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prayer-times.ts
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prayer-times.ts
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// --------------------- Copyright Block ----------------------
/*
PrayTimes.js: Prayer Times Calculator (ver 2.3)
Copyright (C) 2007-2011 PrayTimes.org
Developer: Hamid Zarrabi-Zadeh
License: GNU LGPL v3.0
TERMS OF USE:
Permission is granted to use this code, with or
without modification, in any website or application
provided that credit is given to the original work
with a link back to PrayTimes.org.
This program is distributed in the hope that it will
be useful, but WITHOUT ANY WARRANTY.
PLEASE DO NOT REMOVE THIS COPYRIGHT BLOCK.
*/
// ----------------------- PrayTimes Class ------------------------
type OptionalArgumentType = 'auto' | number
type ParamType = string | number
export type DateTuple = [number, number, number]
export type CoordinatesTuple = [number, number, number] | [number, number]
export type FormatType = '24h' | '12h' | '12hNS' | 'Float'
export type MethodType = 'MWL' | 'ISNA' | 'Egypt' | 'Makkah' | 'Karachi' | 'Tehran' | 'Jafari'
export type Prayer = 'asr' | 'dhuhr' | 'fajr' | 'imsak' | 'isha' | 'maghrib' | 'midnight' | 'sunrise' | 'sunset'
export type IPrayerTimes = Record<Prayer, string>
type IRawPrayerTimes = Record<Prayer, number>
type ISettings = Partial<Record<Prayer | 'highLats', ParamType>>
export namespace DMath {
export function dtr(d: number) {
return (d * Math.PI) / 180.0
}
export function rtd(r: number) {
return (r * 180.0) / Math.PI
}
export function sin(d: number) {
return Math.sin(dtr(d))
}
export function cos(d: number) {
return Math.cos(dtr(d))
}
export function tan(d: number) {
return Math.tan(dtr(d))
}
export function arcsin(d: number) {
return rtd(Math.asin(d))
}
export function arccos(d: number) {
return rtd(Math.acos(d))
}
export function arctan(d: number) {
return rtd(Math.atan(d))
}
export function arccot(x: number) {
return rtd(Math.atan(1 / x))
}
export function arctan2(y: number, x: number) {
return rtd(Math.atan2(y, x))
}
export function fixAngle(a: number) {
return fix(a, 360)
}
export function fixHour(a: number) {
return fix(a, 24)
}
export function fix(a: number, b: number) {
a = a - b * (Math.floor(a / b))
return (a < 0) ? a + b : a
}
}
export const timeNames = {
asr: 'Asr',
dhuhr: 'Dhuhr',
fajr: 'Fajr',
imsak: 'Imsak',
isha: 'Isha',
maghrib: 'Maghrib',
midnight: 'Midnight',
sunrise: 'Sunrise',
sunset: 'Sunset',
}
export const methods = {
Egypt: {
name: 'Egyptian General Authority of Survey',
params: { fajr: 19.5, isha: 17.5 },
},
ISNA: {
name: 'Islamic Society of North America (ISNA)',
params: { fajr: 15, isha: 15 },
},
Jafari: {
name: 'Shia Ithna-Ashari, Leva Institute, Qum',
params: { fajr: 16, isha: 14, maghrib: 4, midnight: 'Jafari' },
},
Karachi: {
name: 'University of Islamic Sciences, Karachi',
params: { fajr: 18, isha: 18 },
},
MWL: {
name: 'Muslim World League',
params: { fajr: 18, isha: 17 },
},
Makkah: {
name: 'Umm Al-Qura University, Makkah',
params: { fajr: 18.5, isha: '90 min' },
}, // fajr was 19 degrees before 1430 hijri
Tehran: {
name: 'Institute of Geophysics, University of Tehran',
params: { fajr: 17.7, isha: 14, maghrib: 4.5, midnight: 'Jafari' },
},
}
export const defaultParams = {
maghrib: '0 min',
midnight: 'Standard',
}
class PrayerTimes {
// Default
private calcMethod: MethodType = 'MWL'
private setting: ISettings = {
asr: 'Standard',
dhuhr: '0 min',
highLats: 'NightMiddle',
imsak: '10 min',
}
private timeFormat: FormatType = '24h'
private timeSuffixes = ['am', 'pm']
private invalidTime = '-----'
private numIterations = 1
private offset = {}
// Local
private lat: number
private lng: number
private elv: number // coordinates
private timeZone: number
private jDate: number // time variables
constructor(method?: MethodType) {
const defParams = defaultParams
for (const meth in methods) {
if (methods.hasOwnProperty(meth)) {
const methodParams = methods[meth].params
for (const j in defParams) {
if ((typeof (methodParams[j]) === 'undefined')) {
methodParams[j] = defParams[j]
}
}
}
}
this.calcMethod = method && methods[method] ? method : this.calcMethod
const params = methods[this.calcMethod].params
for (const id in params) {
if (params.hasOwnProperty(id)) {
this.setting[id] = params[id]
}
}
// init time offsets
for (const i in timeNames) {
if (timeNames.hasOwnProperty(i)) {
this.offset[i] = 0
}
}
}
public set method(method: MethodType) {
this.adjust(methods[method].params)
this.calcMethod = method
}
// get current calculation method
public get method() {
return this.calcMethod
}
// set calculating parameters
public adjust(params: any) {
for (const id in params) {
if (params.hasOwnProperty(id)) {
this.setting[id] = params[id]
}
}
}
// set time offsets
public tune(timeOffsets: any) {
for (const i in timeOffsets) {
if (timeOffsets.hasOwnProperty(i)) {
this.offset[i] = timeOffsets[i]
}
}
}
// get current setting
public get settings() {
return this.setting
}
// get current time offsets
public get offsets() {
return this.offset
}
// get default calc parametrs
public get defaults() {
return methods
}
// convert Gregorian date to Julian day
// Ref: Astronomical Algorithms by Jean Meeus
public julian(year: number, month: number, day: number): number {
if (month <= 2) {
year -= 1
month += 12
}
const A = Math.floor(year / 100)
const B = 2 - A + Math.floor(A / 4)
const JD = Math.floor(365.25 * (year + 4716)) + Math.floor(30.6001 * (month + 1)) + day + B - 1524.5
return JD
}
// return prayer times for a given date
public getTimes(date: Date | DateTuple, coords: CoordinatesTuple, timezone?: OptionalArgumentType,
dst?: OptionalArgumentType, format?: FormatType): PrayerTimes {
this.lat = 1 * coords[0]
this.lng = 1 * coords[1]
this.elv = coords[2] ? 1 * coords[2] : 0
this.timeFormat = format || this.timeFormat
if (date instanceof Date) {
date = [date.getFullYear(), date.getMonth() + 1, date.getDate()]
}
if (typeof (timezone) === 'undefined' || timezone === 'auto') {
timezone = this.getTimeZone(date)
}
if (typeof (dst) === 'undefined' || dst === 'auto') {
dst = this.getDst(date)
}
this.timeZone = 1 * (timezone as number) + (1 * (dst as number) ? 1 : 0)
this.jDate = this.julian(date[0], date[1], date[2]) - this.lng / (15 * 24)
return this.computeTimes()
}
// convert float time to the given format (see timeFormats)
public getFormattedTime(time: number, format: FormatType, suffixes?: any[]): string | number {
if (isNaN(time)) {
return this.invalidTime
}
if (format === 'Float') {
return time
}
suffixes = suffixes || this.timeSuffixes
time = DMath.fixHour(time + 0.5 / 60) // add 0.5 minutes to round
const hours = Math.floor(time)
const minutes = Math.floor((time - hours) * 60)
const suffix = (format === '12h') ? suffixes[hours < 12 ? 0 : 1] : ''
const hour = (format === '24h') ? this.twoDigitsFormat(hours) : ((hours + 12 - 1) % 12 + 1)
return hour + ':' + this.twoDigitsFormat(minutes) + (suffix ? ' ' + suffix : '')
}
// compute mid-day time
public midDay(time: number) {
const eqt = this.sunPosition(this.jDate + time).equation
const noon = DMath.fixHour(12 - eqt)
return noon
}
// compute the time at which sun reaches a specific angle below horizon
public sunAngleTime(angle: number, time: number, direction?: string) {
const decl = this.sunPosition(this.jDate + time).declination
const noon = this.midDay(time)
const t = 1 / 15 * DMath.arccos((-DMath.sin(angle) - DMath.sin(decl) * DMath.sin(this.lat)) /
(DMath.cos(decl) * DMath.cos(this.lat)))
return noon + (direction === 'ccw' ? -t : t)
}
// compute asr time
public asrTime(factor: number, time: number) {
const decl = this.sunPosition(this.jDate + time).declination
const angle = -DMath.arccot(factor + DMath.tan(Math.abs(this.lat - decl)))
return this.sunAngleTime(angle, time)
}
// compute declination angle of sun and equation of time
// Ref: http://aa.usno.navy.mil/faq/docs/SunApprox.php
public sunPosition(jd: number) {
const D = jd - 2451545.0
const g = DMath.fixAngle(357.529 + 0.98560028 * D)
const q = DMath.fixAngle(280.459 + 0.98564736 * D)
const L = DMath.fixAngle(q + 1.915 * DMath.sin(g) + 0.020 * DMath.sin(2 * g))
// const R = 1.00014 - 0.01671 * DMath.cos(g) - 0.00014 * DMath.cos(2 * g)
const e = 23.439 - 0.00000036 * D
const RA = DMath.arctan2(DMath.cos(e) * DMath.sin(L), DMath.cos(L)) / 15
const eqt = q / 15 - DMath.fixHour(RA)
const decl = DMath.arcsin(DMath.sin(e) * DMath.sin(L))
return { declination: decl, equation: eqt }
}
// compute prayer times at given julian date
public computePrayerTimes(times: IRawPrayerTimes) {
times = this.dayPortion(times)
const params = this.setting
const imsak = this.sunAngleTime(this.eval(params.imsak as ParamType), times.imsak, 'ccw')
const fajr = this.sunAngleTime(this.eval(params.fajr as ParamType), times.fajr, 'ccw')
const sunrise = this.sunAngleTime(this.riseSetAngle(), times.sunrise, 'ccw')
const dhuhr = this.midDay(times.dhuhr)
const asr = this.asrTime(this.asrFactor(params.asr as ParamType), times.asr)
const sunset = this.sunAngleTime(this.riseSetAngle(), times.sunset)
const maghrib = this.sunAngleTime(this.eval(params.maghrib as ParamType), times.maghrib)
const isha = this.sunAngleTime(this.eval(params.isha as ParamType), times.isha)
return {
asr, dhuhr, fajr, imsak, isha, maghrib, sunrise, sunset,
}
}
// compute prayer times
public computeTimes() {
// default times
let times: any = {
asr: 13, dhuhr: 12, fajr: 5, imsak: 5, isha: 18, maghrib: 18, sunrise: 6, sunset: 18,
}
// main iterations
for (let i = 1; i <= this.numIterations; i++) {
times = this.computePrayerTimes(times)
}
times = this.adjustTimes(times)
// add midnight time
times.midnight = (this.setting.midnight === 'Jafari') ?
times.sunset + this.timeDiff(times.sunset, times.fajr) / 2 :
times.sunset + this.timeDiff(times.sunset, times.sunrise) / 2
times = this.tuneTimes(times)
return this.modifyFormats(times)
}
// adjust times
public adjustTimes(times: IRawPrayerTimes) {
const params = this.setting
for (const i in times) {
if (times.hasOwnProperty(i)) {
times[i] += this.timeZone - this.lng / 15
}
}
if (params.highLats !== 'None') {
times = this.adjustHighLats(times)
}
if (this.isMin(params.imsak as ParamType)) {
times.imsak = times.fajr - this.eval(params.imsak as ParamType) / 60
}
if (this.isMin(params.maghrib as ParamType)) {
times.maghrib = times.sunset + this.eval(params.maghrib as ParamType) / 60
}
if (this.isMin(params.isha as ParamType)) {
times.isha = times.maghrib + this.eval(params.isha as ParamType) / 60
}
times.dhuhr += this.eval(params.dhuhr as ParamType) / 60
return times
}
// get asr shadow factor
public asrFactor(asrParam: ParamType) {
const factor = { Standard: 1, Hanafi: 2 }[asrParam]
return factor || this.eval(asrParam)
}
// return sun angle for sunset/sunrise
public riseSetAngle() {
const angle = 0.0347 * Math.sqrt(this.elv) // an approximation
return 0.833 + angle
}
// apply offsets to the times
public tuneTimes(times: IRawPrayerTimes) {
for (const i in times) {
if (times.hasOwnProperty(i)) {
times[i] += this.offset[i] / 60
}
}
return times
}
// convert times to given time format
public modifyFormats(times: IRawPrayerTimes): PrayerTimes {
const formattedTimes: any = {}
for (const i in times) {
if (times.hasOwnProperty(i)) {
formattedTimes[i] = this.getFormattedTime(times[i], this.timeFormat)
}
}
return formattedTimes as PrayerTimes
}
// adjust times for locations in higher latitudes
public adjustHighLats(times: IRawPrayerTimes) {
const params = this.setting
const nightTime = this.timeDiff(times.sunset, times.sunrise)
times.imsak = this.adjustHLTime(times.imsak, times.sunrise, this.eval(params.imsak as ParamType), nightTime, 'ccw')
times.fajr = this.adjustHLTime(times.fajr, times.sunrise, this.eval(params.fajr as ParamType), nightTime, 'ccw')
times.isha = this.adjustHLTime(times.isha, times.sunset, this.eval(params.isha as ParamType), nightTime)
times.maghrib = this.adjustHLTime(times.maghrib, times.sunset, this.eval(params.maghrib as ParamType), nightTime)
return times
}
// adjust a time for higher latitudes
public adjustHLTime(time: number, base: number, angle: number, night: number, direction?: string) {
const portion = this.nightPortion(angle, night)
const timeDiff = (direction === 'ccw') ?
this.timeDiff(time, base) :
this.timeDiff(base, time)
if (isNaN(time) || timeDiff > portion) {
time = base + (direction === 'ccw' ? -portion : portion)
}
return time
}
// the night portion used for adjusting times in higher latitudes
public nightPortion(angle: number, night: number) {
const method = this.setting.highLats
let portion = 1 / 2 // MidNight
if (method === 'AngleBased') {
portion = 1 / 60 * angle
}
if (method === 'OneSeventh') {
portion = 1 / 7
}
return portion * night
}
// convert hours to day portions
public dayPortion(times: IRawPrayerTimes) {
for (const i in times) {
if (times.hasOwnProperty(i)) {
times[i] /= 24
}
}
return times
}
// get local time zone
public getTimeZone(date: DateTuple) {
const year = date[0]
const t1 = this.gmtOffset([year, 0, 1])
const t2 = this.gmtOffset([year, 6, 1])
return Math.min(t1, t2)
}
// get daylight saving for a given date
public getDst(date: DateTuple) {
return 1 * (this.gmtOffset(date) !== this.getTimeZone(date) ? 1 : 0)
}
// GMT offset for a given date
public gmtOffset(date: DateTuple) {
const localDate = new Date(date[0], date[1] - 1, date[2], 12, 0, 0, 0)
const UTCString = localDate.toUTCString()
const UTCDate = new Date(UTCString.substring(0, UTCString.lastIndexOf(' ') - 1))
const hoursDiff = (localDate.getTime() - UTCDate.getTime()) / (1000 * 60 * 60)
return hoursDiff
}
// convert given string into a number
public eval(str: string | number) {
const val = str.toString().split(/[^0-9.+-]/)[0]
return 1 * parseFloat(val)
}
// detect if input contains 'min'
public isMin(arg: string | number) {
return arg.toString().indexOf('min') !== -1
}
// compute the difference between two times
public timeDiff(time1: number, time2: number) {
return DMath.fixHour(time2 - time1)
}
// add a leading 0 if necessary
public twoDigitsFormat(num: number) {
return (num < 10) ? '0' + num : num
}
}
export default new PrayerTimes()