From 011dc140a31faccb9f5a6ac2c7fab43de9553322 Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Mon, 30 Sep 2013 16:17:16 -0700
Subject: [PATCH] Handle multipolygon corner case when splitting (fixes #1799)

---
 js/id/actions/split.js     | 11 +++++++++--
 test/spec/actions/split.js | 16 ++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/js/id/actions/split.js b/js/id/actions/split.js
index be1a9153f..b34395b9e 100644
--- a/js/id/actions/split.js
+++ b/js/id/actions/split.js
@@ -29,7 +29,8 @@ iD.actions.Split = function(nodeId, newWayIds) {
         var wayB = iD.Way({id: newWayId, tags: wayA.tags}),
             nodesA,
             nodesB,
-            isArea = wayA.isArea();
+            isArea = wayA.isArea(),
+            isOuter = iD.geo.isSimpleMultipolygonOuterMember(wayA, graph);
 
         if (wayA.isClosed()) {
             var nodes = wayA.nodes.slice(0, -1),
@@ -107,12 +108,18 @@ iD.actions.Split = function(nodeId, newWayIds) {
                     }
                 }
 
+                if (relation === isOuter) {
+                    relation = relation.mergeTags(wayA.tags);
+                    graph = graph.replace(wayA.update({tags: {}}));
+                    graph = graph.replace(wayB.update({tags: {}}));
+                }
+
                 relation = relation.addMember({id: wayB.id, type: 'way', role: role}, i <= j ? i + 1 : i);
                 graph = graph.replace(relation);
             }
         });
 
-        if (isArea) {
+        if (!isOuter && isArea) {
             var multipolygon = iD.Relation({
                 tags: _.extend({}, wayA.tags, {type: 'multipolygon'}),
                 members: [
diff --git a/test/spec/actions/split.js b/test/spec/actions/split.js
index 1f24dc8a1..39f326b4c 100644
--- a/test/spec/actions/split.js
+++ b/test/spec/actions/split.js
@@ -398,6 +398,22 @@ describe("iD.actions.Split", function () {
         expect(_.pluck(graph.entity('r').members, 'id')).to.eql(['~', '-', '=']);
     });
 
+    it("converts simple multipolygon to a proper multipolygon", function () {
+        var graph = iD.Graph({
+                'a': iD.Node({id: 'a'}),
+                'b': iD.Node({id: 'b'}),
+                'c': iD.Node({id: 'c'}),
+                '-': iD.Way({'id': '-', nodes: ['a', 'b', 'c'], tags: {natural: 'water'}}),
+                'r': iD.Relation({id: 'r', members: [{id: '-', type: 'way', role: 'outer'}], tags: {type: 'multipolygon'}})
+            });
+
+        graph = iD.actions.Split('b', ['='])(graph);
+
+        expect(graph.entity('-').tags).to.eql({});
+        expect(graph.entity('r').tags).to.eql({type: 'multipolygon', natural: 'water'});
+        expect(_.pluck(graph.entity('r').members, 'id')).to.eql(['-', '=']);
+    });
+
     ['restriction', 'restriction:bus'].forEach(function (type) {
         it("updates a restriction's 'from' role", function () {
             // Situation: