<?php
/**
 * FuzeWorks Async Library
 *
 * The FuzeWorks PHP FrameWork
 *
 * Copyright (C) 2013-2020 TechFuze
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * @author    TechFuze
 * @copyright Copyright (c) 2013 - 2020, TechFuze. (http://techfuze.net)
 * @license   https://opensource.org/licenses/MIT MIT License
 *
 * @link  http://techfuze.net/fuzeworks
 * @since Version 1.0.0
 *
 * @version Version 1.0.0
 */

namespace FuzeWorks\Async\Constraint;
use FuzeWorks\Async\Constraint;
use FuzeWorks\Async\Task;
use FuzeWorks\Async\Tasks;
use FuzeWorks\Async\TasksException;
use FuzeWorks\Exception\FactoryException;
use FuzeWorks\Exception\LibraryException;
use FuzeWorks\Factory;
use FuzeWorks\Libraries;
use FuzeWorks\Logger;

/**
 * Class DependencyConstraint
 *
 * Use this constraint to prevent a task from running if one or multiple tasks this task depends on hasn't completed yet.
 * This constraint also can be applied to queue multiple tasks. Make a chain of tasks that depend on one another.
 *
 * @package FuzeWorks\Async\Constraint
 */
class DependencyConstraint implements Constraint
{

    protected $dependencies = [];

    protected $delayTimes = 3;

    protected $returnStatus = Task::DELAYED;

    /**
     * DependencyConstraint constructor.
     *
     * To add dependencies, the following array should be supplied:
     * $dependencyList: array(string 'taskId', string 'taskId', string 'taskId')
     *
     * @param array $dependencyList
     * @param int $delayTimes Time that a task should be delayed before retrying
     * @throws TasksException
     */
    public function __construct(array $dependencyList, int $delayTimes = 3)
    {
        $this->dependencies = $dependencyList;
        $this->delayTimes = $delayTimes;

        // Test if async library can be loaded
        $this->loadTasksLib();
    }

    /**
     * @inheritDoc
     */
    public function intervene(Task $task): bool
    {
        // Fetch taskStorage
        try {
            $tasks = $this->loadTasksLib();
            $taskStorage = $tasks->getTaskStorage();

            // Is any dependency unresolved?
            $hasUnresolved = false;

            // Test if any dependency has not been resolved
            foreach ($this->dependencies as $dependency)
            {
                // Get dependency
                $dependencyTask = $taskStorage->getTaskById($dependency);

                // If the dependency task is completed, ignore it and continue to next dependency
                if ($dependencyTask->getStatus() === Task::COMPLETED)
                    continue;
                elseif ($dependencyTask->getStatus() === Task::CANCELLED)
                {
                    // Cancel current task
                    $task->setOutput('', 'Task cancelled due to failed dependency.');
                    $this->returnStatus = Task::CANCELLED;
                    return true;
                }
                else
                    $hasUnresolved = true;
            }

            // If any unresolved tasks exist, delay task execution
            if ($hasUnresolved)
            {
                $this->returnStatus = Task::DELAYED;
                return true;
            }
        } catch (TasksException $e) {
            Logger::logError("Could not constraint task. '" . $e->getMessage() . "'");
            $this->returnStatus = Task::FAILED;
            return true;
        }

        return false;
    }

    /**
     * @inheritDoc
     */
    public function blockCode(): int
    {
        return $this->returnStatus;
    }

    /**
     * @inheritDoc
     */
    public function delayTime(): int
    {
        return time() + $this->delayTimes;
    }

    /**
     * Return a list of dependencies
     *
     * @return array
     */
    public function getDependencies()
    {
        return $this->dependencies;
    }

    /**
     * Load the tasks library, so that dependencies can get scanned later
     *
     * @return Tasks
     * @throws TasksException
     */
    private function loadTasksLib(): Tasks
    {
        try {
            /** @var Libraries $libraries */
            $libraries = Factory::getInstance('libraries');

            /** @var Tasks $tasks */
            $tasks = $libraries->get('async');

            return $tasks;
        } catch (FactoryException | LibraryException $e) {
            throw new TasksException("Could not constrain task. Async library could not be loaded.");
        }
    }
}