metric->getValue();
 * $settings->description->getValue();
 */
class SystemSettings extends \Piwik\Settings\Plugin\SystemSettings
{
    /** @var Setting */
    public $releaseChannel;
    /** @var Setting */
    public $sendPluginUpdateEmail;
    /** @var Setting */
    public $updateToUtf8mb4;
    /**
     * @var ReleaseChannels
     */
    private $releaseChannels;
    public function __construct(ReleaseChannels $releaseChannels)
    {
        $this->releaseChannels = $releaseChannels;
        parent::__construct();
    }
    protected function init()
    {
        $this->title = Piwik::translate('CoreAdminHome_UpdateSettings');
        $isWritable = Piwik::hasUserSuperUserAccess() && CoreAdminController::isGeneralSettingsAdminEnabled();
        $this->releaseChannel = $this->createReleaseChannel();
        $this->releaseChannel->setIsWritableByCurrentUser($isWritable
            && SettingsPiwik::isMultiServerEnvironment() === false);
        $this->sendPluginUpdateEmail = $this->createSendPluginUpdateEmail();
        $this->sendPluginUpdateEmail->setIsWritableByCurrentUser($isWritable
            && PluginUpdateCommunication::canBeEnabled());
        $dbSettings = new Settings();
        if ($isWritable && $dbSettings->getUsedCharset() !== 'utf8mb4' && DbHelper::getDefaultCharset() === 'utf8mb4') {
            $this->updateToUtf8mb4 = $this->createUpdateToUtf8mb4();
        }
    }
    private function createReleaseChannel()
    {
        $releaseChannels = $this->releaseChannels;
        $default = 'latest_stable';
        return $this->makeSettingManagedInConfigOnly('General', 'release_channel', $default, FieldConfig::TYPE_STRING, function (FieldConfig $field) use ($releaseChannels) {
            $field->introduction = Piwik::translate('CoreAdminHome_ReleaseChannel');
            $field->uiControl = FieldConfig::UI_CONTROL_RADIO;
            $field->availableValues = array();
            foreach ($releaseChannels->getAllReleaseChannels() as $channel) {
                $name = $channel->getName();
                $description = $channel->getDescription();
                if (!empty($description)) {
                    $name .= ' (' . $description . ')';
                }
                $field->availableValues[$channel->getId()] = $name;
            }
            $field->validate = function ($channel) use ($releaseChannels) {
                if (!$releaseChannels->isValidReleaseChannelId($channel)) {
                    throw new \Exception('Release channel is not valid');
                }
            };
            $field->inlineHelp = Piwik::translate('CoreAdminHome_DevelopmentProcess')
                            . '
'
                            . Piwik::translate('CoreAdminHome_StableReleases',
                                               array("",
                                                     ""))
                            . '
'
                            . Piwik::translate('CoreAdminHome_LtsReleases');
        });
    }
    private function createSendPluginUpdateEmail()
    {
        return $this->makeSetting('enable_plugin_update_communication', $default = true, FieldConfig::TYPE_BOOL, function (FieldConfig $field) {
            $field->introduction = Piwik::translate('CoreAdminHome_SendPluginUpdateCommunication');
            $field->uiControl = FieldConfig::UI_CONTROL_RADIO;
            $field->availableValues = array('1' => sprintf('%s (%s)', Piwik::translate('General_Yes'), Piwik::translate('General_Default')),
                                            '0' => Piwik::translate('General_No'));
            $field->inlineHelp = Piwik::translate('CoreAdminHome_SendPluginUpdateCommunicationHelp');
        });
    }
    private function createUpdateToUtf8mb4()
    {
        return $this->makeSetting('update_to_utf8mb4', $default = false, FieldConfig::TYPE_BOOL, function (FieldConfig $field) {
            $field->introduction = Piwik::translate('CoreUpdater_ConvertToUtf8mb4');
            $field->title = Piwik::translate('CoreUpdater_TriggerDatabaseConversion');
            $field->uiControl = FieldConfig::UI_CONTROL_CHECKBOX;
            $field->inlineHelp = Piwik::translate('CoreUpdater_Utf8mb4ConversionHelp', [
                '�',
                '' . PIWIK_INCLUDE_PATH . '/console core:convert-to-utf8mb4',
                '',
                ''
            ]);
        });
    }
}