module math

// DivResult[T] represents the result of an integer division (both quotient and remainder)
// See also https://en.wikipedia.org/wiki/Modulo
pub struct DivResult[T] {
pub mut:
    quot T
    rem  T
}

// divide_truncated returns the truncated version of the result of dividing numer to denom
@[inline]
pub fn divide_truncated[T](numer T, denom T) DivResult[T] {
    return DivResult[T]{
        quot: numer / denom
        rem:  numer % denom
    }
}

// divide_euclid returns the Euclidean version of the result of dividing numer to denom
@[inline]
pub fn divide_euclid[T](numer T, denom T) DivResult[T] {
    mut q := numer / denom
    mut r := numer % denom
    if r < 0 {
        if denom > 0 {
            q = q - 1
            r = r + denom
        } else {
            q = q + 1
            r = r - denom
        }
    }
    return DivResult[T]{
        quot: q
        rem:  r
    }
}

// divide_floored returns the floored version of the result of dividing numer to denom
@[inline]
pub fn divide_floored[T](numer T, denom T) DivResult[T] {
    mut q := numer / denom
    mut r := numer % denom
    if (r > 0 && denom < 0) || (r < 0 && denom > 0) {
        q = q - 1
        r = r + denom
    }
    return DivResult[T]{
        quot: q
        rem:  r
    }
}

// modulo_truncated returns the truncated remainder of dividing numer to denom
@[inline]
pub fn modulo_truncated[T](numer T, denom T) T {
    return numer % denom
}

// modulo_euclid returns the Euclidean remainder of dividing numer to denom
@[inline]
pub fn modulo_euclid[T](numer T, denom T) T {
    mut r := numer % denom
    return if r < 0 {
        if denom > 0 {
            r + denom
        } else {
            r - denom
        }
    } else {
        r
    }
}

// modulo_floored returns the floored remainder of dividing numer to denom
@[inline]
pub fn modulo_floored[T](numer T, denom T) T {
    r := numer % denom
    return if (r > 0 && denom < 0) || (r < 0 && denom > 0) {
        r + denom
    } else {
        r
    }
}