/**
 * API 统一请求层（TypeScript）
 *
 * 职责：纯 HTTP 客户端，统一处理 Token / 超时 / 错误码 / Session 失效。
 */
import { API_BASE_URL } from '../env';
import type { ApiResponse } from '../types';

export const REQUEST_ERROR = {
  NETWORK_ERROR: 'NETWORK_ERROR',
  UNAUTHORIZED: 'UNAUTHORIZED',
  FORBIDDEN: 'FORBIDDEN',
  RATE_LIMITED: 'RATE_LIMITED',
  BUSINESS_ERROR: 'BUSINESS_ERROR',
  SERVER_ERROR: 'SERVER_ERROR',
  MAINTENANCE: 'MAINTENANCE',
} as const;

export interface ApiError {
  code: string;
  message: string;
  requestId: string;
  error?: unknown;
}

export class ApiClient {
  baseURL: string;
  token: string | null = null;
  refreshToken: string | null = null;
  onSessionExpired: ((reason: any) => void) | null = null;
  onMaintenance: ((data: any) => void) | null = null;

  constructor() {
    this.baseURL = API_BASE_URL;
  }

  getToken(): string | null {
    if (this.token) return this.token;
    try {
      this.token = wx.getStorageSync('accessToken') as string || null;
      this.refreshToken = wx.getStorageSync('refreshToken') as string || null;
    } catch { /* ignore */ }
    return this.token;
  }

  getRefreshToken(): string | null {
    if (this.refreshToken) return this.refreshToken;
    try {
      this.refreshToken = wx.getStorageSync('refreshToken') as string || null;
    } catch { /* ignore */ }
    return this.refreshToken;
  }

  saveToken(token: string, refreshToken?: string): void {
    this.token = token;
    this.refreshToken = refreshToken || null;
    wx.setStorageSync('accessToken', token);
    if (refreshToken) wx.setStorageSync('refreshToken', refreshToken);
  }

  clearToken(): void {
    this.token = null;
    this.refreshToken = null;
    wx.removeStorageSync('accessToken');
    wx.removeStorageSync('refreshToken');
  }

  generateRequestId(): string {
    return Date.now().toString(36) + Math.random().toString(36).substring(2, 8);
  }

  request<T>(options: {
    url: string;
    method?: 'GET' | 'POST' | 'PUT' | 'DELETE';
    data?: unknown;
    headers?: Record<string, string>;
    idempotencyKey?: string;
    timeout?: number;
  }): Promise<T> {
    const { url, method = 'GET', data, headers = {}, idempotencyKey, timeout = 10000 } = options;
    const token = this.getToken();
    const requestId = this.generateRequestId();

    return new Promise((resolve, reject) => {
      wx.request({
        url: this.baseURL + url,
        method,
        data,
        timeout,
        header: {
          'Content-Type': 'application/json',
          'X-Request-Id': requestId,
          ...(idempotencyKey ? { 'Idempotency-Key': idempotencyKey } : {}),
          ...(token ? { Authorization: `Bearer ${token}` } : {}),
          ...headers,
        },
        success: (res: any) => {
          if (res.statusCode === 503) {
            if (this.onMaintenance) this.onMaintenance(res.data || {});
            reject({ code: REQUEST_ERROR.MAINTENANCE, message: '平台正在维护，请稍后再试', requestId });
            return;
          }
          if (res.statusCode === 200) {
            const body = (res.data as any) || {};
            if (body.success) {
              resolve(body.data as T);
            } else {
              reject({ code: body.code || REQUEST_ERROR.BUSINESS_ERROR, message: body.message, requestId });
            }
          } else if (res.statusCode === 401) {
            this.clearToken();
            if (this.onSessionExpired) this.onSessionExpired({});
            reject({ code: REQUEST_ERROR.UNAUTHORIZED, message: '请重新登录', requestId });
          } else if (res.statusCode === 403) {
            reject({ code: REQUEST_ERROR.FORBIDDEN, message: '无权限访问', requestId });
          } else if (res.statusCode === 429) {
            reject({ code: REQUEST_ERROR.RATE_LIMITED, message: '请求过于频繁，请稍后重试', requestId });
          } else {
            reject({ code: REQUEST_ERROR.SERVER_ERROR, message: '服务暂时不可用', requestId });
          }
        },
        fail: (err) => {
          reject({ code: REQUEST_ERROR.NETWORK_ERROR, message: '网络连接失败', requestId, error: err });
        },
      });
    });
  }

  get<T>(url: string, data?: unknown, headers?: Record<string, string>): Promise<T> {
    return this.request<T>({ url, method: 'GET', data, headers });
  }

  post<T>(url: string, data?: unknown, headers?: Record<string, string>, idempotencyKey?: string): Promise<T> {
    return this.request<T>({ url, method: 'POST', data, headers, idempotencyKey });
  }

  put<T>(url: string, data?: unknown, headers?: Record<string, string>): Promise<T> {
    return this.request<T>({ url, method: 'PUT', data, headers });
  }

  delete<T>(url: string, data?: unknown, headers?: Record<string, string>): Promise<T> {
    return this.request<T>({ url, method: 'DELETE', data, headers });
  }
}

export const api = new ApiClient();
export default api;