feat(GRO-2157): navigation export endpoints (Phase 2.3) (#190)

src/services/navigationExport.ts

@@ -0,0 +1,155 @@
+// Navigation export — turn an optimized groomer route into a deep-link URL that
+// opens the device's native navigation app (Google Maps / Apple Maps).
+//
+// A route is exported as: origin = first stop, destination = last stop, with the
+// in-between stops carried as ordered intermediate waypoints. Each platform caps
+// how many intermediate waypoints a deep link may carry, so callers must validate
+// the route length before handing the URL to the client.
+
+/**
+ * Max intermediate waypoints a Google Maps URLs API deep link supports
+ * (`https://www.google.com/maps/dir/?api=1&...&waypoints=...`). Google documents
+ * a ceiling of 9 waypoints between origin and destination.
+ */
+export const GOOGLE_MAPS_MAX_WAYPOINTS = 9;
+
+/**
+ * Max intermediate waypoints we allow in an Apple Maps `maps://` deep link. Apple's
+ * URL scheme chains destinations with `+to:` but does not publish a hard cap; 15 is
+ * a conservative practical limit that keeps the URL well under length limits.
+ */
+export const APPLE_MAPS_MAX_WAYPOINTS = 15;
+
+export type NavigationPlatform = "google-maps" | "apple-maps";
+
+/** A single ordered point on the route. `label` is optional, for display only. */
+export interface NavigationStop {
+  latitude: number;
+  longitude: number;
+  label?: string | null;
+}
+
+export interface NavigationExportSuccess {
+  platform: NavigationPlatform;
+  url: string;
+  /** Total stops included (origin + waypoints + destination). */
+  stopCount: number;
+  /** Intermediate waypoints only (excludes origin and destination). */
+  waypointCount: number;
+}
+
+export interface NavigationExportError {
+  error: string;
+  status: 400;
+}
+
+export type NavigationExportResult =
+  | NavigationExportSuccess
+  | NavigationExportError;
+
+function isError(r: NavigationExportResult): r is NavigationExportError {
+  return "error" in r;
+}
+
+/** Intermediate waypoints = every stop that is neither origin nor destination. */
+export function intermediateWaypointCount(stopCount: number): number {
+  return Math.max(0, stopCount - 2);
+}
+
+function coord(stop: NavigationStop): string {
+  return `${stop.latitude},${stop.longitude}`;
+}
+
+/**
+ * Builds a Google Maps URLs API driving deep link. On mobile this opens the
+ * native Google Maps app; on desktop it opens maps.google.com.
+ */
+export function buildGoogleMapsUrl(
+  stops: NavigationStop[]
+): NavigationExportResult {
+  if (stops.length === 0) {
+    return { error: "route has no stops to export", status: 400 };
+  }
+  const waypointCount = intermediateWaypointCount(stops.length);
+  if (waypointCount > GOOGLE_MAPS_MAX_WAYPOINTS) {
+    return {
+      error: `route has ${waypointCount} intermediate waypoints, exceeding Google Maps' limit of ${GOOGLE_MAPS_MAX_WAYPOINTS}`,
+      status: 400,
+    };
+  }
+
+  const origin = stops[0]!;
+  const destination = stops[stops.length - 1]!;
+  const params = new URLSearchParams();
+  params.set("api", "1");
+  params.set("travelmode", "driving");
+  params.set("origin", coord(origin));
+  params.set("destination", coord(destination));
+  if (stops.length > 2) {
+    const mids = stops
+      .slice(1, -1)
+      .map(coord)
+      .join("|");
+    params.set("waypoints", mids);
+  }
+
+  return {
+    platform: "google-maps",
+    url: `https://www.google.com/maps/dir/?${params.toString()}`,
+    stopCount: stops.length,
+    waypointCount,
+  };
+}
+
+/**
+ * Builds an Apple Maps `maps://` driving deep link. The first stop is the source
+ * (`saddr`); the remaining stops are chained as destinations with `+to:` (`daddr`).
+ * Built by hand because the `+to:` separators are part of Apple's scheme and must
+ * not be percent-encoded.
+ */
+export function buildAppleMapsUrl(
+  stops: NavigationStop[]
+): NavigationExportResult {
+  if (stops.length === 0) {
+    return { error: "route has no stops to export", status: 400 };
+  }
+  const waypointCount = intermediateWaypointCount(stops.length);
+  if (waypointCount > APPLE_MAPS_MAX_WAYPOINTS) {
+    return {
+      error: `route has ${waypointCount} intermediate waypoints, exceeding Apple Maps' limit of ${APPLE_MAPS_MAX_WAYPOINTS}`,
+      status: 400,
+    };
+  }
+
+  const params: string[] = ["dirflg=d"];
+  if (stops.length === 1) {
+    // Single stop: destination only, no source.
+    params.unshift(`daddr=${coord(stops[0]!)}`);
+  } else {
+    const daddr = stops
+      .slice(1)
+      .map(coord)
+      .join("+to:");
+    params.unshift(`daddr=${daddr}`);
+    params.unshift(`saddr=${coord(stops[0]!)}`);
+  }
+
+  return {
+    platform: "apple-maps",
+    url: `maps://?${params.join("&")}`,
+    stopCount: stops.length,
+    waypointCount,
+  };
+}
+
+/** Dispatches to the correct builder for the requested platform. */
+export function buildNavigationUrl(
+  platform: NavigationPlatform,
+  stops: NavigationStop[]
+): NavigationExportResult {
+  return platform === "google-maps"
+    ? buildGoogleMapsUrl(stops)
+    : buildAppleMapsUrl(stops);
+}
+
+export { isError as isNavigationExportError };