Function nextTimeChangeAtLocation

src/utils/time.ts:265–305

(
    latitude: number,
    longitude: number,
    date: Date = new Date(),
)

}

export function nextTimeChangeAtLocation(
    latitude: number,
    longitude: number,
    date: Date = new Date(),
): number {
    const time = getSunsetSunriseUTCTime(latitude, longitude, date);

    if (time.alwaysDay) {
        return date.getTime() + getDuration({days: 1});
    } else if (time.alwaysNight) {
        return date.getTime() + getDuration({days: 1});
    }

    const [firstTimeOnDay, lastTimeOnDay] = time.sunriseTime < time.sunsetTime ? [time.sunriseTime, time.sunsetTime] : [time.sunsetTime, time.sunriseTime];
    const currentTime = (
        date.getUTCHours() * getDuration({hours: 1}) +
        date.getUTCMinutes() * getDuration({minutes: 1}) +
        date.getUTCSeconds() * getDuration({seconds: 1}) +
        date.getUTCMilliseconds()
    );

    if (currentTime <= firstTimeOnDay!) {
        // Timeline:
        // --- firstTimeOnDay <---> lastTimeOnDay ---
        //  ^
        // Current time
        return Date.UTC(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate(), 0, 0, 0, firstTimeOnDay);
    }
    if (currentTime <= lastTimeOnDay!) {
        // Timeline:
        // --- firstTimeOnDay <---> lastTimeOnDay ---
        //                      ^
        //                 Current time
        return Date.UTC(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate(), 0, 0, 0, lastTimeOnDay);
    }
    // Timeline:
    // --- firstTimeOnDay <---> lastTimeOnDay ---
    //                                         ^
    //                                    Current time
    return Date.UTC(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate() + 1, 0, 0, 0, firstTimeOnDay);
}