//! Bitwise XOR via the [`BitXor`] trait.
use super::U384;
use core::ops::BitXor;

/// Computes the bitwise XOR of two 384-bit integers, producing a
/// result where each bit is set if exactly one of the corresponding
/// input bits is set.
///
/// Applied independently to each of the six `u64` limbs.
///
/// # Examples
///
/// ```
/// use cnfy_uint::u384::U384;
///
/// let a = U384::from_be_limbs([0xFF, 0, 0, 0, 0, 0]);
/// let b = U384::from_be_limbs([0x0F, 0, 0, 0, 0, 0]);
/// assert_eq!(a ^ b, U384::from_be_limbs([0xF0, 0, 0, 0, 0, 0]));
/// ```
impl BitXor for U384 {
    type Output = U384;

    #[inline]
    fn bitxor(self, rhs: U384) -> U384 {
        U384([
            self.0[0] ^ rhs.0[0],
            self.0[1] ^ rhs.0[1],
            self.0[2] ^ rhs.0[2],
            self.0[3] ^ rhs.0[3],
            self.0[4] ^ rhs.0[4],
            self.0[5] ^ rhs.0[5],
        ])
    }
}

#[cfg(test)]
mod ai_tests {
    use super::*;

    /// XOR with self is zero.
    #[test]
    fn self_cancellation() {
        let a = U384::from_be_limbs([0x1234, 0x5678, 0x9ABC, 0xDEF0, 0x1111, 0x2222]);
        assert_eq!(a ^ a, U384::ZERO);
    }

    /// XOR with zero is identity.
    #[test]
    fn xor_zero() {
        let a = U384::from_be_limbs([0x1234, 0x5678, 0x9ABC, 0xDEF0, 0x1111, 0x2222]);
        assert_eq!(a ^ U384::ZERO, a);
    }

    /// XOR with MAX flips all bits.
    #[test]
    fn xor_max() {
        let a = U384::from_be_limbs([0, 0, 0, 0, 0, 0xFF]);
        let expected = U384::from_be_limbs([u64::MAX, u64::MAX, u64::MAX, u64::MAX, u64::MAX, u64::MAX ^ 0xFF]);
        assert_eq!(a ^ U384::MAX, expected);
    }

    /// XOR is commutative.
    #[test]
    fn commutative() {
        let a = U384::from_be_limbs([1, 2, 3, 4, 5, 6]);
        let b = U384::from_be_limbs([7, 8, 9, 10, 11, 12]);
        assert_eq!(a ^ b, b ^ a);
    }

    /// Double XOR is identity.
    #[test]
    fn double_xor() {
        let a = U384::from_be_limbs([0xAB, 0xCD, 0xEF, 0x12, 0x34, 0x56]);
        let b = U384::from_be_limbs([0x11, 0x22, 0x33, 0x44, 0x55, 0x66]);
        assert_eq!((a ^ b) ^ b, a);
    }
}
