/*
 * Copyright (C) 2013 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package retrofit;

/**
 * A hook allowing clients to customize error exceptions for synchronous requests.
 *
 * @author Sam Beran sberan@gmail.com
 */
public interface ErrorHandler {
    /**
     * An {@link ErrorHandler} which returns the original error.
     */
    ErrorHandler DEFAULT = new ErrorHandler() {
        @Override
        public Throwable handleError(RetrofitError cause) {
            return cause;
        }
    };

    /**
     * Return a custom exception to be thrown for a {@link RetrofitError}. It is recommended that you
     * pass the supplied error as the cause to any new exceptions.
     * <p/>
     * If the return exception is checked it must be declared to be thrown on the interface method.
     * <p/>
     * Example usage:
     * <pre>
     * class MyErrorHandler implements ErrorHandler {
     *   @Override public Throwable handleError(RetrofitError cause) {
     *     Response r = cause.getResponse();
     *     if (r != null && r.getStatus() == 401) {
     *       return new UnauthorizedException(cause);
     *     }
     *     return cause;
     *   }
     * }
     * </pre>
     *
     * @param cause the original {@link RetrofitError} exception
     * @return Throwable an exception which will be thrown from the client interface method. Must not
     * be {@code null}.
     */
    Throwable handleError(RetrofitError cause);
}