refactoring and tests

website/src/lib/engine/convert.ts

@@ -0,0 +1,33 @@
+import type { SelectMode } from './types';
+
+export type Wasm = typeof import('gpx-rs');
+
+/** The enumeration of the engine for a way to combine a selection. */
+export function selectMode(wasm: Wasm, mode: SelectMode) {
+    return {
+        replace: wasm.SelectMode.Replace,
+        add: wasm.SelectMode.Add,
+        toggle: wasm.SelectMode.Toggle,
+    }[mode];
+}
+
+/** A flat `[lng, lat, ...]` array as positions. */
+export function toPositions(flat: Float64Array): [number, number][] {
+    const positions: [number, number][] = new Array(flat.length / 2);
+    for (let i = 0; i < positions.length; i++) {
+        positions[i] = [flat[2 * i], flat[2 * i + 1]];
+    }
+    return positions;
+}
+
+export /** Hyphenated UUID strings (as found in the file structures) to the concatenated 16-byte form. */
+function idsToBytes(ids: string[]): Uint8Array {
+    const bytes = new Uint8Array(ids.length * 16);
+    ids.forEach((id, i) => {
+        const hex = id.replaceAll('-', '');
+        for (let j = 0; j < 16; j++) {
+            bytes[i * 16 + j] = parseInt(hex.slice(2 * j, 2 * j + 2), 16);
+        }
+    });
+    return bytes;
+}