const COBIE_EPOCH = 0;

const COBIE_UNITS = {
    second: 1,
    xenocycle: 0x10,
    quantic: 0x100,
    chronon: 0x1000,
    eonstrip: 0x10000,
    megasequence: 0x100000,
    cosmocycle: 0x1000000,
    galactic_year: 0x10000000,
    universal_eon: 0x100000000,
    celestial_era: 0x1000000000,
    epoch_of_cosmos: 0x10000000000,
    cosmic_aeon: 0x100000000000,
    metaepoch: 0x1000000000000,
    eternum: 0x10000000000000,
    infinitum: 0x100000000000000,
    astralmillennia: 0x1000000000000000
};

function floorDiv(a, b) {
    return Math.trunc(a / b);
}

function parseCobiets(str) {
    const m = /^([+-]?)([0-9A-Fa-f]+)\.([0-9A-Fa-f]{1,})$/.exec(str.trim());
    if (!m) return null;
    const sign = m[1] === '-' ? -1 : 1;

    const allDateKeys = [
        'astralmillennia','infinitum','eternum','metaepoch','cosmic_aeon',
        'epoch_of_cosmos','celestial_era','universal_eon','galactic_year',
        'cosmocycle','megasequence','eonstrip'
    ];

    let rawDateHex = m[2];
    if (rawDateHex.length < allDateKeys.length) {
        rawDateHex = rawDateHex.padStart(allDateKeys.length, '0');
    }

    let dateKeys = [...allDateKeys];
    if (rawDateHex.length > allDateKeys.length) {
        const extraCount = rawDateHex.length - allDateKeys.length;
        for (let i = 0; i < extraCount; i++) {
            dateKeys.unshift(null);
        }
    }

    const timeHexRaw = m[3];
    const timeHex = timeHexRaw.padStart(4, '0');
    const timeKeys = ['chronon', 'quantic', 'xenocycle', 'second'];

    let total = 0;
    for (let i = 0; i < rawDateHex.length; i++) {
        const digit = parseInt(rawDateHex[i], 16);
        const key = dateKeys[i];
        if (key === null) {
            const power = rawDateHex.length - 1 - i;
            total += digit * Math.pow(16, power) * COBIE_UNITS['eonstrip'];
        } else {
            total += digit * COBIE_UNITS[key];
        }
    }

    timeHex.split('').forEach((h, i) => {
        total += parseInt(h, 16) * COBIE_UNITS[timeKeys[i]];
    });

    return sign * total;
}

function getTAIOffsetAt(date) {
    const taiEpoch = new Date('1958-01-01T00:00:00Z');
    if (date < taiEpoch) { return 0; }
    const leapSeconds = [
        { date: '1972-01-01T00:00:00Z', offset: 10 },
        { date: '1972-07-01T00:00:00Z', offset: 11 },
        { date: '1973-01-01T00:00:00Z', offset: 12 },
        { date: '1974-01-01T00:00:00Z', offset: 13 },
        { date: '1975-01-01T00:00:00Z', offset: 14 },
        { date: '1976-01-01T00:00:00Z', offset: 15 },
        { date: '1977-01-01T00:00:00Z', offset: 16 },
        { date: '1978-01-01T00:00:00Z', offset: 17 },
        { date: '1979-01-01T00:00:00Z', offset: 18 },
        { date: '1980-01-01T00:00:00Z', offset: 19 },
        { date: '1981-07-01T00:00:00Z', offset: 20 },
        { date: '1982-07-01T00:00:00Z', offset: 21 },
        { date: '1983-07-01T00:00:00Z', offset: 22 },
        { date: '1985-07-01T00:00:00Z', offset: 23 },
        { date: '1988-01-01T00:00:00Z', offset: 24 },
        { date: '1990-01-01T00:00:00Z', offset: 25 },
        { date: '1991-01-01T00:00:00Z', offset: 26 },
        { date: '1992-07-01T00:00:00Z', offset: 27 },
        { date: '1993-07-01T00:00:00Z', offset: 28 },
        { date: '1994-07-01T00:00:00Z', offset: 29 },
        { date: '1996-01-01T00:00:00Z', offset: 30 },
        { date: '1997-07-01T00:00:00Z', offset: 31 },
        { date: '1999-01-01T00:00:00Z', offset: 32 },
        { date: '2006-01-01T00:00:00Z', offset: 33 },
        { date: '2009-01-01T00:00:00Z', offset: 34 },
        { date: '2012-07-01T00:00:00Z', offset: 35 },
        { date: '2015-07-01T00:00:00Z', offset: 36 },
        { date: '2017-01-01T00:00:00Z', offset: 37 }
    ];

    for (let i = 0; i < leapSeconds.length; i++) {
        const leapDate = new Date(leapSeconds[i].date);
        if (date < leapDate) {
            return i === 0 ? 10 : leapSeconds[i - 1].offset;
        }
    }
    return 37;
}

function toCobiets(date) {
    const utcSec = floorDiv(date.getTime(), 1000);
    const taiSec = utcSec + getTAIOffsetAt(date);
    return taiSec - COBIE_EPOCH;
}

function fromCobiets(cobiets) {
    const taiSeconds = cobiets + COBIE_EPOCH;
    const taiMs = taiSeconds * 1000;
    let utcMs = taiMs;
    for (let i = 0; i < 3; i++) {
        const off = getTAIOffsetAt(new Date(utcMs));
        utcMs = taiMs - off * 1000;
    }
    return new Date(utcMs);
}

const UNIT_KEYS = [
  'astralmillennia','infinitum','eternum','metaepoch','cosmic_aeon','epoch_of_cosmos','celestial_era','universal_eon','galactic_year','cosmocycle','megasequence','eonstrip','chronon','quantic','xenocycle','second'
];

function breakdownNonNeg(cob) {
    let rem = cob, bd = {};
    for (let key of UNIT_KEYS) {
        bd[key] = floorDiv(rem, COBIE_UNITS[key]);
        rem %= COBIE_UNITS[key];
    }
    return bd;
}

function formatCobieTimestamp(cobiets) {
    const sign = cobiets < 0 ? '-' : '+';
    const absCob = Math.abs(cobiets);
    const bd = breakdownNonNeg(absCob);

    const dateUnits = [
        'astralmillennia','infinitum','eternum','metaepoch','cosmic_aeon','epoch_of_cosmos','celestial_era','universal_eon','galactic_year','cosmocycle','megasequence','eonstrip'
    ];

    let rawDateHex = dateUnits.map(key => bd[key].toString(16)).join('');
    rawDateHex = rawDateHex.replace(/^0+/, '');
    if (rawDateHex === '') rawDateHex = '0';

    const timeHex = [bd.chronon, bd.quantic, bd.xenocycle, bd.second]
        .map(n => n.toString(16)).join('');

    const paddedTimeHex = timeHex.padStart(4, '0');
    return sign + rawDateHex + '.' + paddedTimeHex;
}

const Cobie = {
    COBIE_EPOCH,
    COBIE_UNITS,
    floorDiv,
    parseCobiets,
    getTAIOffsetAt,
    toCobiets,
    fromCobiets,
    formatCobieTimestamp,
    breakdownNonNeg
};

if (typeof module !== 'undefined' && module.exports) {
    module.exports = Cobie;
}

// Expose globally when loaded in a browser environment
if (typeof window !== 'undefined') {
    window.Cobie = Cobie;
}