class SettingsForm

class SettingsForm extends ConfigFormBase {
    
    /**
     * The advagg cache.
     *
     * @var \Drupal\Core\Cache\CacheBackendInterface
     */
    protected $cache;
    
    /**
     * Constructs a SettingsForm object.
     *
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   The factory for configuration objects.
     * @param \Drupal\Core\Cache\CacheBackendInterface $cache
     *   The advagg cache.
     */
    public function __construct(ConfigFactoryInterface $config_factory, CacheBackendInterface $cache) {
        parent::__construct($config_factory);
        $this->cache = $cache;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('config.factory'), $container->get('cache.advagg'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'advagg_ext_minify_settings';
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getEditableConfigNames() {
        return [
            'advagg_ext_minify.settings',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $form = [];
        // CSS command line.
        $this->generateForm($form, [
            'css',
            $this->t('CSS'),
        ]);
        // JS command line.
        $this->generateForm($form, [
            'js',
            $this->t('JavaScript'),
        ]);
        return parent::buildForm($form, $form_state);
    }
    
    /**
     * Generate a form for css or js depending on the input.
     *
     * @param array $form
     *   The form array to add to.
     * @param array $params
     *   An array where:
     *     key 0 is the machine name.
     *     key 1 is the title.
     */
    private function generateForm(array &$form, array $params) {
        $form[$params[0]] = [
            '#type' => 'fieldset',
            '#title' => $params[1],
        ];
        $form[$params[0]]['cmd'] = [
            '#type' => 'fieldset',
            '#title' => $this->t('Command Line'),
        ];
        $description = $this->t('{%CWD%} = \\Drupal::root(). <br /> {%IN%} = input file. <br /> {%IN_URL_ENC%} = url pointing to the input file that has been url encoded. <br /> {%OUT%} = output file. <br /><br />');
        if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
            $description .= ' ' . $this->t('Example using the <a href="@link1">Microsoft Ajax Minifier</a>. <p><code>@code1</code></p>', [
                '@link1' => 'http://ajaxmin.codeplex.com/',
                '@code1' => 'AjaxMinifier {%IN%} -o {%OUT%}',
            ]);
        }
        if ($params[0] === 'js') {
            $description .= ' ' . $this->t('Example using the <a href="@link1">Google Closure Compiler</a>. <p><code>@code1</code></p>', [
                '@link1' => 'https://developers.google.com/closure/compiler/docs/gettingstarted_app',
                '@code1' => 'java -jar compiler.jar --js {%CWD%}/{%IN%} --js_output_file {%OUT%}',
            ]);
            $description .= ' ' . $this->t('Example using curl to minify via the <a href="@link1">Online Google Closure Compiler</a>. <p><code>@code1</code></p>', [
                '@link1' => 'https://developers.google.com/closure/compiler/docs/api-ref',
                '@code1' => 'curl -o {%OUT%} -d output_info=compiled_code -d code_url={%IN_URL_ENC%} http://closure-compiler.appspot.com/compile',
            ]);
        }
        if ($params[0] === 'css') {
            $description .= ' ' . $this->t('Example using the <a href="@link1">YUI Compressor</a>. <p><code>@code1</code></p>', [
                '@link1' => 'http://yui.github.io/yuicompressor/',
                '@code1' => 'java -jar yuicompressor-x.y.z.jar --type css --line-break 4096 {%CWD%}/{%IN%} -o {%OUT%}',
            ]);
            $description .= ' ' . $this->t('Example using curl to minify via an online <a href="@link1">CSS Minifier</a>. <p><code>@code1</code></p>', [
                '@link1' => 'http://cnvyr.io/',
                '@code1' => 'curl -o {%OUT%} -F \'files0=@{%IN%}\' http://srv.cnvyr.io/v1?min=css',
            ]);
        }
        $form[$params[0]]['cmd'][$params[0] . '_cmd'] = [
            '#type' => 'textfield',
            '#title' => $this->t('Command to run'),
            '#default_value' => $this->config('advagg_ext_minify.settings')
                ->get($params[0] . '_cmd'),
            '#description' => $description,
        ];
        $form[$params[0]]['cmd'][$params[0] . '_enabled'] = [
            '#type' => 'checkbox',
            '#title' => $this->t('Enable external @type minification', [
                '@type' => $params[1],
            ]),
            '#default_value' => $this->config('advagg_ext_minify.settings')
                ->get($params[0] . '_cmd'),
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $this->config('advagg_ext_minify.settings')
            ->set('js_cmd', $form_state->getValue('js_cmd'))
            ->set('js_enabled', $form_state->getValue('js_enabled'))
            ->set('css_cmd', $form_state->getValue('css_cmd'))
            ->set('css_enabled', $form_state->getValue('css_enabled'))
            ->save();
        parent::submitForm($form, $form_state);
        // Clear relevant caches.
        Cache::invalidateTags([
            'library_info',
        ]);
    }

}