<?php

/**
 * Class MC4WP_Queue
 *
 * @ignore
 */
class MC4WP_Queue
{
    /**
     * @var MC4WP_Queue_Job[]
     */
    protected $jobs;

    /**
     * @var string
     */
    protected $option_name;

    /**
     * @var bool
     */
    protected $dirty = false;

    /**
     * @var int
     */
    private const MAX_JOB_COUNT = 1000;

    /**
     * MC4WP_Ecommerce_Queue constructor.
     *
     * @param string $option_name
     */
    public function __construct($option_name)
    {
        $this->option_name = $option_name;

        register_shutdown_function([ $this, 'save' ]);
    }

    /**
     * Load jobs from option
     */
    protected function load()
    {
        if ($this->jobs !== null) {
            return;
        }

        $jobs = get_option($this->option_name, []);

        if (! is_array($jobs)) {
            $jobs = [];
        } else {
            $valid_jobs = [];

            foreach ($jobs as $i => $obj) {
                // filter invalid data from array
                if (! is_object($obj) || empty($obj->data)) {
                    continue;
                }

                // make sure each job is instance of MC4WP_Queue_Job
                if ($obj instanceof MC4WP_Queue_Job) {
                    $job = $obj;
                } else {
                    $job     = new MC4WP_Queue_Job($obj->data);
                    $job->id = $obj->id;
                }

                $valid_jobs[] = $job;
            }

            $jobs = $valid_jobs;
        }

        $this->jobs = $jobs;
    }

    /**
     * Get all jobs in the queue
     *
     * @return MC4WP_Queue_Job[] Array of jobs
     */
    public function all()
    {
        $this->load();
        return $this->jobs;
    }

    /**
     * Add job to queue
     *
     * @param mixed $data
     * @return boolean
     */
    public function put($data)
    {
        $this->load();

        // check if we already have a job with same data
        foreach ($this->jobs as $job) {
            if ($job->data === $data) {
                return false;
            }
        }

        // if we have more than MAX_JOB_COUNT jobs, remove first job item.
        // this protects against an ever-growing job list, but also potentially loses jobs if the queue is not processed soon enough.
        if (count($this->jobs) > self::MAX_JOB_COUNT) {
            array_shift($this->jobs);
        }

        // add job to end of jobs array
        $job          = new MC4WP_Queue_Job($data);
        $this->jobs[] = $job;
        $this->dirty  = true;
        return true;
    }

    /**
     * Get all jobs in the queue
     *
     * @return MC4WP_Queue_Job|false
     */
    public function get()
    {
        $this->load();

        // do we have jobs?
        if (count($this->jobs) === 0) {
            return false;
        }

        // return first element
        return reset($this->jobs);
    }

    /**
     * @param MC4WP_Queue_Job $job
     */
    public function delete(MC4WP_Queue_Job $job)
    {
        $this->load();

        $index = array_search($job, $this->jobs, true);

        // check for "false" here, as 0 is a valid index.
        if ($index !== false) {
            unset($this->jobs[ $index ]);
            $this->jobs  = array_values($this->jobs);
            $this->dirty = true;
        }
    }

    /**
     * @param MC4WP_Queue_Job $job
     */
    public function reschedule(MC4WP_Queue_Job $job)
    {
        $this->load();

        // delete job from start of queue
        $this->delete($job);

        // add job to end of queue
        $this->jobs[] = $job;
        $this->dirty  = true;
    }

    /**
     * Reset queue
     */
    public function reset()
    {
        $this->jobs  = [];
        $this->dirty = true;
    }

    /**
     * Save the queue
     */
    public function save()
    {
        if (! $this->dirty || $this->jobs === null) {
            return false;
        }

        $success = update_option($this->option_name, $this->jobs, false);

        if ($success) {
            $this->dirty = false;
        }

        return $success;
    }
}
