/**
 * "Open in maps" handoff — deep links to external navigation apps.
 * ─────────────────────────────────────────────────────────────────────────────
 * The in-app RouteDialog deliberately keeps routing on our own map (OSRM +
 * Transitous) so nothing goes to Google by default. This module is the *opt-in*
 * escape hatch: build links so a user who wants real turn-by-turn / offline
 * navigation can hand the trip to another app.
 *
 * Providers are chosen for reliable, keyless web URLs that also deep-link into
 * their native apps:
 *   • Google Maps  — supports driving / walking / bicycling / transit
 *   • Apple Maps   — iOS/macOS (opens the web version elsewhere)
 *   • OpenStreetMap — car / bike / foot (no transit)
 *   • Organic Maps — Android `geo:` intent (privacy-first, offline)
 *
 * Handing off *does* share the trip with that provider — hence opt-in.
 */
import { Capacitor } from '@capacitor/core';
import type { TravelMode } from '@/lib/routing';

export interface DirectionsLink {
  id: string;
  label: string;
  url: string;
}

interface Point {
  lat: number;
  lng: number;
}

const GOOGLE_MODE: Record<TravelMode, string> = {
  foot: 'walking',
  bike: 'bicycling',
  moto: 'driving',
  car: 'driving',
  transit: 'transit',
};

function googleUrl(from: Point, to: Point, mode: TravelMode): string {
  return `https://www.google.com/maps/dir/?api=1&origin=${from.lat},${from.lng}&destination=${to.lat},${to.lng}&travelmode=${GOOGLE_MODE[mode]}`;
}

/** Apple Maps "dirflg": w = walking, r = public transit, d = driving. */
function appleFlag(mode: TravelMode): string {
  if (mode === 'foot') return 'w';
  if (mode === 'transit') return 'r';
  return 'd'; // car / moto / bike
}

function appleUrl(from: Point, to: Point, mode: TravelMode): string {
  return `https://maps.apple.com/?saddr=${from.lat},${from.lng}&daddr=${to.lat},${to.lng}&dirflg=${appleFlag(mode)}`;
}

/** OSM has no public-transport routing; returns null for transit. */
function osmEngine(mode: TravelMode): string | null {
  if (mode === 'foot') return 'fossgis_osrm_foot';
  if (mode === 'bike') return 'fossgis_osrm_bike';
  if (mode === 'transit') return null;
  return 'fossgis_osrm_car'; // car / moto
}

function osmUrl(from: Point, to: Point, mode: TravelMode): string | null {
  const engine = osmEngine(mode);
  if (!engine) return null;
  return `https://www.openstreetmap.org/directions?engine=${engine}&route=${from.lat},${from.lng};${to.lat},${to.lng}`;
}

/** `geo:` intent — Android hands it to Organic Maps (or the default map app). */
function organicUrl(to: Point, label: string): string {
  return `geo:${to.lat},${to.lng}?q=${to.lat},${to.lng}(${encodeURIComponent(label)})`;
}

export function buildDirectionsLinks(
  from: Point,
  to: Point,
  mode: TravelMode,
  destinationLabel: string,
): DirectionsLink[] {
  const links: DirectionsLink[] = [
    { id: 'google', label: 'Google Maps', url: googleUrl(from, to, mode) },
    { id: 'apple', label: 'Apple Maps', url: appleUrl(from, to, mode) },
  ];

  const osm = osmUrl(from, to, mode);
  if (osm) links.push({ id: 'osm', label: 'OpenStreetMap', url: osm });

  if (Capacitor.getPlatform() === 'android') {
    links.push({ id: 'organic', label: 'Organic Maps', url: organicUrl(to, destinationLabel) });
  }

  return links;
}

/**
 * Open an external URL. Capacitor intercepts the `_system` target and hands the
 * URL to the OS (system browser / registered app); on the web it's a new tab.
 */
export function openExternal(url: string): void {
  window.open(url, '_system');
}