/**
 *  Copyright 1999-2019 Seata.io Group.
 *
 *  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 io.seata.spring.kt.support

import io.seata.core.context.RootContext
import kotlinx.coroutines.ThreadContextElement
import kotlin.coroutines.AbstractCoroutineContextElement
import kotlin.coroutines.CoroutineContext

/**
 * TransactionCoroutineContext
 * 
 * @author sustly
 */
class TransactionCoroutineContext(private val xid: String? = RootContext.getXID()) :
    AbstractCoroutineContextElement(TransactionCoroutineContext),
    ThreadContextElement<String?> {

    companion object : CoroutineContext.Key<TransactionCoroutineContext>

    override fun restoreThreadContext(context: CoroutineContext, oldState: String?) {
        if (oldState != xid && oldState != null) {
            RootContext.bind(oldState)
        } else {
            RootContext.unbind()
        }
    }

    override fun updateThreadContext(context: CoroutineContext): String? {
        return RootContext.getXID().apply {
            if (xid != null) RootContext.bind(xid)
        }
    }
}
