From b7d66943d7e2796bff994da131c613d5f3bfe094 Mon Sep 17 00:00:00 2001
From: Adlai Holler <guy.on.internet@icloud.com>
Date: Fri, 9 Sep 2016 16:05:47 -0700
Subject: [PATCH] Support UITableView interactive reordering

---
 AsyncDisplayKit/ASTableView.mm              | 22 +++++++++++++++++++++
 AsyncDisplayKit/Details/ASDataController.h  |  8 ++++++++
 AsyncDisplayKit/Details/ASDataController.mm | 19 ++++++++++++++++++
 3 files changed, 49 insertions(+)

diff --git a/AsyncDisplayKit/ASTableView.mm b/AsyncDisplayKit/ASTableView.mm
index 8dc50524..574f8675 100644
--- a/AsyncDisplayKit/ASTableView.mm
+++ b/AsyncDisplayKit/ASTableView.mm
@@ -146,6 +146,8 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
     unsigned int asyncDataSourceNumberOfSectionsInTableView:1;
     unsigned int asyncDataSourceTableViewNodeBlockForRowAtIndexPath:1;
     unsigned int asyncDataSourceTableViewNodeForRowAtIndexPath:1;
+    unsigned int asyncDataSourceTableViewCanMoveRowAtIndexPath:1;
+    unsigned int asyncDataSourceTableViewMoveRowAtIndexPath:1;
   } _asyncDataSourceFlags;
 }
 
@@ -301,6 +303,8 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
     _asyncDataSourceFlags.asyncDataSourceNumberOfSectionsInTableView = [_asyncDataSource respondsToSelector:@selector(numberOfSectionsInTableView:)];
     _asyncDataSourceFlags.asyncDataSourceTableViewNodeForRowAtIndexPath = [_asyncDataSource respondsToSelector:@selector(tableView:nodeForRowAtIndexPath:)];
     _asyncDataSourceFlags.asyncDataSourceTableViewNodeBlockForRowAtIndexPath = [_asyncDataSource respondsToSelector:@selector(tableView:nodeBlockForRowAtIndexPath:)];
+    _asyncDataSourceFlags.asyncDataSourceTableViewCanMoveRowAtIndexPath = [_asyncDataSource respondsToSelector:@selector(tableView:canMoveRowAtIndexPath:)];
+    _asyncDataSourceFlags.asyncDataSourceTableViewMoveRowAtIndexPath = [_asyncDelegate respondsToSelector:@selector(tableView:moveRowAtIndexPath:toIndexPath:)];
     
     // Data source must implement tableView:nodeBlockForRowAtIndexPath: or tableView:nodeForRowAtIndexPath:
     ASDisplayNodeAssertTrue(_asyncDataSourceFlags.asyncDataSourceTableViewNodeBlockForRowAtIndexPath || _asyncDataSourceFlags.asyncDataSourceTableViewNodeForRowAtIndexPath);
@@ -660,6 +664,24 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
   return [_dataController numberOfRowsInSection:section];
 }
 
+- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
+{
+  if (_asyncDataSourceFlags.asyncDataSourceTableViewCanMoveRowAtIndexPath) {
+    return [_asyncDataSource tableView:self canMoveRowAtIndexPath:indexPath];
+  } else {
+    return NO;
+  }
+}
+
+- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath *)destinationIndexPath
+{
+  if (_asyncDataSourceFlags.asyncDataSourceTableViewMoveRowAtIndexPath) {
+    [_asyncDataSource tableView:self moveRowAtIndexPath:sourceIndexPath toIndexPath:destinationIndexPath];
+  }
+  // Move node after informing data source in case they call nodeAtIndexPath:
+  [_dataController moveCompletedNodeAtIndexPath:sourceIndexPath toIndexPath:destinationIndexPath];
+}
+
 - (void)tableView:(UITableView *)tableView willDisplayCell:(_ASTableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
 {
   _pendingVisibleIndexPath = indexPath;
diff --git a/AsyncDisplayKit/Details/ASDataController.h b/AsyncDisplayKit/Details/ASDataController.h
index 7d748663..58e7b35b 100644
--- a/AsyncDisplayKit/Details/ASDataController.h
+++ b/AsyncDisplayKit/Details/ASDataController.h
@@ -188,6 +188,14 @@ FOUNDATION_EXPORT NSString * const ASDataControllerRowNodeKind;
  */
 - (NSArray<NSArray <ASCellNode *> *> *)completedNodes;
 
+/**
+ * Immediately move this item. This is called by ASTableView when the user has finished an interactive
+ * item move and the table view is requesting a model update.
+ * 
+ * This must be called on the main thread.
+ */
+- (void)moveCompletedNodeAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath;
+
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/AsyncDisplayKit/Details/ASDataController.mm b/AsyncDisplayKit/Details/ASDataController.mm
index e6ec2b76..3183dbcb 100644
--- a/AsyncDisplayKit/Details/ASDataController.mm
+++ b/AsyncDisplayKit/Details/ASDataController.mm
@@ -898,6 +898,25 @@ NSString * const ASDataControllerRowNodeKind = @"_ASDataControllerRowNodeKind";
   return _externalCompletedNodes ? : _completedNodes[ASDataControllerRowNodeKind];
 }
 
+- (void)moveCompletedNodeAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath
+{
+  ASDisplayNodeAssertMainThread();
+  if (_externalCompletedNodes != nil) {
+    NSMutableArray *oldSection = _externalCompletedNodes[indexPath.section];
+    ASCellNode *node = oldSection[indexPath.item];
+    [oldSection removeObjectAtIndex:indexPath.item];
+    [_externalCompletedNodes[newIndexPath.section] insertObject:node atIndex:newIndexPath.item];
+  }
+
+  NSMutableArray *internalCompletedNodes = _completedNodes[ASDataControllerRowNodeKind];
+  if (internalCompletedNodes != nil) {
+    NSMutableArray *oldSection = internalCompletedNodes[indexPath.section];
+    ASCellNode *node = oldSection[indexPath.item];
+    [oldSection removeObjectAtIndex:indexPath.item];
+    [internalCompletedNodes[newIndexPath.section] insertObject:node atIndex:newIndexPath.item];
+  }
+}
+
 #pragma mark - Dealloc
 
 - (void)dealloc