<?php
/*
	version: $Id: wsod.module,v 1.9 2009-04-03 11:03:36 kenorb Exp $
	author: kenorb@gmail.com
*/

/**
 * Implementation of hook_boot(). Runs even for cached pages.
 */
function wsod_boot() {
    register_shutdown_function('wsod_check_wsod');
} 

/**
 * Implementation of hook_form_alter().
 */
function wsod_form_alter($form, $form_state, $form_id) {
    global $active_forms;
    $active_forms[] = $form_id;
}

/**
 * Detect WSOD and fix it
 * 
 * @param bool $verbose
 * @param bool $fix_on_fly
 * @return string
 * 
 */
function wsod_check_wsod($verbose = FALSE, $fix_on_fly = TRUE, $emergency = FALSE) {
    static $drupal_path;
    // CHECK FOR FATAL ERRORS  (which Drupal can't handle)
    if (wsod_fatal_error_checker($output, $fix_on_fly)) {
        $verbose ? print $output : print 'n/a' ;
        return; // can't continue, if there are some fatal errors
    }

    // ignore wsod checking on batch processing and maintenance work
    if (defined('MAINTENANCE_MODE') || isset($_SESSION['batch_form_state'])) {
        return;
    }

    // ignore wsod checking on POST forms, it breaking the forms (#416616) (TODO: later it could be supported - )
    if (!empty($_POST['form_build_id'])) {
        return;
    }

    // ignore if we are on non-html page
    $headers = drupal_get_headers(); // FIXME: any other way to get headers?
    $ignore_formats = array('xml', 'javascript', 'json', 'plain', 'image', 'application', 'csv', 'x-comma-separated-values');
        foreach ($ignore_formats as $format) {
        if (strstr($headers, $format)) {
            return;
        }
    }

    // ignore some specified callbacks (like Rebuilding permissions)
    $router_item = menu_get_item();
    if ($router_item['page_callback'] == 'system_batch_page') {
        return;
    }

    // init variables
    $output = '';
    $nl = t('<br>');

    /* set base Drupal path as current especially during shutdown */
    if (!wsod_drupal_path()) { // change it if it's wrong
        $drupal_path = wsod_detect_drupal_path(drupal_get_path('module', 'node')); // FIXME: Any other function which returns current Drupal path?
        !empty($drupal_path) ? chdir($drupal_path) : NULL; // change dir to Drupal path
    }

    module_load_include('inc', 'wsod', 'wsod'); // include functions

    // check input variables
    $path = $_GET['q'];
    isset($_GET['fix']) ? $fix_on_fly = TRUE : NULL; // if fix is defined, then switch to fixing mode

    /* check menu handler */
    ob_start();
    $return = menu_execute_active_handler(); // use q argument to change default path
    $content_output = ob_get_clean(); // TODO: what if there is some content?
    // CHECK FOR FATAL ERRORS again
    if (wsod_fatal_error_checker($output, $fix_on_fly)) {
        $verbose ? print $output : print 'n/a' ;
        return; // can't continue, if there is some fatal error
    }

    if (is_null($return)) { /* check menu handler */
        $output .= t("%function: returned %handler - it's very bad!", array('%function' => 'menu_execute_active_handler()', '%handler' => 'NULL')).$nl;
        $output .= t("WSOD detected!").t('&nbsp;').t("Checking for problems...").$nl;
        $output .= t("ERROR: %function returned empty value!", array('%function' => 'menu_execute_active_handler()')).$nl;
        /* check theme hooks */
        $res = wsod_validate_theme_hooks($verbose, $output);
        if (!$res) {
            if ($fix_on_fly) {
                wsod_clear_caches(); // clear all caches
                module_rebuild_cache(); // rebuild paths in system table
                $output .= t("Re-testing...").$nl;
                $res = wsod_validate_theme_hooks($verbose, $output);
                if (!$res) {
                    $output .= t("There is still problem related to theme hooks").$nl; // FIXME
                } else {
                    $output .= t("Fixed?!").$nl;
                }
            } else {
                $output .= t("fix_on_fly is no enabled, please enable it to fix the problem").$nl;
            }
        } else {
            $output .= t("Validation theme hooks completed.").$nl;
        }
        /* check menu router hooks */
        $router_item = menu_get_item($path); // get router item
        if (!function_exists($router_item['page_callback'])) { // check if page callback exist
            $output .= t("ERROR: Callback: %callback() doesn't exist!<br>",array('%callback' => $router_item['page_callback'])).$nl;
        } else {
            wsod_check_page_callback($router_item, $verbose, $output, $content); // get content of page callback
            if (empty($content)) { // check if page callback returned some content
                $output .= t("ERROR: Callback: %callback() returned empty content!",array('%callback' => $router_item['page_callback'])).$nl;
                $output .= t("NOTICE: router_item = %item!",array('%item' => print_r($router_item,true))).$nl;
                if ($fix_on_fly) { // if fix mode, then fix the errors
                    module_load_include('inc', 'system', 'system.admin'); // include functions
                    $output .= wsod_clear_caches(); // clear all caches
                    module_rebuild_cache();
                    $output .= t('Rebuilded module cache.').$nl; // module rebuild cache
                } else {
                    $output .= t("fix_on_fly is no enabled, please enable it to fix the problem").$nl;
                }
            }
        }
        /* check forms */
        /* TODO
        $invalid_forms = wsod_check_forms();
	if (!empty($invalid_forms)) {
	    $output .= "empty forms = ".print_r($invalid_forms,true)."<br>";
	}
         */

        // PRINT ALL ERRORS FROM SESSION WHICH WILL HELP TO IDENTIFY THE PROBLEM
        if ($_SESSION['messages']['error']) {
            $error_messages = $_SESSION['messages']['error'];
            foreach ($error_messages as $error) {
                $error = str_replace(dirname($drupal_path),'',$error); // delete Drupal full path for security reason
                $output .= print_r($error,true); // show session errors
            }
        }
        $output .= t("Done.").$nl;
    } else {
      /* Standard Drupal behavior section. */
      switch ($return) {
	case MENU_NOT_FOUND:
            $page_output = drupal_not_found(); // return page not found, there can be some status error messages
            if (empty($page_output)) {
                $err = t('ERROR: Page is empty!').$nl;
            } else {
                $output .= $page_output; // if nothing to show, output standard page not found
                if ($emergency) {
                    /* TODO: don't print it twice */
                    //drupal_set_message(t('%function: %handler - seems ok!', array('%function' => 'menu_execute_active_handler()', '%handler' => 'MENU_NOT_FOUND')).$nl);
                }
            }
	    break;
	case MENU_ACCESS_DENIED:
            $page_output = drupal_access_denied(); // return permission denied page , there can be some status error messages
            if (empty($page_output)) {
                $err = t('ERROR: Page is empty!').$nl;
            } else {
                $output .= $page_output; // if nothing to show, output standard page not found
                if ($emergency) {
                    /* TODO: don't print it twice */
                    //drupal_set_message(t('%function: %handler - seems ok!', array('%function' => 'menu_execute_active_handler()', '%handler' => 'MENU_ACCESS_DENIED')).$nl);
                }
            }
	    break;
	case MENU_SITE_OFFLINE:
            $page_output = drupal_site_offline(); // return site offline page, there can be some status error messages
            if (empty($page_output)) {
                $err = t('ERROR: Page is empty!').$nl;
            } else {
                $output .= $page_output; // if nothing to show, output standard page not found
                if ($emergency) {
                    /* TODO: don't print it twice */
                    //drupal_set_message(t('%function: %handler - seems ok!', array('%function' => 'menu_execute_active_handler()', '%handler' => 'MENU_SITE_OFFLINE')).$nl);
                }
            }
	    break;
        default: // other cases
            if (module_exists('content_profile')) {
                /* TODO: Sometimes can't render page on shutdown, because of some errors recently
                    Like: Fatal error: Class 'content_profile_theme_variables' not found in content_profile\content_profile.module on line 585
                 */
                break;
            }
            //$page_output = theme('page', $return); // return page not found, there can be some status error messages
            if (empty($page_output)) {
                $err = t('ERROR: Page is empty!').$nl;
                if ($emergency) {
                    /* TODO: don't print it twice */
                    //drupal_set_message(t('%function: %handler - seems ok!', array('%function' => 'menu_execute_active_handler()', '%handler' => "$return")).$nl);
                }
            } else {
                $output .= $page_output; // if nothing to show, output standard page not found
            }
      }
    }
    $verbose ? print (!empty($output) ? $output : '.') : NULL ; // if you see dots, that mean nothing to show (no WSOD on front page, see README.txt)
    if (!empty($output)) {
        watchdog('wsod', $output); // log the error
    }
    return $output;
}

/**
 * Clear all caches
 */
function wsod_clear_caches() {
    $output = '';
    $nl = t('<br>');
    cache_clear_all(NULL, 'cache');
    $output .= t("Cleared cache via %function", array('%function' => 'cache_clear_all()')).$nl;
    drupal_flush_all_caches();
    $output .= t("Cleared cache via %function", array('%function' => 'drupal_flush_all_caches()')).$nl;
    return $output;
}

/**
 * Check for fatal errors
 */
function wsod_fatal_error_checker(&$output = NULL, $fix_on_fly = TRUE) {
    // CHECK FOR FATAL ERRORS (which Drupal can't handle)
    $isError = FALSE;
    if ($error = error_get_last()){
        switch($error['type']){
            case E_ERROR:
            case E_CORE_ERROR:
            case E_COMPILE_ERROR:
            case E_USER_ERROR:
                $isError = TRUE;
                break;
        }
        /* Show fatal error on the page.
           Most people don't use this module, if they don't have any problem,
           so our priority is to show what's wrong with the website
         */
        if ($isError){
            var_dump($error);
            wsod_fatal_error_fix($error['message'], $output, $fix_on_fly); // check if we can fix handled error
            $output .= "ERROR: Script execution halted with error: {$error['message']}<br>";
        } else {
            $output .= "NOTICE: Script execution completed with error: {$error['message']}<br>";
        }
    }
    return $isError;
}

/**
 * Try to fix fatal error
 */
function wsod_fatal_error_fix($error, &$output, $fix_on_fly = TRUE) {
    if (strpos($error,"Cannot redeclare cache") !== FALSE) {
        if ($fix_on_fly) { // if fix mode, then fix the errors
            /* TODO: We can't use Drupal functions in case of fatal error
            module_load_include('inc', 'system', 'system.admin'); // include functions
            $output .= t('Trying to rebuild module cache.'); // module rebuild cache
            module_rebuild_cache();
             */
        }
        $output .= 'Tip: Try to disable additional cache module from your settings.php.<br>\n';
    } else if (strpos($error,"Cannot redeclare") !== FALSE) {
        if ($fix_on_fly) { // if fix mode, then fix the errors
            /* TODO: We can't use Drupal functions in case of fatal error
            module_load_include('inc', 'system', 'system.admin'); // include functions
            $output .= t('Trying to rebuild module cache.'); // module rebuild cache
            module_rebuild_cache();
             */
        }
    } else if (strpos($error,"Call to undefined function") !== FALSE) {
        if ($fix_on_fly) { // if fix mode, then fix the errors
            /* TODO:
                Solution 1:
                    We can load all module files and check where it's defined.
                    After that we can compare and check if the module weight is correct.
                    Needed module can be detected from $error via function name.
                    Dependend module can be detected via filename $error['file']
                    Fix: we can increase weight of the module depends of the other module.
                    Example code:
                        $weight = (int) db_result(db_query("SELECT weight FROM {system} WHERE name = 'module1'"));
                        db_query("UPDATE {system} SET weight = %d WHERE name = 'module2'", $weight + 1);
                Solution 2:
                    If module with specified function wasn't found, maybe there is wrong dependency.
                    Propose to user to install missing module (get module name from $error).
             */
        }
    }
    if (!$fix_on_fly) {
        $output .= t("fix_on_fly is no enabled, please enable it to fix the problem").$nl;
    }
}

function wsod_check_forms() {
    global $active_forms;
    $active_forms=array_unique($active_forms); // remove duplicates
    $empty_forms = array();
    $form_state = array ('storage' => NULL, 'submitted' => FALSE, 'post' => array ());
    $node = array ('storage' => NULL, 'submitted' => FALSE, 'post' => array ());
    $max_count = count($active_forms); // get count of array
    foreach ($active_forms as $key => $form_id) {
	$id = $form_id;
	//$form = drupal_get_form($id); //$form = drupal_retrieve_form($form_id, $form_state);

	$form = drupal_retrieve_form($form_id, $form_state);
	module_invoke_all('form_alter', $form);
	if (empty($form)) {
	    $empty_forms[] = $form_id;
	}

	//$form_content = drupal_render_form($form_id, $form);
	$form_content = drupal_get_form($form_id);
	if (empty($form_content)) {
	    $empty_forms[] = $form_content;
	}

	if ($key > $max_count+1) {
	    print "Recurrency detected in form_alter hook!<br>";
	    break;
	}
    }
    return array_unique($empty_forms);
}


/** 
 * Detect Drupal path by scanning each level of current path
 * 
 */ 
function wsod_detect_drupal_path(&$output = NULL, $start_dir = __FILE__) {
    $drupal_path = FALSE; // set init variable
    $path_arr = wsod_pathposall(dirname($start_dir));
    $bootstrap_file = '/includes/bootstrap.inc';
    foreach ($path_arr as $path) {
        if (file_exists($path.$bootstrap_file)) {
            $drupal_path = $path;
        } else {
            $output .= "Couldn't find $path$bootstrap_file!<br>\n";
        }
    }
    return $drupal_path;
}

/** 
 * pathposall 
 * 
 * Find all occurrences of a subdirs in a path
 * 
 * @param string $dir
 * @return array
 */ 
function wsod_pathposall($dir){ 
    $slash = wsod_detect_filesystem_slash();
    $pos = wsod_strposall($dir,$slash);
    foreach ($pos as $no) {
        $subdir[] = substr($dir, 0, $no);
    }
    if (is_array($subdir)) {
        rsort($subdir); // make list in reverse
        return $subdir; // return array of available subdir paths
    } else {
        return array();
    }
} 

/** 
 * Find all occurrences of a needle in a haystack 
 * 
 * @param string $haystack 
 * @param string $needle 
 * @return array or false 
 */ 
function wsod_strposall($haystack,$needle){ 
    $s=0; $i=0; 
    while (is_integer($i)){ 
        $i = strpos($haystack,$needle,$s); 
        if (is_integer($i)) { 
            $aStrPos[] = $i; 
            $s = $i+strlen($needle); 
        } 
    } 
    if (isset($aStrPos)) { 
        return $aStrPos; 
    } else { 
        return false; 
    } 
} 

/** 
 * Detect slash type of filesystem
 * 
 */ 
function wsod_detect_filesystem_slash() {
    if (strpos(__FILE__, '/') !== FALSE) { // detect filesystem
        return '/'; // Unix style
    } else {
        return '\\'; // Windows style
    }
}

/**
 * Check if Drupal is in current path
 * 
 */
function wsod_drupal_path() {
    $path = getcwd();
    $bootstrap_file = '/includes/bootstrap.inc';
    return file_exists($path.$bootstrap_file);
}

/**
 * Get content type of page header 
 * 
 * @return string
 * 
 */
function wsod_get_header_content_type($header = 'text/html') {
    $headers = explode("\n", drupal_get_headers());
    $ct_key = 'Content-Type: ';
    foreach ($headers as $header_line) {
        if (($pos = strpos($ct_key, $header_line)) === FALSE) {
            $header = substr($header_line, $pos+strlen($ct_key));
        }
    }
    return $header;
}

/**
 * Get content type of page header 
 * 
 * @return string
 * 
 */
function wsod_sess_close() {
    wsod_check_wsod();
    return TRUE;
}

/**
 * WSOD version of Drupal drupal_bootstrap()
 */
function wsod_drupal_bootstrap_run($phase) {
  static $phases = array(DRUPAL_BOOTSTRAP_CONFIGURATION, DRUPAL_BOOTSTRAP_EARLY_PAGE_CACHE, DRUPAL_BOOTSTRAP_DATABASE, DRUPAL_BOOTSTRAP_ACCESS, DRUPAL_BOOTSTRAP_SESSION, DRUPAL_BOOTSTRAP_LATE_PAGE_CACHE, DRUPAL_BOOTSTRAP_LANGUAGE, DRUPAL_BOOTSTRAP_PATH, DRUPAL_BOOTSTRAP_FULL), $phase_index = 0;

  while ($phase >= $phase_index && isset($phases[$phase_index])) {
    $current_phase = $phases[$phase_index];
    unset($phases[$phase_index++]);
    wsod_drupal_bootstrap($current_phase);
  }
}

/**
 * WSOD version of Drupal _drupal_bootstrap()
 *
 * Modifications:
 * - replace handler sess_close() by WSOD
 *   Some fatal errors can't be handled by set_error_handler(), but can be handled by session_set_save_handler()
 *
 * @param $phase
 *   A constant. Allowed values are:
 *     DRUPAL_BOOTSTRAP_CONFIGURATION: initialize configuration.
 *     DRUPAL_BOOTSTRAP_EARLY_PAGE_CACHE: try to call a non-database cache fetch routine.
 *     DRUPAL_BOOTSTRAP_DATABASE: initialize database layer.
 *     DRUPAL_BOOTSTRAP_ACCESS: identify and reject banned hosts.
 *     DRUPAL_BOOTSTRAP_SESSION: initialize session handling.
 *     DRUPAL_BOOTSTRAP_LATE_PAGE_CACHE: load bootstrap.inc and module.inc, start
 *       the variable system and try to serve a page from the cache.
 *     DRUPAL_BOOTSTRAP_LANGUAGE: identify the language used on the page.
 *     DRUPAL_BOOTSTRAP_PATH: set $_GET['q'] to Drupal path of request.
 *     DRUPAL_BOOTSTRAP_FULL: Drupal is fully loaded, validate and fix input data.
 */
function wsod_drupal_bootstrap($phase) {
  global $conf;

  switch ($phase) {

    case DRUPAL_BOOTSTRAP_CONFIGURATION:
      drupal_unset_globals();
      // Start a page timer:
      timer_start('page');
      // Initialize the configuration
      conf_init();
      break;

    case DRUPAL_BOOTSTRAP_EARLY_PAGE_CACHE:
      // Allow specifying special cache handlers in settings.php, like
      // using memcached or files for storing cache information.
      require_once variable_get('cache_inc', './includes/cache.inc');
      // If the page_cache_fastpath is set to TRUE in settings.php and
      // page_cache_fastpath (implemented in the special implementation of
      // cache.inc) printed the page and indicated this with a returned TRUE
      // then we are done.
      if (variable_get('page_cache_fastpath', FALSE) && page_cache_fastpath()) {
        exit;
      }
      break;

    case DRUPAL_BOOTSTRAP_DATABASE:
      // Initialize the default database.
      require_once './includes/database.inc';
      db_set_active();
      break;

    case DRUPAL_BOOTSTRAP_ACCESS:
      // Deny access to hosts which were banned - t() is not yet available.
      if (drupal_is_denied('host', ip_address())) {
        header('HTTP/1.1 403 Forbidden');
        print 'Sorry, '. check_plain(ip_address()) .' has been banned.';
        exit();
      }
      break;

    case DRUPAL_BOOTSTRAP_SESSION:
      require_once variable_get('session_inc', './includes/session.inc');
      session_set_save_handler('sess_open', 'wsod_sess_close', 'sess_read', 'sess_write', 'sess_destroy_sid', 'sess_gc'); // WSOD: replace wsod handle for sess_close()
      if(!isset($_SESSION)){ // WSOD: additional condition if session has been already started
          session_start();
      }
      break;

    case DRUPAL_BOOTSTRAP_LATE_PAGE_CACHE:
      // Initialize configuration variables, using values from settings.php if available.
      $conf = variable_init(isset($conf) ? $conf : array());
      $cache_mode = variable_get('cache', CACHE_DISABLED);
      // Get the page from the cache.
      $cache = $cache_mode == CACHE_DISABLED ? '' : page_get_cache();
      // If the skipping of the bootstrap hooks is not enforced, call hook_boot.
      if (!$cache || $cache_mode != CACHE_AGGRESSIVE) {
        // Load module handling.
        require_once './includes/module.inc';
        bootstrap_invoke_all('boot');
      }
      // If there is a cached page, display it.
      if ($cache) {
        drupal_page_cache_header($cache);
        // If the skipping of the bootstrap hooks is not enforced, call hook_exit.
        if ($cache_mode != CACHE_AGGRESSIVE) {
          bootstrap_invoke_all('exit');
        }
        // We are done.
        exit;
      }
      // Prepare for non-cached page workflow.
      drupal_page_header();
      break;

    case DRUPAL_BOOTSTRAP_LANGUAGE:
      drupal_init_language();
      break;

    case DRUPAL_BOOTSTRAP_PATH:
      require_once './includes/path.inc';
      // Initialize $_GET['q'] prior to loading modules and invoking hook_init().
      drupal_init_path();
      break;

    case DRUPAL_BOOTSTRAP_FULL:
      require_once './includes/common.inc';
      _drupal_bootstrap_full();
      break;
  }
}