From d82d5dc3d04b5f407118444a22afc38437291add Mon Sep 17 00:00:00 2001
From: Bryan Housel <bryan@mapbox.com>
Date: Thu, 21 Dec 2017 14:54:15 -0500
Subject: [PATCH] Add skipID to geoChooseEdge, to ignore dragging node

---
 modules/geo/geo.js   | 15 +++++----
 test/spec/geo/geo.js | 77 +++++++++++++++++++++++++++++++++++++-------
 2 files changed, 74 insertions(+), 18 deletions(-)

diff --git a/modules/geo/geo.js b/modules/geo/geo.js
index e96bc81b9..318283931 100644
--- a/modules/geo/geo.js
+++ b/modules/geo/geo.js
@@ -157,14 +157,17 @@ export function geoRotate(points, angle, around) {
 // projection onto that edge, if such a projection exists, or the distance to
 // the closest vertex on that edge. Returns an object with the `index` of the
 // chosen edge, the chosen `loc` on that edge, and the `distance` to to it.
-export function geoChooseEdge(nodes, point, projection) {
+export function geoChooseEdge(nodes, point, projection, skipID) {
     var dist = geoEuclideanDistance;
     var points = nodes.map(function(n) { return projection(n.loc); });
+    var ids = nodes.map(function(n) { return n.id; });
     var min = Infinity;
     var idx;
     var loc;
 
     for (var i = 0; i < points.length - 1; i++) {
+        if (ids[i] === skipID || ids[i + 1] === skipID) continue;
+
         var o = points[i];
         var s = geoVecSubtract(points[i + 1], o);
         var v = geoVecSubtract(point, o);
@@ -187,11 +190,11 @@ export function geoChooseEdge(nodes, point, projection) {
         }
     }
 
-    return {
-        index: idx,
-        distance: min,
-        loc: loc
-    };
+    if (idx !== undefined) {
+        return { index: idx, distance: min, loc: loc };
+    } else {
+        return null;
+    }
 }
 
 
diff --git a/test/spec/geo/geo.js b/test/spec/geo/geo.js
index 989c55714..c9762e051 100644
--- a/test/spec/geo/geo.js
+++ b/test/spec/geo/geo.js
@@ -291,20 +291,12 @@ describe('iD.geo', function() {
         var projection = function (l) { return l; };
         projection.invert = projection;
 
-        it('returns undefined properties for a degenerate way (no nodes)', function() {
-            expect(iD.geoChooseEdge([], [0, 0], projection)).to.eql({
-                index: undefined,
-                distance: Infinity,
-                loc: undefined
-            });
+        it('returns null for a degenerate way (no nodes)', function() {
+            expect(iD.geoChooseEdge([], [0, 0], projection)).to.be.null;
         });
 
-        it('returns undefined properties for a degenerate way (single node)', function() {
-            expect(iD.geoChooseEdge([iD.osmNode({loc: [0, 0]})], [0, 0], projection)).to.eql({
-                index: undefined,
-                distance: Infinity,
-                loc: undefined
-            });
+        it('returns null for a degenerate way (single node)', function() {
+            expect(iD.geoChooseEdge([iD.osmNode({loc: [0, 0]})], [0, 0], projection)).to.be.null;
         });
 
         it('calculates the orthogonal projection of a point onto a segment', function() {
@@ -344,6 +336,67 @@ describe('iD.geo', function() {
             expect(choice.distance).to.eql(5);
             expect(choice.loc).to.eql([5, 0]);
         });
+
+        it('skips the given nodeID at end of way', function() {
+            //
+            // a --*-- b
+            //     e   |
+            //     |   |
+            //     d - c
+            //
+            // * = [2, 0]
+            var a = [0, 0];
+            var b = [5, 0];
+            var c = [5, 5];
+            var d = [2, 5];
+            var e = [2, 0.1];  // e.g. user is dragging e onto ab
+            var nodes = [
+                iD.osmNode({id: 'a', loc: a}),
+                iD.osmNode({id: 'b', loc: b}),
+                iD.osmNode({id: 'c', loc: c}),
+                iD.osmNode({id: 'd', loc: d}),
+                iD.osmNode({id: 'e', loc: e})
+            ];
+            var choice = iD.geoChooseEdge(nodes, e, projection, 'e');
+            expect(choice.index).to.eql(1);
+            expect(choice.distance).to.eql(0.1);
+            expect(choice.loc).to.eql([2, 0]);
+        });
+
+        it('skips the given nodeID in middle of way', function() {
+            //
+            // a --*-- b
+            //     d   |
+            //   /   \ |
+            // e       c
+            //
+            // * = [2, 0]
+            var a = [0, 0];
+            var b = [5, 0];
+            var c = [5, 5];
+            var d = [2, 0.1];  // e.g. user is dragging d onto ab
+            var e = [0, 5];
+            var nodes = [
+                iD.osmNode({id: 'a', loc: a}),
+                iD.osmNode({id: 'b', loc: b}),
+                iD.osmNode({id: 'c', loc: c}),
+                iD.osmNode({id: 'd', loc: d}),
+                iD.osmNode({id: 'e', loc: e})
+            ];
+            var choice = iD.geoChooseEdge(nodes, d, projection, 'd');
+            expect(choice.index).to.eql(1);
+            expect(choice.distance).to.eql(0.1);
+            expect(choice.loc).to.eql([2, 0]);
+        });
+
+        it('returns null if all nodes are skipped', function() {
+            var nodes = [
+                iD.osmNode({id: 'a', loc: [0, 0]}),
+                iD.osmNode({id: 'b', loc: [5, 0]}),
+            ];
+            var choice = iD.geoChooseEdge(nodes, [2, 2], projection, 'a');
+            expect(choice).to.be.null;
+        });
     });
 
     describe('geoLineIntersection', function() {