<?php
/**
 * File containing the ezcWorkflowNodeMerge class.
 *
 * @package Workflow
 * @version 1.0
 * @copyright Copyright (C) 2005-2007 eZ systems as. All rights reserved.
 * @license http://ez.no/licenses/new_bsd New BSD License
 */

/**
 * Base class for nodes that merge multiple threads of execution.
 *
 * @package Workflow
 * @version 1.0
 */
abstract class ezcWorkflowNodeMerge extends ezcWorkflowNode
{
    /**
     * Constraint: The minimum number of incoming nodes this node has to have
     * to be valid.
     *
     * @var integer
     */
    protected $minInNodes = 2;

    /**
     * Constraint: The maximum number of incoming nodes this node has to have
     * to be valid.
     *
     * @var integer
     */
    protected $maxInNodes = false;

    /**
     * @var array
     */
    protected $state;

    /**
     * Prepares this node for activation.
     *
     * @param ezcWorkflowExecution $execution
     * @param int $threadId
     * @throws ezcWorkflowExecutionException
     */
    protected function prepareActivate( ezcWorkflowExecution $execution, $threadId = 0 )
    {
        $parentThreadId = $execution->getParentThreadId( $threadId );

        foreach ( $this->state as $oldThreadId )
        {
            if ( $parentThreadId != $execution->getParentThreadId( $oldThreadId ) )
            {
                throw new ezcWorkflowExecutionException(
                  'Cannot synchronize threads that were started by different branches.'
                );
            }
        }

        $this->state[] = $threadId;
    }

    /**
     * Performs the merge by ending the incoming threads and
     * activating the outgoing node.
     *
     * @param ezcWorkflowExecution $execution
     */
    protected function doMerge( ezcWorkflowExecution $execution )
    {
        foreach ( $this->state as $threadId )
        {
            $execution->endThread( $threadId );
        }

        $this->activateNode( $execution, $this->outNodes[0] );
        $this->initState();

        return parent::execute( $execution );
    }

    /**
     * Initializes the state of this node.
     */
    protected function initState()
    {
        $this->state = array();
    }
}
?>