PrayerTimes.js

import SolarTime from './SolarTime';
import TimeComponents from './TimeComponents';
import Prayer from './Prayer';
import Astronomical from './Astronomical';
import {
    dateByAddingDays,
    dateByAddingMinutes,
    dateByAddingSeconds,
    roundedMinute,
    dayOfYear,
    isValidDate
} from './DateUtils';
import { Madhab, shadowLength } from './Madhab';
import { PolarCircleResolution, polarCircleResolvedValues } from './PolarCircleResolution';

export default class PrayerTimes {
    constructor(coordinates, date, calculationParameters) {
        this.coordinates = coordinates;
        this.date = date;
        this.calculationParameters = calculationParameters;

        var solarTime = new SolarTime(date, coordinates);

        var fajrTime;
        var sunriseTime;
        var dhuhrTime;
        var asrTime;
        var maghribTime;
        var ishaTime;

        var nightFraction;

        dhuhrTime = new TimeComponents(solarTime.transit).utcDate(date.getFullYear(), date.getMonth(), date.getDate());
        sunriseTime = new TimeComponents(solarTime.sunrise).utcDate(date.getFullYear(), date.getMonth(), date.getDate());
        var sunsetTime = new TimeComponents(solarTime.sunset).utcDate(date.getFullYear(), date.getMonth(), date.getDate());
        var tomorrow = dateByAddingDays(date, 1);
        var tomorrowSolarTime = new SolarTime(tomorrow, coordinates);

        const polarCircleResolver = calculationParameters.polarCircleResolution;
        if (
          (!isValidDate(sunriseTime) || !isValidDate(sunsetTime) || isNaN(tomorrowSolarTime.sunrise))
          && polarCircleResolver !== PolarCircleResolution.Unresolved
        ) {
            const resolved = polarCircleResolvedValues(polarCircleResolver, date, coordinates);
            this.coordinates = resolved.coordinates;
            this.date.setTime(resolved.date.getTime());
            solarTime = resolved.solarTime;
            tomorrow = resolved.tomorrow;
            tomorrowSolarTime = resolved.tomorrowSolarTime;
            const dateComponents = [date.getFullYear(), date.getMonth(), date.getDate()];

            dhuhrTime = new TimeComponents(solarTime.transit).utcDate(...dateComponents);
            sunriseTime = new TimeComponents(solarTime.sunrise).utcDate(...dateComponents);
            sunsetTime = new TimeComponents(solarTime.sunset).utcDate(...dateComponents);
        }

        asrTime = new TimeComponents(solarTime.afternoon(shadowLength(calculationParameters.madhab))).utcDate(date.getFullYear(), date.getMonth(), date.getDate());

        var tomorrowSunrise = new TimeComponents(tomorrowSolarTime.sunrise).utcDate(tomorrow.getFullYear(), tomorrow.getMonth(), tomorrow.getDate());
        var night = (tomorrowSunrise - sunsetTime) / 1000;

        fajrTime = new TimeComponents(solarTime.hourAngle(-1 * calculationParameters.fajrAngle, false)).utcDate(date.getFullYear(), date.getMonth(), date.getDate());

        // special case for moonsighting committee above latitude 55
        if (calculationParameters.method == "MoonsightingCommittee" && coordinates.latitude >= 55) {
            nightFraction = night / 7;
            fajrTime = dateByAddingSeconds(sunriseTime, -nightFraction);
        }

        var safeFajr = (function () {
            if (calculationParameters.method == "MoonsightingCommittee") {
                return Astronomical.seasonAdjustedMorningTwilight(coordinates.latitude, dayOfYear(date), date.getFullYear(), sunriseTime);
            }
            else {
                var portion = calculationParameters.nightPortions().fajr;
                nightFraction = portion * night;
                return dateByAddingSeconds(sunriseTime, -nightFraction);
            }
        })();

        if (fajrTime == null || isNaN(fajrTime.getTime()) || safeFajr > fajrTime) {
            fajrTime = safeFajr;
        }

        if (calculationParameters.ishaInterval > 0) {
            ishaTime = dateByAddingMinutes(sunsetTime, calculationParameters.ishaInterval);
        } else {
            ishaTime = new TimeComponents(solarTime.hourAngle(-1 * calculationParameters.ishaAngle, true)).utcDate(date.getFullYear(), date.getMonth(), date.getDate());

            // special case for moonsighting committee above latitude 55
            if (calculationParameters.method == "MoonsightingCommittee" && coordinates.latitude >= 55) {
                nightFraction = night / 7;
                ishaTime = dateByAddingSeconds(sunsetTime, nightFraction);
            }

            var safeIsha = (function () {
                if (calculationParameters.method == "MoonsightingCommittee") {
                    return Astronomical.seasonAdjustedEveningTwilight(coordinates.latitude, dayOfYear(date), date.getFullYear(), sunsetTime);
                }
                else {
                    var portion = calculationParameters.nightPortions().isha;
                    nightFraction = portion * night;
                    return dateByAddingSeconds(sunsetTime, nightFraction);
                }
            })();

            if (ishaTime == null || isNaN(ishaTime.getTime()) || safeIsha < ishaTime) {
                ishaTime = safeIsha;
            }
        }

        maghribTime = sunsetTime;
        if (calculationParameters.maghribAngle) {
            let angleBasedMaghrib = new TimeComponents(solarTime.hourAngle(-1 * calculationParameters.maghribAngle, true)).utcDate(date.getFullYear(), date.getMonth(), date.getDate());
            if (sunsetTime < angleBasedMaghrib && ishaTime > angleBasedMaghrib) {
                maghribTime = angleBasedMaghrib;
            }
        }

        var fajrAdjustment = (calculationParameters.adjustments.fajr || 0) + (calculationParameters.methodAdjustments.fajr || 0);
        var sunriseAdjustment = (calculationParameters.adjustments.sunrise || 0) + (calculationParameters.methodAdjustments.sunrise || 0);
        var dhuhrAdjustment = (calculationParameters.adjustments.dhuhr || 0) + (calculationParameters.methodAdjustments.dhuhr || 0);
        var asrAdjustment = (calculationParameters.adjustments.asr || 0) + (calculationParameters.methodAdjustments.asr || 0);
        var maghribAdjustment = (calculationParameters.adjustments.maghrib || 0) + (calculationParameters.methodAdjustments.maghrib || 0);
        var ishaAdjustment = (calculationParameters.adjustments.isha || 0) + (calculationParameters.methodAdjustments.isha || 0);

        this.fajr = roundedMinute(dateByAddingMinutes(fajrTime, fajrAdjustment));
        this.sunrise = roundedMinute(dateByAddingMinutes(sunriseTime, sunriseAdjustment));
        this.dhuhr = roundedMinute(dateByAddingMinutes(dhuhrTime, dhuhrAdjustment));
        this.asr = roundedMinute(dateByAddingMinutes(asrTime, asrAdjustment));
        this.maghrib = roundedMinute(dateByAddingMinutes(maghribTime, maghribAdjustment));
        this.isha = roundedMinute(dateByAddingMinutes(ishaTime, ishaAdjustment));
    }

    timeForPrayer(prayer) {
        if (prayer == Prayer.Fajr) {
            return this.fajr;
        }
        else if (prayer == Prayer.Sunrise) {
            return this.sunrise;
        }
        else if (prayer == Prayer.Dhuhr) {
            return this.dhuhr;
        }
        else if (prayer == Prayer.Asr) {
            return this.asr;
        }
        else if (prayer == Prayer.Maghrib) {
            return this.maghrib;
        }
        else if (prayer == Prayer.Isha) {
            return this.isha;
        }
        else {
            return null;
        }
    }

    currentPrayer(date) {
        if (typeof date === 'undefined') {
            date = new Date();
        }
        if (date >= this.isha) {
            return Prayer.Isha;
        }
        else if (date >= this.maghrib) {
            return Prayer.Maghrib;
        }
        else if (date >= this.asr) {
            return Prayer.Asr;
        }
        else if (date >= this.dhuhr) {
            return Prayer.Dhuhr;
        }
        else if (date >= this.sunrise) {
            return Prayer.Sunrise;
        }
        else if (date >= this.fajr) {
            return Prayer.Fajr;
        }
        else {
            return Prayer.None;
        }
    }

    nextPrayer(date) {
        if (typeof date === 'undefined') {
            date = new Date();
        }
        if (date >= this.isha) {
            return Prayer.None;
        }
        else if (date >= this.maghrib) {
            return Prayer.Isha;
        }
        else if (date >= this.asr) {
            return Prayer.Maghrib;
        }
        else if (date >= this.dhuhr) {
            return Prayer.Asr;
        }
        else if (date >= this.sunrise) {
            return Prayer.Dhuhr;
        }
        else if (date >= this.fajr) {
            return Prayer.Sunrise;
        }
        else {
            return Prayer.Fajr;
        }
    }
}