<?php
/**
 * RRDGraph Plugin: Action Plugin
 *
 * @author Daniel Goß <developer@flashsystems.de>
 * @license MIT
 */

if (! defined ( 'DOKU_INC' )) die ();

/**
 * Structure for storing the media information passed to the media manager.
 * This contains the path within the configured virtual namespace. 
 *
 */
class rrdMediaInfo
{
    /** @var string PageID of the page containing the image. */
    public $pageId;
    
    /** @var string ImageID of the image on the page referenced by $pageID. */
    public $imageId;
}

/**
 * Action Plugin Class for RRDGraph 
 *
 */
class action_plugin_rrdgraph extends DokuWiki_Action_Plugin {
    
    /**
     * Checks if the necessary dependencies for this plugin are installed.
     * @return Array Returns an array of error messages for missing dependencies. If all dependencies are installed an empty array is returned.  
     */
    private function &getMissingDependencies()
    {
        $deps = array();
        
        if (!function_exists("imagecreatetruecolor")) array_push($deps, $this->getLang('gd_missing'));
        if (!function_exists("rrd_graph")) array_push($deps, $this->getLang('rrd_missing'));
        
        return $deps;
    }
    
    /**
     * Creates a rrdMediaInfo instance from a given wiki path.
     * @param string $media Wiki path of the media file including namespace.
     * @return Returns a rrdMediaInfo-Instance if the supplied wiki path is within the virtual media namespace. If it's outside the namespace false is returned. If it's wihin the namespace but the ImageId is invalid NULl is returned.
     */
    private function &parseMediaPath($media)
    {
        $parts = explode(":", $media);
        if (count($parts) < 3) return false;

        $result = new rrdMediaInfo();

        //-- Check if we are within the rrdgraph virtual namespace.
        $mediaNamespace = $this->getConf('graph_media_namespace');
        if (strcmp(array_shift($parts), $mediaNamespace) != 0) return false;

        $result->imageId = array_pop($parts);
        $result->pageId = implode(':', $parts);
        
        //-- Verify the imageId
        if (strspn($result->imageId, '0123456789abcdef') != strlen($result->imageId)) return null;
        
        return $result;
    }
    
	/**
	 * Register the necessary events.
	 * @param Doku_Event_Handler $controller Event-Handler for registering the necessary events.
	 */
	public function register(Doku_Event_Handler $controller) {
	    //-- Performe some checks and show an error message (if an admin is loged in) to inform him that
	    //   some key parts are missing.
	    //   This uses the msg-Function. I don't know if this function is part of the public API. So beware!
        foreach ($this->getMissingDependencies() as $missingDepMessage) {
            msg($missingDepMessage, -1, '', '', MSG_ADMINS_ONLY);
        }
        
        //-- Register the callback hooks
        $controller->register_hook ( 'PARSER_CACHE_USE', 'BEFORE', $this, '_handle_cache_use' );
        $controller->register_hook ( 'MEDIA_SENDFILE', 'BEFORE', $this, '_handle_media_sendfile' );
        $controller->register_hook ( 'FETCH_MEDIA_STATUS', 'BEFORE', $this, '_handle_fetch_media_status' );
	}
	
	/**
	 * Event-Handler for PARSER_CACHE_USE.
	 * This handler is called BEFORE the cache is used and determins the dependencies of the page. It checks the metadata
	 * if an RRD graph is present and retrieves the dependencies of the graphs on this page from the metadata. 
	 * 
	 * @param Doku_Event $event The Doku_Event object
	 * @param mixed      $param Value provided as fifth argument to register_hook()
	 */
	public function _handle_cache_use(&$event, $param) {
		$cache = &$event->data;
		
		if (! (isset ( $cache->page ) && isset ( $cache->mode )))
			return;
		
		$dependencies = p_get_metadata ( $cache->page, 'plugin_' . $this->getPluginName () . ' dependencies' );
		
		if (! empty ( $dependencies )) {
			foreach ( $dependencies as $dependency ) {
				$cache->depends ['files'] [] = wikiFN ( $dependency );
			}
		}
	}
	
	/**
	 * Event-Handler for MEDIA_SENDFILE.
	 * This handler ist called BEFORE media files are sent to the user. If the configured virtual media namespace
	 * is detected. The graph renderer is called and a virtual rrdgraph file ist sent.
	 * @param Doku_Event $event The Doku_Event object
	 * @param mixed      $param Value provided as fifth argument to register_hook()
	 * @throws Exception
	 */
	public function _handle_media_sendfile(&$event, $param) {
	    global $INPUT;
	    
	    $data = &$event->data;
	    $mediaPath = $this->parseMediaPath($data['media']);
	    
	    if ($mediaPath !== false) {
	     
    	    //-- Load the rrdgraph helper. This helper contains the cache manager and other stuff used here.
    	    $rrdGraphHelper = &plugin_load('helper', 'rrdgraph');
    	    if ($rrdGraphHelper === null) throw new Exception("rrdgraph helper not found.");
    	    
    	    //-- Read some more parameters
    	    $rangeNr = $INPUT->int('range', 0, true);
    	    $mode = $INPUT->str('mode', helper_plugin_rrdgraph::MODE_GRAPH_EMBEDDED, true);
    	    $bindingSource = $INPUT->str('bind');
    
    	    //-- Call the helper function to render and send the graph.
    	    $rrdGraphHelper->sendRrdImage($mediaPath->pageId, $mediaPath->imageId, $rangeNr, $mode, $bindingSource);
    	    
            //-- The graph was successfully send. Suppress any more processing
            $event->preventDefault();	    
	    }
	}

	/**
	 * Event-Handler for FETCH_MEDIA_STATUS.
	 * This handler ist called BEFORE the status of the media file is retrieved. If the configured virtual meida
	 * namespace is detected the method checks if the parameters look valid. If that's the case, the status code
	 * is set to 200 and DokuWiki calls the MEDIA_SENDFILE event hook. if the virtual namespace is not detected
	 * the method falls through and the normal media processing takes place.
	 * @param Doku_Event $event The Doku_Event object
	 * @param mixed      $param Value provided as fifth argument to register_hook()
	 * @throws Exception
	 */
	public function _handle_fetch_media_status(&$event, $param) {
	    $data = &$event->data;	    
	    $mediaPath = $this->parseMediaPath($data['media']);
	    
	    if ($mediaPath !== false)
	    {
	        //-- Check if the key features (GD and RRD) are installed and fail with a 500 error if they are missing.
	        if (count($this->getMissingDependencies()) == 0) {
        	    if ($mediaPath === null) {
        	        $data['status'] = 404;
        	        $data['statusmessage'] = "Invalid graph request.";
        	    } else {
                    $data['status'] = 200;
                    $data['statusmessage'] = "";
        	    }
	        } else {
	            $data['status'] = 500;
	            $data['statusmessage'] = "Could not render RRD graph. GD or rrd extension missing.";
	        }
	    }
	}
}