/**
 * API基础服务
 */

// 默认API基础URL
const API_BASE_URL = process.env.API_BASE_URL || 'http://localhost:8000';

/**
 * 通用API响应格式
 */
export interface ApiResponse<T> {
  status: 'success' | 'error';
  data?: T;
  message?: string;
  error?: {
    code: string;
    details?: any;
  };
}

/**
 * 分页请求参数
 */
export interface PaginationParams {
  page: number;
  pageSize: number;
}

/**
 * 分页响应数据
 */
export interface PaginatedResponse<T> {
  items: T[];
  totalItems: number;
  totalPages: number;
  currentPage: number;
  pageSize: number;
}

/**
 * 统一错误处理
 */
export class ApiError extends Error {
  statusCode: number;
  errorCode: string;
  details?: any;

  constructor(message: string, statusCode: number, errorCode: string, details?: any) {
    super(message);
    this.name = 'ApiError';
    this.statusCode = statusCode;
    this.errorCode = errorCode;
    this.details = details;
  }
}

/**
 * 构建请求URL
 */
export function buildUrl(path: string, params?: Record<string, any>): string {
  const url = new URL(`${API_BASE_URL}${path}`);
  
  if (params) {
    Object.entries(params).forEach(([key, value]) => {
      if (value !== undefined && value !== null) {
        url.searchParams.append(key, String(value));
      }
    });
  }
  
  return url.toString();
}

/**
 * 通用API请求函数
 */
export async function apiRequest<T>(
  url: string,
  method: 'GET' | 'POST' | 'PUT' | 'DELETE' = 'GET',
  body?: any,
  headers?: Record<string, string>
): Promise<T> {
  const requestInit: RequestInit = {
    method,
    headers: {
      'Content-Type': 'application/json',
      'Accept': 'application/json',
      ...headers
    }
  };
  
  if (body) {
    requestInit.body = JSON.stringify(body);
  }
  
  const response = await fetch(url, requestInit);
  
  // 获取响应数据
  const data = await response.json() as ApiResponse<T>;
  
  // 检查状态码
  if (!response.ok) {
    throw new ApiError(
      data.message || '请求失败',
      response.status,
      data.error?.code || 'UNKNOWN_ERROR',
      data.error?.details
    );
  }
  
  // 检查业务状态
  if (data.status === 'error') {
    throw new ApiError(
      data.message || '请求失败',
      response.status, 
      data.error?.code || 'BUSINESS_ERROR',
      data.error?.details
    );
  }
  
  return data.data as T;
}