class Debug

class Debug extends \Twig_Extension {
    
    /**
     * The devel dumper service.
     *
     * @var \Drupal\devel\DevelDumperManagerInterface
     */
    protected $dumper;
    
    /**
     * Constructs a Debug object.
     *
     * @param \Drupal\devel\DevelDumperManagerInterface $dumper
     *   The devel dumper service.
     */
    public function __construct(DevelDumperManagerInterface $dumper) {
        $this->dumper = $dumper;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getName() {
        return 'devel_debug';
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFunctions() {
        $functions = [];
        foreach ([
            'devel_dump',
            'kpr',
        ] as $function) {
            $functions[] = new \Twig_SimpleFunction($function, [
                $this,
                'dump',
            ], [
                'is_safe' => [
                    'html',
                ],
                'needs_environment' => TRUE,
                'needs_context' => TRUE,
                'is_variadic' => TRUE,
            ]);
        }
        foreach ([
            'devel_message',
            'dpm',
            'dsm',
        ] as $function) {
            $functions[] = new \Twig_SimpleFunction($function, [
                $this,
                'message',
            ], [
                'is_safe' => [
                    'html',
                ],
                'needs_environment' => TRUE,
                'needs_context' => TRUE,
                'is_variadic' => TRUE,
            ]);
        }
        foreach ([
            'devel_breakpoint',
        ] as $function) {
            $functions[] = new \Twig_SimpleFunction($function, [
                $this,
                'breakpoint',
            ], [
                'needs_environment' => TRUE,
                'needs_context' => TRUE,
                'is_variadic' => TRUE,
            ]);
        }
        return $functions;
    }
    
    /**
     * Provides debug function to Twig templates.
     *
     * Handles 0, 1, or multiple arguments.
     *
     * @param \Twig_Environment $env
     *   The twig environment instance.
     * @param array $context
     *   An array of parameters passed to the template.
     * @param array $args
     *   An array of parameters passed the function.
     *
     * @return string
     *   String representation of the input variables.
     *
     * @see \Drupal\devel\DevelDumperManager::dump()
     */
    public function dump(\Twig_Environment $env, array $context, array $args = []) {
        if (!$env->isDebug()) {
            return;
        }
        ob_start();
        // No arguments passed, display full Twig context.
        if (empty($args)) {
            $context_variables = $this->getContextVariables($context);
            $this->dumper
                ->dump($context_variables, 'Twig context');
        }
        else {
            foreach ($args as $variable) {
                $this->dumper
                    ->dump($variable);
            }
        }
        return ob_get_clean();
    }
    
    /**
     * Provides debug function to Twig templates.
     *
     * Handles 0, 1, or multiple arguments.
     *
     * @param \Twig_Environment $env
     *   The twig environment instance.
     * @param array $context
     *   An array of parameters passed to the template.
     * @param array $args
     *   An array of parameters passed the function.
     *
     * @return void
     *
     * @see \Drupal\devel\DevelDumperManager::message()
     */
    public function message(\Twig_Environment $env, array $context, array $args = []) {
        if (!$env->isDebug()) {
            return;
        }
        // No arguments passed, display full Twig context.
        if (empty($args)) {
            $context_variables = $this->getContextVariables($context);
            $this->dumper
                ->message($context_variables, 'Twig context');
        }
        else {
            foreach ($args as $variable) {
                $this->dumper
                    ->message($variable);
            }
        }
    }
    
    /**
     * Provides XDebug integration for Twig templates.
     *
     * To use this features simply put the following statement in the template
     * of interest:
     *
     * @code
     * {{ devel_breakpoint() }}
     * @endcode
     *
     * When the template is evaluated is made a call to a dedicated method in
     * devel twig debug extension in which is used xdebug_break(), that emits a
     * breakpoint to the debug client (the debugger break on the specific line as
     * if a normal file/line breakpoint was set on this line).
     * In this way you'll be able to inspect any variables available in the
     * template (environment, context, specific variables etc..) in your IDE.
     *
     * @param \Twig_Environment $env
     *   The twig environment instance.
     * @param array $context
     *   An array of parameters passed to the template.
     * @param array $args
     *   An array of parameters passed the function.
     */
    public function breakpoint(\Twig_Environment $env, array $context, array $args = []) {
        if (!$env->isDebug()) {
            return;
        }
        if (function_exists('xdebug_break')) {
            xdebug_break();
        }
    }
    
    /**
     * Filters the Twig context variable.
     *
     * @param array $context
     *  The Twig context.
     *
     * @return array
     *   An array Twig context variables.
     */
    protected function getContextVariables(array $context) {
        $context_variables = [];
        foreach ($context as $key => $value) {
            if (!$value instanceof \Twig_Template) {
                $context_variables[$key] = $value;
            }
        }
        return $context_variables;
    }

}