<?php
// $Id: tasks_advanced.module,v 1.16 2007/01/19 19:26:43 moonray Exp $

/**
 * @file tasks_advanced.module
 *
 * The tasks_advanced module allows extends the tasks module. It provides more
 * detailed overviews, and additional categorization and filters.
 *
 * Some of the code is loosely based on:
 * - project.module
 * - tasks.module
 */


/**
 * @defgroup tasks_advanced_core Core drupal hooks
 */


/**
 * Implementation of hook_perm().
 *
 * @ingroup tasks_advanced_core
 */
function tasks_advanced_perm() {
  return array('access own tasks', 'access all tasks');
}


/**
 * Implementation of hook_menu().
 *
 * @ingroup tasks_advanced_core
 */
function tasks_advanced_menu($may_cache) {
  global $user;

  $items = array();

  if ($may_cache) {
    // callbacks
    $items[] = array(
      'path' => 'tasks',
      'title' => t('Tasks'),
      'callback' => '_tasks_advanced_main',
      'access' => user_access('access tasks main page') && user_access('access all tasks'),
      'type' => MENU_CALLBACK
    );
    $items[] = array(
      'path' => 'tasks/user',
      'title' => t('My tasks'),
      'callback' => '_tasks_advanced_main',
      'callback arguments' => array('user'),
      'access' => user_access('access tasks main page') && user_access('access all tasks'),
      'type' => MENU_CALLBACK
    );

    // dynamic menu items
    $items[] = array(
      'path' => 'tasks',
      'title' => t('Tasks'),
      'callback' => '_tasks_advanced_main',
      'access' => user_access('access tasks main page') && user_access('access all tasks'),
      'type' => MENU_DYNAMIC_ITEM
    );
    if ($user->uid) {
      $items[] = array(
        'path' => 'tasks/user/'.$user->uid,
        'title' => t('My tasks'),
        'callback' => '_tasks_advanced_main',
        'callback arguments' => array('user', $user->uid),
        'access' => user_access('access tasks main page') && user_access('access own tasks'),
        'type' => MENU_DYNAMIC_ITEM
      );
    }
  }

  return $items;
}


/**
 * Implementation of hook_form_alter().
 *
 * @ingroup tasks_advanced_core
 */
function tasks_advanced_form_alter($form_id, &$form) {
  global $user;
  drupal_add_css(drupal_get_path('module', 'tasks_advanced').'/tasks_advanced.css');

  $node = isset($form['#node']) ? $form['#node'] : NULL;

  $tasks_advanced_visible = (variable_get('event_nodeapi_'. $type, TRUE) ? FALSE : TRUE);
  $taskcategories = _tasks_advanced_taskcategory();
  $tasktypes      = _tasks_advanced_tasktype();

  if ($form_id == 'tasks_node_form') {
    $form['tasks_advanced'] = array(
      '#type' => 'fieldset',
      '#title' => t('Details'),
      '#collapsible' => FALSE,
      '#collapsed' => $tasks_advanced_visible,
      '#attributes' => array("id" => "tasks_advanced"),
      '#weight' => -14,
    );
    $form['tasks_advanced']['taskcategory'] = array(
      '#type'          => 'select',
      '#title'         => t('Task Category'),
      '#default_value' => (isset($node->taskcategory) ? $node->taskcategory : 'unknown'),
      '#options'       => $taskcategories,
      '#description'   => t(''),
      '#weight'        => 0,
    );
    $form['tasks_advanced']['tasktype'] = array(
      '#type'          => 'radios',
      '#title'         => t('Task Type'),
      '#default_value' => (isset($node->tasktype) ? $node->tasktype : 'action'),
      '#options'       => $tasktypes,
      '#description'   => t(''),
      '#weight'        => 0,
    );
    $form['from'] = array(
      '#type' => 'hidden',
      '#value' => arg(3).(arg(4) ? '/'.arg(4).(arg(5) ? '/'.arg(5) : '') : ''),
    );

    // alter parent tasklist to only contain project types, and add a class for styling
    $parents = _tasks_advanced_projects($node->nid);

    $form['parent']['#prefix']  = '<div id="parent-tasklist">';
    $form['parent']['#suffix']  = '</div>';
    $form['parent']['#options'] = $parents;
  }
}


function _tasks_advanced_projects($nid) {
  if (!$nid) {
    $nid = 0;
  }
  $result = db_query("SELECT n.nid, n.title, t.task_parent as parent FROM {node} n INNER JOIN {tasks} t ON t.nid = n.nid INNER JOIN {tasks_advanced} a ON a.nid = n.nid WHERE n.type='tasks' AND t.completed = '0000-00-00' AND a.tasktype = 'project' AND n.nid != {$nid} ORDER BY IF(t.task_parent = 0,0,1), n.title ASC");

  while ($tasklist = db_fetch_object($result)) {
    if ($tasklist->parent == 0) {
      $tasklist->title = t('-- MASTER TASKLIST --');
    }
    $tasklists[$tasklist->nid] = $tasklist->title;
    $not_master = 1;
  }
  if (!$not_master) {
    $tasklists[0] = t('NO PARENT - THIS IS THE MASTER TASKLIST');
  }
  return $tasklists;
}


function _tasks_advanced_taskcategory($taskcategory = NULL) {
  $taskcategories = array('unknown' => t('Unknown'), 'next' => t('Next Action'), 'waiting' => t('Waiting For'), 'someday' => t('Some Day'), 'list' => t('List'), 'reference' => t('Reference'), 'inactive' => t('Inactive'));
  return ($taskcategory != NULL ? $taskcategories[$taskcategory] : $taskcategories);
}


function _tasks_advanced_tasktype($tasktype = NULL) {
  $tasktypes = array('action' => t('Action'), 'project' => t('Project'));
  return ($tasktype != NULL ? $tasktypes[$tasktype] : $tasktypes);
}


/**
 * Implementation of hook_nodeapi().
 *
 * @ingroup tasks_advanced_core
 */
function tasks_advanced_nodeapi(&$node, $op, $teaser = NULL, $page = NULL) {
  // only apply to task nodes
  if ($node->type == 'tasks') {
    switch ($op) {
      case 'validate':
      case 'submit':
        // lets make sure we get good values
        $taskcategories = _tasks_advanced_taskcategory();
        $tasktypes      = _tasks_advanced_tasktype();

        if (!array_key_exists($node->taskcategory, $taskcategories)) {
          $node->taskcategory = 'unknown';
        }
        if (!array_key_exists($node->tasktype, $tasktypes)) {
          $node->tasktype = 'action';
        }
        break;

      case 'insert':
        // fetch parent for tree info
        $parent_node = _tasks_advanced_get_node($node->parent);

        // update tree to make place for new node
        _tasks_advanced_tree_insert($parent_node);

        // insert new record
        db_query("INSERT INTO {tasks_advanced} (nid, taskcategory, tasktype, task_tree_left, task_tree_right, task_tree_depth) VALUES (%d, '%s', '%s', %d, %d, %d)", $node->nid, $node->taskcategory, $node->tasktype, $parent_node->task_tree_right, $parent_node->task_tree_right + 1, $parent_node->task_tree_depth + 1);
        break;

      case 'update':
        // update the tree if the parent has changed
        if (($_GET['action'] == 'up' || $_GET['action'] == 'down') == FALSE) {
          if (_tasks_advanced_tree_move($node, $node->parent)) {
            drupal_set_message(t('Task <b>'.$node->title.'</b> has been moved to another location on the tasklist.'));
          }
        }

        // update record
        db_query("UPDATE {tasks_advanced} SET taskcategory = '%s', tasktype = '%s' WHERE nid = %d", $node->taskcategory, $node->tasktype, $node->nid);

        if ($node->from) {
          $_REQUEST['destination'] = $node->from;
        }
        break;

      case 'delete':
        // update tree to fill place of missing node
        _tasks_advanced_tree_extract($node);

        // delete record
        db_query("DELETE FROM {tasks_advanced} WHERE nid = %d", $node->nid);
        break;

      case 'load':
        $record = db_query('SELECT taskcategory, tasktype, task_tree_left, task_tree_right, task_tree_depth FROM {tasks_advanced} WHERE nid = %d', $node->nid);
        $object = db_fetch_object($record);

        return array(
            'taskcategory'    => $object->taskcategory,
            'tasktype'        => $object->tasktype,
            'task_tree_left'  => $object->task_tree_left,
            'task_tree_right' => $object->task_tree_right,
            'task_tree_depth' => $object->task_tree_depth,
          );
        break;

      case 'view':
      case 'rss item':
        break;
    }
  }
}


/**
 * Implementation of hook_user().
 *
 * @ingroup tasks_advanced_core
 */
function tasks_advanced_user($op, &$edit, &$user, $category = NULL) {
  if($op == "view") {
    $items[] = array(
      'title' => t("Tasks"),
      'value' => l(t('View !s\'s tasks', array('!s' => $user->name)), "tasks/user/".$user->uid),
      'class' => 'tasks',
    );
    return array(t('Tasks') => $items);
  }
}

/**
 * @defgroup tasks_advanced_callback Functions which are the menu callbacks for this module
 */


/**
 * Output user headers.
 *
 * @ingroup tasks_advanced_callback
 * @param $type   string 'user' for individual user page
 * @param $uid    integer User's id
 * @return string html
 */
function _tasks_advanced_main($type = NULL, $uid = NULL) {
  global $user;

  drupal_add_js(drupal_get_path('module', 'tasks').'/tasks_view.js');
  drupal_add_css(drupal_get_path('module', 'tasks_advanced').'/tasks_advanced.css');

  // Set proper breadcrumb
  $bc = drupal_get_breadcrumb();
  if ($type == NULL) {
    $bc[] = l(t('Tasks'), 'tasks');
  }
  elseif ($type == 'user' && $uid == $user->uid) {
    // Need to remove 'my tasks' part off breadcrumb
    array_pop($bc);
  }

  if ($type == 'user') {
    if ($uid == NULL) {
      // Need to redirect to current user
      drupal_goto('tasks/user/'.$user->uid);
    }
    else {
      if ($uid === 0 || $uid == '0') {
        // Add title and special headers
        drupal_set_title(t('Unassigned Tasks'));

        // Add breadcrumb trail
        $bc[] = l(t('Unassigned'), 'tasks/user/'.$uid);
      }
      else {
        $new_user = user_load(array('uid' => $uid));
        if (!$new_user->uid) {
          return drupal_not_found();
        }

        // Add title and special headers
        drupal_set_title(t('%name&#8217;s Tasks', array('%name' => ucfirst($new_user->name))));
        $output = '<p>User ID: '.$uid.'</p>';

        // Add breadcrumb trail
        $bc[] = l(t('!name', array('!name' => ucfirst($new_user->name))), 'tasks/user/'.$uid);
      }

    }
  }
  else {
    drupal_set_title(t('Tasks'));

    if (!user_access('access all tasks')) {
      drupal_goto('tasks/user/'.$user->uid);
    }
    if ($uid != NULL) {
      drupal_goto('tasks');
    }
  }

  // Finalize breadcrumb
  drupal_set_breadcrumb($bc);

  // Look to see if we need to change node order in this list
  if (($action = $_GET['action']) && ($tid = $_GET['task'])) {
    $task = node_load(array('nid' => $tid, 'type' => 'tasks'));
    if ($action == 'up') {
      $task->order_by -= 1.3;
      node_save($task);
      if (_tasks_advanced_tree_sort($task, -1)) {
        drupal_set_message(t('Task <b>'.$task->title.'</b> has been moved <b>up</b> the tasklist.'));
      }
    }
    elseif ($action == 'down') {
      $task->order_by += 1.3;
      node_save($task);
      if (_tasks_advanced_tree_sort($task, 1)) {
        drupal_set_message(t('Task <b>'.$task->title.'</b> has been moved <b>down</b> the tasklist.'));
      }
    }

    if ($type == 'user') {
      drupal_goto('tasks/user/'.$uid);
    }
    else {
      drupal_goto('tasks');
    }
  }

  // Setup filtering
  $query = new StdClass();
  if (isset($_SESSION['_tasks_advanced_query'])) {
    $query = $_SESSION['_tasks_advanced_query'];
  }
  else {
    // Set filtering defaults
    $query->status       = array(1);
  }

  // Add user to filter
  if ($uid == NULL) {
    unset($query->uid);
  }
  else {
    $query->uid = array($uid);
  }

  // Populate filter
  $query = _tasks_advanced_query_parse($query);
  $_SESSION['_tasks_advanced_query'] = $query;

  // Make database calls
  $sql      = _tasks_advanced_query_sql($query);
  $result   = db_query($sql);
  $num_rows = db_num_rows($result);

  // Enable the list of tasks to be filtered
  $output .= drupal_get_form('tasks_advanced_view_filter_form', $num_rows, $query);

  // only proceed if we have tasks to display
  if ($num_rows > 0) {
    $rows = array();

    $init = TRUE;
    $userid   = -1;
    $username = -1;

    // loop through each task
    while ($task = db_fetch_object($result)) {
      // is this a new user?
      if ($username != $task->assigned_name) {
        // if we're showing all user's tasks, we need to add headers for each user
        if ($type != 'user') {
          if ($init == FALSE) {
            $output .= _tasks_advanced_user_headers($userid, $username);
            $output .= _tasks_advanced_row_headers($rows);
            $rows = array();
          }
          else {
            // initialization complete
            $init = FALSE;
          }
        }
        $userid   = $task->assigned_to;
        $username = $task->assigned_name;
        unset($previous_task);
      }

      // Is another user the owner of our parent?
      // If so, we need to insert an 'unknown' parent
      // to keep hierarchy somewhat consistent.
      // It's still a bit of a hack, since it doesn't
      // show the real parent, and doesn't reflect
      // the depth either.
      if (isset($previous_task)) {
        if (($task->task_tree_depth > $previous_task->task_tree_depth && $task->parent != $previous_task->nid) ||
            ($task->task_tree_depth == $previous_task->task_tree_depth && $task->parent != $previous_task->parent)) {
          if ($task->task_tree_left > $previous_task->task_tree_left && $task->task_tree_right < $previous_task->task_tree_right && $task->task_tree_depth > 2) {
            // this is a grandchild of this task
            $rows[] =_tasks_advanced_task_placeholder($task, $type, $uid, TRUE);
          }
          else {
            $rows[] =_tasks_advanced_task_placeholder($task, $type, $uid);
          }
        }
      }
      else {
        if ($task->task_tree_depth > 1) {
          $rows[] =_tasks_advanced_task_placeholder($task, $type, $uid);
        }
      }
      $previous_task = drupal_clone($task);

      $task_rows = _tasks_advanced_task($task, $type, $uid);
      $rows[] = $task_rows[0];
      $rows[] = $task_rows[1];
    }

    if ($type != 'user') {
      $output .= _tasks_advanced_user_headers($userid, $username);
    }
    $output .= _tasks_advanced_row_headers($rows);
    $rows = array();
  }
  else {
    // no tasks to display
    $output .= '<p>'.t('No tasks found.').'</p>';
  }

  print theme('page', $output);
}

/**
 * Filtering for tasklist
 */
function tasks_advanced_view_filter_form($num_rows, &$query) {
  // Create dropdown options lists
  $status         = array(1 => t('Incomplete Tasks'), 2 => t('Complete Tasks'), 0 => t('All Tasks'));
  $taskcategories = array_merge(array(0 => 'All Tasks'), _tasks_advanced_taskcategory());
  $tasktypes      = array_merge(array(0 => 'All Tasks'), _tasks_advanced_tasktype());

  // Enable the list of tasks to be filtered
  $form['filter'] = array(
    '#type' => 'fieldset',
    '#title' => t('Filter'),
    '#collapsible' => TRUE,
    '#collapsed' => FALSE,
    '#weight' => -1,
  );
  $form['filter']['label'] = array(
    '#value' => t('<strong>Showing %num_rows tasks.</strong>', array('%num_rows' => $num_rows)),
  );
  $form['filter']['status'] = array(
    '#type' => 'select',
    '#title' => t('Status'),
    '#default_value' => (isset($query->status) ? $query->status[0] : '0'),
    '#options' => $status,
  );
  $form['filter']['taskcategory'] = array(
    '#type' => 'select',
    '#title' => t('Category'),
    '#default_value' => (isset($query->taskcategory) ? $query->taskcategory[0] : '0'),
    '#options' => $taskcategories,
  );
  $form['filter']['tasktype'] = array(
    '#type' => 'select',
    '#title' => t('Task Type'),
    '#default_value' => (isset($query->tasktype) ? $query->tasktype[0] : '0'),
    '#options' => $tasktypes,
  );
  $form['filter']['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Filter')
  );
  $form['#redirect'] = FALSE;

  return $form;
}


function _tasks_advanced_query_parse($query = NULL) {
  $fields = array('status', 'taskcategory', 'tasktype');

  if ($_SERVER['REQUEST_METHOD'] == 'POST' && $_POST['form_id'] == 'tasks_advanced_view_filter_form') {
    foreach ($_POST as $key => $value) {
      if (!empty($value) && in_array($key, $fields)) {
        $query->$key = !is_array($value) ? explode(',', $value) : $value;
        $_POST[$key] = is_array($value) ? implode(',', $value) : $value;
      }
      else {
        unset($query->$key);
      }
    }
    $_POST = array();
  }
  else {
    foreach ($_GET as $key => $value) {
      if (!empty($value) && in_array($key, $fields)) {
        $query->$key = explode(',', $value);
      }
      else {
        unset($query->$key);
      }
    }
  }

  return $query;
}

function _tasks_advanced_query_sql_field($field, $values, $operator = ' OR ') {
  $sql = array();
  if (!is_array($values)) {
    $values = array($values);
  }
  foreach ($values as $value) {
    $value = db_escape_string($value);
    $sql[] = ($like && $field != 'p.pid') ? "$field LIKE '%$value%'" : "$field = '$value'";
  }
  if ($sql) {
    return '('. implode($operator, $sql) .')';
  }
}

function _tasks_advanced_query_sql($query) {
  $order = 'u.name, a.task_tree_left ASC, IF(t.completed = 0, 0, 1), t.completed DESC';
  $sql = array();

  foreach ($query as $key => $value) {
    switch ($key) {
      case 'status':
        switch ($value[0]) {
          case 1:
            $order = 'u.name, a.task_tree_left ASC';
            $sql[] = 't.completed = 0000-00-00';
            break;
          case 2:
            $order = 'u.name, a.task_tree_left ASC, t.completed DESC';
            $sql[] = 't.completed != 0000-00-00';
            break;
        }
        break;
      case 'taskcategory':
        $sql[] = _tasks_advanced_query_sql_field('a.taskcategory', $value);
        break;
      case 'tasktype':
        $sql[] = _tasks_advanced_query_sql_field('a.tasktype', $value);
        break;
      case 'uid':
        $sql[] = _tasks_advanced_query_sql_field('u.uid', $value);
        break;
    }
  }

  $sql_str = "SELECT n.nid, t.task_parent as parent, u.name AS assigned_name, t.assigned_to, a.taskcategory, a.tasktype, a.task_tree_left, a.task_tree_right, a.task_tree_depth, u.data
FROM {node} n
INNER JOIN {tasks} t ON t.nid = n.nid
INNER JOIN {tasks_advanced} a ON a.nid = n.nid
LEFT JOIN {users} u ON u.uid = t.assigned_to
WHERE n.status = 1
AND n.type='tasks' ".
(count($sql) > 0 ?" AND (". implode(") AND (", $sql) .")" : '').' '."
ORDER BY {$order}";

  $sql = db_rewrite_sql($sql_str);

  return $sql;
}


/**
 * Rebuild tree structure.
 *
 * Based on "Modified Preorder Tree Traversal" article at
 * http://www.sitepoint.com/article/hierarchical-data-database
 *
 * @param $parent object  task
 * @param $left   integer left side of tree
 * @return $right integer
 */
function tasks_advanced_rebuild_tree($parent, $left, $depth = 0) {
  // the right value of this node is the left value + 1
  $right = $left + 1;

  // get all children of this node
  $result = db_query("SELECT nid tas_parent as parent FROM {tasks} WHERE task_parent = %d", $parent);

  while ($row = db_fetch_object($result)) {
    // recursive execution of this function for each
    // child of this node
    // $right is the current right value, which is
    // incremented by the rebuild_tree function
    $right = tasks_advanced_rebuild_tree($row->parent, $right, $depth + 1);
  }

  // we've got the left value, and now that we've processed
  // the children of this node we also know the right value
  db_query("UPDATE {tasks_advanced} SET task_tree_left = %d, task_tree_right = %d, task_tree_depth = %d WHERE nid = %d", $left, $right, $depth, $parent);

  // return the right value of this node + 1
  $return = $right + 1;
  return $return;
}


/**
 * @defgroup tasks_advanced_support Functions that support the tasks_advanced system
 */


/**
 * Retrieve tasks_advanced part of a node using its nid.
 *
 * @ingroup tasks_advanced_support
 * @param $nid      integer Node's nid
 * @return void
 */
function _tasks_advanced_get_node($nid) {
  $record = db_query('SELECT t.nid, t.task_parent as parent, a.tasktype, a.task_tree_left, a.task_tree_right, a.task_tree_depth FROM {tasks} t INNER JOIN {tasks_advanced} a ON a.nid = t.nid WHERE t.nid = %d LIMIT 1', $nid);
  $object = db_fetch_object($record);
  return $object;
}


/**
 * Retrieve tasks_advanced part of a node using its left value.
 *
 * @ingroup tasks_advanced_support
 * @param $left     integer Node's left
 * @return void
 */
function _tasks_advanced_get_node_by_left($left) {
  $record = db_query('SELECT * FROM {tasks_advanced} WHERE task_tree_left = %d LIMIT 1', $left);
  $object = db_fetch_object($record);
  return $object;
}


/**
 * Retrieve tasks_advanced part of a node using its right value.
 *
 * @ingroup tasks_advanced_support
 * @param $right    integer Node's right
 * @return void
 */
function _tasks_advanced_get_node_by_right($right) {
  $record = db_query('SELECT * FROM {tasks_advanced} WHERE task_tree_right = %d LIMIT 1', $right);
  $object = db_fetch_object($record);
  return $object;
}


/**
 * Insert node into tree structure as child of parent.
 *
 * @ingroup tasks_advanced_support
 * @param $parent_node object Node where to insert child into tree
 * @param $children    integer Amount of children you want to make space for; default 1
 * @return void
 */
function _tasks_advanced_tree_insert(&$parent_node, $children = 1) {
  $space = $children * 2;
  db_query("UPDATE {tasks_advanced} SET task_tree_right = (task_tree_right + ".$space.") WHERE task_tree_right > %d", $parent_node->task_tree_right - 1);
  db_query("UPDATE {tasks_advanced} SET task_tree_left = (task_tree_left + ".$space.") WHERE task_tree_left > %d", $parent_node->task_tree_right - 1);

  return TRUE;
}


/**
 * Extract node from tree structure.
 *
 * @ingroup tasks_advanced_support
 * @param $node     object Node to extract from tree
 * @param $children integer Amount of children you want to remove space for; default 1
 * @return void
 */
function _tasks_advanced_tree_extract(&$node, $children = 1) {
  $space = $children * 2;
  db_query("UPDATE {tasks_advanced} SET task_tree_right = (task_tree_right - ".$space.") WHERE task_tree_right > %d", $node->task_tree_right - 1);
  db_query("UPDATE {tasks_advanced} SET task_tree_left = (task_tree_left - ".$space.") WHERE task_tree_left > %d", $node->task_tree_right - 1);

  return TRUE;
}


/**
 * Move a branch of the tree to a different parent.
 *
 * @ingroup tasks_advanced_support
 * @param $records  recordset Recordset to extract nids from
 * @return array    Array of nids
 */
function _tasks_advanced_fetch_ids_from_recordset($records) {
  $ids = array();
  while ($row = db_fetch_object($records)) {
    $ids[] = $row->nid;
  }

  return $ids;
}


/**
 * Change the order of a node, limited to the same parent.
 *
 * @ingroup tasks_advanced_support
 * @param $node      object Node to change order of
 * @param $direction integer 1 or -1
 * @return boolean   TRUE on success, FALSE on failure
 */
function _tasks_advanced_tree_sort(&$node, $direction) {
  // get node to swap with: WHERE right = left - 1 || WHERE left = right + 1
  if ($direction < 0) {
    $node_b = _tasks_advanced_get_node_by_right($node->task_tree_left - 1);
    $node_a = $node;
  }
  else {
    $node_a = _tasks_advanced_get_node_by_left($node->task_tree_right + 1);
    $node_b = $node;
  }

  // get list of IDs for branch A
  $records = db_query("SELECT nid FROM {tasks_advanced} WHERE task_tree_left BETWEEN %d AND %d", $node_a->task_tree_left, $node_a->task_tree_right);
  $ids_a   = _tasks_advanced_fetch_ids_from_recordset($records);
  if (count($ids_a) == 0) {
    return FALSE;
  }
  $space_a = $node_b->task_tree_right - $node_b->task_tree_left + 1;

  // get list of IDs for branch B
  $records = db_query("SELECT nid FROM {tasks_advanced} WHERE task_tree_left BETWEEN %d AND %d", $node_b->task_tree_left, $node_b->task_tree_right);
  $ids_b   = _tasks_advanced_fetch_ids_from_recordset($records);
  if (count($ids_b) == 0) {
    return FALSE;
  }
  $space_b = $node_a->task_tree_right - $node_a->task_tree_left + 1;

  // update branch A
  db_query("UPDATE {tasks_advanced} SET task_tree_left = (task_tree_left - %d), task_tree_right = (task_tree_right - %d) WHERE nid IN (%s)", $space_a, $space_a, implode(', ', $ids_a));

  // update branch B
  db_query("UPDATE {tasks_advanced} SET task_tree_left = (task_tree_left + %d), task_tree_right = (task_tree_right + %d) WHERE nid IN (%s)", $space_b, $space_b, implode(', ', $ids_b));

  return TRUE;
}


/**
 * Move a branch of the tree to a different parent.
 *
 * @ingroup tasks_advanced_support
 * @param $node     object Node to move
 * @param $parent   integer Parent node's nid
 * @return boolean  TRUE on success, FALSE on failure
 */
function _tasks_advanced_tree_move(&$node, $parent) {
  // fetch parent node
  $parent_node = _tasks_advanced_get_node($parent);

  // make sure we're not moving to a child of current branch
  if ($node->task_tree_left < $parent_node->task_tree_left && $node->task_tree_right > $parent_node->task_tree_right) {
    return FALSE;
  }

  // make sure we're not moving a node with an unchanged parent
  if ($parent_node->task_tree_left < $node->task_tree_left &&
      $parent_node->task_tree_right > $node->task_tree_right &&
      $parent_node->task_tree_depth == $node->task_tree_depth - 1) {
/*
    print "Not doing anything...<br />\n";
    print "Level: {$node->task_tree_depth}<br />\n";
    print "Parent Level: {$parent_node->task_tree_depth}<br />\n";
*/
    return FALSE;
  }

  // fetch ids for branch we're moving
  $records = db_query("SELECT nid FROM {tasks_advanced} WHERE task_tree_left BETWEEN %d AND %d", $node->task_tree_left, $node->task_tree_right);
  $ids     = _tasks_advanced_fetch_ids_from_recordset($records);
  $ids_str = implode(', ', $ids);

  // calculate size of extracted node
  $size_of_node = $node->task_tree_right - $node->task_tree_left + 1;
  $depth_diff   = $parent_node->task_tree_depth + 1 - $node->task_tree_depth;

  // calculate min and max for left and right that we need to move
  // this makes sure we don't affect any records needlessly
  if ($parent_node->task_tree_left < $node->task_tree_left &&
      $parent_node->task_tree_right > $node->task_tree_right &&
      $parent_node->task_tree_depth < $node->task_tree_depth - 1) {

    // moving up the chain
    $minmax_a  = $node->task_tree_right + 1;
    $minmax_b  = $parent_node->task_tree_right - 1;
    $direction = -1;
    $size_of_move = $parent_node->task_tree_right - 1 - $node->task_tree_right;
  }
  elseif ($parent_node->task_tree_left < $node->task_tree_left) {
    // moving left
    $minmax_a  = $parent_node->task_tree_right;
    $minmax_b  = $node->task_tree_left;
    $direction = 1;
    $size_of_move = $parent_node->task_tree_right + $size_of_node - 1 - $node->task_tree_right;
  }
  else {
    // moving right
    $minmax_a  = $parent_node->task_tree_right - 1;
    $minmax_b  = $node->task_tree_right;
    $direction = -1;
    $size_of_move = $parent_node->task_tree_right - 1 - $node->task_tree_right;
  }
  $min = min($minmax_a, $minmax_b);
  $max = max($minmax_a, $minmax_b);

  // remove space for item we're moving
  db_query("UPDATE {tasks_advanced} SET task_tree_left = (task_tree_left + %d) WHERE task_tree_left >= %d AND task_tree_left <= %d AND nid NOT IN (%s)", $size_of_node * $direction, $min, $max, $ids_str);
  db_query("UPDATE {tasks_advanced} SET task_tree_right = (task_tree_right + %d) WHERE task_tree_right >= %d AND task_tree_right <= %d AND nid NOT IN (%s)", $size_of_node * $direction, $min, $max, $ids_str);

  // insert node as last of new parent node's children
  db_query("UPDATE {tasks_advanced} SET task_tree_left = (task_tree_left + %d), task_tree_right = (task_tree_right + %d), task_tree_depth = (task_tree_depth + %d) WHERE nid IN (%s)", $size_of_move, $size_of_move, $depth_diff, $ids_str);

  return TRUE;
}


/**
 * Output user headers.
 *
 * @ingroup tasks_advanced_support
 * @param $uid      integer User's id
 * @param $username string User's name
 * @return string html
 */
function _tasks_advanced_user_headers($uid, $username) {
  if ($username) {
    $output .= '<h3>'.l(t('%name&#8217;s Tasks', array('%name' => ucfirst($username))), 'tasks/user/'.$uid, array(), NULL, NULL, FALSE, TRUE).'</h3>';
  }
  else {
    $output .= '<h3>'.l(t('Unassigned Tasks'), 'tasks/user/'.$uid, array(), NULL, NULL, FALSE, TRUE).'</h3>';
  }

  return $output;
}


/**
 * Output row headers.
 *
 * @ingroup tasks_advanced_support
 * @param $rows   array row
 * @return string html
 */
function _tasks_advanced_row_headers(&$rows) {
  $header = array(
    array('data' => '', 'class' => 'tasks_advanced-colourcode'),
    array('data' => t('Assigned'), 'class' => 'tasks_advanced-assigned'),
    array('data' => t('Task'), 'class' => 'tasks_advanced-title'),
    array('data' => t('Complete?'), 'class' => 'tasks_advanced-completed'),
    array('data' => t('Details'), 'class' => 'tasks_advanced-details'),
    array('data' => t('Edit'), 'class' => 'tasks_advanced-edit'),
    array('data' => t('Order'), 'class' => 'tasks_advanced-order'),
  );
  $output = theme('table', $header, $rows, array('class' => 'task-list'));

  return $output;
}


/**
 * Output a placeholder parent task.
 *
 * @ingroup tasks_advanced_support
 * @param $object object task
 * @param $type   string "user" for individual user page
 * @param $uid    integer User's id
 * @return array of table row
 */
function _tasks_advanced_task_placeholder(&$object, $type = NULL, $uid = NULL, $subtask = FALSE) {
  $assigned_name = $object->assigned_name;
  if ($object->assigned_to == 0) {
    $assigned_name = t('none');
  }
  $extra = drupal_unpack($object);
  $tasks_colour = $extra->tasks_colour;
  $task = node_load(array('nid' => $object->nid, 'type' => 'tasks'));

  $row = array(
    'data' => array(
      array(
        'data'  => '<span'.($tasks_colour ? ' style="background-color: '.$tasks_colour.';"' : '').'>+</span>',
        'class' => 'tasks_advanced-colourcode',
      ),
      array(
        'data'  => l($assigned_name, "tasks/user/{$task->assigned_to}"),
        'class' => 'tasks_advanced-assigned',
      ),
      array(
        'data'  => ($subtask ? '<span style="font-family: monospace;">'.'&#160;&#x2514;&#x2500; '.'</span>'.t('Unknown Subtask') : t('Unknown Task')),
        'class' => 'tasks_advanced-title',
      ),
      array(
        'data' => '&#160;',
        'class' => 'tasks_advanced-completed',
      ),
      array(
        'data' => '&#160;',
        'class' => 'tasks_advanced-details',
      ),
      array(
        'data' => '&#160;',
        'class' => 'tasks_advanced-edit',
      ),
      array(
        'data' => '&#160;',
        'class' => 'tasks_advanced-order',
      ),
    ),
  );

  return $row;
}


/**
 * Output a single task.
 *
 * @ingroup tasks_advanced_support
 * @param $object object task
 * @param $type   string "user" for individual user page
 * @param $uid    integer User's id
 * @return array of table rows
 */
function _tasks_advanced_task(&$object, $type = NULL, $uid = NULL) {
  $rows = array();

  $assigned_name = $object->assigned_name;
  if ($object->assigned_to == 0) {
    $assigned_name = t('none');
  }
  $extra = drupal_unpack($object);
  $tasks_colour = $extra->tasks_colour;
  $task = node_load(array('nid' => $object->nid, 'type' => 'tasks'));
  $tasks_indent = ($object->task_tree_depth > 1 ? ((($object->task_tree_depth - 2) * 3) + 3) : 0);

  $rows[] = array(
    'data' => array(
      array(
        'data'  => l('<span'.($tasks_colour ? ' style="background-color: '.$tasks_colour.';"' : '').'>'.($task->tasktype == 'project' ? '+' : '&#160;').'</span>', "node/{$task->nid}", array(), NULL, NULL, FALSE, TRUE ),
        'class' => 'tasks_advanced-colourcode',
      ),
      array(
        'data'  => l($assigned_name, "tasks/user/{$task->assigned_to}"),
        'class' => 'tasks_advanced-assigned',
      ),
      array(
        'data'  => ($object->task_tree_depth > 1 ? '<span style="font-family: monospace;">'.str_repeat('&#160;', ($object->task_tree_depth - 2) * 4).'&#160;&#x2514;&#x2500; '.'</span>' : '').l($task->title, "node/{$task->nid}", array('name' => 'task'.$task->nid)), //"[{$task->task_tree_left}, {$task->task_tree_right}]".
        'class' => 'tasks_advanced-title',
        'style' => ($task->completed > 0 ? 'text-decoration: line-through; ' : '').($tasks_indent > 0 ? "padding-left: {$tasks_indent}ex; text-indent: -{$tasks_indent}ex;" : ''),
      ),
      array(
        'data' => ($task->completed > 0 ? $task->completed : t('No')),
        'class' => 'tasks_advanced-completed',
      ),
      array(
        'data' => "<a href='javascript: void(true);' onClick=\"javascript:toggleVisibility('row-{$task->nid}');\">".t('View')."</a> ",
        'class' => 'tasks_advanced-details',
      ),
      array(
        'data' => l("<img src=\"".base_path().drupal_get_path('module', 'tasks')."/icon_edit.gif\" border=\"0\" />", "node/{$task->nid}/edit/tasks".($type ? "/{$type}" : '').($uid ? "/{$uid}" : ''),array(),null,null,false,true),
        'class' => 'tasks_advanced-edit',
      ),
      array(
        'data' => l(t('Up'), $_GET['q'], array(), "action=up&task={$task->nid}").' '.l(t('Down'), $_GET['q'], array(), "action=down&task={$task->nid}"),
        'class' => 'tasks_advanced-order',
      ),
    ),
  );
  $task = node_prepare($task);
  $rows[] = array(
    'data'  => array(
      '',
      array(
        'data'    => $task->body,
        'colspan' => '6',
      ),
    ),
    'id'    => "row-$task->nid",
    'class' => 'task-expand',
    'style' => 'display:none;',
  );

  return $rows;
}