const API_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:5000/api/v1';

export class ApiError extends Error {
  constructor(
    public status: number,
    message: string,
    public data?: any
  ) {
    super(message);
    this.name = 'ApiError';
  }
}

async function handleResponse<T>(response: Response): Promise<T> {
  if (!response.ok) {
    const errorData = await response.json().catch(() => ({}));
    throw new ApiError(
      response.status,
      errorData.message || response.statusText,
      errorData
    );
  }

  if (response.status === 204) {
    return {} as T;
  }

  return response.json();
}

export async function apiRequest<T>(
  endpoint: string,
  options: RequestInit = {}
): Promise<T> {
  const url = `${API_URL}${endpoint}`;

  const headers: Record<string, string> = {
    'Content-Type': 'application/json',
  };

  // Add auth token if available
  if (typeof window !== 'undefined') {
    const token = localStorage.getItem('accessToken');
    if (token) {
      headers['Authorization'] = `Bearer ${token}`;
    }
  }

  // Merge with options headers
  if (options.headers) {
    Object.assign(headers, options.headers);
  }

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

  const response = await fetch(url, config);
  return handleResponse<T>(response);
}

export const api = {
  get: <T>(endpoint: string, options?: RequestInit) =>
    apiRequest<T>(endpoint, { ...options, method: 'GET' }),

  post: <T>(endpoint: string, data?: any, options?: RequestInit) =>
    apiRequest<T>(endpoint, {
      ...options,
      method: 'POST',
      body: JSON.stringify(data),
    }),

  put: <T>(endpoint: string, data?: any, options?: RequestInit) =>
    apiRequest<T>(endpoint, {
      ...options,
      method: 'PUT',
      body: JSON.stringify(data),
    }),

  patch: <T>(endpoint: string, data?: any, options?: RequestInit) =>
    apiRequest<T>(endpoint, {
      ...options,
      method: 'PATCH',
      body: JSON.stringify(data),
    }),

  delete: <T>(endpoint: string, options?: RequestInit) =>
    apiRequest<T>(endpoint, { ...options, method: 'DELETE' }),
};