<?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\Supervisors;
use FuzeWorks\Async\Executor;
use FuzeWorks\Async\SuperVisor;
use FuzeWorks\Async\Task;
use FuzeWorks\Async\TasksException;
use FuzeWorks\Async\TaskStorage;

class ParallelSuperVisor implements SuperVisor
{
    /**
     * @var TaskStorage
     */
    protected $taskStorage;

    /**
     * @var Executor
     */
    protected $executor;

    /**
     * @var Task[]
     */
    protected $tasks = [];

    public function __construct(TaskStorage $taskStorage, Executor $executor, array $options = [])
    {
        $this->taskStorage = $taskStorage;
        $this->executor = $executor;
    }

    /**
     * @inheritDoc
     */
    public function cycle(): int
    {
        // First: if there are no tasks, load them
        $this->tasks = $this->taskStorage->readTasks(true);

        // If there are still no tasks, nothing is queued, so this cycle can end.
        if (empty($this->tasks))
            return SuperVisor::FINISHED;

        for ($i=0;$i<count($this->tasks);$i++)
        {
            $task = $this->tasks[$i];
            
            // PENDING: should start if not constrained
            if ($task->getStatus() === Task::PENDING)
            {
                // Test if constrained
                $task = $this->testConstraints($task);

                // If the task changed status, task is no longer pending and should be processed by another statement
                if ($task->getStatus() !== Task::PENDING)
                    continue;

                // Start the process using the executor service
                $task = $this->executor->startTask($task);
                $task->setStatus(Task::RUNNING);
                $task->startTaskTime();

                // Modify the task in TaskStorage
                $this->taskStorage->modifyTask($task);
                fwrite(STDOUT, "\nChanged status of task '".$task->getId()."' to status " . Task::getStatusType($task->getStatus()));
            }

            // DELAYED: If task is delayed, and enough time has passed, change the status back to pending
            elseif ($task->getStatus() === Task::DELAYED && time() > $task->getDelayTime())
            {
                $task->setStatus(Task::PENDING);
                $this->taskStorage->modifyTask($task);
                fwrite(STDOUT, "\nChanged status of task '".$task->getId()."' to status " . Task::getStatusType($task->getStatus()));
            }

            // RUNNING: check if task is still running. If not, set result based on output
            elseif ($task->getStatus() === Task::RUNNING)
            {
                $isRunning = $this->executor->getTaskRunning($task);
                $output = $this->taskStorage->readTaskOutput($task);
                $hasOutput = !is_null($output);

                // If nothing is found, the process has crashed and status PFAILED should be set
                if (!$isRunning && !$hasOutput)
                    $task->setStatus(Task::PFAILED);
                // @todo Set PFAILED after $max_Time
                // If output is found, use the status code from that
                elseif (!$isRunning && $hasOutput)
                {
                    try {
                        $task->setOutput($output['output'], $output['errors']);
                        $task->setStatus($output['statusCode']);
                    } catch (TasksException $e) {
                        // On failure to set output, consider as a process failure
                        $task->setStatus(Task::PFAILED);
                    }
                }
                // In any other situation the process is still running and should be left alone
                else
                    continue;

                // If any changes have been made, they should be written to TaskStorage
                $task->endTaskTime();
                $this->taskStorage->modifyTask($task);
                fwrite(STDOUT, "\nChanged status of task '".$task->getId()."' to status " . Task::getStatusType($task->getStatus()));
            }

            // FAILED: if a process has failed, attempt to rety if requested to do so
            elseif ($task->getStatus() === Task::PFAILED || $task->getStatus() === Task::FAILED)
            {
                // First fetch retry conditions
                $settings = $task->getSettings();

                // First test if any retries should be tried at all
                if ($settings['retryOnFail'] === true && $task->getRetries() < $settings['maxRetries'])
                {
                    // Then test if this type of failure should be retried and whether the mexRetries has been exceeded
                    if (
                        ($task->getStatus() === Task::PFAILED && $settings['retryPFailures'] === true) ||
                        ($task->getStatus() === Task::FAILED && $settings['retryRFailures'] === true)
                    )
                    {
                        // If eligible, reset task to pending
                        $task->addRetry();
                        $task = $this->executor->startTask($task);
                        $task->setStatus(Task::RUNNING);
                        $task->startTaskTime();
                        $this->taskStorage->modifyTask($task);
                        fwrite(STDOUT, "\nChanged status of task '".$task->getId()."' to status " . Task::getStatusType($task->getStatus()));
                        continue;
                    }
                }

                // If the task is not eligible for a retry, either cancel it or move it to a postHandler
                if ($task->getUsePostHandler() === true)
                {
                    $task->resetRetries();
                    $task = $this->executor->startTask($task, true);
                    $task->startPostTime();
                    $task->setStatus(Task::POST);
                }
                else
                    $task->setStatus(Task::CANCELLED);

                $this->taskStorage->modifyTask($task);
                fwrite(STDOUT, "\nChanged status of task '".$task->getId()."' to status " . Task::getStatusType($task->getStatus()));
            }

            // SUCCESS: if a task has succeeded, see if it needs a postHandler
            elseif ($task->getStatus() === Task::SUCCESS)
            {
                if ($task->getUsePostHandler() === true)
                {
                    $task->resetRetries();
                    $task = $this->executor->startTask($task, true);
                    $task->startPostTime();
                    $task->setStatus(Task::POST);
                }
                else
                    $task->setStatus(Task::COMPLETED);

                $this->taskStorage->modifyTask($task);
                fwrite(STDOUT, "\nChanged status of task '".$task->getId()."' to status " . Task::getStatusType($task->getStatus()));
            }

            // POST: when a task is currently running in it's postHandler
            elseif ($task->getStatus() === Task::POST)
            {
                $isRunning = $this->executor->getTaskRunning($task);
                $output = $this->taskStorage->readPostOutput($task);
                $hasOutput = !is_null($output);

                // If a task is not running and has no output, an error has occurred
                if (!$isRunning && !$hasOutput)
                {
                    // Test if a retry should be attempted
                    $settings = $task->getSettings();
                    if ($settings['retryOnFail'] === true && $settings['retryPostFailures'] === true && $settings['maxRetries'] > $task->getRetries())
                    {
                        $task->addRetry();
                        $task = $this->executor->startTask($task, true);
                    }
                    elseif ($settings['retryOnFail'] === true && $settings['retryPostFailures'] === true && $settings['maxRetries'] <= $task->getRetries())
                        $task->setStatus(Task::CANCELLED);
                    else
                        $task->setStatus(Task::CANCELLED);
                }
                // @todo Retry after $max_Time
                // If a task is not running and has output, set that output and mark as completed
                elseif (!$isRunning && $hasOutput)
                {
                    $task->setPostOutput($output['output'], $output['errors']);
                    if ($output['statusCode'] === Task::SUCCESS)
                        $task->setStatus(Task::COMPLETED);
                    else
                        $task->setStatus(Task::CANCELLED);
                }
                // If the task is still running, leave it be
                else
                    continue;

                // If any changes have been made, they should be written to TaskStorage
                $task->endPostTime();
                $this->taskStorage->modifyTask($task);
                fwrite(STDOUT, "\nChanged status of task '".$task->getId()."' to status " . Task::getStatusType($task->getStatus()));
            }

        }

        // Check if all tasks are completed
        $allCompleted = true;
        $anyDelayed = false;
        foreach ($this->tasks as $task)
        {
            if ($task->getStatus() !== Task::COMPLETED && $task->getStatus() !== Task::CANCELLED)
                $allCompleted = false;
            elseif ($task->getStatus() === Task::DELAYED)
                $anyDelayed = true;
        }

        // If all are finished and none are delayed
        if ($allCompleted && !$anyDelayed)
            return SuperVisor::FINISHED;
        if ($allCompleted && $anyDelayed)
            return SuperVisor::CONSTRAINED;
        else
            return SuperVisor::RUNNING;
    }

    private function testConstraints(Task $task): Task
    {
        $constraints = $task->getConstraints();
        foreach ($constraints as $constraint)
        {
            if ($constraint->intervene($task) && $constraint->blockCode() != 0)
            {
                $task->setStatus($constraint->blockCode());
                if ($constraint->blockCode() === Task::DELAYED)
                    $task->setDelayTime($constraint->delayTime());

                // Save changes to TaskStorage
                $this->taskStorage->modifyTask($task);
                fwrite(STDOUT, "\nChanged status of task '".$task->getId()."' to status " . Task::getStatusType($task->getStatus()));
            }
        }

        return $task;
    }


}