import { afterEach, describe, expect, it, vi } from 'vitest'
import { ApiError, apiFetch } from '../src/api/client'

/* fetch is stubbed with Response-shaped objects — the client only needs
   status/ok/json, and this keeps the test independent of jsdom's fetch. */

function stubFetch(body: unknown, status = 200) {
  const mock = vi.fn().mockResolvedValue({
    status,
    ok: status >= 200 && status < 300,
    statusText: 'status text',
    json: () => Promise.resolve(body),
  })
  vi.stubGlobal('fetch', mock)
  return mock
}

afterEach(() => {
  vi.unstubAllGlobals()
})

describe('apiFetch', () => {
  it('decodes a JSON response', async () => {
    stubFetch([{ id: 1, title: 'First' }])

    await expect(apiFetch('/api/v1/items')).resolves.toEqual([{ id: 1, title: 'First' }])
  })

  it('sends method, JSON headers and a JSON body', async () => {
    const mock = stubFetch({ id: 1 })

    await apiFetch('/api/v1/items', { method: 'POST', body: JSON.stringify({ title: 'x' }) })

    const [path, init] = mock.mock.calls[0]! as [string, RequestInit]
    expect(path).toBe('/api/v1/items')
    expect(init.method).toBe('POST')
    expect(init.body).toBe(JSON.stringify({ title: 'x' }))
    expect(init.headers).toMatchObject({ 'Content-Type': 'application/json' })
  })

  it('returns undefined for 204 responses', async () => {
    stubFetch(null, 204)

    await expect(apiFetch<void>('/api/v1/items/1', { method: 'DELETE' })).resolves.toBeUndefined()
  })

  it('turns the backend error envelope into an ApiError', async () => {
    stubFetch({ error: { code: 'validation_failed', message: 'title: required' } }, 400)

    const err = await apiFetch('/api/v1/items', { method: 'POST' }).catch(e => e)

    expect(err).toBeInstanceOf(ApiError)
    expect(err).toMatchObject({
      status: 400,
      code: 'validation_failed',
      message: 'title: required',
    })
  })

  it('falls back to statusText when the body is not the envelope', async () => {
    stubFetch('<html>gateway timeout</html>', 504)

    const err = await apiFetch('/api/v1/items').catch(e => e)

    expect(err).toMatchObject({ status: 504, code: 'unknown', message: 'status text' })
  })

  it('wraps network failures (backend down) as a network ApiError', async () => {
    vi.stubGlobal(
      'fetch',
      vi.fn().mockRejectedValue(new TypeError('fetch failed')),
    )

    const err = await apiFetch('/api/v1/items').catch(e => e)

    expect(err).toBeInstanceOf(ApiError)
    expect(err.code).toBe('network')
    expect(err.message).toContain('Go server')
  })
})