refactor: migrate lib function passesBoundaryCheck

src/lib/passesBoundaryCheck.ts

@@ -0,0 +1,88 @@
+import type { Feature, Map } from 'ol'
+import type { Coordinate } from 'ol/coordinate'
+import VectorLayer from 'ol/layer/Vector'
+import VectorSource from 'ol/source/Vector'
+
+// arbitrarily give up after 10s of stalling (100 * 100ms)
+const readinessCheckLimit = 100
+const readinessWaitTime = 100
+
+export const errors = {
+	undefinedBoundaryLayer: Symbol.for('Boundary Layer undefined'),
+	undefinedBoundarySource: Symbol.for('Boundary Source undefined'),
+	sourceNotReady: Symbol.for('Source not ready'),
+} as const
+
+/**
+ * @param source - source to check for readiness
+ * @returns Promise that resolves true if source is in 'ready' state with at
+ * least one feature within time limit; else resolves false.
+ */
+async function isReady(source: VectorSource) {
+	let readinessChecks = 0
+
+	while (source.getState() !== 'ready' || source.getFeatures().length === 0) {
+		if (readinessChecks++ < readinessCheckLimit) {
+			await new Promise((resolve) => {
+				setTimeout(resolve, readinessWaitTime)
+			})
+		} else {
+			return false
+		}
+	}
+
+	return true
+}
+
+/**
+ * Checks whether the given coordinate is withing the boundary of the layer that
+ * has the given layer id.
+ *
+ * @returns Resolves true if coordinate is within boundary, false if outside of
+ * boundary, and an error symbol if something about the check broke. If no
+ * boundaryLayerId is set, it always resolves true, as in "no boundary exists".
+ */
+export async function passesBoundaryCheck(
+	map: Map,
+	boundaryLayerId: string | undefined,
+	coordinate: Coordinate
+) {
+	if (typeof boundaryLayerId === 'undefined') {
+		return true
+	}
+
+	const boundaryLayer = map
+		.getLayers()
+		.getArray()
+		.find((layer) => layer.get('id') === boundaryLayerId)
+
+	if (!(boundaryLayer instanceof VectorLayer)) {
+		console.error(
+			`No layer configured to match boundaryLayerId "${boundaryLayerId}".`
+		)
+		return errors.undefinedBoundaryLayer
+	}
+
+	const boundaryLayerSource = boundaryLayer.getSource()
+
+	if (!(boundaryLayerSource instanceof VectorSource)) {
+		console.error(
+			`Layer with boundaryLayerId "${boundaryLayerId}" missing source.`
+		)
+		return errors.undefinedBoundarySource
+	}
+
+	const sourceReady = await isReady(boundaryLayerSource)
+
+	if (!sourceReady) {
+		console.error(
+			`Layer with boundaryLayerId "${boundaryLayerId}" did not load or is featureless.`
+		)
+		return errors.sourceNotReady
+	}
+
+	const features = boundaryLayerSource.getFeatures() as Feature[]
+	return features.some((feature) =>
+		feature.getGeometry()?.intersectsCoordinate(coordinate)
+	)
+}