refactoring

website/src/lib/data/example/index.ts

@@ -0,0 +1,63 @@
+/**
+ * The statistics of an example file (a ride of 102 trackpoints with timestamps and temperatures),
+ * for the pages that show the elevation profile and the statistics without a file: the home page
+ * and the documentation. They are the ones that the engine computes for `example.gpx`, kept as
+ * they are (see `example-data.ts`) so that the example does not need the engine.
+ */
+import type { GlobalStatistics, SelectionStatistics } from '$lib/engine';
+import { exampleData as data } from '$lib/data/example/example-data';
+
+const length = data.lng.length;
+
+// the values that are cumulative over the selection: those of a range are the difference of its ends
+const cumulative = {
+    totalDistance: data.totalDistance,
+    movingDistance: data.movingDistance,
+    totalTime: data.totalTime,
+    movingTime: data.movingTime,
+    elevationGain: data.elevationGain,
+    elevationLoss: data.elevationLoss,
+};
+
+/** The statistics of the trackpoints from `start` to `end` (both included), as the engine does. */
+function slice(start: number, end: number): GlobalStatistics | undefined {
+    if (!(start >= 0 && start <= end && end < length)) {
+        return undefined;
+    }
+    const delta = (values: number[]) => values[end] - values[start];
+    // the times are in ms, in seconds in the statistics; a range cannot last a negative time
+    const totalTime = Math.max(0, delta(cumulative.totalTime));
+    const movingTime = Math.max(0, delta(cumulative.movingTime));
+    const totalDistance = delta(cumulative.totalDistance);
+    const movingDistance = delta(cumulative.movingDistance);
+    const hours = (ms: number) => ms / 3_600_000;
+    return {
+        ...data.global,
+        totalDistance,
+        movingDistance,
+        totalTime: totalTime / 1000,
+        movingTime: movingTime / 1000,
+        elevationGain: delta(cumulative.elevationGain),
+        elevationLoss: delta(cumulative.elevationLoss),
+        startTime: data.timestamps[start],
+        endTime: data.timestamps[end],
+        totalSpeed: totalTime > 0 ? totalDistance / hours(totalTime) : undefined,
+        movingSpeed: movingTime > 0 ? movingDistance / hours(movingTime) : undefined,
+    };
+}
+
+export const exampleStatistics: SelectionStatistics = {
+    global: data.global,
+    length,
+    totalDistance: Float64Array.from(data.totalDistance),
+    slope: Float64Array.from(data.slope),
+    lng: Float64Array.from(data.lng),
+    lat: Float64Array.from(data.lat),
+    ele: Float64Array.from(data.ele),
+    timestamps: BigInt64Array.from(data.timestamps, (time) => BigInt(time)),
+    speed: Float64Array.from(data.speed),
+    atemp: Float64Array.from(data.atemp),
+    slopeSegmentSlope: Float64Array.from(data.slopeSegmentSlope),
+    slopeSegmentDistance: Float64Array.from(data.slopeSegmentDistance),
+    slice,
+};