class PluginSettingsBase

abstract class PluginSettingsBase extends PluginBase implements PluginSettingsInterface, DependentPluginInterface {
    
    /**
     * The plugin settings.
     *
     * @var array
     */
    protected $settings = [];
    
    /**
     * The plugin settings injected by third party modules.
     *
     * @var array
     *
     * @see hooks
     */
    protected $thirdPartySettings = [];
    
    /**
     * Whether default settings have been merged into the current $settings.
     *
     * @var bool
     */
    protected $defaultSettingsMerged = FALSE;
    
    /**
     * {@inheritdoc}
     */
    public static function defaultSettings() {
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSettings() {
        // Merge defaults before returning the array.
        if (!$this->defaultSettingsMerged) {
            $this->mergeDefaults();
        }
        return $this->settings;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSetting($key) {
        // Merge defaults if we have no value for the key.
        if (!$this->defaultSettingsMerged && !array_key_exists($key, $this->settings)) {
            $this->mergeDefaults();
        }
        return $this->settings[$key] ?? NULL;
    }
    
    /**
     * Merges default settings values into $settings.
     */
    protected function mergeDefaults() {
        $this->settings += static::defaultSettings();
        $this->defaultSettingsMerged = TRUE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setSettings(array $settings) {
        $this->settings = $settings;
        $this->defaultSettingsMerged = FALSE;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setSetting($key, $value) {
        $this->settings[$key] = $value;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getThirdPartySettings($module = NULL) {
        if ($module) {
            return $this->thirdPartySettings[$module] ?? [];
        }
        return $this->thirdPartySettings;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getThirdPartySetting($module, $key, $default = NULL) {
        return $this->thirdPartySettings[$module][$key] ?? $default;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setThirdPartySetting($module, $key, $value) {
        $this->thirdPartySettings[$module][$key] = $value;
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function unsetThirdPartySetting($module, $key) {
        unset($this->thirdPartySettings[$module][$key]);
        // If the third party is no longer storing any information, completely
        // remove the array holding the settings for this module.
        if (empty($this->thirdPartySettings[$module])) {
            unset($this->thirdPartySettings[$module]);
        }
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getThirdPartyProviders() {
        return array_keys($this->thirdPartySettings);
    }
    
    /**
     * {@inheritdoc}
     */
    public function calculateDependencies() {
        if (!empty($this->thirdPartySettings)) {
            // Create dependencies on any modules providing third party settings.
            return [
                'module' => array_keys($this->thirdPartySettings),
            ];
        }
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function onDependencyRemoval(array $dependencies) {
        $changed = FALSE;
        if (!empty($this->thirdPartySettings) && !empty($dependencies['module'])) {
            $old_count = count($this->thirdPartySettings);
            $this->thirdPartySettings = array_diff_key($this->thirdPartySettings, array_flip($dependencies['module']));
            $changed = $old_count != count($this->thirdPartySettings);
        }
        return $changed;
    }

}