const AUTH_ERROR_MESSAGES: Record<string, string> = {
  google_error: 'Google вернул ошибку авторизации',
  invalid_state: 'Сессия авторизации устарела, попробуйте снова',
  exchange_failed: 'Не удалось обменять код авторизации',
  userinfo_failed: 'Не удалось получить данные аккаунта Google',
  account_not_allowed: 'Этот Google-аккаунт не разрешён для входа',
}

export function authErrorMessage(code: string): string {
  return AUTH_ERROR_MESSAGES[code] ?? 'Неизвестная ошибка авторизации'
}

async function request<T>(path: string, options: RequestInit = {}): Promise<T> {
  const res = await fetch(path, {
    credentials: 'include',
    headers: { 'Content-Type': 'application/json', ...(options.headers ?? {}) },
    ...options,
  })
  if (!res.ok) {
    let detail = `${res.status}`
    try {
      const body = await res.json()
      detail = body.detail ?? detail
    } catch {
      // ignore
    }
    throw new Error(detail)
  }
  return res.json()
}

export interface AuthStatus {
  authenticated: boolean
  connected: boolean
  email: string | null
}

export function getAuthStatus() {
  return request<AuthStatus>('/api/auth/status')
}

export function startGoogleAuth() {
  window.location.href = '/api/auth/google/start'
}

export function logout() {
  return request<{ ok: boolean }>('/api/auth/logout', { method: 'POST' })
}

export interface ChannelDto {
  id: number
  youtube_channel_id: string
  title: string
  description: string | null
  thumbnail_url: string | null
  uploads_playlist_id: string | null
  subscribed: boolean
  last_synced_at: string | null
  category_ids: number[]
}

export function getChannel(channelId: number) {
  return request<ChannelDto>(`/api/channels/${channelId}`)
}

export function listChannels(
  params: { search?: string; categoryId?: number; uncategorized?: boolean } = {},
) {
  const qs = new URLSearchParams()
  if (params.search) qs.set('search', params.search)
  if (params.categoryId != null) qs.set('category_id', String(params.categoryId))
  if (params.uncategorized) qs.set('uncategorized', 'true')
  const suffix = qs.toString() ? `?${qs.toString()}` : ''
  return request<ChannelDto[]>(`/api/channels${suffix}`)
}

export function setChannelCategories(channelId: number, categoryIds: number[]) {
  return request<ChannelDto>(`/api/channels/${channelId}/categories`, {
    method: 'PUT',
    body: JSON.stringify({ category_ids: categoryIds }),
  })
}

export interface CategoryDto {
  id: number
  name: string
  slug: string
  sort_order: number
  channel_count: number
}

export function listCategories() {
  return request<CategoryDto[]>('/api/categories')
}

export function createCategory(name: string) {
  return request<CategoryDto>('/api/categories', {
    method: 'POST',
    body: JSON.stringify({ name }),
  })
}

export function updateCategory(id: number, name: string) {
  return request<CategoryDto>(`/api/categories/${id}`, {
    method: 'PATCH',
    body: JSON.stringify({ name }),
  })
}

export function deleteCategory(id: number) {
  return fetch(`/api/categories/${id}`, { method: 'DELETE', credentials: 'include' }).then((res) => {
    if (!res.ok) throw new Error(`${res.status}`)
  })
}

export function reorderCategories(categoryIds: number[]) {
  return request<CategoryDto[]>('/api/categories/reorder', {
    method: 'POST',
    body: JSON.stringify({ category_ids: categoryIds }),
  })
}

export interface SyncStatus {
  status: string
  started_at?: string
  finished_at?: string | null
  error?: string | null
  running: boolean
  [key: string]: unknown
}

export function getSyncStatus() {
  return request<{ subscriptions: SyncStatus; videos: SyncStatus }>('/api/sync/status')
}

export function syncSubscriptions() {
  return request<SyncStatus>('/api/sync/subscriptions', { method: 'POST' })
}

export function syncVideos() {
  return request<SyncStatus>('/api/sync/videos', { method: 'POST' })
}

export interface FeedVideoDto {
  youtube_video_id: string
  title: string
  description: string | null
  channel: {
    id: number
    youtube_channel_id: string
    title: string
    thumbnail_url: string | null
  }
  thumbnail_url: string | null
  published_at: string
  duration_seconds: number | null
  youtube_url: string
  categories: { id: number; name: string }[]
  local: {
    available: boolean
    status: string
    progress_percent: number | null
    media_url: string | null
  }
}

export function getVideo(youtubeVideoId: string) {
  return request<FeedVideoDto>(`/api/videos/${youtubeVideoId}`)
}

export interface DownloadJobDto {
  status: string
  progress_percent: number | null
  media_url: string | null
  error_message: string | null
  requested_at?: string
  started_at?: string | null
  completed_at?: string | null
}

export function downloadVideo(youtubeVideoId: string) {
  return request<DownloadJobDto>(`/api/videos/${youtubeVideoId}/download`, { method: 'POST' })
}

export function getDownloadStatus(youtubeVideoId: string) {
  return request<DownloadJobDto>(`/api/videos/${youtubeVideoId}/download-status`)
}

export function recheckLocal(youtubeVideoId: string) {
  return request<DownloadJobDto>(`/api/videos/${youtubeVideoId}/recheck-local`, { method: 'POST' })
}

export function getFeed(
  params: { categoryId?: number; uncategorized?: boolean; channelId?: number; cursor?: string } = {},
) {
  const qs = new URLSearchParams()
  if (params.categoryId != null) qs.set('category_id', String(params.categoryId))
  if (params.uncategorized) qs.set('uncategorized', 'true')
  if (params.channelId != null) qs.set('channel_id', String(params.channelId))
  if (params.cursor) qs.set('cursor', params.cursor)
  const suffix = qs.toString() ? `?${qs.toString()}` : ''
  return request<{ items: FeedVideoDto[]; next_cursor: string | null }>(`/api/feed${suffix}`)
}