import { ref } from 'vue'
import { ApiError, createApiClient } from '@/shared/api'
import type {
  AthleteStanding,
  AuditLog,
  CurrentUser,
  DisplayCommand,
  EntryWithResult,
  Event,
  EventSettings,
  HealthInfo,
  Page,
  PageQuery,
  PointAdjustment,
  PublishPayload,
  RecordEntry,
  Result,
  SaveDraftPayload,
  ScoringProfile,
  Sport,
  StandingRow,
  Team,
  TeamBreakdown,
} from '@/shared'
import { mockDb } from './mock'

/**
 * 管理端数据入口。
 *
 * 后端未就绪（连接失败 / 超时 / 响应不是约定结构）时自动降级到内存示例数据，
 * 并把 `mockMode` 置为 true，界面据此显示「示例数据」标记。
 * 业务错误（鉴权失败、校验失败、冲突）不降级——那些是真实服务端的回答，必须原样呈现。
 */

const FALLBACK_CODES = ['NETWORK', 'TIMEOUT', 'PARSE_FAILED']

export const mockMode = ref(false)
export const mockReason = ref<string | null>(null)

let unauthorizedHandler: (() => void) | null = null

export function setUnauthorizedHandler(handler: () => void): void {
  unauthorizedHandler = handler
}

const client = createApiClient({
  onUnauthorized: () => unauthorizedHandler?.(),
})

function isFallback(error: unknown): boolean {
  // 404 表示该接口在当前服务端尚未实现（或整个后端没起来），同样按「未就绪」降级。
  return error instanceof ApiError && (FALLBACK_CODES.includes(error.code) || error.status === 404)
}

async function call<T>(real: () => Promise<T>, mock: () => T | Promise<T>): Promise<T> {
  try {
    const value = await real()
    if (mockMode.value) {
      mockMode.value = false
      mockReason.value = null
    }
    return value
  } catch (error) {
    if (!isFallback(error)) throw error
    mockMode.value = true
    mockReason.value = error instanceof Error ? error.message : '无法连接服务端'
    return await mock()
  }
}

export interface Bootstrap {
  settings: EventSettings
  teams: Team[]
  sports: Sport[]
  events: Event[]
  profiles: ScoringProfile[]
  standings: StandingRow[]
  athleteStandings: AthleteStanding[]
}

async function bootstrap(): Promise<Bootstrap> {
  return call(
    async () => {
      const [settings, teams, sports, events, profiles, standings, athleteStandings] =
        await Promise.all([
          client.settings.get(),
          client.teams.list(),
          client.sports.list(),
          client.events.list(),
          client.scoringProfiles.list(),
          client.standings.teams(),
          client.standings.athletes(),
        ])
      return { settings, teams, sports, events, profiles, standings, athleteStandings }
    },
    () => mockDb.bootstrap(),
  )
}

export const adminApi = {
  client,
  bootstrap,

  eventDetail: (id: number): Promise<Event> =>
    call(() => client.events.get(id), () => mockDb.eventDetail(id)),

  entries: (eventId: number): Promise<EntryWithResult[]> =>
    call(() => client.events.entries(eventId), () => mockDb.listEntries(eventId)),

  saveDraft: (payload: SaveDraftPayload): Promise<Result[]> =>
    call(() => client.results.saveDraft(payload), () => mockDb.saveDraft(payload)),

  publish: (payload: PublishPayload): Promise<Result[]> =>
    call(() => client.results.publish(payload), () => mockDb.publish(payload)),

  unpublish: (payload: PublishPayload): Promise<Result[]> =>
    call(() => client.results.unpublish(payload), () => mockDb.unpublish(payload)),

  standings: (): Promise<StandingRow[]> =>
    call(() => client.standings.teams(), () => mockDb.standings()),

  athleteStandings: (): Promise<AthleteStanding[]> =>
    call(() => client.standings.athletes(), () => mockDb.athleteStandings()),

  breakdown: (teamId: number): Promise<TeamBreakdown> =>
    call(() => client.standings.breakdown(teamId), () => mockDb.breakdown(teamId)),

  records: (): Promise<RecordEntry[]> =>
    call(() => client.records.list(), () => mockDb.records()),

  adjustments: (query: PageQuery = {}): Promise<Page<PointAdjustment>> =>
    call(() => client.adjustments.list(query), () => mockDb.adjustments()),

  auditLogs: (query: PageQuery = {}): Promise<Page<AuditLog>> =>
    call(() => client.auditLogs.list(query), () => mockDb.auditLogs(query.page ?? 1, query.size ?? 20)),

  displayCommand: (command: DisplayCommand): Promise<void> =>
    call(() => client.display.command(command), () => undefined),

  login: (username: string, password: string): Promise<CurrentUser> =>
    call(
      () => client.auth.login(username, password),
      () => mockDb.login(username),
    ),

  logout: (): Promise<void> => call(() => client.auth.logout(), () => undefined),

  me: (): Promise<CurrentUser> =>
    call(
      () => client.auth.me(),
      () => {
        // 示例数据模式下没有真实会话，统一按「未登录」处理。
        throw new ApiError('AUTH_REQUIRED', '示例数据模式下无会话', 0)
      },
    ),

  changePassword: (currentPassword: string, newPassword: string): Promise<{ relogin: boolean }> =>
    call(
      () => client.auth.changePassword(currentPassword, newPassword),
      () => {
        throw new ApiError('INTERNAL', '示例数据模式下无法修改密码', 0)
      },
    ),

  health: (): Promise<HealthInfo> =>
    call(
      () => client.health(),
      () => mockDb.health(),
    ),

  exportUrl: (kind: 'standings' | 'breakdown' | 'results'): string | null => {
    if (mockMode.value) return null
    if (kind === 'standings') return client.exports.standingsUrl()
    if (kind === 'breakdown') return client.exports.breakdownUrl({})
    return client.exports.resultsUrl()
  },
}

export type AdminApi = typeof adminApi
export { ApiError }