import { describe, it, expect, vi, beforeEach } from 'vitest'
import { render, screen, fireEvent, waitFor } from '@testing-library/svelte'
import DeckPreview from './DeckPreview.svelte'
import { auth } from '../lib/stores/auth.js'

const mockPush = vi.fn()
vi.mock('svelte-spa-router', () => ({
  push: (...args) => mockPush(...args),
}))

vi.mock('../lib/stores/auth.js', () => {
  const { writable } = require('svelte/store')
  const store = writable({ user: { id: 'u1' }, loading: false, error: null })
  return { auth: { subscribe: store.subscribe, set: store.set } }
})

const mockFetchDeckWithQuestions = vi.fn()
const mockUserHasDeck = vi.fn()
const mockCopyDeckToUser = vi.fn()
vi.mock('../lib/api/decks.js', () => ({
  fetchDeckWithQuestions: (...args) => mockFetchDeckWithQuestions(...args),
  userHasDeck: (...args) => mockUserHasDeck(...args),
  copyDeckToUser: (...args) => mockCopyDeckToUser(...args),
}))

describe('DeckPreview', () => {
  beforeEach(() => {
    vi.clearAllMocks()
    auth.set({ user: { id: 'u1' }, loading: false, error: null })
    mockFetchDeckWithQuestions.mockResolvedValue({
      id: 'd1',
      title: 'Preview Deck',
      description: 'Desc',
      published: true,
      owner_id: 'o1',
      copied_from_deck_id: null,
      questions: [{ prompt: 'Q?', answers: ['A'], correct_answer_indices: [0] }],
    })
    mockUserHasDeck.mockResolvedValue(false)
  })

  it('loads and shows deck title', async () => {
    render(DeckPreview, { props: { params: { id: 'd1' } } })
    expect(screen.getByText('Loading deck…')).toBeInTheDocument()
    await waitFor(() => expect(screen.getByText('Preview Deck')).toBeInTheDocument())
    expect(mockFetchDeckWithQuestions).toHaveBeenCalledWith(expect.anything(), 'd1')
  })

  it('shows error when deck not available', async () => {
    mockFetchDeckWithQuestions.mockResolvedValue({
      id: 'd1',
      title: 'Private',
      published: false,
      owner_id: 'o1',
      questions: [],
    })
    render(DeckPreview, { props: { params: { id: 'd1' } } })
    await waitFor(() => expect(screen.getByText('This deck is not available.')).toBeInTheDocument())
  })

  it('goBack pushes to community for published deck', async () => {
    render(DeckPreview, { props: { params: { id: 'd1' } } })
    await waitFor(() => expect(screen.getByText('Preview Deck')).toBeInTheDocument())
    await fireEvent.click(screen.getByRole('button', { name: /Community/ }))
    expect(mockPush).toHaveBeenCalledWith('/community')
  })

  it('addToMyDecks calls copyDeckToUser', async () => {
    render(DeckPreview, { props: { params: { id: 'd1' } } })
    await waitFor(() => expect(screen.getByText('Preview Deck')).toBeInTheDocument())
    const addBtn = screen.getByRole('button', { name: /Add to My decks/i })
    mockCopyDeckToUser.mockResolvedValue(undefined)
    await fireEvent.click(addBtn)
    await waitFor(() => expect(mockCopyDeckToUser).toHaveBeenCalledWith(expect.anything(), 'd1', 'u1'))
  })

  it('addToMyDecks without userId shows sign in error', async () => {
    auth.set({ user: null, loading: false, error: null })
    render(DeckPreview, { props: { params: { id: 'd1' } } })
    await waitFor(() => expect(screen.getByText('Preview Deck')).toBeInTheDocument())
    const addBtn = screen.getByRole('button', { name: /Add to My decks/i })
    await fireEvent.click(addBtn)
    expect(screen.getByText(/Sign in to add this deck/)).toBeInTheDocument()
  })
})