<?php
/* Please see the README and LICENSE files. */

/**
 * This class intercepts user errors from trigger_error and lower system errors.
 * It processes the errors.
 */
class System_Error implements System_Component {

    ////////////////////////////////////////////////////////////////////////////
    // START CONFIGURABLE
    ////////////////////////////////////////////////////////////////////////////
    
    // Pages
    protected static $redirect_404 = "/404.php";
    protected static $redirect_403 = "/403.php";
    
    // Output
    protected static $enable_client = false;         // Show errors to users?
    protected static $min_show_client = 16384;   // Minmum level to display
    protected static $backtrace_client = false;
    protected static $show_file_client = true;
    protected static $show_context_client = false;
    protected static $show_line_client = true;
    protected static $short_filename_client = true;
    
    // Logging
    protected static $enable_log = false;           // Write to log?
    protected static $min_show_log = E_USER_WARNING;
    protected static $backtrace_log = false;   
    protected static $show_file_log = true;
    protected static $show_context_log = false;
    protected static $show_line_log = true; 
    protected static $short_filename_log = false;
    
    ////////////////////////////////////////////////////////////////////////////
    // STOP CONFIGURABLE
    ////////////////////////////////////////////////////////////////////////////
    
    private static $pending_action = 0;
    const ACT_REDIRECT = 1;
    const ACT_DIE = 2;
    const E403 = 32768;
    const E404 = 65536;

    /**
     * @see System_Component
     */
    public function start() {
        set_error_handler(array($this, "handle_error"));
    }
    
    /**
     * @see System_Component
     */
    public function stop(){} // Cannot stop this train

    /**
     * Replaces the default error handler. Automagically called by some system errors
     * and by trigger_error()
     *
     * @see set_error_handler()
     */
    public static function handle_error($errno, $errstr, $errfile, $errline, $errcontext) {
        switch($errstr){
            case self::E404:
            case self::E403:
                self::$pending_action = self::ACT_REDIRECT;
                break;
        }
        $parsed = array_merge(self::parse_error($errno),array(
            "message"=>$errstr,
            "file"=>$errfile,
            "line"=>$errline,
            "context"=>$errcontext));
        if(self::$enable_log && $errno < self::$min_show_log){
            self::log_error($parsed);
        }
        self::do_pending($errstr);
        if(self::$enable_client && $errno < self::$min_show_client){
            self::output_error($parsed);
        }
    }

    /**
     * Convert an error into an array of attributes
     * 
     * @see Error::handler(...)
     * @return String[] The attributes
     */
    protected static function parse_error($level) {
        switch ($level) {            
            case E_NOTICE:
            case E_USER_NOTICE:
                $level = "Notice";
                $level_color = "#409CED";
                break;
            case E_WARNING:
            case E_USER_WARNING:
                $level = "Warning";
                $level_color = "#DB8427";
                break;
            case E_USER_ERROR:
                $level = "Error";
                $level_color = "#BF3E28";
                break;
            case E_STRICT:
                $level = "Strict Error";
                $level_color = "#BF3E28";
                break;
            default:
                $level = "Unknown";
                $level_color = "#F5FC23";
                break;
        }
        
        return array(
            "level"=>$level,
            "color"=>$level_color);
    }    
    
    
    /**
     * Does whatever pending action was discovered during error parsing
     * 
     * @param String $errstr The error string
     */
    protected static function do_pending($errstr){
        if(self::$pending_action == 0){return false;}
        switch(self::$pending_action){
            case self::ACT_REDIRECT:
                switch($errstr){
                    case self::E404:
                        header("Location: ".self::$redirect_404);
                        break;
                    case self::E403:
                        header("Location: ".self::$redirect_403);
                        break;
                } 
                die();
                break;
            case self::ACT_DIE:   
                die();
        }
    }
    
    
    /**
     * Prints an error message to the current page/buffer
     *
     * @param String[] $message Array with information to print
     */
    protected static function output_error($array) {
        if(class_exists("Template_File") && class_exists("Template_FileParser") && class_exists("Template_Parser")){
            $file = new Template_File("html/error");
            if($file->exists()){
                $tfp = new Template_FileParser($file);
                $tfp->parse($array);
                return;
            }
        }        
        echo '<span style="font-size:12px;font-weight:normal;display:inline-block;border:2px solid '.$array['color'].';padding:6px;padding-top:3px;padding-left:10px">';
        echo '<span style="color:'.$array['color'].';margin-left:-7px;"> <b>'.$array['level'].'</b> </span> '.
                    (self::$show_file_client ? 
                        (self::$short_filename_client ?
                            str_replace(__DIR__,"",$array['file']) :
                            $array['file']
                        ).(self::$show_line_client ?
                            " [Line: ".$array['line']."]":
                            ""
                        )."<br/>":
                        ""
                    );
        echo $array['message']."<br/>";
        if(self::$show_context_client){
            echo("<pre>Context:");
            print_r($array['context']);
            echo("</pre>");
        }
        if(self::$backtrace_client){
            echo("<pre>Backtrace:");
            print_r(debug_backtrace());
            echo("</pre>");
        }
        echo("</span><br/><br/>");
    }

    /**
     * Writes an error entry in a log file
     *
     * @param String[] $message Array with information to print
     */
    protected static function log_error($message) {
        # TODO
        # Write to file, need a clean, modular, reusable way to do it
    }
}

?>