export interface ApiResponse<T = any> {
  error?: string;
  success: boolean;
  data?: T;
  message?: string;
  requires2FA?: boolean;
}

class ApiClient {
  private getBaseURL(): string {
    if (typeof window === 'undefined') {
      // Server-side calls downstream Spring Boot
      return process.env.API_URL_SERVER || 'http://localhost:8080';
    }
    // Client-side calls Next.js API Routes proxy
    return process.env.NEXT_PUBLIC_API_URL || 'http://localhost:3000/api';
  }

  private async request<T>(
    method: string,
    endpoint: string,
    body?: any,
    config?: RequestInit & { timeoutMs?: number }
  ): Promise<any> {
    const baseURL = this.getBaseURL();
    const url = `${baseURL}${endpoint}`;

    const headers: Record<string, string> = {
      'Content-Type': 'application/json',
      ...(config?.headers as any),
    };

    const controller = new AbortController();
    const id = setTimeout(() => controller.abort(), config?.timeoutMs || 10000);

    const options: RequestInit = {
      method,
      headers,
      signal: controller.signal,
      ...config,
    };

    if (body !== undefined) {
      options.body = JSON.stringify(body);
    }

    try {
      const res = await fetch(url, options);
      clearTimeout(id);

      if (!res.ok && res.status !== 400 && res.status !== 401 && res.status !== 403) {
        throw new Error(`HTTP error! status: ${res.status}`);
      }

      return await res.json();
    } catch (err: any) {
      clearTimeout(id);
      if (err.name === 'AbortError') {
        throw new Error('Request timeout');
      }
      throw err;
    }
  }

  get<T>(endpoint: string, config?: RequestInit & { timeoutMs?: number }) {
    return this.request<T>('GET', endpoint, undefined, config);
  }

  post<T>(endpoint: string, data?: any, config?: RequestInit & { timeoutMs?: number }) {
    return this.request<T>('POST', endpoint, data, config);
  }

  put<T>(endpoint: string, data?: any, config?: RequestInit & { timeoutMs?: number }) {
    return this.request<T>('PUT', endpoint, data, config);
  }

  delete<T>(endpoint: string, config?: RequestInit & { timeoutMs?: number }) {
    return this.request<T>('DELETE', endpoint, undefined, config);
  }
}

export const apiClient = new ApiClient();