2025/tools/lib/weather/providers/open-meteo.js

const { fetch: httpFetch } = require("undici");
const { DateTime } = require("luxon");
const { hasValue } = require("../constants");
const { buildTimeWindow } = require("../time");

function isConfigured(config) {
    return config && Number.isFinite(config.latitude) && Number.isFinite(config.longitude);
}

function normalizeTarget(target, zone) {
    if (!target) return null;
    if (DateTime.isDateTime(target)) return target.setZone(zone || undefined);
    if (target instanceof Date) return DateTime.fromJSDate(target, { zone });
    if (typeof target === "string") return DateTime.fromISO(target, { zone });
    return null;
}

function selectNearestHour(hourly, target, timezone, windowMinutes) {
    if (!hourly || !Array.isArray(hourly.time) || hourly.time.length === 0) return null;

    const window = buildTimeWindow(target, windowMinutes);
    let nearest = null;
    let smallestDiff = Number.POSITIVE_INFINITY;

    for (let i = 0; i < hourly.time.length; i++) {
        const timeValue = DateTime.fromISO(hourly.time[i], { zone: timezone });
        if (!timeValue.isValid) continue;

        if (timeValue < window.start || timeValue > window.end) continue;

        const diff = Math.abs(timeValue.diff(target).as("milliseconds"));

        if (diff < smallestDiff) {
            smallestDiff = diff;
            nearest = {
                time: timeValue,
                temperature_2m: hourly.temperature_2m?.[i],
                relative_humidity_2m: hourly.relative_humidity_2m?.[i],
                surface_pressure: hourly.surface_pressure?.[i],
                shortwave_radiation: hourly.shortwave_radiation?.[i],
                precipitation: hourly.precipitation?.[i],
                wind_speed_10m: hourly.wind_speed_10m?.[i],
                wind_direction_10m: hourly.wind_direction_10m?.[i],
            };
        }
    }

    return nearest;
}

function createOpenMeteoProvider(config = {}, globalConfig = {}) {
    if (!isConfigured(config)) return null;

    const windowMinutes = config.windowMinutes ?? globalConfig.windowMinutes ?? 60;
    const precipitationThreshold = config.precipitationThreshold ?? globalConfig.precipitationThreshold ?? 0.1;
    const pressureOffset = Number.isFinite(config.pressureOffset) ? config.pressureOffset : 0;
    const illuminanceToLuxFactor = Number.isFinite(config.illuminanceToLuxFactor)
        ? config.illuminanceToLuxFactor
        : Number.isFinite(globalConfig.providers?.openMeteo?.illuminanceToLuxFactor)
            ? globalConfig.providers.openMeteo.illuminanceToLuxFactor
            : 126.7;
    const timezone = config.timezone || globalConfig.timezone || "UTC";

    async function fetchData({ target }) {
        const normalized = normalizeTarget(target, timezone);

        if (!normalized || !normalized.isValid) return null;

        const isFuture = normalized > DateTime.now().setZone(timezone).plus({ days: 1 });
        const baseUrl = isFuture ? "https://api.open-meteo.com/v1/forecast" : "https://archive-api.open-meteo.com/v1/archive";
        const params = new URLSearchParams({
            latitude: config.latitude.toString(),
            longitude: config.longitude.toString(),
            timezone,
            start_date: normalized.toISODate(),
            end_date: normalized.toISODate(),
            hourly: [
                "temperature_2m",
                "relative_humidity_2m",
                "surface_pressure",
                "shortwave_radiation",
                "precipitation",
                "wind_speed_10m",
                "wind_direction_10m",
            ].join(","),
        });

        if (isFuture) {
            params.set("forecast_days", "16");
            params.set("past_days", "7");
        }

        const url = `${baseUrl}?${params.toString()}`;
        let json;

        try {
            const response = await httpFetch(url);

            if (!response || typeof response.ok === "undefined") {
                const sanitizedUrl = url
                    .replace(/(latitude=)[^&]+/, "$1***")
                    .replace(/(longitude=)[^&]+/, "$1***");
                console.error("Open-Meteo unexpected response", {
                    type: typeof response,
                    ctor: response?.constructor?.name,
                    url: sanitizedUrl,
                });
                throw new Error("Invalid response object");
            }

            if (!response.ok) {
                let details = "";
                try {
                    details = await response.text();
                } catch (_) {
                    // ignore
                }
                const suffix = details ? `: ${details}` : "";
                throw new Error(`HTTP ${response.status}${suffix}`);
            }

            json = await response.json();
        } catch (error) {
            console.error(`Open-Meteo error: ${error.message}`);
            return null;
        }

        if (!json?.hourly) return null;

        const nearest = selectNearestHour(json.hourly, target, timezone, windowMinutes);
        if (!nearest) return null;

        const weather = {};

        if (hasValue(nearest.temperature_2m)) weather.temperature = nearest.temperature_2m;
        if (hasValue(nearest.relative_humidity_2m)) weather.humidity = nearest.relative_humidity_2m;
        if (hasValue(nearest.surface_pressure)) weather.pressure = nearest.surface_pressure + pressureOffset;
        if (hasValue(nearest.shortwave_radiation)) {
            const factor = Number.isFinite(illuminanceToLuxFactor) ? illuminanceToLuxFactor : 126.7;
            weather.illuminance = nearest.shortwave_radiation * factor;
        }

        if (hasValue(nearest.precipitation)) {
            weather.precipitations = nearest.precipitation > precipitationThreshold;
        }

        if (hasValue(nearest.wind_speed_10m)) weather.wind_speed = nearest.wind_speed_10m;
        if (hasValue(nearest.wind_direction_10m)) weather.wind_direction = nearest.wind_direction_10m;

        if (Object.keys(weather).length === 0) return null;

        weather.source = ["open-meteo"];

        return weather;
    }

    return {
        name: "open-meteo",
        fetch: fetchData,
    };
}

module.exports = {
    createOpenMeteoProvider,
};