From f30bcbc0e7f680d527bdc0ae2a84f82c87f94896 Mon Sep 17 00:00:00 2001
From: Sean Lip <sll@google.com>
Date: Fri, 1 Jul 2016 15:55:51 -0700
Subject: [PATCH] Fix connection compatibility rules. Use the previous
 connection when 'pasting above' a block that already has a previous block.

---
 accessible/clipboard.service.js        | 47 +++++++++++++++++++++-----
 accessible/workspace-tree.component.js | 11 +++++-
 2 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/accessible/clipboard.service.js b/accessible/clipboard.service.js
index 41e5bdb14..db65e2d9f 100644
--- a/accessible/clipboard.service.js
+++ b/accessible/clipboard.service.js
@@ -63,12 +63,22 @@ blocklyApp.ClipboardService = ng.core
       return this.canBeCopiedToMarkedConnection(block);
     },
     canBeCopiedToMarkedConnection: function(block) {
-      var blockConnection = block.outputConnection || block.previousConnection;
-      return Boolean(
-          this.markedConnection_ &&
-          this.markedConnection_.sourceBlock_.workspace &&
-          this.areConnectionsCompatible_(
-              blockConnection, this.markedConnection_));
+      if (!this.markedConnection_ ||
+          !this.markedConnection_.getSourceBlock().workspace) {
+        return false;
+      }
+
+      var potentialConnections = [
+          block.outputConnection,
+          block.previousConnection,
+          block.nextConnection
+      ];
+
+      var that = this;
+      return potentialConnections.some(function(connection) {
+        return that.areConnectionsCompatible_(
+            connection, that.markedConnection_);
+      });
     },
     markConnection: function(connection) {
       this.markedConnection_ = connection;
@@ -110,9 +120,28 @@ blocklyApp.ClipboardService = ng.core
       var xml = Blockly.Xml.blockToDom(block);
       var reconstitutedBlock = Blockly.Xml.domToBlock(
           blocklyApp.workspace, xml);
-      this.markedConnection_.connect(
-          reconstitutedBlock.outputConnection ||
-          reconstitutedBlock.previousConnection);
+
+      var potentialConnections = [
+          reconstitutedBlock.outputConnection,
+          reconstitutedBlock.previousConnection,
+          reconstitutedBlock.nextConnection
+      ];
+
+      var connectionSuccessful = false;
+      for (var i = 0; i < potentialConnections.length; i++) {
+        if (this.areConnectionsCompatible_(
+            this.markedConnection_, potentialConnections[i])) {
+          this.markedConnection_.connect(potentialConnections[i]);
+          connectionSuccessful = true;
+          break;
+        }
+      }
+
+      if (!connectionSuccessful) {
+        console.error('ERROR: Could not connect block to marked spot.');
+        return;
+      }
+
       if (announce) {
         alert(
             Blockly.Msg.PASTED_BLOCK_TO_MARKED_SPOT_MSG +
diff --git a/accessible/workspace-tree.component.js b/accessible/workspace-tree.component.js
index 5e5a094ac..5c7f4dc5f 100644
--- a/accessible/workspace-tree.component.js
+++ b/accessible/workspace-tree.component.js
@@ -147,7 +147,16 @@ blocklyApp.WorkspaceTreeComponent = ng.core
     pasteToConnection_: function(connection) {
       var that = this;
       this.treeService.runWhilePreservingFocus(function() {
-        that.clipboardService.pasteFromClipboard(connection);
+        // If the connection is a 'previousConnection' and that connection is
+        // already joined to something, use the 'nextConnection' of the
+        // previous block instead in order to do an insertion.
+        if (connection.type == Blockly.PREVIOUS_STATEMENT &&
+            connection.isConnected()) {
+          that.clipboardService.pasteFromClipboard(
+              connection.targetConnection);
+        } else {
+          that.clipboardService.pasteFromClipboard(connection);
+        }
       }, this.tree.id);
     },
     sendToMarkedSpot_: function() {