<?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\Executors;
use FuzeWorks\Async\Executor;
use FuzeWorks\Async\Task;
use FuzeWorks\Async\TasksException;

class ShellExecutor implements Executor
{

    private $binary;
    private $worker;
    private $bootstrapFile;
    private $stdout = "> /dev/null";
    private $stderr = "2> /dev/null";

    /**
     * ShellExecutor constructor.
     *
     * @param array $parameters
     * @throws TasksException
     */
    public function __construct(array $parameters)
    {
        if (!isset($parameters['workerFile']) || !isset($parameters['bootstrapFile']))
            throw new TasksException("Could not construct ShellExecutor. Parameter failure.");

        // Fetch workerFile
        $this->worker = $parameters['workerFile'];
        if (!file_exists($this->worker))
            throw new TasksException("Could not construct ShellExecutor. ShellWorker script does not exist.");

        // First determine the PHP binary
        $this->binary = PHP_BINDIR . DS . 'php';
        $this->bootstrapFile = $parameters['bootstrapFile'];
        if (!file_exists($this->bootstrapFile))
            throw new TasksException("Could not construct ShellExecutor. No bootstrap file found.");
    }

    public function startTask(Task $task, bool $post = false): Task
    {
        // First prepare the command used to spawn workers
        $commandString = "$this->binary $this->worker --bootstrap=".$this->bootstrapFile." -t %s ".($post ? '-p' : '')." $this->stdout $this->stderr & echo $!";

        // Then execute the command using the base64_encoded string of the taskID
        $output = $this->shellExec($commandString, [base64_encode($task->getId())]);
        $pid = intval($output[0]);
        $task->addAttribute('pid', $pid);

        // And finally return the task
        return $task;
    }

    public function stopTask(Task $task, bool $harshly = false): ?Task
    {
        // First prepare the kill command
        $commandString = "kill " . ($harshly ? '-9 ' : '') . "%s";

        // Fetch the process ID from the task
        $pid = $task->attribute('pid');
        if (is_null($pid))
            return null;

        // Then execute the command
        $this->shellExec($commandString, [$pid]);
        if (!$this->getTaskRunning($task))
            $task->removeAttribute('pid');

        return $task;
    }

    public function getTaskRunning(Task $task): bool
    {
        $stats = $this->getTaskStats($task);
        return !is_null($stats);
    }

    public function getTaskStats(Task $task): ?array
    {
        // First prepare the command used to gather info on processes
        $commandString = "ps -o pid,%%cpu,%%mem,state,start -p %s | sed 1d";

        // First we must determine what process is used.
        $pid = $task->attribute('pid');
        if (is_null($pid))
            return null;

        // And we execute the commandString to fetch info on the process
        $output = $this->shellExec($commandString, [$pid]);

        // If not output is provided, the command failed and should return null
        if (count($output) < 1)
            return null;

        // ??
        $last = $output[count($output) - 1];
        if (trim($last) === "")
            return null;

        // Split up the info
        $parts = preg_split("/\s+/", trim($last));

        // Determine the state of the process
        // If the process is in a 'zombie' state, it should be considered fully executed.
        // Cleanup of Zombie processes must take place by periodically restarting the SuperVisor, or by using a SuperVisor which does not have the zombie problem
        $state = strtoupper(trim($parts[3]));
        if ("{$pid}" !== $parts[0] || $state === 'Z')
            return null;

        // Finally, return the Task information
        return ['pid' => (int) $parts[0], 'cpu' => (float) $parts[1], 'mem' => (float) $parts[2], 'state' => $parts[3], 'start' => $parts[4]];
    }

    protected function shellExec($format, array $parameters = [])
    {
        $parameters = array_map("escapeshellarg", $parameters);
        array_unshift($parameters, $format);
        $command = call_user_func_array("sprintf", $parameters);
        exec($command, $output);
        return $output;
    }
}