Moving albums around with a drag and drop interface seems to work and preserve the left right pointers.

* changed _lock and _unlock to protected methods lock and lock respectively
* added a moveTo method on the Item_Model
* Corrected the hole closure  on delete.
* added moveTo on the ORM_MTPP class
* Changed the rearrange javascript to do moves with ajax

5 files changed, 146 insertions, 23 deletions

diff --git a/core/controllers/welcome.php b/core/controllers/welcome.php
index 8f8421d3..1d2082d4 100644
--- a/core/controllers/welcome.php
+++ b/core/controllers/welcome.php
@@ -125,7 +125,7 @@ class Welcome_Controller extends Template_Controller {
     $data = "digraph G {\n";
     foreach ($items as $item) {
       $data .= "  $item->parent_id -> $item->id\n";
-      $data .= "  $item->id [label=\"$item->id <$item->left, $item->right>\"]\n";
+      $data .= "  $item->id [label=\"$item->id $item->title <$item->left, $item->right>\"]\n";
     }
     $data .= "}\n";
 
diff --git a/core/libraries/ORM_MPTT.php b/core/libraries/ORM_MPTT.php
index bac4da92..2290c83a 100644
--- a/core/libraries/ORM_MPTT.php
+++ b/core/libraries/ORM_MPTT.php
@@ -53,7 +53,7 @@ class ORM_MPTT_Core extends ORM {
    * @return ORM
    */
   function add_to_parent($parent_id) {
-    $this->_lock();
+    $this->lock();
 
     try {
       // Make a hole in the parent for this new item
@@ -71,11 +71,11 @@ class ORM_MPTT_Core extends ORM {
       $this->level = $parent->level + 1;
       $this->save();
     } catch (Exception $e) {
-      $this->_unlock();
+      $this->unlock();
       throw $e;
     }
 
-    $this->_unlock();
+    $this->unlock();
     return $this;
   }
 
@@ -93,18 +93,18 @@ class ORM_MPTT_Core extends ORM {
       $this->reload();
     }
 
-    $this->_lock();
+    $this->lock();
     try {
       $this->db->query(
-        "UPDATE `{$this->table_name}` SET `left` = `left` - 2 WHERE `left` >= {$this->right}");
+        "UPDATE `{$this->table_name}` SET `left` = `left` - 2 WHERE `left` > {$this->right}");
       $this->db->query(
-        "UPDATE `{$this->table_name}` SET `right` = `right` - 2 WHERE `right` >= {$this->right}");
+        "UPDATE `{$this->table_name}` SET `right` = `right` - 2 WHERE `right` > {$this->right}");
     } catch (Exception $e) {
-      $this->_unlock();
+      $this->unlock();
       throw $e;
     }
 
-    $this->_unlock();
+    $this->unlock();
     parent::delete();
   }
 
@@ -225,11 +225,88 @@ class ORM_MPTT_Core extends ORM {
     return parent::reload();
   }
 
+  /**
+   * Move this item to the specified target.
+   *
+   * @chainable
+   * @param   Item_Model $target  Target item (must be an album
+   * @param   boolean    $locked  The called is already holding the lock
+   * @return  ORM_MTPP
+   */
+  function moveTo($target, $locked=false) {
+    if ($target->type != "album") {
+      throw new Exception("@todo '{$target->type}' IS NOT A VALID MOVE TARGET");
+    }
+
+    if ($this->id == 1) {
+      throw new Exception("@todo '{$this->title}' IS NOT A VALID SOURCE");
+    }
+
+    $numberToMove = (int)(($this->right - $this->left) / 2 + 1);
+    $size_of_hole = $numberToMove * 2;
+    $original_parent = $this->parent;
+
+    if (empty($locked)) {
+      $this->lock();
+    }
+    try {
+      // Make a hole in the target for the move
+      $target->db->query(
+        "UPDATE `{$target->table_name}` SET `left` = `left` + $size_of_hole" .
+        " WHERE `left` >= {$target->right}");
+      $target->db->query(
+        "UPDATE `{$target->table_name}` SET `right` = `right` + $size_of_hole" .
+        " WHERE `right` >= {$target->right}");
+
+      // Change the parent.
+      $this->db->query(
+        "UPDATE `{$this->table_name}` SET `parent_id` = {$target->id}" .
+        " WHERE `id` = {$this->id}");
+
+      // If the source is to the right of the target then we just adjusted its left and right above.
+      $left = $this->left;
+      $right = $this->right;
+      if ($this->left > $target->right) {
+        $left += $size_of_hole;
+        $right += $size_of_hole;
+      }
+
+      $newOffset = $target->left - $left + 1;
+      $this->db->query(
+        "UPDATE `{$this->table_name}`" .
+        "   SET `left` = `left` + $newOffset," .
+        "       `right` = `right` + $newOffset" .
+      " WHERE `left` >= $left" .
+        "   AND `right` <= $right");
+
+      // Close the hole in the source's parent after the move
+      $this->db->query(
+        "UPDATE `{$this->table_name}` SET `left` = `left` - $size_of_hole" .
+        " WHERE `left` > $right");
+      $this->db->query(
+        "UPDATE `{$this->table_name}` SET `right` = `right` - $size_of_hole" .
+        " WHERE `right` > $right");
+
+    } catch (Exception $e) {
+      if (empty($locked)) {
+        $this->unlock();
+      }
+      throw $e;
+    }
+
+    if (empty($locked)) {
+      $this->_unlock();
+    }
+
+    // Lets reload to get the changes.
+    $this->reload();
+    return $this;
+  }
 
   /**
    * Lock the tree to prevent concurrent modification.
    */
-  private function _lock() {
+  protected function lock() {
     $result = $this->db->query("SELECT GET_LOCK('{$this->table_name}', 1) AS L")->current();
     if (empty($result->L)) {
       throw new Exception("@todo UNABLE_TO_LOCK_EXCEPTION");
@@ -239,7 +316,7 @@ class ORM_MPTT_Core extends ORM {
   /**
    * Unlock the tree.
    */
-  private function _unlock() {
+  protected function unlock() {
     $this->db->query("SELECT RELEASE_LOCK('{$this->table_name}')");
   }
 }
diff --git a/core/models/item.php b/core/models/item.php
index fbaca0e7..495508ec 100644
--- a/core/models/item.php
+++ b/core/models/item.php
@@ -53,6 +53,32 @@ class Item_Model extends ORM_MPTT {
   }
 
   /**
+   * Move this item to the specified target.
+   *
+   * @chainable
+   * @param   Item_Model $target  Target item (must be an album
+   * @return  ORM_MTPP
+   */
+  function moveTo($target) {
+    $this->lock();
+    try {
+      $original_path = $this->file_path();
+
+      parent::moveTo($target, true);
+
+      $new_path = $this->file_path();
+      rename($original_path, $new_path);
+
+    } catch (Exception $e) {
+      $this->unlock();
+      throw $e;
+    }
+
+    $this->unlock();
+    return $this;
+  }
+
+  /**
    * album: /var/albums/album1/album2
    * photo: /var/albums/album1/album2/photo.jpg
    */
diff --git a/modules/rearrange/controllers/rearrange.php b/modules/rearrange/controllers/rearrange.php
index 59c1b069..6118e07e 100644
--- a/modules/rearrange/controllers/rearrange.php
+++ b/modules/rearrange/controllers/rearrange.php
@@ -22,14 +22,26 @@ class Rearrange_Controller extends Controller {
   public function show($id=null) {
     $view = new View("rearrange_item_list.html");
 
-    if (empty($id)) {
-      $item = ORM::factory("item", 1);
-      $view->children = array($item);
-    } else {
-      $item = ORM::factory("item", $id);
-      $view->children = $item->children();
-    }
+    $isRoot = empty($id);
+    $item = ORM::factory("item", $isRoot ? 1 : $id);
+
+    $view->children = $isRoot ? array($item) : $item->children();
 
     print $view;
   }
+
+  public function move($source_id, $target_id) {
+    $source = ORM_MPTT::factory("item", $source_id);
+    $target = ORM_MPTT::factory("item", $target_id);
+
+    try {
+      $source->moveTo($target);
+      print "success";
+    } catch (Exception $e) {
+      Kohana::log("error", $e->getMessage() . "\n" + $e->getTraceAsString());
+      header("HTTP/1.1 500");
+      print  $e->getMessage();
+    }
+  }
+
 }
\ No newline at end of file
diff --git a/modules/rearrange/js/jquery.gallery.rearrange.tree.js b/modules/rearrange/js/jquery.gallery.rearrange.tree.js
index 09284a25..c423becd 100644
--- a/modules/rearrange/js/jquery.gallery.rearrange.tree.js
+++ b/modules/rearrange/js/jquery.gallery.rearrange.tree.js
@@ -70,9 +70,19 @@ if(jQuery) (function($){
             hoverClass: "droppable-hover",
             drop: function(ev, ui) {
               source_element = ui.draggable;
-              source_parent = source_element.parent();
+              source_parent = getParent(source_element);
               target = ui.element;
-              alert(source_element.attr("id") + "\n" + target.attr("id"));
+
+              $.ajax({
+                url: "rearrange/move/" + source_element.attr("id") + "/" + target.attr("id"),
+                success: function(data, textStatus) {
+                  collapse(source_parent);
+                  showTree(source_parent, source_parent.attr("id"));
+                },
+                error: function(xhr, textStatus, errorThrown) {
+                  alert("Http Error Code: " + xhr.status + "Text Status: " + textStatus);
+                }
+              });
             }
           });
           bindTree(c);
@@ -168,9 +178,7 @@ if(jQuery) (function($){
                 showTree(parent, parent.attr("id"));
               },
               error: function(xhr, textStatus, errorThrown) {
-                alert(xhr.status);
-                alert(textStatus);
-                alert(errorThrown);
+                alert("Http Error Code: " + xhr.status + "Text Status: " + textStatus);
               },
               type: "DELETE"
             });