import { apiErrorBodySchema } from '@lingxi/shared';

import { useAuthStore } from '@/stores/auth-store';

const DEFAULT_BASE_URL = 'http://127.0.0.1:3000/api/v1';

export type HttpMethod = 'GET' | 'POST' | 'PUT' | 'PATCH' | 'DELETE';

export interface RequestOptions {
  method?: HttpMethod;
  body?: unknown;
  headers?: Record<string, string>;
  signal?: AbortSignal;
  /** 登录、刷新等接口不需要携带 token */
  auth?: boolean;
}

export interface ApiErrorInit {
  code: number;
  status: number;
  message: string;
  details?: unknown;
  traceId?: string;
}

/** 前端统一 API 错误：与服务端错误体 {code,message,details,trace_id} 对齐 */
export class ApiError extends Error {
  readonly code: number;
  readonly status: number;
  readonly details?: unknown;
  readonly traceId?: string;

  constructor(init: ApiErrorInit) {
    super(init.message);
    this.name = 'ApiError';
    this.code = init.code;
    this.status = init.status;
    this.details = init.details;
    this.traceId = init.traceId;
  }
}

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

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

function baseUrl(): string {
  const configured = import.meta.env.VITE_PUBLIC_API_BASE_URL;
  return (configured ?? DEFAULT_BASE_URL).replace(/\/+$/, '');
}

function buildUrl(path: string): string {
  if (/^https?:\/\//.test(path)) {
    return path;
  }
  return `${baseUrl()}${path.startsWith('/') ? path : `/${path}`}`;
}

function serializeBody(body: unknown): BodyInit | undefined {
  if (body === undefined) {
    return undefined;
  }
  if (
    typeof body === 'string' ||
    body instanceof FormData ||
    body instanceof Blob ||
    body instanceof URLSearchParams ||
    body instanceof ArrayBuffer
  ) {
    return body;
  }
  return JSON.stringify(body);
}

function fallbackCode(status: number): number {
  if (status === 401) return 40101;
  if (status === 403) return 40301;
  if (status === 404) return 40401;
  if (status === 409) return 40903;
  if (status === 429) return 42901;
  if (status >= 500) return 50001;
  return 40001;
}

async function toApiError(response: Response): Promise<ApiError> {
  let payload: unknown = null;
  try {
    payload = await response.json();
  } catch {
    payload = null;
  }
  const parsed = apiErrorBodySchema.safeParse(payload);
  if (parsed.success) {
    return new ApiError({
      code: parsed.data.code,
      status: response.status,
      message: parsed.data.message,
      details: parsed.data.details,
      traceId: parsed.data.trace_id,
    });
  }
  return new ApiError({
    code: fallbackCode(response.status),
    status: response.status,
    message: `请求失败（HTTP ${response.status}）`,
  });
}

/** 刷新失败：清本地会话并通知外壳跳登录（会话过期统一入口） */
function failRefresh(): false {
  useAuthStore.getState().clearSession();
  unauthorizedHandler?.();
  return false;
}

let refreshPromise: Promise<boolean> | null = null;

/** 单飞刷新：并发 401 只触发一次 /auth/refresh */
export function refreshSession(): Promise<boolean> {
  refreshPromise ??= doRefresh().finally(() => {
    refreshPromise = null;
  });
  return refreshPromise;
}

async function doRefresh(): Promise<boolean> {
  const { refreshToken } = useAuthStore.getState();
  if (refreshToken === null) {
    return failRefresh();
  }
  let response: Response;
  try {
    response = await fetch(buildUrl('/auth/refresh'), {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ refreshToken }),
    });
  } catch {
    return failRefresh();
  }
  if (!response.ok) {
    return failRefresh();
  }
  const payload: unknown = await response.json().catch(() => null);
  const accessToken =
    typeof payload === 'object' && payload !== null && 'accessToken' in payload
      ? payload.accessToken
      : null;
  const nextRefreshToken =
    typeof payload === 'object' && payload !== null && 'refreshToken' in payload
      ? payload.refreshToken
      : null;
  if (typeof accessToken !== 'string' || accessToken.length === 0) {
    return failRefresh();
  }
  useAuthStore.getState().setTokens({
    accessToken,
    refreshToken: typeof nextRefreshToken === 'string' ? nextRefreshToken : refreshToken,
  });
  return true;
}

async function send<T>(path: string, options: RequestOptions, allowRefresh: boolean): Promise<T> {
  const { accessToken } = useAuthStore.getState();
  const headers = new Headers(options.headers);
  const body = serializeBody(options.body);
  if (body !== undefined && !(body instanceof FormData) && !headers.has('Content-Type')) {
    headers.set('Content-Type', 'application/json');
  }
  if (options.auth !== false && accessToken !== null) {
    headers.set('Authorization', `Bearer ${accessToken}`);
  }

  const response = await fetch(buildUrl(path), {
    method: options.method ?? 'GET',
    headers,
    body,
    signal: options.signal,
  });

  if (response.status === 401 && allowRefresh && options.auth !== false) {
    const refreshed = await refreshSession();
    if (refreshed) {
      return send<T>(path, options, false);
    }
  }

  if (!response.ok) {
    throw await toApiError(response);
  }
  if (response.status === 204) {
    return undefined as T;
  }
  return (await response.json()) as T;
}

/** 业务请求入口：自动注入 token、401 单飞刷新、统一错误体解析 */
export function request<T>(path: string, options: RequestOptions = {}): Promise<T> {
  return send<T>(path, options, true);
}