label === 'a non-ok response') {
        fetchMock.mockResolvedValue({ ok: false, status: 404 })
      } else {
        fetchMock.mockRejectedValue(new Error('offline'))
      }
      openMock.mockReturnValue({})

      await expect(
        triggerDownload('https://cdn.example.com/file.pdf')
      ).resolves.toBeUndefined()

      expect(openMock).toHaveBeenCalledWith(
        'https://cdn.example.com/file.pdf',
        '_blank',
        'noopener,noreferrer'
      )
    }
  )

  it('uses a raw-url anchor when the popup is blocked', async () => {
    fetchMock.mockRejectedValue(new Error('offline'))
    openMock.mockReturnValue(null)
    const appendSpy = vi.spyOn(document.body, 'appendChild')
    const removeSpy = vi.spyOn(document.body, 'removeChild')

    await expect(
      triggerDownload('https://cdn.example.com/file.pdf')
    ).resolves.toBeUndefined()

    const anchor = appendSpy.mock.calls.at(-1)?.[0] as HTMLAnchorElement
    expect(anchor.href).toBe('https://cdn.example.com/file.pdf')
    expect(anchor.download).toBe('file.pdf')
    expect(anchor.target).toBe('_blank')
    expect(anchor.rel).toBe('noopener noreferrer')
    expect(removeSpy).toHaveBeenCalledWith(anchor)
  })
})