const hoursperday = 24
const minutesperhour = 60
const secondsperminute = 60
const secondms = 1000
const minutems = secondms * secondsperminute
const hourms = minutems * minutesperhour
const dayms = hourms * hoursperday

const solaryear = 365.2425

const yeardays = 366
const leapchange = -6
const leapyeardays = yeardays + leapchange

const monthdays = 30

const leapfreq = 8

const exleapfreq = 800;
const exleapyear = 500;
const exleapyearlowbound = Math.floor(exleapyear / leapfreq) * leapfreq;
const exleapyearupbound = exleapyearlowbound + leapfreq;
const exleapyearlowbounddays = (exleapyearlowbound * yeardays) + ((exleapyearlowbound / leapfreq) * leapchange);
const exleapyearupbounddays = (exleapyearupbound * yeardays) + leapchange + ((exleapyearupbound / leapfreq) * leapchange);

const exleapcycledays = (exleapfreq * yeardays) + leapchange + ((exleapfreq / leapfreq) * leapchange)

const leapcycledays = (leapfreq * yeardays) + leapchange;

const unityzero = Date.parse("2000-03-08T00:00:00.000Z");

export function unixtounity(unixtime) {
    const unitytime = unixtime - unityzero;
    const days = unitytime / dayms;

    const exleapcycles = Math.floor(days / exleapcycledays);
    const exleapcycleprogress = days - exleapcycles * exleapcycledays;

    let leapcycles;
    let leapcycleprogress;
    let leapcyclehasex;
    if (exleapcycleprogress < exleapyearupbounddays) {
        leapcycles = Math.floor(exleapcycleprogress / leapcycledays);
        leapcycleprogress = exleapcycleprogress - leapcycles * leapcycledays;
        leapcyclehasex = exleapcycleprogress >= exleapyearlowbounddays;
    } else {
        leapcycles = Math.floor((exleapcycleprogress - leapchange)/ leapcycledays);
        leapcycleprogress = (exleapcycleprogress - (leapcycles * leapcycledays)) - leapchange;
        leapcyclehasex = false;
    }
    
    let leapyearspassed;
    if (leapcycleprogress < leapyeardays) {
        leapyearspassed = 0;
    } else if (!leapcyclehasex || leapcycleprogress < (2 * leapyeardays) + (3 * yeardays)) {
        leapyearspassed = 1;
    } else {
        leapyearspassed = 2;
    }

    const years = Math.floor((leapcycleprogress - (leapchange * leapyearspassed)) / yeardays);
    const yearprogress = leapcycleprogress - ((years * yeardays) + (leapchange * leapyearspassed));

    const months = Math.floor(yearprogress / monthdays);
    const monthprogress = yearprogress - months * monthdays;

    const day = Math.floor(monthprogress);

    const weekday = day % 6;

    const date = {
        year: 12000 + (exleapcycles * exleapfreq) + (leapcycles * leapfreq) + years,
        month: months,
        day: day,
        weekday: weekday,
    };

    return date

}

// console.log(unixtounity(Date.parse("1990-06-06")))
// console.log(unixtounity(Date.parse("1890-06-06")))
// console.log(unixtounity(Date.parse("1990-06-06")))
// console.log(unixtounity(Date.parse("1993-06-06")))
// console.log(unixtounity(Date.parse("1998-06-06")))
// console.log(unixtounity(Date.parse("1999-06-06")))
// console.log(unixtounity(Date.parse("1999-12-31")))
// console.log(unixtounity(Date.parse("2000-03-01")))
// console.log(unixtounity(Date.parse("2000-03-02")))
// console.log(unixtounity(Date.parse("2000-03-07")))
// console.log(unixtounity(Date.parse("2000-03-08")))
// console.log(unixtounity(Date.parse("2000-03-09")))
// console.log(unixtounity(Date.parse("2000-04-07")))
// console.log(unixtounity(Date.parse("2000-06-06")))
// console.log(unixtounity(Date.parse("2001-06-06")))
// console.log(unixtounity(Date.parse("2002-06-06")))
// console.log(unixtounity(Date.parse("2006-06-06")))
// console.log(unixtounity(Date.parse("2010-06-06")))
// console.log(unixtounity(new Date()))