From 2bd6178f07d30cc12cc528b84791efb62ee1ca8c Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Fri, 29 Mar 2013 14:32:06 -0700
Subject: [PATCH] Split on self-intersections

---
 js/id/actions/split.js     | 16 +++++++++++----
 test/spec/actions/split.js | 41 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/js/id/actions/split.js b/js/id/actions/split.js
index d4c88595a..0f679fc77 100644
--- a/js/id/actions/split.js
+++ b/js/id/actions/split.js
@@ -15,9 +15,17 @@ iD.actions.Split = function(nodeId, newWayIds) {
             parents = graph.parentWays(node);
 
         return parents.filter(function(parent) {
-            return parent.isClosed() ||
-                (parent.first() !== nodeId &&
-                 parent.last()  !== nodeId);
+            if (parent.isClosed()) {
+                return true;
+            }
+
+            for (var i = 1; i < parent.nodes.length - 1; i++) {
+                if (parent.nodes[i] === nodeId) {
+                    return true;
+                }
+            }
+
+            return false;
         });
     }
 
@@ -41,7 +49,7 @@ iD.actions.Split = function(nodeId, newWayIds) {
                 nodesB = nodes.slice(idxB).concat(nodes.slice(0, idxA + 1));
             }
         } else {
-            var idx = _.indexOf(wayA.nodes, nodeId);
+            var idx = _.indexOf(wayA.nodes, nodeId, 1);
             nodesA = wayA.nodes.slice(0, idx + 1);
             nodesB = wayA.nodes.slice(idx);
         }
diff --git a/test/spec/actions/split.js b/test/spec/actions/split.js
index bc7227ba1..ec8042708 100644
--- a/test/spec/actions/split.js
+++ b/test/spec/actions/split.js
@@ -25,6 +25,18 @@ describe("iD.actions.Split", function () {
             expect(iD.actions.Split('*').disabled(graph)).not.to.be.ok;
         });
 
+        it("returns falsy for a self-intersection", function () {
+            var graph = iD.Graph({
+                    'a': iD.Node({id: 'a'}),
+                    'b': iD.Node({id: 'b'}),
+                    'c': iD.Node({id: 'c'}),
+                    'd': iD.Node({id: 'c'}),
+                    '-': iD.Way({id: '-', nodes: ['a', 'b', 'c', 'a', 'd']})
+            });
+
+            expect(iD.actions.Split('a').disabled(graph)).not.to.be.ok;
+        });
+
         it("returns 'not_eligible' for the first node of a single way", function () {
             var graph = iD.Graph({
                     'a': iD.Node({id: 'a'}),
@@ -148,6 +160,35 @@ describe("iD.actions.Split", function () {
         expect(graph.entity('¦').nodes).to.eql(['*', 'd']);
     });
 
+    it("splits self-intersecting ways", function () {
+        // Situation:
+        //            b
+        //           / |
+        //          /  |
+        //         c - a -- d
+        //
+        // Split at a.
+        //
+        // Expected result:
+        //            b
+        //           / |
+        //          /  |
+        //         c - a == d
+        //
+        var graph = iD.Graph({
+                'a': iD.Node({id: 'a'}),
+                'b': iD.Node({id: 'b'}),
+                'c': iD.Node({id: 'c'}),
+                'd': iD.Node({id: 'c'}),
+                '-': iD.Way({id: '-', nodes: ['a', 'b', 'c', 'a', 'd']})
+        });
+
+        graph = iD.actions.Split('a', ['='])(graph);
+
+        expect(graph.entity('-').nodes).to.eql(['a', 'b', 'c', 'a']);
+        expect(graph.entity('=').nodes).to.eql(['a', 'd']);
+    });
+
     it("splits a closed way at the given point and its antipode", function () {
         // Situation:
         //    a ---- b