/*
 * Copyright (C) 2005-2010 Alfresco Software Limited.
 *
 * This file is part of Alfresco
 *
 * Alfresco is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Alfresco is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
 */
package org.alfresco.repo.transaction;

import javax.transaction.UserTransaction;

import org.alfresco.repo.admin.SysAdminParams;
import org.alfresco.repo.security.authentication.AuthenticationContext;
import org.alfresco.service.transaction.TransactionService;
import org.alfresco.util.VmShutdownListener;
import org.alfresco.util.transaction.SpringAwareUserTransaction;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.TransactionDefinition;

/**
 * Default implementation of Transaction Service.
 * <p>
 * Default retry behaviour: see {@link RetryingTransactionHelper#RetryingTransactionHelper()}
 * 
 * @author David Caruana
 */
public class TransactionServiceImpl implements TransactionService
{
    private static VmShutdownListener shutdownListener = new VmShutdownListener("TransactionService");

    private PlatformTransactionManager transactionManager;
    private AuthenticationContext authenticationContext;
    private int maxRetries = -1;
    private int minRetryWaitMs = -1;
    private int maxRetryWaitMs = -1;
    private int retryWaitIncrementMs = -1;

    // SysAdmin cache - used to cluster certain configuration parameters
    private SysAdminParams sysAdminParams;
    private boolean allowWrite;

    /**
     * Set the transaction manager to use
     * 
     * @param transactionManager
     *            platform transaction manager
     */
    public void setTransactionManager(PlatformTransactionManager transactionManager)
    {
        this.transactionManager = transactionManager;
    }

    /**
     * Sets the authentication context.
     * 
     * @param authenticationContext
     *            the authentication context
     */
    public void setAuthenticationContext(AuthenticationContext authenticationContext)
    {
        this.authenticationContext = authenticationContext;
    }

    public void setSysAdminParams(SysAdminParams sysAdminParams)
    {
        this.sysAdminParams = sysAdminParams;
    }

    /**
     * Set the read-only mode for all generated transactions.
     * 
     * @param allowWrite
     *            false if all transactions must be read-only
     */
    public void setAllowWrite(boolean allowWrite)
    {
        this.allowWrite = allowWrite;
    }

    public boolean isReadOnly()
    {
        if (shutdownListener.isVmShuttingDown())
        {
            return true;
        }
        // Make the repo writable to the system user, so that e.g. the allow write flag can still be edited by JMX
        return !this.allowWrite || !this.authenticationContext.isCurrentUserTheSystemUser()
                && !this.sysAdminParams.getAllowWrite();
    }

    /**
     * @see RetryingTransactionHelper#setMaxRetries(int)
     */
    public void setMaxRetries(int maxRetries)
    {
        this.maxRetries = maxRetries;
    }

    /**
     * @see RetryingTransactionHelper#setMinRetryWaitMs(int)
     */
    public void setMinRetryWaitMs(int minRetryWaitMs)
    {
        this.minRetryWaitMs = minRetryWaitMs;
    }

    /**
     * @see RetryingTransactionHelper#setMaxRetryWaitMs(int)
     */
    public void setMaxRetryWaitMs(int maxRetryWaitMs)
    {
        this.maxRetryWaitMs = maxRetryWaitMs;
    }

    /**
     * @see RetryingTransactionHelper#setRetryWaitIncrementMs(int)
     */
    public void setRetryWaitIncrementMs(int retryWaitIncrementMs)
    {
        this.retryWaitIncrementMs = retryWaitIncrementMs;
    }

    /**
     * @see org.springframework.transaction.TransactionDefinition#PROPAGATION_REQUIRED
     */
    public UserTransaction getUserTransaction()
    {
        SpringAwareUserTransaction txn = new SpringAwareUserTransaction(transactionManager, isReadOnly(),
                TransactionDefinition.ISOLATION_DEFAULT, TransactionDefinition.PROPAGATION_REQUIRED,
                TransactionDefinition.TIMEOUT_DEFAULT);
        return txn;
    }

    /**
     * @see org.springframework.transaction.TransactionDefinition#PROPAGATION_REQUIRED
     */
    public UserTransaction getUserTransaction(boolean readOnly)
    {
        SpringAwareUserTransaction txn = new SpringAwareUserTransaction(transactionManager, (readOnly | isReadOnly()),
                TransactionDefinition.ISOLATION_DEFAULT, TransactionDefinition.PROPAGATION_REQUIRED,
                TransactionDefinition.TIMEOUT_DEFAULT);
        return txn;
    }

    /**
     * @see org.springframework.transaction.TransactionDefinition#PROPAGATION_REQUIRES_NEW
     */
    public UserTransaction getNonPropagatingUserTransaction()
    {
        SpringAwareUserTransaction txn = new SpringAwareUserTransaction(transactionManager, isReadOnly(),
                TransactionDefinition.ISOLATION_DEFAULT, TransactionDefinition.PROPAGATION_REQUIRES_NEW,
                TransactionDefinition.TIMEOUT_DEFAULT);
        return txn;
    }

    /**
     * @see org.springframework.transaction.TransactionDefinition#PROPAGATION_REQUIRES_NEW
     */
    public UserTransaction getNonPropagatingUserTransaction(boolean readOnly)
    {
        SpringAwareUserTransaction txn = new SpringAwareUserTransaction(transactionManager, (readOnly | isReadOnly()),
                TransactionDefinition.ISOLATION_DEFAULT, TransactionDefinition.PROPAGATION_REQUIRES_NEW,
                TransactionDefinition.TIMEOUT_DEFAULT);
        return txn;
    }

    /**
     * Creates a new helper instance. It can be reused or customized by the client code: each instance is new and
     * initialized afresh.
     */
    public RetryingTransactionHelper getRetryingTransactionHelper()
    {
        RetryingTransactionHelper helper = new RetryingTransactionHelper();
        helper.setTransactionService(this);
        helper.setReadOnly(isReadOnly());
        if (maxRetries >= 0)
        {
            helper.setMaxRetries(maxRetries);
        }
        if (minRetryWaitMs > 0)
        {
            helper.setMinRetryWaitMs(minRetryWaitMs);
        }
        if (maxRetryWaitMs > 0)
        {
            helper.setMaxRetryWaitMs(maxRetryWaitMs);
        }
        if (retryWaitIncrementMs > 0)
        {
            helper.setRetryWaitIncrementMs(retryWaitIncrementMs);
        }
        return helper;
    }
}