feat: server-side checking

src/lib/index.ts

@@ -2,5 +2,34 @@ export interface GameData {
 	center: [number, number];
 	lines: [GeoJSON.Feature, string][];
 	stopName: string;
-	stop: GeoJSON.Position;
+	stopId: string;
+}
+
+export interface CheckData {
+	stopId: string;
+	latlng: [number, number];
+}
+
+export interface CheckResponse {
+	solution: [number, number];
+	distance: number;
+	score: number;
+}
+
+type FetchType = typeof fetch;
+
+const linesUrl =
+	"https://data.grandlyon.com/geoserver/sytral/ows?SERVICE=WFS&VERSION=2.0.0&request=GetFeature&typename=sytral:tcl_sytral.tcllignemf_2_0_0&outputFormat=application/json&SRSNAME=EPSG:4171&sortBy=gid";
+const stopsUrl =
+	"https://data.grandlyon.com/geoserver/sytral/ows?SERVICE=WFS&VERSION=2.0.0&request=GetFeature&typename=sytral:tcl_sytral.tclarret&outputFormat=application/json&SRSNAME=EPSG:4171&sortBy=gid";
+
+let lazyLines: GeoJSON.FeatureCollection | null = null;
+let lazyStops: GeoJSON.FeatureCollection | null = null;
+
+export async function getLines(fetch: FetchType): Promise<GeoJSON.FeatureCollection> {
+	return lazyLines ?? (lazyLines = await fetch(linesUrl).then((r) => r.json()));
+}
+
+export async function getStops(fetch: FetchType): Promise<GeoJSON.FeatureCollection> {
+	return lazyStops ?? (lazyStops = await fetch(stopsUrl).then((r) => r.json()));
 }

src/routes/+page.svelte

@@ -6,6 +6,7 @@
 	import "leaflet/dist/leaflet.css";
 	import "leaflet-defaulticon-compatibility/dist/leaflet-defaulticon-compatibility.css";
 	import "leaflet-defaulticon-compatibility";
+	import type { CheckData, CheckResponse } from "$lib";
 
 	interface Props {
 		data: PageData;
@@ -16,7 +17,6 @@
 	const hidden = !$page.url.searchParams.has("debug");
 
 	const lignes = data.gameData.lines;
-	const point = L.latLng(data.gameData.stop[1], data.gameData.stop[0]);
 	const center = L.latLng(data.gameData.center);
 
 	const linesJson = lignes.map(([feature, color]) => {
@@ -24,12 +24,10 @@
 	});
 
 	let latlng = $state(L.latLng(0, 0));
-	let distance = $derived(latlng.distanceTo(point));
-	let points = $derived(calculatePoints());
+	let results: CheckResponse | null = $state(null);
 
 	let lines = $state(true);
 	let labels = $state(false);
-	let submitted = $state(false);
 
 	let map: L.Map | null = $state(null);
 	let playerMarker: L.Marker | null = $state(null);
@@ -61,28 +59,29 @@
 		playerMarker = L.marker([0, 0]).addTo(map);
 
 		map.on("click", (e) => {
-			if (map && playerMarker && !submitted) {
+			if (map && playerMarker && !results) {
 				playerMarker.setLatLng(e.latlng);
 				latlng = e.latlng;
 			}
 		});
 	}
 
-	function calculatePoints(): number {
-		const lenientDistance = Math.max(0, distance - 20);
-		const score = 5000 * Math.exp(-lenientDistance / 750);
+	async function checkLocation() {
+		const checkData: CheckData = {
+			stopId: data.gameData.stopId,
+			latlng: [latlng.lat, latlng.lng],
+		};
 
-		let multiplier = 1; /*
-		if (lines) multiplier *= 0.5;
-		if (labels) multiplier *= 0.5; */
+		const response = await fetch("/api/check", {
+			method: "POST",
+			body: JSON.stringify(checkData),
+		});
 
-		return score * multiplier;
-	}
+		if (response.ok && map) {
+			const res: CheckResponse = await response.json();
 
-	function checkLocation() {
-		submitted = true;
-		if (map) {
-			L.marker(point).bindPopup(data.gameData.stopName).addTo(map).openPopup();
+			L.marker(res.solution).bindPopup(data.gameData.stopName).addTo(map).openPopup();
+			results = res;
 		}
 	}
 </script>
@@ -90,16 +89,12 @@
 <div class="container">
 	<h1>{data.gameData.stopName}</h1>
 
-	<div hidden={submitted}>
+	<div hidden={results === null}>
 		<button onclick={checkLocation} disabled={latlng.lat === 0 || latlng.lng === 0}>SUBMIT</button>
 	</div>
 
-	<div class="results" hidden={!submitted}>
-		{Math.floor(points)} points! Vous etiez à {Math.floor(distance)}m.
-	</div>
-
-	<div {hidden}>
-		<span>distance: {distance}, points: {points}</span>
+	<div class="results" hidden={!results}>
+		{Math.floor(results?.score ?? 0)} points! Vous etiez à {Math.floor(results?.distance ?? 0)}m.
 	</div>
 
 	<div {hidden}>

src/routes/api/check/+server.ts

@@ -0,0 +1,51 @@
+import { getStops, type CheckData, type CheckResponse } from "$lib";
+import type { RequestHandler } from "./$types";
+
+export const POST: RequestHandler = async ({ fetch, request }) => {
+	const stops = await getStops(fetch);
+
+	const data: CheckData = await request.json();
+	const stop = stops.features.find((f) => f.id === data.stopId);
+
+	if (stop) {
+		// GeoJSON data is LonLat, not LatLon
+		const coords = stop.geometry.type === "Point" ? stop.geometry.coordinates : [0, 0];
+		const latlng: [number, number] = [coords[1], coords[0]];
+
+		const distance = calcDistance(data.latlng, latlng);
+		const score = calculatePoints(distance);
+
+		const res: CheckResponse = { solution: latlng, distance, score };
+		return Response.json(res);
+	} else {
+		return new Response(null, { status: 404 });
+	}
+};
+
+function calculatePoints(distance: number): number {
+	const lenientDistance = Math.max(0, distance - 20);
+	const score = 5000 * Math.exp(-lenientDistance / 750);
+
+	const multiplier = 1; /*
+    if (lines) multiplier *= 0.5;
+    if (labels) multiplier *= 0.5; */
+
+	return score * multiplier;
+}
+
+// Mean Earth Radius, as recommended for use by
+// the International Union of Geodesy and Geophysics,
+// see https://rosettacode.org/wiki/Haversine_formula
+const R = 6371000;
+
+// https://github.com/Leaflet/Leaflet/blob/142f94a9ba5757f7e7180ffa6cbed2b3a9bc73c9/src/geo/crs/CRS.Earth.js#L23
+function calcDistance(latlng1: [number, number], latlng2: [number, number]): number {
+	const rad = Math.PI / 180,
+		lat1 = latlng1[0] * rad,
+		lat2 = latlng2[0] * rad,
+		sinDLat = Math.sin(((latlng2[0] - latlng1[0]) * rad) / 2),
+		sinDLon = Math.sin(((latlng2[1] - latlng1[1]) * rad) / 2),
+		a = sinDLat * sinDLat + Math.cos(lat1) * Math.cos(lat2) * sinDLon * sinDLon,
+		c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
+	return R * c;
+}

src/routes/api/data/+server.ts

@@ -1,19 +1,9 @@
 import type { RequestHandler } from "./$types";
-import type { GameData } from "$lib";
-
-const linesUrl =
-	"https://data.grandlyon.com/geoserver/sytral/ows?SERVICE=WFS&VERSION=2.0.0&request=GetFeature&typename=sytral:tcl_sytral.tcllignemf_2_0_0&outputFormat=application/json&SRSNAME=EPSG:4171&sortBy=gid";
-const stopsUrl =
-	"https://data.grandlyon.com/geoserver/sytral/ows?SERVICE=WFS&VERSION=2.0.0&request=GetFeature&typename=sytral:tcl_sytral.tclarret&outputFormat=application/json&SRSNAME=EPSG:4171&sortBy=gid";
-
-let lazyLines: GeoJSON.FeatureCollection | null = null;
-let lazyStops: GeoJSON.FeatureCollection | null = null;
+import { getLines, getStops, type GameData } from "$lib";
 
 export const GET: RequestHandler = async ({ fetch }) => {
-	const lines: GeoJSON.FeatureCollection =
-		lazyLines || (lazyLines = await fetch(linesUrl).then((r) => r.json()));
-	const stops: GeoJSON.FeatureCollection =
-		lazyStops || (lazyStops = await fetch(stopsUrl).then((r) => r.json()));
+	const lines = await getLines(fetch);
+	const stops = await getStops(fetch);
 
 	const bbox = lines.bbox ?? [0, 0, 0, 0];
 	const centerLat = (bbox[1] + bbox[3]) / 2;
@@ -42,13 +32,12 @@ export const GET: RequestHandler = async ({ fetch }) => {
 	);
 
 	const randomStop = uniqueStops[Math.floor(Math.random() * uniqueStops.length)];
-	const coords = randomStop.geometry.type === "Point" ? randomStop.geometry.coordinates : [0, 0];
 
 	const data: GameData = {
 		center: [centerLat, centerLon],
 		lines: lineColors,
 		stopName: randomStop.properties!.nom,
-		stop: coords,
+		stopId: randomStop.id!.toString(),
 	};
 
 	return Response.json(data);