<?php

/*
+---------------------------------------------------------------------------+
| Revive Adserver                                                           |
| http://www.revive-adserver.com                                            |
|                                                                           |
| Copyright: See the COPYRIGHT.txt file.                                    |
| License: GPLv2 or later, see the LICENSE.txt file.                        |
+---------------------------------------------------------------------------+
*/

require_once MAX_PATH . '/lib/OA/Task.php';

/**
 * A class for storing a collection of tasks, and then running those tasks
 * (in order) when requested.
 *
 * @package    OpenX
 * @subpackage Tasks
 */
class OA_Task_Runner
{
    public const TASK_ORDER_BEFORE = -1;
    public const TASK_ORDER_REPLACE = 0;
    public const TASK_ORDER_AFTER = 1;

    /**
     * The collection of Task objects
     * @var array
     */
    public $aTasks = [];

    /**
     * A method to run the run() method of each task in the collection,
     * in the registered order.
     *
     * @todo We should really make OA_Task::run return a boolean we can check.
     */
    public function runTasks()
    {
        // Remove tasks from the queue and unset them when done to prevent
        // useless memory consumption
        while ($oTask = array_shift($this->aTasks)) {
            OA::debug('Task begin: ' . get_class($oTask), PEAR_LOG_INFO);
            $oTask->run();
            OA::debug('Task complete: ' . get_class($oTask), PEAR_LOG_INFO);
            unset($oTask);
        }
    }

    /**
     * A method to register a new Task object in the collection of tasks.
     * The task may be added to the end of the task list, replace an existing task
     * or be inserted before or after an existing task.
     *
     * @param OA_Task $oTask An object that implements the OA_Task interface.
     * @param string $className An optional string specifying the class name of a task
     *                       already in the collection, which this task is to be inserted
     *                       to run just after or replace.
     * @param boolean $order -1 if the task is to be added before the specified class name,
     *                      1 if the task is to be added after the specified class name,
     *                      0 if the task is to replace the specified class name.
     * @return boolean Returns true on add success, false on failure.
     */
    public function addTask($oTask, $className = null, $order = self::TASK_ORDER_AFTER)
    {
        if (!is_null($className)) {

            // Try to locate the task supplied
            foreach ($this->aTasks as $key => $oExistingTask) {
                if (is_a($oExistingTask, $className)) {
                    if ($order == self::TASK_ORDER_AFTER) {

                        // Insert the new task after this item
                        $this->aTasks = array_merge(
                            array_slice($this->aTasks, 0, $key + 1),
                            [$oTask],
                            array_slice($this->aTasks, $key + 1)
                        );
                    } elseif ($order == self::TASK_ORDER_REPLACE) {

                        // Replace the specified task
                        $this->aTasks[$key] = $oTask;
                    } elseif ($order == self::TASK_ORDER_BEFORE) {

                        // Insert the new task before this item
                        $this->aTasks = array_merge(
                            array_slice($this->aTasks, 0, $key),
                            [$oTask],
                            array_slice($this->aTasks, $key)
                        );
                    }
                    return true;
                }
            }
            // The existing task specified was not found
            return false;
        }

        if (is_a($oTask, 'OA_Task')) {
            $this->aTasks[] = &$oTask;
            return true;
        }
        return false;
    }
}
