/**
 * Core HTTP client for React Query integration
 * 
 * Architecture:
 * - Axios: HTTP client for making requests
 * - This Client: Handles auth tokens, tenant context, and error formatting
 * - Services: Business logic that uses this client
 * - React Query Hooks: Data fetching layer that uses services
 * 
 * React Query doesn't replace HTTP clients - it manages data fetching/caching/sync
 */
import axios, { AxiosInstance, AxiosRequestConfig, AxiosResponse, AxiosError } from 'axios';

export interface ApiError {
  message: string;
  status?: number;
  code?: string;
  details?: any;
}

class ApiClient {
  private client: AxiosInstance;
  private baseURL: string;
  private authToken: string | null = null;
  private tenantId: string | null = null;

  constructor(baseURL: string = import.meta.env.VITE_API_BASE_URL || 'http://localhost:8000/api/v1') {
    this.baseURL = baseURL;
    
    this.client = axios.create({
      baseURL: this.baseURL,
      timeout: 30000,
      headers: {
        'Content-Type': 'application/json',
      },
    });

    this.setupInterceptors();
  }

  private setupInterceptors() {
    // Request interceptor to add auth headers
    this.client.interceptors.request.use(
      (config) => {
        if (this.authToken) {
          config.headers.Authorization = `Bearer ${this.authToken}`;
        }
        
        if (this.tenantId) {
          config.headers['X-Tenant-ID'] = this.tenantId;
        }

        return config;
      },
      (error) => {
        return Promise.reject(this.handleError(error));
      }
    );

    // Response interceptor for error handling
    this.client.interceptors.response.use(
      (response) => response,
      (error) => {
        return Promise.reject(this.handleError(error));
      }
    );
  }

  private handleError(error: AxiosError): ApiError {
    if (error.response) {
      // Server responded with error status
      const { status, data } = error.response;
      return {
        message: (data as any)?.detail || (data as any)?.message || `Request failed with status ${status}`,
        status,
        code: (data as any)?.code,
        details: data,
      };
    } else if (error.request) {
      // Network error
      return {
        message: 'Network error - please check your connection',
        status: 0,
      };
    } else {
      // Other error
      return {
        message: error.message || 'Unknown error occurred',
      };
    }
  }

  // Configuration methods
  setAuthToken(token: string | null) {
    this.authToken = token;
  }

  setTenantId(tenantId: string | null) {
    this.tenantId = tenantId;
  }

  getAuthToken(): string | null {
    return this.authToken;
  }

  getTenantId(): string | null {
    return this.tenantId;
  }

  // HTTP Methods - Return direct data for React Query
  async get<T = any>(url: string, config?: AxiosRequestConfig): Promise<T> {
    const response: AxiosResponse<T> = await this.client.get(url, config);
    return response.data;
  }

  async post<T = any, D = any>(
    url: string,
    data?: D,
    config?: AxiosRequestConfig
  ): Promise<T> {
    const response: AxiosResponse<T> = await this.client.post(url, data, config);
    return response.data;
  }

  async put<T = any, D = any>(
    url: string,
    data?: D,
    config?: AxiosRequestConfig
  ): Promise<T> {
    const response: AxiosResponse<T> = await this.client.put(url, data, config);
    return response.data;
  }

  async patch<T = any, D = any>(
    url: string,
    data?: D,
    config?: AxiosRequestConfig
  ): Promise<T> {
    const response: AxiosResponse<T> = await this.client.patch(url, data, config);
    return response.data;
  }

  async delete<T = any>(url: string, config?: AxiosRequestConfig): Promise<T> {
    const response: AxiosResponse<T> = await this.client.delete(url, config);
    return response.data;
  }

  // File upload helper
  async uploadFile<T = any>(
    url: string,
    file: File | FormData,
    config?: AxiosRequestConfig
  ): Promise<T> {
    const formData = file instanceof FormData ? file : new FormData();
    if (file instanceof File) {
      formData.append('file', file);
    }

    return this.post<T>(url, formData, {
      ...config,
      headers: {
        ...config?.headers,
        'Content-Type': 'multipart/form-data',
      },
    });
  }

  // Raw axios instance for advanced usage
  getAxiosInstance(): AxiosInstance {
    return this.client;
  }
}

// Create and export singleton instance
export const apiClient = new ApiClient();
export default apiClient;