<?php
// $Id: update_status_proxy.module,v 1.2 2010/08/25 07:37:02 robknight Exp $

/**
 * @file
 * Update status proxy module file.
 *
 * Contains the implementation of the update status proxy module
 * 
 * @author Rob Knight <mail@robknight.org.uk>
 */

/**
 * Implementation of hook_perm()
 */
function update_status_proxy_perm() {
  return array ('administer update status proxy', 'retri');
}

/**
 * Implementation of hook_menu()
 */
function update_status_proxy_menu() {
  $items = array();
  
  $items['update-status-proxy'] = array(
    'page callback' => 'update_status_proxy_get_updates',
    'page arguments' => array(1, 2),
    'type' => MENU_CALLBACK,
    'access callback' => 'user_access',
    'access arguments' => array('access content')
  );
  
  $items['admin/settings/update-status-proxy'] = array(
    'title' => 'Update status proxy',
    'description' => 'Configure querying of module update status via a proxy',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('update_status_proxy_admin_settings'),
    'access callback' => 'user_access',
    'access arguments' => array('administer update status proxy'),
    'type' => MENU_NORMAL_ITEM,
    'file' => 'update_status_proxy.admin.inc',
  );
  
  return $items;
}

/**
 * Retrieve the updates via the proxy server
 * 
 * We begin by checking to see if a proxy server has been set - if not, simply redirect the
 * client to the 'original' unproxied URL.
 * 
 * If we have a proxy, then we just carry out the update status request to the appropriate
 * URL and return the headers and data to the client.
 */
function update_status_proxy_get_updates($module, $core_compat) {
  
  if ((variable_get('update_status_proxy_status', 0) == 0) || !$module || !$core_compat) {
    drupal_not_found();
    exit;
  }
  
  $sitekey = $_GET['site_key'];
  $version = $_GET['version'];
  
  $proxy_host = variable_get('update_status_proxy_proxy_host', '');
  $proxy_port = variable_get('update_status_proxy_proxy_port', 8080);
  $proxy_user = variable_get('update_status_proxy_proxy_user', '');
  $proxy_pass = variable_get('update_status_proxy_proxy_pass', '');
  $update_url = variable_get('update_status_proxy_update_url', UPDATE_DEFAULT_URL);
  
  if (drupal_strlen($proxy_host) > 0) {
    
    /**
     * Some modules and themes have their own update URLs.  Retrieve the info about the
     * project so that we can use the alternate URL.
     */
    $info = update_status_proxy_get_module_info($module);

    // Does an alternate URL exist?
    if (isset($info['_project status url'])) {
      $update_url = $info['_project status url'];
    }

    $update_url_components = parse_url($update_url);
    
    // The path to pass to the proxy server
    $path = $update_url_components['path'] . '/' . $module . '/' . $core_compat;
    
    // Stick any necessary query string values on the end
    $path .= (strpos($path, '?') === TRUE) ? '&' : '?';
    $path .= 'site_key=';
    $path .= rawurlencode($site_key);
    
    if ($version) {
      $path .= '&version=';
      $path .= rawurlencode($version);
    }
    
    // Include proxy authentication values if specified
    if (drupal_strlen($proxy_user) && drupal_strlen($proxy_pass)) {
      $auth = "{$proxy_user}:{$proxy_pass}@";
    } else {
      $auth = '';
    }
    
    // URL to the proxy server
    $url = "http://{$auth}{$proxy_host}:{$proxy_port}/" . $path;
    
    // We need to pass the 'host' header to the proxy server so it knows where to go
    $headers = array(
      'Host' => $update_url_components['host']
    );
    
    $result = drupal_http_request($url, $headers);
    
    if ($result->headers) {
      foreach ($result->headers as $header => $value) {
        drupal_set_header("{$header}: {$value}");
      }
    }
    
    echo $result->data;
    
    exit;
  } else {
    // Get project info
    $info = update_status_proxy_get_module_info($module);

    // Does an alternate URL exist?
    if (isset($info['_project status url'])) {
      $update_url = $info['_project status url'];
    }

    $redirect = $update_url . '/' . $module . '/' . $core_compat;
    
      // Stick any necessary query string values on the end
    $redirect .= (strpos($redirect, '?') === TRUE) ? '&' : '?';
    $redirect .= 'site_key=';
    $redirect .= rawurlencode($site_key);
    
    if ($version) {
      $redirect .= '&version=';
      $redirect .= rawurlencode($version);
    }
    
    drupal_goto($redirect);
    
  }

  
}

/**
 * Really simply function to grab and unserialize the information about a module
 * from the system table
 * @param $module The module/theme name
 */
function update_status_proxy_get_module_info($module) {
  $q = db_query("SELECT info FROM {system} WHERE name = '%s'", $module);
  
  return unserialize(db_result($q));
}


/**
 * Implementation of hook_system_info_alter
 * 
 * Bit of magic goes on here.  When checking for updates, Drupal rebuilds the cache
 * of information about each project by reading the .info files.  However, we have
 * a problem with modules which specify their own 'project status url' - we can't
 * tell Drupal's update module to come to us instead for these.  So we just 'hide' 
 * these URLs by prepending a '_' character, so we can still read it but Drupal 
 * can't, which means that Drupal will always try to access the proxy for updates.
 * 
 * @param $info Information about the project
 * @param $file
 */
function update_status_proxy_system_info_alter(&$info, $file) {
  if (isset($info['project status url'])) {
    $url = $info['project status url'];
    unset($info['project status url']);
    $info['_project status url'] = $url;
  }
}

/**
 * Enable the update_status_proxy
 */
function update_status_proxy_enable($show_message = TRUE) {
  
  variable_set('update_status_proxy_status', 1);
  // TODO: consider whether Strongarm integration makes more sense here
  variable_set('update_fetch_url', url('update-status-proxy', array('absolute' => TRUE)));
  
  if ($show_message) {
    drupal_set_message(t('Update Status Proxy enabled.'));
  }
}


/**
 * The reverse of the enable function above
 */
function update_status_proxy_disable($show_message = TRUE) {
  
  variable_set('update_status_proxy_status', 0);
  variable_set('update_fetch_url', variable_get('update_status_proxy_update_url', UPDATE_DEFAULT_URL));
  
  if ($show_message) {
    drupal_set_message(t('Update Status Proxy disabled.'));
  }
}