<?php

namespace Illuminate\Queue;

use Closure;
use Illuminate\Support\ProcessUtils;
use Symfony\Component\Process\Process;
use Symfony\Component\Process\PhpExecutableFinder;

class Listener
{
    /**
     * The command working path.
     *
     * @var string
     */
    protected $commandPath;

    /**
     * The environment the workers should run under.
     *
     * @var string
     */
    protected $environment;

    /**
     * The amount of seconds to wait before polling the queue.
     *
     * @var int
     */
    protected $sleep = 3;

    /**
     * The amount of times to try a job before logging it failed.
     *
     * @var int
     */
    protected $maxTries = 0;

    /**
     * The queue worker command line.
     *
     * @var string
     */
    protected $workerCommand;

    /**
     * The output handler callback.
     *
     * @var \Closure|null
     */
    protected $outputHandler;

    /**
     * Create a new queue listener.
     *
     * @param  string  $commandPath
     * @return void
     */
    public function __construct($commandPath)
    {
        $this->commandPath = $commandPath;
        $this->workerCommand = $this->buildCommandTemplate();
    }

    /**
     * Build the environment specific worker command.
     *
     * @return string
     */
    protected function buildCommandTemplate()
    {
        $command = 'queue:work %s --once --queue=%s --delay=%s --memory=%s --sleep=%s --tries=%s';

        return "{$this->phpBinary()} {$this->artisanBinary()} {$command}";
    }

    /**
     * Get the PHP binary.
     *
     * @return string
     */
    protected function phpBinary()
    {
        return ProcessUtils::escapeArgument(
            (new PhpExecutableFinder)->find(false)
        );
    }

    /**
     * Get the Artisan binary.
     *
     * @return string
     */
    protected function artisanBinary()
    {
        return defined('ARTISAN_BINARY')
                        ? ProcessUtils::escapeArgument(ARTISAN_BINARY)
                        : 'artisan';
    }

    /**
     * Listen to the given queue connection.
     *
     * @param  string  $connection
     * @param  string  $queue
     * @param  \Illuminate\Queue\ListenerOptions  $options
     * @return void
     */
    public function listen($connection, $queue, ListenerOptions $options)
    {
        $process = $this->makeProcess($connection, $queue, $options);

        while (true) {
            $this->runProcess($process, $options->memory);
        }
    }

    /**
     * Create a new Symfony process for the worker.
     *
     * @param  string  $connection
     * @param  string  $queue
     * @param  \Illuminate\Queue\ListenerOptions  $options
     * @return \Symfony\Component\Process\Process
     */
    public function makeProcess($connection, $queue, ListenerOptions $options)
    {
        $command = $this->workerCommand;

        // If the environment is set, we will append it to the command string so the
        // workers will run under the specified environment. Otherwise, they will
        // just run under the production environment which is not always right.
        if (isset($options->environment)) {
            $command = $this->addEnvironment($command, $options);
        }

        // Next, we will just format out the worker commands with all of the various
        // options available for the command. This will produce the final command
        // line that we will pass into a Symfony process object for processing.
        $command = $this->formatCommand(
            $command, $connection, $queue, $options
        );

        return new Process(
            $command, $this->commandPath, null, null, $options->timeout
        );
    }

    /**
     * Add the environment option to the given command.
     *
     * @param  string  $command
     * @param  \Illuminate\Queue\ListenerOptions  $options
     * @return string
     */
    protected function addEnvironment($command, ListenerOptions $options)
    {
        return $command.' --env='.ProcessUtils::escapeArgument($options->environment);
    }

    /**
     * Format the given command with the listener options.
     *
     * @param  string  $command
     * @param  string  $connection
     * @param  string  $queue
     * @param  \Illuminate\Queue\ListenerOptions  $options
     * @return string
     */
    protected function formatCommand($command, $connection, $queue, ListenerOptions $options)
    {
        return sprintf(
            $command,
            ProcessUtils::escapeArgument($connection),
            ProcessUtils::escapeArgument($queue),
            $options->delay, $options->memory,
            $options->sleep, $options->maxTries
        );
    }

    /**
     * Run the given process.
     *
     * @param  \Symfony\Component\Process\Process  $process
     * @param  int  $memory
     * @return void
     */
    public function runProcess(Process $process, $memory)
    {
        $process->run(function ($type, $line) {
            $this->handleWorkerOutput($type, $line);
        });

        // Once we have run the job we'll go check if the memory limit has been exceeded
        // for the script. If it has, we will kill this script so the process manager
        // will restart this with a clean slate of memory automatically on exiting.
        if ($this->memoryExceeded($memory)) {
            $this->stop();
        }
    }

    /**
     * Handle output from the worker process.
     *
     * @param  int  $type
     * @param  string  $line
     * @return void
     */
    protected function handleWorkerOutput($type, $line)
    {
        if (isset($this->outputHandler)) {
            call_user_func($this->outputHandler, $type, $line);
        }
    }

    /**
     * Determine if the memory limit has been exceeded.
     *
     * @param  int  $memoryLimit
     * @return bool
     */
    public function memoryExceeded($memoryLimit)
    {
        return (memory_get_usage() / 1024 / 1024) >= $memoryLimit;
    }

    /**
     * Stop listening and bail out of the script.
     *
     * @return void
     */
    public function stop()
    {
        exit;
    }

    /**
     * Set the output handler callback.
     *
     * @param  \Closure  $outputHandler
     * @return void
     */
    public function setOutputHandler(Closure $outputHandler)
    {
        $this->outputHandler = $outputHandler;
    }
}
