/*
 * Copyright 2002-2018 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.transaction.annotation;

import java.io.Serializable;
import java.lang.reflect.AnnotatedElement;
import java.util.ArrayList;
import java.util.List;

import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.core.annotation.AnnotationAttributes;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.lang.Nullable;
import org.springframework.transaction.interceptor.NoRollbackRuleAttribute;
import org.springframework.transaction.interceptor.RollbackRuleAttribute;
import org.springframework.transaction.interceptor.RuleBasedTransactionAttribute;
import org.springframework.transaction.interceptor.TransactionAttribute;

/**
 * Strategy implementation for parsing Spring's {@link Transactional} annotation.
 *
 * @author Juergen Hoeller
 * @since 2.5
 */
@SuppressWarnings("serial")
public class SpringTransactionAnnotationParser implements TransactionAnnotationParser, Serializable {

	@Override
	@Nullable
	public TransactionAttribute parseTransactionAnnotation(AnnotatedElement element) {
		//从element对象中获取@Transactional注解 然后把注解属性封装到了AnnotationAttributes
		AnnotationAttributes attributes = AnnotatedElementUtils.findMergedAnnotationAttributes(
				element, Transactional.class, false, false);
		if (attributes != null) {
			//解析出真正的事务属性对象
			return parseTransactionAnnotation(attributes);
		}
		else {
			return null;
		}
	}

	public TransactionAttribute parseTransactionAnnotation(Transactional ann) {
		return parseTransactionAnnotation(AnnotationUtils.getAnnotationAttributes(ann, false, false));
	}

	protected TransactionAttribute parseTransactionAnnotation(AnnotationAttributes attributes) {
		//创建一个基础规则的事务属性对象
		RuleBasedTransactionAttribute rbta = new RuleBasedTransactionAttribute();
		//解析我们@Transactionl上的传播行为
		Propagation propagation = attributes.getEnum("propagation");
		rbta.setPropagationBehavior(propagation.value());
		//解析我们@Transactionl上的隔离级别
		Isolation isolation = attributes.getEnum("isolation");
		rbta.setIsolationLevel(isolation.value());
		//解析我们@Transactionl上的事务超时事件
		rbta.setTimeout(attributes.getNumber("timeout").intValue());
		rbta.setReadOnly(attributes.getBoolean("readOnly"));
		//解析我们@Transactionl上的事务管理器的名称
		rbta.setQualifier(attributes.getString("value"));

		//解析我们的针对哪种异常回滚
		List<RollbackRuleAttribute> rollbackRules = new ArrayList<>();
		for (Class<?> rbRule : attributes.getClassArray("rollbackFor")) {
			rollbackRules.add(new RollbackRuleAttribute(rbRule));
		}
		//对哪种异常进行回滚
		for (String rbRule : attributes.getStringArray("rollbackForClassName")) {
			rollbackRules.add(new RollbackRuleAttribute(rbRule));
		}
		//对哪种异常不回滚
		for (Class<?> rbRule : attributes.getClassArray("noRollbackFor")) {
			rollbackRules.add(new NoRollbackRuleAttribute(rbRule));
		}
		//对哪种类型不回滚
		for (String rbRule : attributes.getStringArray("noRollbackForClassName")) {
			rollbackRules.add(new NoRollbackRuleAttribute(rbRule));
		}
		rbta.setRollbackRules(rollbackRules);

		return rbta;
	}


	@Override
	public boolean equals(Object other) {
		return (this == other || other instanceof SpringTransactionAnnotationParser);
	}

	@Override
	public int hashCode() {
		return SpringTransactionAnnotationParser.class.hashCode();
	}

}
