refactor(weather): share the day weather anchor and icon map between desktop and phone

The day plan, the day panel, the phone timeline and the phone day sheet read
the day local weather anchor from dayWeatherAnchor, and every weather icon
comes from one map in weatherIcons.

client/src/utils/dayWeather.test.ts

@@ -0,0 +1,51 @@
+// FE-UTIL-DAYWEATHER-001 to -005: the day-local weather anchor the desktop day
+// plan, the desktop day panel, the phone timeline and the phone day sheet read.
+import { describe, expect, it, vi } from 'vitest';
+
+import { buildAssignment, buildPlace } from '../../tests/helpers/factories';
+import { dayWeatherAnchor, hasWeatherCoords } from './dayWeather';
+
+const HOTEL = { place_lat: 46.2, place_lng: 7.1, place_name: 'Hotel Alpina' };
+const stop = (lat: number | null, lng: number | null, name = 'Stop') =>
+  buildAssignment({ place: buildPlace({ lat, lng, name }) });
+
+describe('dayWeatherAnchor', () => {
+  it('FE-UTIL-DAYWEATHER-001: the first stop with coordinates wins and the hotel is never looked up', () => {
+    const wakeUpHotel = vi.fn(() => HOTEL);
+    const anchor = dayWeatherAnchor(
+      [stop(null, null, 'Unlocated'), stop(48.1, 11.5, 'Museum'), stop(1, 2)],
+      wakeUpHotel
+    );
+    expect(anchor).toEqual({ lat: 48.1, lng: 11.5, name: 'Museum' });
+    expect(wakeUpHotel).not.toHaveBeenCalled();
+  });
+
+  it('FE-UTIL-DAYWEATHER-002: without a located stop the hotel you wake up in stands in', () => {
+    expect(dayWeatherAnchor([stop(null, 3)], () => HOTEL)).toEqual({ lat: 46.2, lng: 7.1, name: 'Hotel Alpina' });
+    expect(dayWeatherAnchor([], () => ({ place_lat: 1, place_lng: 2, place_name: null }))).toEqual({
+      lat: 1,
+      lng: 2,
+      name: null,
+    });
+  });
+
+  it('FE-UTIL-DAYWEATHER-003: neither a stop nor a hotel leaves the day without an anchor', () => {
+    expect(dayWeatherAnchor([stop(null, null)], () => undefined)).toEqual({ lat: null, lng: null, name: null });
+  });
+
+  it('FE-UTIL-DAYWEATHER-004: by default a zero coordinate does not count as located', () => {
+    expect(hasWeatherCoords(stop(0, 9))).toBe(false);
+    expect(hasWeatherCoords(stop(9, 9))).toBe(true);
+    expect(hasWeatherCoords(buildAssignment({ place: undefined as never }))).toBe(false);
+    expect(dayWeatherAnchor([stop(0, 9, 'Equator'), stop(5, 6, 'Inland')], () => HOTEL).name).toBe('Inland');
+  });
+
+  it('FE-UTIL-DAYWEATHER-005: the phone timeline counts any set coordinate, zero included', () => {
+    const anyCoords = (a: ReturnType<typeof stop>) => a.place?.lat != null && a.place?.lng != null;
+    expect(dayWeatherAnchor([stop(0, 9, 'Equator'), stop(5, 6, 'Inland')], () => HOTEL, anyCoords)).toEqual({
+      lat: 0,
+      lng: 9,
+      name: 'Equator',
+    });
+  });
+});

client/src/utils/dayWeather.ts

@@ -0,0 +1,32 @@
+import type { Accommodation, Assignment } from '../types';
+
+/** Where a day's forecast is read, and the name the weather is captioned with. */
+export interface DayWeatherAnchor {
+  lat: number | null;
+  lng: number | null;
+  name: string | null;
+}
+
+/** A stop the day plan reads the weather at: both coordinates set and neither of them zero. */
+export const hasWeatherCoords = (a: Assignment): boolean => !!(a.place?.lat && a.place?.lng);
+
+/**
+ * The day-local weather anchor (#2167): the day's first stop that `isLocated`
+ * accepts, else the hotel you wake up in. Never a place from another day: on a
+ * road trip that silently showed another city's weather with nothing naming the
+ * place. The hotel is only looked up when no stop qualifies, and where you wake up
+ * is a fact about the day, so callers look it up whatever the routing settings say.
+ */
+export function dayWeatherAnchor(
+  stops: Assignment[],
+  wakeUpHotel: () => Pick<Accommodation, 'place_lat' | 'place_lng' | 'place_name'> | undefined,
+  isLocated: (a: Assignment) => boolean = hasWeatherCoords
+): DayWeatherAnchor {
+  const located = stops.find(isLocated)?.place;
+  const hotel = located ? undefined : wakeUpHotel();
+  return {
+    lat: located?.lat ?? hotel?.place_lat ?? null,
+    lng: located?.lng ?? hotel?.place_lng ?? null,
+    name: located?.name ?? hotel?.place_name ?? null,
+  };
+}