import { toast } from 'sonner';
import { AxiosError } from 'axios';

interface BackendErrorResponse {
  message?: string;
  status?: boolean;
  data?: unknown;
}

/**
 * Handles backend errors and displays appropriate toast messages.
 *
 * Expected error response format:
 * {
 *   "message": "exception.login.failed",
 *   "status": false,
 *   "data": null
 * }
 *
 * If the response doesn't match this format, it will show the error message
 * from the exception instead.
 */
export const handleBackendError = (error: unknown): void => {
  // Check if it's an AxiosError
  if (error instanceof Error && 'isAxiosError' in error) {
    const axiosError = error as AxiosError<BackendErrorResponse>;
    const response = axiosError.response;

    // Handle errors with response (non-2xx status codes)
    if (response) {
      const errorData = response.data;

      // Check if the response matches the expected format
      if (errorData && typeof errorData === 'object' && 'message' in errorData && 'status' in errorData) {
        // Use the message from the backend response
        const errorMessage = errorData.message || 'An error occurred';
        toast.error(errorMessage);
        return;
      }

      // If the response doesn't match the expected format,
      // try to extract a message from the response data
      if (errorData && typeof errorData === 'object') {
        const errorObj = errorData as Record<string, unknown>;
        const message =
          (typeof errorObj.message === 'string' ? errorObj.message : null) ||
          (typeof errorObj.error === 'string' ? errorObj.error : null) ||
          response.statusText ||
          'An error occurred';
        toast.error(message);
        return;
      }
    }

    // Handle network errors (no response) - connection refused, timeout, etc.
    if (axiosError.code === 'ERR_NETWORK' || !response) {
      const networkErrorMessage = axiosError.message || 'Network error. Please check your connection and try again.';
      toast.error(networkErrorMessage);
      return;
    }

    // Fallback for other AxiosError cases
    const errorMessage = axiosError.message || 'An error occurred';
    toast.error(errorMessage);
    return;
  }

  // If it's not an axios error, show a generic message
  if (error instanceof Error) {
    toast.error(error.message || 'An error occurred');
    return;
  }

  // Final fallback
  toast.error('An unexpected error occurred');
};