/*
 * Copyright 2002-2019 the original author or authors.
 *
 * 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
 *
 *      https://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 org.springframework.core.annotation;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.lang.Nullable;

Log facade used to handle annotation introspection failures (in particular TypeNotPresentExceptions). Allows annotation processing to continue, assuming that when Class attribute values are not resolvable the annotation should effectively disappear. 
Author:
Phillip Webb
Since:
5.2/**
 * Log facade used to handle annotation introspection failures (in particular
 * {@code TypeNotPresentExceptions}). Allows annotation processing to continue,
 * assuming that when Class attribute values are not resolvable the annotation
 * should effectively disappear.
 *
 * @author Phillip Webb
 * @since 5.2
 */
enum IntrospectionFailureLogger {

	DEBUG {
		@Override
		public boolean isEnabled() {
			return getLogger().isDebugEnabled();
		}
		@Override
		public void log(String message) {
			getLogger().debug(message);
		}
	},

	INFO {
		@Override
		public boolean isEnabled() {
			return getLogger().isInfoEnabled();
		}
		@Override
		public void log(String message) {
			getLogger().info(message);
		}
	};


	@Nullable
	private static Log logger;


	void log(String message, @Nullable Object source, Exception ex) {
		String on = (source != null ? " on " + source : "");
		log(message + on + ": " + ex);
	}

	abstract boolean isEnabled();

	abstract void log(String message);


	private static Log getLogger() {
		Log logger = IntrospectionFailureLogger.logger;
		if (logger == null) {
			logger = LogFactory.getLog(MergedAnnotation.class);
			IntrospectionFailureLogger.logger = logger;
		}
		return logger;
	}

}