const API_BASE_URL = "http://localhost:8080/api";

export interface ApiError {
  message: string;
}

const getAuthToken = (): string | null => localStorage.getItem("token");

const getHeaders = (includeContentType = false): HeadersInit => {
  const token = getAuthToken();
  const headers: HeadersInit = {};

  if (token) {
    headers.Authorization = `Bearer ${token}`;
  }

  if (includeContentType) {
    headers["Content-Type"] = "application/json";
  }

  return headers;
};

const handleResponse = async <T>(response: Response): Promise<T> => {
  if (!response.ok) {
    const error: ApiError = await response.json().catch(() => ({
      message: "An error occurred",
    }));
    throw new Error(error.message);
  }

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

  return response.json();
};

export const apiClient = {
  get: async <T>(endpoint: string): Promise<T> => {
    const response = await fetch(`${API_BASE_URL}${endpoint}`, {
      headers: getHeaders(),
    });
    return handleResponse<T>(response);
  },

  post: async <T>(endpoint: string, data?: unknown): Promise<T> => {
    const response = await fetch(`${API_BASE_URL}${endpoint}`, {
      method: "POST",
      headers: getHeaders(!!data),
      body: data ? JSON.stringify(data) : undefined,
    });
    return handleResponse<T>(response);
  },

  put: async <T>(endpoint: string, data?: unknown): Promise<T> => {
    const response = await fetch(`${API_BASE_URL}${endpoint}`, {
      method: "PUT",
      headers: getHeaders(!!data),
      body: data ? JSON.stringify(data) : undefined,
    });
    return handleResponse<T>(response);
  },

  delete: async <T>(endpoint: string): Promise<T> => {
    const response = await fetch(`${API_BASE_URL}${endpoint}`, {
      method: "DELETE",
      headers: getHeaders(),
    });
    return handleResponse<T>(response);
  },
};