/**
 * Transit presentation helpers
 * ─────────────────────────────────────────────────────────────────────────────
 * Shared by RouteDialog (the itinerary) and StopDepartures (the departure
 * board), so the mode → icon/colour vocabulary lives in exactly one place.
 * Modes are MOTIS's own `mode` values.
 */

import type { TransitItinerary, TransitLeg } from './routing';

/** Line colour for a transit leg, keyed by the MOTIS mode. */
export function transitLegColor(mode: string): string {
  switch (mode) {
    case 'BUS':
    case 'COACH': return '#22c55e';
    case 'TRAM': return '#eab308';
    case 'SUBWAY':
    case 'METRO': return '#3b82f6';
    case 'RAIL':
    case 'REGIONAL_RAIL':
    case 'REGIONAL_FAST_RAIL':
    case 'LONG_DISTANCE':
    case 'HIGHSPEED_RAIL':
    case 'NIGHT_RAIL':
    case 'SUBURBAN': return '#ef4444';
    case 'FERRY': return '#06b6d4';
    default: return '#ccff00';
  }
}

/** Emoji for a transit leg's mode. */
export function transitModeEmoji(mode: string): string {
  switch (mode) {
    case 'BUS':
    case 'COACH': return '🚌';
    case 'TRAM': return '🚊';
    case 'SUBWAY':
    case 'METRO': return '🚇';
    case 'RAIL':
    case 'REGIONAL_RAIL':
    case 'REGIONAL_FAST_RAIL':
    case 'LONG_DISTANCE':
    case 'HIGHSPEED_RAIL':
    case 'NIGHT_RAIL':
    case 'SUBURBAN': return '🚆';
    case 'FERRY': return '⛴️';
    case 'WALK': return '🚶';
    case 'BIKE': return '🚲';
    default: return '🚇';
  }
}

/** Leading emoji for a whole itinerary — its first vehicle leg, else walking. */
export function transitPrimaryEmoji(it: TransitItinerary): string {
  const vehicle = it.legs.find((l) => l.mode !== 'WALK' && l.mode !== 'BIKE');
  return transitModeEmoji(vehicle?.mode ?? 'WALK');
}

/** Seconds between a leg's start and end (0 when either time is missing). */
export function legDurationS(leg: TransitLeg): number {
  if (!leg.startISO || !leg.endISO) return 0;
  const ms = Date.parse(leg.endISO) - Date.parse(leg.startISO);
  return Number.isFinite(ms) && ms > 0 ? Math.round(ms / 1000) : 0;
}

/**
 * The transit mode picker's groups, each mapping to MOTIS `transitModes`
 * values. ⚠️ MOTIS classifies a German S-Bahn as `METRO` (verified live), so it
 * lands under "Metro", not "Train" — that is the feed's own classification.
 */
export const TRANSIT_MODE_GROUPS: ReadonlyArray<{
  key: string;
  label: string;
  emoji: string;
  modes: readonly string[];
}> = [
  { key: 'bus', label: 'Bus', emoji: '🚌', modes: ['BUS', 'COACH'] },
  { key: 'tram', label: 'Tram', emoji: '🚊', modes: ['TRAM'] },
  { key: 'metro', label: 'Metro', emoji: '🚇', modes: ['SUBWAY', 'METRO'] },
  {
    key: 'train',
    label: 'Train',
    emoji: '🚆',
    modes: [
      'RAIL',
      'REGIONAL_RAIL',
      'REGIONAL_FAST_RAIL',
      'HIGHSPEED_RAIL',
      'LONG_DISTANCE',
      'NIGHT_RAIL',
      'SUBURBAN',
    ],
  },
  { key: 'ferry', label: 'Ferry', emoji: '⛴️', modes: ['FERRY'] },
];