const API_BASE_URL = process.env['NEXT_PUBLIC_API_URL'] || 'http://localhost:3001';

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

type RequestOptions = Omit<RequestInit, 'body'> & {
  body?: unknown;
};

async function request<T>(endpoint: string, options: RequestOptions = {}): Promise<T> {
  const { body, headers, ...rest } = options;

  const res = await fetch(`${API_BASE_URL}${endpoint}`, {
    ...rest,
    headers: {
      'Content-Type': 'application/json',
      ...headers,
    },
    body: body ? JSON.stringify(body) : undefined,
  });

  if (!res.ok) {
    const error = await res.json().catch(() => ({ message: res.statusText }));
    throw new ApiError(res.status, error.message || 'Request failed');
  }

  return res.json();
}

function authHeaders(token: string): HeadersInit {
  return { Authorization: `Bearer ${token}` };
}

export const apiClient = {
  get: <T>(endpoint: string, headers?: HeadersInit) =>
    request<T>(endpoint, { method: 'GET', headers }),

  post: <T>(endpoint: string, body?: unknown, headers?: HeadersInit) =>
    request<T>(endpoint, { method: 'POST', body, headers }),

  patch: <T>(endpoint: string, body?: unknown, headers?: HeadersInit) =>
    request<T>(endpoint, { method: 'PATCH', body, headers }),

  authGet: <T>(endpoint: string, token: string) =>
    request<T>(endpoint, { method: 'GET', headers: authHeaders(token) }),

  authPost: <T>(endpoint: string, token: string, body?: unknown) =>
    request<T>(endpoint, { method: 'POST', body, headers: authHeaders(token) }),

  authPatch: <T>(endpoint: string, token: string, body?: unknown) =>
    request<T>(endpoint, { method: 'PATCH', body, headers: authHeaders(token) }),
};