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() {
        $options = [
            'is_safe' => [
                'html',
            ],
            'needs_environment' => TRUE,
            'needs_context' => TRUE,
            'is_variadic' => TRUE,
        ];
        return [
            new \Twig_SimpleFunction('devel_dump', [
                $this,
                'dump',
            ], $options),
            new \Twig_SimpleFunction('kpr', [
                $this,
                'dump',
            ], $options),
            // Preserve familiar kint() function for dumping.
new \Twig_SimpleFunction('kint', [
                $this,
                'kint',
            ], $options),
            new \Twig_SimpleFunction('devel_message', [
                $this,
                'message',
            ], $options),
            new \Twig_SimpleFunction('dpm', [
                $this,
                'message',
            ], $options),
            new \Twig_SimpleFunction('dsm', [
                $this,
                'message',
            ], $options),
            new \Twig_SimpleFunction('devel_breakpoint', [
                $this,
                'breakpoint',
            ], [
                'needs_environment' => TRUE,
                'needs_context' => TRUE,
                'is_variadic' => TRUE,
            ]),
        ];
    }
    
    /**
     * 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 = []) {
        return $this->doDump($env, $context, $args);
    }
    
    /**
     * @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.
     * @param string $plugin_id
     *   The plugin id. Defaults to null.
     *
     * @return string|null
     *   String representation of the input variables, or null if twig_debug mode
     *   is tunred off.
     */
    private function doDump(\Twig_Environment $env, array $context, array $args = [], $plugin_id = NULL) {
        if (!$env->isDebug()) {
            return NULL;
        }
        ob_start();
        // No arguments passed, display full Twig context.
        if (empty($args)) {
            $context_variables = $this->getContextVariables($context);
            $this->dumper
                ->dump($context_variables, 'Twig context', $plugin_id);
        }
        else {
            $parameters = $this->guessTwigFunctionParameters();
            foreach ($args as $index => $variable) {
                $name = !empty($parameters[$index]) ? $parameters[$index] : NULL;
                $this->dumper
                    ->dump($variable, $name, $plugin_id);
            }
        }
        return ob_get_clean();
    }
    
    /**
     * Similar to dump() but always uses the kint dumper if available.
     *
     * 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 kint(\Twig_Environment $env, array $context, array $args = []) {
        return $this->doDump($env, $context, $args, 'kint');
    }
    
    /**
     * 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.
     *
     * @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 {
            $parameters = $this->guessTwigFunctionParameters();
            foreach ($args as $index => $variable) {
                $name = !empty($parameters[$index]) ? $parameters[$index] : NULL;
                $this->dumper
                    ->message($variable, $name);
            }
        }
    }
    
    /**
     * 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;
    }
    
    /**
     * Gets the twig function parameters for the current invocation.
     *
     * @return array
     *   The detected twig function parameters.
     */
    protected function guessTwigFunctionParameters() {
        $callee = NULL;
        $template = NULL;
        $backtrace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS | DEBUG_BACKTRACE_PROVIDE_OBJECT);
        foreach ($backtrace as $index => $trace) {
            if (isset($trace['object']) && $trace['object'] instanceof \Twig_Template && 'Twig_Template' !== get_class($trace['object'])) {
                $template = $trace['object'];
                $callee = $backtrace[$index - 1];
                break;
            }
        }
        $parameters = [];
        
        /** @var \Twig_Template $template */
        if (NULL !== $template && NULL !== $callee) {
            $line_number = $callee['line'];
            $debug_infos = $template->getDebugInfo();
            if (isset($debug_infos[$line_number])) {
                $source_line = $debug_infos[$line_number];
                $source_file_name = $template->getTemplateName();
                if (is_readable($source_file_name)) {
                    $source = file($source_file_name, FILE_IGNORE_NEW_LINES);
                    $line = $source[$source_line - 1];
                    preg_match('/\\((.+)\\)/', $line, $matches);
                    if (isset($matches[1])) {
                        $parameters = array_map('trim', explode(',', $matches[1]));
                    }
                }
            }
        }
        return $parameters;
    }

}