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drizzli/src/routes/weather/utils/weather-codes.ts
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2026-08-03 11:05:34 +02:00

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TypeScript

import * as m from '$lib/paraglide/messages';
const weatherCodes: Record<number, string> = {
0: 'clear',
1: 'clear',
2: 'cloudy',
3: 'overcast',
4: 'fog',
5: 'fog',
10: 'fog',
11: 'fog',
12: 'lightning',
18: 'strong-wind',
20: 'fog',
21: 'rain-mix',
22: 'rain-mix',
23: 'rain',
24: 'snow',
25: 'hail',
26: 'thunderstorm',
27: 'dust',
28: 'dust',
29: 'dust',
30: 'fog',
31: 'fog',
32: 'fog',
33: 'fog',
34: 'fog',
35: 'fog',
40: 'rain-mix',
41: 'sprinkle',
42: 'rain',
43: 'sprinkle',
44: 'rain',
45: 'fog',
46: 'hail',
47: 'snow',
48: 'fog',
50: 'sprinkle',
51: 'sprinkle',
52: 'rain',
53: 'sprinkle',
54: 'sprinkle',
55: 'rain',
56: 'rain-mix',
57: 'rain-mix',
58: 'rain',
60: 'sprinkle',
61: 'sprinkle',
62: 'rain',
63: 'rain',
64: 'hail',
65: 'rain',
66: 'rain-mix',
67: 'rain-mix',
68: 'rain-mix',
70: 'snow',
71: 'snow',
72: 'snow',
73: 'snow',
74: 'snow',
75: 'snow',
76: 'snow',
77: 'snow',
78: 'snow',
80: 'showers',
81: 'showers',
82: 'rain',
83: 'rain',
84: 'storm-showers',
85: 'snow',
86: 'snow',
87: 'rain-mix',
89: 'hail',
90: 'lightning',
91: 'storm-showers',
92: 'thunderstorm',
93: 'thunderstorm',
94: 'lightning',
95: 'thunderstorm',
96: 'thunderstorm',
99: 'storm-showers'
};
// Conditions that ship as a single neutral glyph (no day/night variant). The
// file is not always wi-<name>: 'overcast' uses the flat cloud, which keeps it
// distinct from 'cloudy' (code 2), whose glyph carries a sun or moon.
const NEUTRAL_ICONS: Record<string, string> = {
'snowflake-cold': 'wi-snowflake-cold',
'strong-wind': 'wi-strong-wind',
dust: 'wi-dust',
tornado: 'wi-tornado',
overcast: 'wi-cloudy'
};
export function getWeatherIconName(code: number, daytime: boolean): string {
const name = weatherCodes[code as keyof typeof weatherCodes] ?? 'clear';
const neutral = NEUTRAL_ICONS[name];
if (neutral) return neutral;
return `wi-${daytime ? 'day' : 'night'}-${name}`;
}
// Plain-language name for each code open-meteo actually emits (WMO 4677 subset),
// used as the hover title on the pictograms. A glyph alone is ambiguous - the
// hail-thunderstorm swirl in particular reads as something far more dramatic
// than "thunderstorm with heavy hail".
const WMO_DESCRIPTIONS: Record<number, () => string> = {
0: m.wmo_0,
1: m.wmo_1,
2: m.wmo_2,
3: m.wmo_3,
45: m.wmo_45,
48: m.wmo_48,
51: m.wmo_51,
53: m.wmo_53,
55: m.wmo_55,
56: m.wmo_56,
57: m.wmo_57,
61: m.wmo_61,
63: m.wmo_63,
65: m.wmo_65,
66: m.wmo_66,
67: m.wmo_67,
71: m.wmo_71,
73: m.wmo_73,
75: m.wmo_75,
77: m.wmo_77,
80: m.wmo_80,
81: m.wmo_81,
82: m.wmo_82,
85: m.wmo_85,
86: m.wmo_86,
95: m.wmo_95,
96: m.wmo_96,
99: m.wmo_99
};
/** Localized condition text for a weather code; '' for codes we have no name for. */
export function getWeatherDescription(code: number | null | undefined): string {
if (code == null || !Number.isFinite(code)) return '';
return WMO_DESCRIPTIONS[code]?.() ?? '';
}
// ─── Local day/night weather codes ──────────────────────────────────────────
// Open-meteo's daily weather_code is a plain numeric max over all 24 hourly
// codes (VariableDaily.swift: `.max(.weathercode)`) — there is no day/night
// split in the API, and numeric max has known flaws: one foggy hour wins the
// whole day (open-meteo issue #228), "slight showers" (80) outranks "heavy
// rain" (65), one overcast hour beats a mostly-clear day. The aggregation
// below derives a separate code for the daylight hours (sunrise→sunset) and
// the following night (sunset→next sunrise), ranking hazards by group first
// (thunder > freezing > snow > rain > drizzle) and picking the most frequent
// intensity within the winning group, with a persistence rule for fog and a
// mean (not max) for plain sky states.
// Only the code subset open-meteo actually emits (WeatherCode.swift) matters here.
const THUNDER = new Set([95, 96, 99]);
const FREEZING = new Set([56, 57, 66, 67]);
const SNOW = new Set([71, 73, 75, 77, 85, 86]);
const RAIN = new Set([61, 63, 65, 80, 81, 82]);
const DRIZZLE = new Set([51, 53, 55]);
const FOG = new Set([45, 48]);
// Showers / snow grains count as the same intensity as their steady
// counterparts when breaking frequency ties (fixes 80 "outranking" 65).
const INTENSITY_EQUIV: Record<number, number> = { 80: 61, 81: 63, 82: 65, 77: 71, 85: 71, 86: 75 };
/**
* Most frequent code; ties go to the more intense (then higher) code, or with
* `preferLower` to the least intense one.
*
* Thunder is the one group that ties downwards. Within it the code only
* describes how much hail comes with the storm, and letting the worst of them
* win a coin-flip tie is how a single hour of 99 used to brand a whole day as
* the most extreme thing on the scale. Elsewhere the heavier code winning a tie
* is the point (heavy rain over slight showers).
*/
function modeWithHighTiebreak(codes: number[], preferLower = false): number {
const counts = new Map<number, number>();
for (const c of codes) counts.set(c, (counts.get(c) ?? 0) + 1);
let best = codes[0];
let bestCount = -1;
for (const [code, count] of counts) {
const intensity = INTENSITY_EQUIV[code] ?? code;
const bestIntensity = INTENSITY_EQUIV[best] ?? best;
const winsTie = preferLower
? intensity < bestIntensity || (intensity === bestIntensity && code < best)
: intensity > bestIntensity || (intensity === bestIntensity && code > best);
if (count > bestCount || (count === bestCount && winsTie)) {
best = code;
bestCount = count;
}
}
return best;
}
/** Aggregates one daypart's hourly codes into a single representative code. */
function daypartCode(codes: number[]): number | null {
const hours = codes.filter((c) => Number.isFinite(c));
const n = hours.length;
if (n === 0) return null;
// Hazards, worst group first: a single hour is enough to lead the icon
// (open-meteo's "don't hide hazards" philosophy, kept per-group).
for (const group of [THUNDER, FREEZING, SNOW, RAIN, DRIZZLE]) {
const hits = hours.filter((c) => group.has(c));
if (hits.length > 0) return modeWithHighTiebreak(hits, group === THUNDER);
}
// Fog needs persistence (≥2h and ≥¼ of the daypart) so one misty hour at
// dawn doesn't brand the whole day — the issue #228 complaint.
const fogHits = hours.filter((c) => FOG.has(c));
if (fogHits.length >= Math.max(2, Math.ceil(n / 4))) return modeWithHighTiebreak(fogHits);
// Sky states: mean, not max — one overcast hour shouldn't win. Short fog
// spells below the threshold count as overcast (3).
const sky = hours.map((c) => (FOG.has(c) ? 3 : c)).filter((c) => c >= 0 && c <= 3);
if (sky.length === 0) return null;
const mean = sky.reduce((a, b) => a + b, 0) / sky.length;
return Math.min(3, Math.max(0, Math.round(mean)));
}
export interface DayNightWeatherCodes {
/** Per daily index: code for sunrise→sunset, or null if no hourly data fell in the window. */
day: (number | null)[];
/** Per daily index: code for sunset→next sunrise (the night following that day). */
night: (number | null)[];
}
/**
* Splits hourly weather codes into per-day daylight and following-night
* buckets using the API's own sunrise/sunset timestamps, and aggregates each
* bucket. Timestamps share the response's epoch basis (hourly in ms, daily
* sunrise/sunset in seconds).
*/
export function computeDayNightWeatherCodes(
hourlyTimestampsMs: number[],
hourlyWeatherCodes: number[],
sunriseSec: number[],
sunsetSec: number[]
): DayNightWeatherCodes {
const days = sunriseSec.length;
const day: (number | null)[] = new Array(days).fill(null);
const night: (number | null)[] = new Array(days).fill(null);
if (hourlyWeatherCodes.length === 0) return { day, night };
for (let i = 0; i < days; i++) {
const rise = sunriseSec[i];
const set = sunsetSec[i];
if (!rise || !set || set <= rise) continue; // missing / polar edge cases
const nightEnd = sunriseSec[i + 1] || Infinity; // last day: whatever hours remain
const dayCodes: number[] = [];
const nightCodes: number[] = [];
for (let h = 0; h < hourlyTimestampsMs.length; h++) {
const t = hourlyTimestampsMs[h] / 1000;
if (t >= rise && t < set) dayCodes.push(hourlyWeatherCodes[h]);
else if (t >= set && t < nightEnd) nightCodes.push(hourlyWeatherCodes[h]);
}
day[i] = daypartCode(dayCodes);
night[i] = daypartCode(nightCodes);
}
return { day, night };
}
export default weatherCodes;