feat(train): a route's line pulled out into a new waypoint, and any waypoint taken off (ADR 0030, D59)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/train/halkyon_train_flutter/test/feature/route/route_editor_cubit_test.dart

@@ -168,6 +168,29 @@ void main() {
     await cubit.close();
   });
 
+  test('a waypoint pulled out of the line goes between the two around it, '
+      'and any one is taken off (D59)', () async {
+    final cubit = editor();
+    await cubit.open();
+    await cubit.add(home);
+    await cubit.add(river);
+
+    await cubit.insert(1, park);
+    expect(cubit.state.route.waypoints, [home, park, river]);
+    expect(routing.asked.last.waypoints, [home, park, river]);
+    expect(cubit.state.route.planned, straightRoute(const [home, park, river]));
+
+    await cubit.remove(0);
+    expect(cubit.state.route.waypoints, [park, river]);
+    expect(routing.asked.last.waypoints, [park, river]);
+
+    await cubit.remove(1);
+    expect(cubit.state.route.waypoints, [park]);
+    expect(cubit.state.route.planned, isNull);
+    expect(routing.asked, hasLength(3));
+    await cubit.close();
+  });
+
   test('the activity picks its profile, which the person can change and '
       'which plans again', () async {
     final cubit = editor();

apps/train/halkyon_train_flutter/test/feature/route/route_legs_test.dart

@@ -0,0 +1,91 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:halkyon_train_flutter/src/feature/route/model/route_legs.dart';
+import 'package:latlong2/latlong.dart';
+
+/// Where a waypoint pulled out of the route's line goes (ADR 0030, D59):
+/// between the two waypoints of the stretch it was grabbed on.
+void main() {
+  const start = LatLng(47.55, 9.68);
+  const middle = LatLng(47.53, 9.71);
+  const end = LatLng(47.50, 9.74);
+
+  /// The way planned through start, middle and end: points between each.
+  const line = [
+    start,
+    LatLng(47.545, 9.69),
+    LatLng(47.54, 9.70),
+    middle,
+    LatLng(47.52, 9.72),
+    LatLng(47.51, 9.73),
+    end,
+  ];
+
+  test(
+    'a point grabbed on the first stretch goes after the first waypoint',
+    () {
+      expect(
+        insertionIndex(
+          const [start, middle, end],
+          line,
+          const LatLng(47.54, 9.70),
+        ),
+        1,
+      );
+    },
+  );
+
+  test('a point grabbed on the last stretch goes before the last waypoint', () {
+    expect(
+      insertionIndex(
+        const [start, middle, end],
+        line,
+        const LatLng(47.515, 9.725),
+      ),
+      2,
+    );
+  });
+
+  test('a point grabbed beside the line goes on the stretch nearest it', () {
+    expect(
+      insertionIndex(
+        const [start, middle, end],
+        line,
+        const LatLng(47.50, 9.70),
+      ),
+      2,
+    );
+  });
+
+  test('a route of two waypoints takes it between them, wherever grabbed', () {
+    expect(insertionIndex(const [start, end], line, start), 1);
+    expect(insertionIndex(const [start, end], line, end), 1);
+  });
+
+  test('a route that comes back past a waypoint keeps its stretches in '
+      'order', () {
+    // Out to the turn and back the same way: the way back passes the
+    // first stretch's points again.
+    const turn = LatLng(47.53, 9.71);
+    const back = [start, LatLng(47.54, 9.70), turn, LatLng(47.54, 9.70), start];
+    expect(
+      insertionIndex(
+        const [start, turn, start],
+        back,
+        const LatLng(47.5401, 9.7001),
+      ),
+      1,
+    );
+  });
+
+  test('without a way planned, the straight lines between the waypoints are '
+      'the line', () {
+    expect(
+      insertionIndex(
+        const [start, middle, end],
+        const [start, middle, end],
+        const LatLng(47.52, 9.725),
+      ),
+      2,
+    );
+  });
+}