module big

struct JS.BigInt {}

#const jsNumber = Number;

pub struct Number {
}

pub fn new() Number {
    return Number{}
}

pub fn from_int(i int) Number {
    n := Number{}
    #n.value = BigInt(+i)

    return n
}

pub fn from_u64(u u64) Number {
    n := Number{}
    #n.value = BigInt(u.val)

    return n
}

pub fn from_hex_string(input string) Number {
    n := Number{}
    #n.value = BigInt(input.val)

    return n
}

pub fn from_string(input string) Number {
    n := Number{}
    #n.value = BigInt(input.val)

    return n
}

pub fn (n &Number) int() int {
    r := 0
    #r.val = jsNumber(n.val.value)

    return r
}

pub fn (n &Number) str() string {
    s := ''
    #s.str = n.val.value + ""

    return s
}

pub fn (a &Number) + (b &Number) Number {
    c := Number{}
    #c.value = a.val.value + b.val.value

    return c
}

pub fn (a &Number) - (b &Number) Number {
    c := Number{}
    #c.value = a.val.value - b.val.value

    return c
}

pub fn (a &Number) / (b &Number) Number {
    c := Number{}
    #c.value = a.val.value / b.val.value

    return c
}

pub fn (a &Number) * (b &Number) Number {
    c := Number{}
    #c.value = a.val.value * b.val.value

    return c
}

/*
pub fn (a &Number) % (b &Number) Number {
    c := Number{}
    # c.value = a.val.value % b.val.value
    return c
}*/

pub fn div_mod(a &Number, b &Number) (Number, Number) {
    c := Number{}
    d := Number{}
    #c.value = a.val.value / b.val.value
    #d.value = a.val.value % b.val.value

    return c, d
}

pub fn cmp(a &Number, b &Number) int {
    res := 0

    #if (a.val.value < b.val.value) res.val = -1
    #else if (a.val.value > b.val.value) res.val = 1
    #else res.val = 0

    return res
}

pub fn (a &Number) is_zero() bool {
    res := false
    #res.val = a.val.value == BigInt(0)

    return res
}

pub fn (mut a Number) inc() {
    #a.val.value = a.val.value + BigInt(1)
}

pub fn (mut a Number) dec() {
    #a.val.value = a.val.value - BigInt(1)
}

pub fn (a &Number) isqrt() Number {
    b := Number{}
    #let x0 = a.val.value >> 1n
    #if (x0) {
    #let x1 = (x0 + a.val.value / x0) >> 1n
    #while (x1 < x0) {
    #x0 = x1
    #x1 = (x0 + a.val.value / x0) >> 1n
    #}
    #b.value = x0
    #} else { b.value = a.val.value; }

    return b
}

pub fn bitwise_and(a &Number, b &Number) Number {
    c := Number{}
    #c.value = a.val.value & b.val.value

    return c
}

pub fn bitwise_or(a &Number, b &Number) Number {
    c := Number{}
    #c.value = a.val.value | b.val.value

    return c
}

pub fn bitwise_xor(a &Number, b &Number) Number {
    c := Number{}
    #c.value = a.val.value ^ b.val.value

    return c
}

pub fn (a &Number) left_shift(amount int) Number {
    c := Number{}
    #c.value = a.val.value << BigInt(+amount)

    return c
}

pub fn (a &Number) right_shift(amount int) Number {
    c := Number{}
    #c.value = a.val.value << BigInt(+amount)

    return c
}

pub fn (a &Number) clone() Number {
    b := Number{}
    #b.value = a.val.value

    return b
}

pub fn factorial(nn &Number) Number {
    mut n := nn.clone()
    mut a := nn.clone()
    n.dec()
    mut i := 1
    for !n.is_zero() {
        res := a * n
        n.dec()
        a = res
        i++
    }
    return a
}

pub fn factorial_int(n int) Number {
    return factorial(from_int(n))
}