Manager.php

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<?php
/*
 You may not change or alter any portion of this comment or credits
 of supporting developers from this source code or any supporting source code
 which is considered copyrighted (c) material of the original comment or credit authors.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*/

namespace Xoops\Core\Service;

use Xoops\Core\Yaml;

class Manager
{
    const MODE_EXCLUSIVE = 1;

    const MODE_CHOICE = 2;

    const MODE_PREFERENCE = 4;

    const MODE_MULTIPLE  = 8;

    const PRIORITY_SELECTED = 0;
    const PRIORITY_HIGH     = 1;
    const PRIORITY_MEDIUM   = 5;
    const PRIORITY_LOW      = 9;

    protected $services = array();

    protected $providerPrefs = null;

    private $providerPrefsFilename = 'var/configs/system_provider_prefs.yml';

    private $providerPrefsCacheKey = 'system/provider/prefs';

    protected function __construct()
    {
        $this->providerPrefs = $this->readProviderPrefs();
    }

    public static function getInstance()
    {
        static $instance = false;

        if (!$instance) {
            $instance = new Manager();
        }

        return $instance;
    }

    public function readYamlProviderPrefs()
    {
        $xoops = \Xoops::getInstance();

        $providerPrefs = array();

        try {
            $file = $xoops->path($this->providerPrefsFilename);
            if (file_exists($file)) {
                $providerPrefs = Yaml::read($xoops->path($file));
            }
            if (empty($providerPrefs)) {
                $providerPrefs = array();
            }
        } catch (\Exception $e) {
            $xoops->events()->triggerEvent('core.exception', $e);
            $providerPrefs = array();
        }
        return $providerPrefs;
    }

    protected function readProviderPrefs()
    {
        $xoops = \Xoops::getInstance();
        $providerPrefs = $xoops->cache()->cacheRead(
            $this->providerPrefsCacheKey,
            array($this, 'readYamlProviderPrefs')
        );
        return $providerPrefs;
    }

    protected function saveProviderPrefs($providerPrefs)
    {
        if (is_array($providerPrefs)) {
            $xoops = \Xoops::getInstance();
            try {
                Yaml::save($providerPrefs, $xoops->path($this->providerPrefsFilename));
                $xoops->cache()->write($this->providerPrefsCacheKey, $providerPrefs);
            } catch (\Exception $e) {
                $xoops->events()->triggerEvent('core.exception', $e);
            }
        }
    }

    public function saveChoice($service, $choices)
    {
        // read current preferences
        $prefs = $this->readProviderPrefs();
        // replace prefs for selected service
        $prefs[$service] = $choices;
        // save the changes
        $this->saveProviderPrefs($prefs);
        // apply to current manager instance
        $this->registerChoice($service, $choices);
    }

    public function registerChoice($service, $choices)
    {
        $provider = $this->locate($service);
        $providers = $provider->getRegistered();
        foreach ($providers as $p) {
            $name = strtolower($p->getName());
            if (isset($choices[$name])) {
                $p->setPriority($choices[$name]);
            }
        }
        $provider->sortProviders();
    }

    public function listChoices($service)
    {
        $providers = $this->locate($service)->getRegistered();
        return $providers;
    }

    public function locate($service)
    {
        $service = strtolower($service);
        if (isset($this->services[$service])) {
            // service already located
            $provider = $this->services[$service];
        } else {
            $xoops = \Xoops::getInstance();
            $provider = new Provider($this, $service);
            $event = 'core.service.locate.' . $service;
            // locate service provider(s)
            // In response to trigger message, the contract implementor should register()
            $xoops->events()->triggerEvent($event, $provider);
            // get reference to the list of providers and prioritize it.
            $registered=$provider->getRegistered();
            if (count($registered)) {
                $choices = isset($this->providerPrefs[$service]) ? $this->providerPrefs[$service] : array();
                foreach ($registered as $p) {
                    $name = strtolower($p->getName());
                    if (isset($choices[$name])) {
                        $p->setPriority($choices[$name]);
                    }
                }
                $provider->sortProviders();
            } else {
                // replace with a null provider since no contract implementers were
                $provider = new NullProvider($this, $service);
            }
            $this->services[$service] = $provider;
        }

        return $provider;
    }
}