flm01/web/drupal/modules/logger/logger.module

<?php

//
// logger.module : support module for charting data stored in RRD's
// Copyright (c) 2008-2009 jokamajo.org
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
// $Id$
//

/**
 * @file
 * Support module for charting data stored in RRD's
 */


/**
 * Constants
 */
define('RED',    'F1572F');
define('BLUE',   '44C3D3');
define('GREEN',  '7AAB5A');
define('ORANGE', 'F37E2B');
define('YELLOW', 'FBEB0D');
define('PURPLE', 'A052A0');

/**
 * Implementation of hook_perm().
 */
function logger_perm() {
  return array('logger');
}

/**
 * Implementation of hook_menu() for logger
 * Don't forget to create a primary menu item in the Drupal administration section with the title 'ecology' linking to the '/logger' path
 */
function logger_menu() {
  $items = array();

  $items['admin/settings/logger'] = array(
    'title'               => 'Logger settings',
    'description'         => 'Configure settings for logging metering values.',
    'page callback'       => 'drupal_get_form',
    'page arguments'      => array('_logger_admin_settings'),
    'access arguments'    => array('administer site configuration'),
  );
  $items['logger'] = array(
    'title'               => 'your dashboard', // isn't printed as title on the page, therefore resort to drupal_set_title (t('your ecological dashboard')) in ecology_dashboard;
    'description'         => 'Configure settings for logging metering values.',
    'page callback'       => '_logger_dashboard', //takes the callback from the MENU_DEFAULT_LOCAL_TASK -> lightest level-two menu
    'page arguments'      => array('electricity', 'main', 'hour'),
    'access callback'     => TRUE,
    'type'                => MENU_CALLBACK,
  );
  $items['logger/add'] = array(
    'title'               => 'add this user to the chart',
    'page callback'       => '_logger_add',
    'access arguments'    => array('logger'),
    'type'                => MENU_CALLBACK,
  );
  $items['logger/remove'] = array(
    'title'               => 'remove this user from the chart',
    'page callback'       => '_logger_remove',
    'access arguments'    => array('logger'),
    'type'                => MENU_CALLBACK,
  );
  $items['logger/unit'] = array(
    'title'               => 'change the unit',
    'page callback'       => '_logger_unit',
    'access arguments'    => array('logger'),
    'type'                => MENU_CALLBACK,
  );
  $items['logger/electricity'] = array(
    'title'               => 'electricity',
//    'page callback'       => '_logger_dashboard',
//    'page arguments'      => array('electricity', 'main', 'hour'),
    'access callback'     => TRUE,
    'type'                => MENU_DEFAULT_LOCAL_TASK,
  );

/**
  $items['logger/water'] = array(
    'title'               => 'water',
    'page callback'       => '_logger_dashboard',
    'page arguments'      => array('water', 'main', 'hour'),
    'access callback'     => TRUE,
    'type'                => MENU_LOCAL_TASK,
  );
  $items['logger/gas'] = array(
    'title'               => 'gas',
    'page callback'       => '_logger_dashboard',
    'page arguments'      => array('gas', 'main', 'hour'),
    'access callback'     => TRUE,
    'type'                => MENU_LOCAL_TASK,
  );
**/

  $items['logger/electricity/hour'] = array(
    'title'               => 'hour',
    'page callback'       => '_logger_dashboard',
    'page arguments'      => array('electricity', 'main', 'hour'),
    'access callback'     => TRUE,
    'type'                => MENU_LOCAL_TASK,
    'weight'              => 0,
  );
  $items['logger/electricity/day'] = array(
    'title'               => 'day',
    'page callback'       => '_logger_dashboard',
    'page arguments'      => array('electricity', 'main', 'day'),
    'access callback'     => TRUE,
    'type'                => MENU_LOCAL_TASK,
    'weight'              => 1,
  );
  $items['logger/electricity/month'] = array(
    'title'               => 'month',
    'page callback'       => '_logger_dashboard',
    'page arguments'      => array('electricity', 'main', 'month'),
    'access callback'     => TRUE,
    'type'                => MENU_LOCAL_TASK,
    'weight'              => 2,
  );
  $items['logger/electricity/year'] = array(
    'title'               => 'year',
    'page callback'       => '_logger_dashboard',
    'page arguments'      => array('electricity', 'main', 'year'),
    'access callback'     => TRUE,
    'type'                => MENU_LOCAL_TASK,
    'weight'              => 3,
  );
  $items['logger/electricity/night'] = array(
    'title'               => 'night',
    'page callback'       => '_logger_dashboard',
    'page arguments'      => array('electricity', 'main', 'night'),
    'access callback'     => TRUE,
    'type'                => MENU_LOCAL_TASK,
    'weight'              => 4,
  );
  $items['installation'] = array(
    'title'               => '',
    'description'         => 'Howto install a Fluksometer',
    'page callback'       => '_logger_installation',
    'access callback'     => TRUE,
    'type'                => MENU_CALLBACK,
  );
  $items['user/%user_uid_optional/privacy'] = array(
    'title'               => 'Privacy',
    'page callback'       => '_logger_privacy',
    'access callback'     => '_logger_privacy_access',
    'access arguments'    => array('logger', 1),
    'type'                => MENU_LOCAL_TASK,
  );

  return $items;
}


function _logger_installation(){
  $output = '<div class="install">';
  $output .= "<a class='img' href = 'http://www.flukso.net/installation'><img src='http://www.flukso.net/sites/default/files/images/step1.png' height='120' width='150' alt='step 1'/></a>";
  $output .= "<p><b>STEP 1: CONFIGURING WIFI</b><br/>Power up the Fluksometer. Connect your computer to the Fluksometer's ethernet port. Surf to <a href = 'http://192.168.255.1'>http://192.168.255.1</a>. Configure the wireless interface with the proper name and security key.</p>";
  $output .= "<a class='img' href = 'http://www.flukso.net/installation'><img src='http://www.flukso.net/sites/default/files/images/step2.png' height='120' width='150' alt='step 2'/></a>";
  $output .= "<p><b>STEP 2: SECURING THE FLUKSOMETER</b><br/>Disconnect all cables from the Fluksometer. Find a suitable location near the fuse box to install the Fluksometer. Secure the Fluksometer with the plastic cable tie.</p>";
  $output .= "<a class='img' href = 'http://www.flukso.net/installation'><img src='http://www.flukso.net/sites/default/files/images/step3.png' height='120' width='150' alt='step 3'/></a>";
  $output .= "<p><b>STEP 3: ATTACHING THE CURRENT CLAMP</b><br/>For safety reasons, switch off the main electricity supply. For a single phase supply, attach the current clamp to one of the two cables running from the electricity meter to the fuse box. Close the clamp firmly.</p>";
  $output .= "<a class='img' href = 'http://www.flukso.net/installation'><img src='http://www.flukso.net/sites/default/files/images/step4.png' height='120' width='150' alt='step 4'/></a>";
  $output .= "<p><b>STEP 4: CONNECTING THE CLAMP'S SENSOR CABLE</b><br/>Connect the cable from the current clamp to the Fluksometer's input port. Take care of connecting the black and red cable as shown in the drawing on the right. Only apply gentle force when fastening the two screws.</p>";
  $output .= "<a class='img' href = 'http://www.flukso.net/installation'><img src='http://www.flukso.net/sites/default/files/images/step5.png' height='120' width='150' alt='step 4'/></a>";
  $output .= "<p><b>STEP 5: POWERING UP</b><br/>Switch the main electricity supply back on. Activate the Fluksometer by connecting the power plug.</p>";
  $output .= "</div>";

  return $output;
}

/**
 * Callback functions registered in the logger_menu section
 */
function _logger_dashboard($type, $function, $interval) {
  // watchdog('dashboard', 'arguments: %type, %function, %interval', array('%type' => $type, '%function' => $function, '%interval' => $interval), WATCHDOG_DEBUG);

  if (user_access('logger')) {
    drupal_set_title(t('your dashboard'));
    global $user;
  }
  else {  //show users who don't have 'logger' permissions icrarus'es chart
    drupal_set_title(t("a Fluksonian's dashboard"));
    $user = new stdClass();
    $user->uid = 1;
    $user->name = 'icarus75';
    $user->timezone = '3600';
  }

  $root_path = drupal_get_path('module', 'logger');
  $graph_path = $root_path .'/graphs/'. $interval .'/';
  $pngid = md5(uniqid()); //generate random numbers for the png chart so that the browser doesn't use the cached one, use cron to clean up the dir hourly
  switch ($interval) {
    case 'hour':
      $data_path = $root_path .'/data/base/';
      $start = 'end-1h';
      break;
    case 'day':
      $data_path = $root_path .'/data/base/';
      $start = 'end-1d';
      break;
    case 'month':
      $data_path = $root_path .'/data/base/';
      $start = 'end-60d';
      break;
    case 'year':
      $data_path = $root_path .'/data/base/';
      $start = 'end-1y';
      break;
    case 'night':
      $data_path = $root_path .'/data/night/';
      $start = 'end-60d';
      break;
  }

  $result_me = db_query("SELECT lm.meter, lm.function, lm.unit, lu.private
	                FROM {logger_meters} lm
	                INNER JOIN {logger_users} lu on lm.uid = lu.uid
	                WHERE lm.uid = %d AND lm.type = '%s'
	                ORDER BY lm.function", $user->uid, $type);

  $meter_me = db_fetch_object($result_me);

  $result_sub = db_query("SELECT u.name, lm.meter, lu.private
                          FROM ((({users} u
                          INNER JOIN {user_relationships} ur ON u.uid = ur.requestee_id)
                          INNER JOIN {user_relationship_types} urt ON ur.rtid = urt.rtid)
                          INNER JOIN {logger_meters} lm ON u.uid = lm.uid)
                          INNER JOIN {logger_users} lu ON u.uid = lu.uid
                          WHERE ur.requester_id = %d AND urt.name = '%s' AND type = '%s' AND function = '%s'
                          ORDER BY ur.rid", $user->uid, 'subscription', $type, $function);

  switch ($type) {
    case 'electricity':
      switch ($meter_me->unit) {
        case 'watt':
          $unit = 'watt';
          $factor = 3600; // 1Wh/s = 3600 W
          break;
        case 'kwh':
          $unit = 'kWh/year';
          $factor = 31536;
          break;
        case 'eur':
          $unit = 'euro/year';
          $factor = 5676; // 18 EURcent/kWh
          break;
        case 'aud':
          $unit = 'aud/year';
          $factor = 5991; // 19 AUDcent/kWh
          break;
      }
  }

  $color = array(RED, BLUE, GREEN, YELLOW, PURPLE);

  $i = 0;

  $string->line = ' COMMENT:"\s"';
  if (user_access('logger') && ((!$meter_sub = db_fetch_object($result_sub)) || $meter_me->private)) {
    do {
      $string->def  .= _logger_chart_def($i, $data_path, $meter_me->meter, $factor);
      $string->line .= _logger_chart_line($i, $color[$i], $meter_me->function);
      $i++;
    } while ($meter_me = db_fetch_object($result_me));
  }
  elseif (user_access('logger')) {
    $string->def  .= _logger_chart_def($i, $data_path, $meter_me->meter, $factor);
    $string->line .= _logger_chart_line($i, $color[$i], $user->name);

    do {
      $i++;   
      // check whether the person who's datastream you'd like to superimpose on the graph is in private mode
      if ($meter_sub->private) {
        // shift the data left by 1 year = 31556926 seconds to prevent the datastream from being displayed
        $string->def  .= ' DEF:data'. $i .'='. $data_path . $meter_sub->meter .'.rrd:meter:AVERAGE'.
                         ' CDEF:meter'. $i .'=data'. $i .','. $factor .',*'.
                         ' SHIFT:meter'. $i .':-31556926'; 

        // substitute the actual min/max/avg/last values by 'prv'
        $string->line .= ' LINE1:meter'. $i .'#'. $color[$i] .':'.'"'. substr($meter_sub->name.'               ', 0, 15) .'"'.
                         ' COMMENT:"min\:  prv"'.
                         ' COMMENT:"\tmax\:  prv"'.
                         ' COMMENT:"\tavg\:  prv"'.
                         ' COMMENT:"\tlast\:  prv\l"';
      }

      // the peer has not set his datastream to private so print it!
      else {
        $string->def  .= _logger_chart_def($i, $data_path, $meter_sub->meter, $factor); 
	$string->line .= _logger_chart_line($i, $color[$i], $meter_sub->name);
      }
    } while($meter_sub = db_fetch_object($result_sub));
  }
  else {
    $string->def  .= _logger_chart_def($i, $data_path, $meter_me->meter, $factor);
    $string->line .= _logger_chart_line($i, $color[$i], $user->name);
  }

  //construct the TZ=GMT-02:00 format from the $user->timezone object updated by the autotimezone module
  if ($user->timezone >= 0)
    $TZ = 'TZ="GMT-';
  else
    $TZ = 'TZ="GMT+';
  $TZ .= gmdate('h:i', abs($user->timezone)) .'" ';
  //insert the TZ prior to launching rrdtool to obtain a proper time conversion
  $command = $TZ . $root_path .'/rrdtool graph '. $graph_path . $pngid .'.png -s '. $start .
             ' --vertical-label '. $unit .' --lower-limit 0 -w 500 -h 350 -E -X 0 --font LEGEND:8:';
  $command .= $string->def;
  $command .= $string->line;
  exec($command, $output, $return_var);
  // watchdog('dashboard', 'arguments: %command ++ %output ++ %return_var', array('%command' => $command, '%output' => serialize($output), '%return_var' => $return_var), WATCHDOG_DEBUG);
  return theme('chart', $graph_path . $pngid .'.png');
}

function _logger_chart_def($i, $path, $meter, $factor) {
  return ' DEF:data'. $i .'='. $path . $meter .'.rrd:meter:AVERAGE'.
         ' CDEF:meter'. $i .'=data'. $i .','. $factor .',*'.
         ' VDEF:min'. $i .'=meter'. $i .',MINIMUM'.
         ' VDEF:max'. $i .'=meter'. $i .',MAXIMUM'.
         ' VDEF:avg'. $i .'=meter'. $i .',AVERAGE'.
         ' VDEF:last'. $i .'=meter'. $i .',LAST';
}

function _logger_chart_line($i, $color, $caption) {
  return ' LINE1:meter'. $i .'#'. $color .':'.'"'. substr($caption.'               ', 0, 15) .'"'.
         ' GPRINT:min'. $i .':"min\:%5.0lf"'.
         ' GPRINT:max'. $i .':"\tmax\:%5.0lf"'.
         ' GPRINT:avg'. $i .':"\tavg\:%5.0lf"'.
         ' GPRINT:last'. $i .':"\tlast\:%5.0lf\l"';
}

function _logger_add($uid) {
  global $user;
  $rtid = db_result(db_query("SELECT rtid
                              FROM {user_relationship_types}
                              WHERE name = '%s'", 'subscription'));

  $result = db_fetch_array(db_query("SELECT COUNT(rid), MAX(rid)
                                     FROM {user_relationships}
                                     WHERE requester_id = %d AND rtid = %d
                                     GROUP BY rtid", $user->uid, $rtid));

  // max subscriptions = 4
  if ($result['COUNT(rid)'] < 4) {
    user_relationships_request_relationship($user->uid, $uid, $rtid, TRUE);
  }
  else {
    //check whether the requested relationship doesn't already exist
    if (!db_result(db_query("SELECT rid
                             FROM {user_relationships}
                             WHERE requester_id = %d AND requestee_id = %d AND rtid = %d", $user->uid, $uid, $rtid))) {

      // if not, delete the most recently added relationship and replace it with the newly selected one
      db_query("DELETE
                FROM {user_relationships}
                WHERE rid = %d", $result['MAX(rid)']);

      user_relationships_request_relationship($user->uid, $uid, $rtid, TRUE);
    }
  }

  _logger_cache_clear('subscriptions');
  $destination = drupal_get_destination();
  drupal_goto($destination);
}

function _logger_remove($rid) {
  global $user;
  // check whether the to-be-deleted relationship was created by the same user
  if ($user->uid == db_result(db_query("SELECT requester_id
                                        FROM {user_relationships}
                                        WHERE rid = %d", $rid))) {
    db_query("DELETE
              FROM {user_relationships}
              WHERE rid = %d", $rid);
  }
  else {
    watchdog('relationships', 'attempt to delete rid %rid by non-authorized user %uid', array('%rid' => $rid, '%uid' => $user->uid), WATCHDOG_ERROR);
  }

  _logger_cache_clear('subscriptions');
  $destination = drupal_get_destination();
  drupal_goto($destination);
}

function _logger_unit($unit) {
  global $user;
  // hardcoded type and function
  db_query("UPDATE {logger_meters}
            SET unit = '%s'
            WHERE uid = %d AND type = '%s' AND function = '%s'", $unit, $user->uid, 'electricity', 'main');

  _logger_cache_clear('unit');
  $destination = drupal_get_destination();
  drupal_goto($destination);
}

/**
 * Clear the specific (per user) cache entry in the {cache_block} table
 */
function _logger_cache_clear($delta) {
  global $theme;
  //the theme variable isn't set on these callbacks so force it
  $theme = 'flukso';

  $block = db_fetch_object(db_query("SELECT *
                                     FROM {blocks}
                                     WHERE module = '%s' AND delta = '%s' AND theme = '%s'", 'logger', $delta, 'flukso'));

  $cid = _block_get_cache_id($block);
  // prevent the whole chache_block being cleared when _block_get_cache_id returns an empty string (e.g. uid = 1)
  if ($cid != '') cache_clear_all($cid, 'cache_block');
  //watchdog('block_cache', '%cid | %cache', array('%cid' => $cid, '%cache' => variable_get('block_cache', 100)), WATCHDOG_DEBUG);
}

/**
 * Implementation of hook_user() for logger
 * Flush the fluksonians block entries in the block cache 
 */
function logger_user($op) {
  switch($op) {
    // new user is being inserted into the database
    case 'insert':
      // flush the fluksonians block entries
      cache_clear_all('logger:fluksonians', 'cache_block', TRUE);
      break;
  }
}

/**
 * Implementation of hook_theme() for logger
 */
function logger_theme() {
  return array(
    'chart' => array(
      'arguments' => array('chart' => NULL),
    ),
    'logger_item_list' => array(
      'arguments' => array('items' => NULL, 'title' => NULL),
    ),
  );
}

/**
 * Theming the chart
 */
function theme_chart($chart) {
  $output .= '<p id="chart"><img src="'. base_path() . $chart .'" alt="Flukso"/></p><!-- end chart-->';
  return $output;
}

/**
 * Implementation of hook_block() for logger
 * Adds two blocks to the logger pages for (de-)selecting users and
 * another one for selecting the desired unit
 */
function logger_block($op = 'list', $delta = 0, $edit = array()) {
  global $user;

  switch ($op) {
    case 'list':
      $blocks['subscriptions']['info'] = t('Subscriptions');
      $blocks['subscriptions']['status'] = TRUE;
      $blocks['subscriptions']['region'] = 'right';
      $blocks['subscriptions']['weight'] = 0;
      $blocks['subscriptions']['pages'] = 'logger<br />logger/*';
      $blocks['subscriptions']['cache'] = BLOCK_CACHE_PER_USER;

      $blocks['fluksonians']['info'] = t('Fluksonians');
      $blocks['fluksonians']['status'] = TRUE;
      $blocks['fluksonians']['region'] = 'right';
      $blocks['fluksonians']['weight'] = 1;
      $blocks['fluksonians']['pages'] = 'logger<br />logger/*';
      $blocks['fluksonians']['cache'] = BLOCK_CACHE_PER_USER;

      $blocks['unit']['info'] = t('Unit');
      $blocks['unit']['status'] = TRUE;
      $blocks['unit']['region'] = 'right';
      $blocks['unit']['weight'] = 2;
      $blocks['unit']['pages'] = 'logger<br />logger/*';
      $blocks['unit']['cache'] = BLOCK_CACHE_PER_USER;

      return $blocks;

    case 'view':
      //pass along our current destination in the query string so that logger_add and logger_remove can return after processing their task
      $destination = drupal_get_destination();

      if ($delta == 'subscriptions' && user_access('logger')) {
        $result = db_query("SELECT u.uid, u.name, ur.rid
                            FROM ({users} u
                            INNER JOIN {user_relationships} ur ON u.uid = ur.requestee_id)
                            INNER JOIN {user_relationship_types} urt ON ur.rtid = urt.rtid
                            WHERE ur.requester_id = %d AND urt.name = '%s'
                            ORDER BY ur.rid", $user->uid, 'subscription');

        $items = array();
        while ($subscription = db_fetch_object($result)) {
          $items[] = l('[x]', 'logger/remove/'. $subscription->rid, array('attributes' => array('title' => "unsubscribe from ". $subscription->name ."'s stream"), 'query' => $destination, 'alias' => TRUE)) .' '. l($subscription->name, 'user/'. $subscription->uid, array('alias' => FALSE));
        }
        $block['subject'] = t('Subscriptions');
        $block['content'] = theme('logger_item_list', $items);
      }

      elseif ($delta == 'fluksonians' && user_access('logger')) {
        // list all users having the fluksionian role for now
        // to be replaced by a real buddylist later on
        $result = db_query("SELECT u.uid, u.name
                            FROM ({users} u
                            INNER JOIN {users_roles} ur ON u.uid = ur.uid)
                            INNER JOIN {role} r ON ur.rid = r.rid
                            WHERE r.name = '%s' AND NOT u.uid = %d
                            ORDER BY u.name", 'fluksonian', $user->uid);
        $items = array();
        while ($fluksonian = db_fetch_object($result)) {
          $items[] = l('[+]', 'logger/add/'. $fluksonian->uid, array('attributes' => array('title' => "subscribe to ". $fluksonian->name ."'s stream"), 'query' => $destination, 'alias' => TRUE)) .' '. l($fluksonian->name, 'user/'. $fluksonian->uid, array('alias' => FALSE));
        }
        $block['subject'] = t('Fluksonians');
        $block['content'] = theme('logger_item_list', $items);
      }

      elseif ($delta == 'unit' && user_access('logger')) {
        //hardcoded the type and function parameters for now
        $unit = db_result(db_query("SELECT unit
                                    FROM {logger_meters}
                                    WHERE uid = %d AND type = '%s' AND function = '%s'", $user->uid, 'electricity', 'main'));

        $items = array();
        $items[0] = l('watt', 'logger/unit/watt', array('attributes' => array('title' => "switch to watt"), 'query' => $destination, 'alias' => TRUE));
        $items[1] = l('kWh/year', 'logger/unit/kwh', array('attributes' => array('title' => "switch to kWh/year"), 'query' => $destination, 'alias' => TRUE));
        $items[2] = l('euro/year [@ 0.18eur/kWh]', 'logger/unit/eur', array('attributes' => array('title' => "switch to euro/year"), 'query' => $destination, 'alias' => TRUE));
        $items[3] = l('aud/year [@ 0.19aud/kWh]', 'logger/unit/aud', array('attributes' => array('title' => "switch to aud/year"), 'query' => $destination, 'alias' => TRUE));

        // 'unlink' the currently selected unit option
        switch ($unit) {
          case 'watt':
            $items[0] = 'watt';
            break;
          case 'kwh':
            $items[1] = 'kWh/year';
            break;
          case 'eur':
            $items[2] = 'euro/year [@ 0.18eur/kWh]';
            break;
          case 'aud':
            $items[3] = 'aud/year [@ 0.19aud/kWh]';
            break;
        }
        $block['subject'] = t('Unit');
        $block['content'] = theme('logger_item_list', $items);
      }

      return $block;
  }
}

/**
 * Implementing a simple non-bulleted list for the logger_block
 */
function theme_logger_item_list($items, $title = NULL) {
  $output = '';
  foreach ($items as $item) {
    $output .= $item .'<br />';
  }
  return $output;
}

/**
 * Callback function for the user/x/privacy page
 */
function _logger_privacy() {
  $output .= drupal_get_form('_logger_privacy_form');
  return $output;
}

/**
 * Generates the privacy form.
 */
function _logger_privacy_form() {
  global $user;

  $form['privacy'] = array(
    '#title' => t('Set your preferred privacy mode'),
    '#type' => 'radios',
    '#options' => array(
      t('Shared within Flukso'),
      t('Private'),
    ),
    '#description' => t("When selecting Private mode, your data stream will not be drawn on other people's graph and all statistics will be marked as 'prv'. Conversely, nobody else's data stream will be drawn on your chart."),
    '#default_value' => db_result(db_query("SELECT private
                                            FROM {logger_users}
                                            WHERE uid = %d", $user->uid)),
  );
  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Submit'),
  );
  return $form;
}

/**
 * Process settings form submissions.
 */
function _logger_privacy_form_submit($form, &$form_state) {
  global $user;

  // the built-in validation function already checks elements with options
  $private = $form_state['values']['privacy'];
  db_query("UPDATE {logger_users}
            SET private = %d
            WHERE uid = %d", $private, $user->uid);

  // page redirection to the dashboard after form submission
  $form_state['redirect'] = 'logger';
}

/**
 * Access callback ensuring the user profile tabs are visible only to their
 * owner.
 *
 * @param $permission
 *   Required permission to view the item.
 * @param $account
 *   A user object.
 */
function _logger_privacy_access($permission, $account) {
  return ($account->uid == $GLOBALS['user']->uid && user_access($permission));
}

/**
 * Define the administration settings form for the logger module
 */
function _logger_admin_settings() {
//TODO
}

/**
 * Implementation of hook_cron().
 * Cron will call this hook periodically [e.g. 1 hour interval] to perform housekeeping on the png's.
 */
function logger_cron() {
  exec('rm sites/all/modules/logger/graphs/hour/*');
  exec('rm sites/all/modules/logger/graphs/day/*');
  exec('rm sites/all/modules/logger/graphs/month/*');
  exec('rm sites/all/modules/logger/graphs/year/*');
  exec('rm sites/all/modules/logger/graphs/night/*');
}