feat(routing): use road max speed for verbal pre instruction distance

src/lib/services/navigation/routing.svelte.ts

@@ -6,6 +6,7 @@ import type { LngLatBoundsLike } from "maplibre-gl";
 import { generateVoiceGuidance } from "./VoiceGuidance";
 import { keepScreenOn } from "tauri-plugin-keep-screen-on-api";
 import { m } from "$lang/messages";
+import { getFeature, getSpeed } from "../TileMeta";
 
 export const routing = $state({
 	geojson: {
@@ -150,6 +151,28 @@ export async function startRoute(trip: Trip) {
 let hasAnnouncedPreInstruction = false;
 const USE_LANDMARK_INSTRUCTIONS = false;
 
+let maneuverSpeed = { idx: -1, speed: 50 };
+
+async function getSpeedForManeuver(idx: number) {
+	if (maneuverSpeed.idx === idx) {
+		return maneuverSpeed.speed;
+	}
+
+	if (!routing.currentTrip) return 50;
+
+	const esi = routing.currentTrip!.legs[0].maneuvers[idx].end_shape_index;
+	const shape = routing.currentTrip!.legs[0].shape;
+	const polyline = decodePolyline(shape);
+	const point = polyline[esi];
+
+	const feature = await getFeature(point, "transportation");
+	if (!feature || !feature.properties) return 50;
+
+	const speed = getSpeed(feature.properties.maxspeed || "50") || 50;
+	maneuverSpeed = { idx, speed };
+	return speed;
+}
+
 async function tickRoute() {
 	const trip = routing.currentTrip;
 	const info = routing.currentTripInfo;
@@ -201,7 +224,7 @@ async function tickRoute() {
 		// console.log("Distance to end of current maneuver: ", distanceToEnd, " meters");
 		// console.log("Speed: ", location.speed, " km/h");
 		const verbalDistance = verbalPreInstructionDistance(
-			location.speed || 50, // Assuming location has a speed property
+			await getSpeedForManeuver(routing.currentTripInfo.maneuverIdx),
 		);
 		if (distanceToEnd <= verbalDistance) {
 			hasAnnouncedPreInstruction = true;