From 26b2fb9ff842a3e95251a03767d4c513e26faf0a Mon Sep 17 00:00:00 2001
From: Thomas Rasch <thomas.rasch@outdooractive.com>
Date: Thu, 8 Aug 2024 15:39:49 +0200
Subject: [PATCH] MultiLineString

---
 Sources/GISTools/Algorithms/LineOverlap.swift | 10 +++-
 .../Algorithms/LineOverlapTests.swift         | 46 +++++++++++--------
 2 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/Sources/GISTools/Algorithms/LineOverlap.swift b/Sources/GISTools/Algorithms/LineOverlap.swift
index ec7077e..0e3997f 100644
--- a/Sources/GISTools/Algorithms/LineOverlap.swift
+++ b/Sources/GISTools/Algorithms/LineOverlap.swift
@@ -235,7 +235,7 @@ extension GeoJson {
     ///
     /// - Returns: All segments that at least overlap with one other segment. Each segment will only be
     ///            in the result once.
-    public func overlappingSegments(tolerance: CLLocationDistance = 0.0) -> [LineSegment] {
+    public func overlappingSegments(tolerance: CLLocationDistance = 0.0) -> MultiLineString? {
         let tolerance = abs(tolerance)
         let sortedSegments: [LineSegment] = lineSegments
             .map { lineSegment in
@@ -284,7 +284,13 @@ extension GeoJson {
             }
         }
 
-        return result.map { sortedSegments[$0] }
+        var lineStrings: [LineString] = []
+
+        for range in result.rangeView {
+            lineStrings.append(LineString(range.map { sortedSegments[$0] })!)
+        }
+
+        return MultiLineString(lineStrings)
     }
 
 }
diff --git a/Tests/GISToolsTests/Algorithms/LineOverlapTests.swift b/Tests/GISToolsTests/Algorithms/LineOverlapTests.swift
index 3cbb257..40e0060 100644
--- a/Tests/GISToolsTests/Algorithms/LineOverlapTests.swift
+++ b/Tests/GISToolsTests/Algorithms/LineOverlapTests.swift
@@ -137,11 +137,10 @@ final class LineOverlapTests: XCTestCase {
             Coordinate3D(latitude: 12.0, longitude: 12.0),
         ])!
 
-        let overlapping = lineString.overlappingSegments()
-        XCTAssertEqual(overlapping.count, 0)
+        XCTAssertNil(lineString.overlappingSegments()?.lineStrings)
     }
 
-    func testSelfOverlap1() {
+    func testSelfOverlap1() throws {
         let lineString = LineString([
             Coordinate3D(latitude: 0.0, longitude: 0.0),
             Coordinate3D(latitude: 1.0, longitude: 1.0), // overlap
@@ -155,32 +154,33 @@ final class LineOverlapTests: XCTestCase {
             Coordinate3D(latitude: 0.0, longitude: 1.0), // "
         ])!
 
-        let overlapping = lineString.overlappingSegments()
+        let overlapping = try XCTUnwrap(lineString.overlappingSegments()?.lineStrings)
         XCTAssertEqual(overlapping.count, 3)
     }
 
-    func testSelfOverlap2() {
+    func testSelfOverlap2() throws {
         let lineString = LineString([
-            Coordinate3D(latitude: 0.0, longitude: 0.0),
-            Coordinate3D(latitude: 8.0, longitude: -8.0),
+            Coordinate3D(latitude: 0.0, longitude: 0.0),  // overlap
+            Coordinate3D(latitude: 8.0, longitude: -8.0), // "
             Coordinate3D(latitude: 7.0, longitude: -9.0),
             Coordinate3D(latitude: 6.0, longitude: -9.0),
-            Coordinate3D(latitude: 6.0, longitude: -6.0),
-            Coordinate3D(latitude: 5.0, longitude: -5.0),
+            Coordinate3D(latitude: 6.0, longitude: -6.0), // overlap
+            Coordinate3D(latitude: 5.0, longitude: -5.0), // "
             Coordinate3D(latitude: 5.0, longitude: -7.0),
             Coordinate3D(latitude: 4.0, longitude: -7.0),
-            Coordinate3D(latitude: 4.0, longitude: -4.0),
-            Coordinate3D(latitude: 3.0, longitude: -3.0),
+            Coordinate3D(latitude: 4.0, longitude: -4.0), // overlap
+            Coordinate3D(latitude: 3.0, longitude: -3.0), // "
             Coordinate3D(latitude: 3.0, longitude: -1.0),
-            Coordinate3D(latitude: 1.0, longitude: -1.0),
-            Coordinate3D(latitude: 0.0, longitude: 0.0),
+            Coordinate3D(latitude: 1.0, longitude: -1.0), // overlap
+            Coordinate3D(latitude: 0.0, longitude: 0.0),  // "
         ])!
 
-        let overlapping = lineString.overlappingSegments()
+        let overlapping = try XCTUnwrap(lineString.overlappingSegments()?.lineStrings)
+        FeatureCollection(overlapping).dump()
         XCTAssertEqual(overlapping.count, 4)
     }
 
-    func testSelfOverlap3() {
+    func testSelfOverlap3() throws {
         let lineString = LineString([
             Coordinate3D(latitude: 0.0, longitude: 0.0),
             Coordinate3D(latitude: 2.0, longitude: 0.0),
@@ -194,11 +194,11 @@ final class LineOverlapTests: XCTestCase {
             Coordinate3D(latitude: 0.0, longitude: 0.0),
         ])!
 
-        let overlapping = lineString.overlappingSegments()
+        let overlapping = try XCTUnwrap(lineString.overlappingSegments()?.lineStrings)
         XCTAssertEqual(overlapping.count, 3)
     }
 
-    func testSelfOverlap3WithSegments() {
+    func testSelfOverlap3WithSegments() throws {
         let lineString = LineString([
             Coordinate3D(latitude: 0.0, longitude: 0.0),
             Coordinate3D(latitude: 2.0, longitude: 0.0),
@@ -212,8 +212,18 @@ final class LineOverlapTests: XCTestCase {
             Coordinate3D(latitude: 0.0, longitude: 0.0),
         ])!
 
-        let overlapping = lineString.overlappingSegments()
+        let overlapping = try XCTUnwrap(lineString.overlappingSegments()?.lineStrings)
         XCTAssertEqual(overlapping.count, 3)
     }
 
+    func testLongRouteSelfOverlap() throws {
+        let lineString = try XCTUnwrap(TestData.featureCollection(package: "LineOverlap", name: "LongRoute").features.first)
+
+        let overlapping = try XCTUnwrap(lineString.overlappingSegments(tolerance: 10.0)?.lineStrings)
+        print(overlapping.count)
+        print(overlapping.reduce(0.0, { $0 + $1.length }))
+        print(lineString.length)
+
+    }
+
 }