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// Copyright (C) 2019-2021 Aleo Systems Inc.
// This file is part of the snarkVM library.

// The snarkVM library is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// The snarkVM library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with the snarkVM library. If not, see <https://www.gnu.org/licenses/>.

use crate::{errors::SignedIntegerError, integers::int::*, traits::integers::Neg};
use snarkvm_fields::PrimeField;
use snarkvm_r1cs::ConstraintSystem;

macro_rules! neg_int_impl {
    ($($gadget: ident)*) => ($(
        impl<F: PrimeField> Neg<F> for $gadget {
            type ErrorType = SignedIntegerError;

            fn neg<CS: ConstraintSystem<F>>(
                &self,
                cs: CS
            ) -> Result<Self, Self::ErrorType> {
                let value = match self.value {
                    Some(val) => {
                        match val.checked_neg() {
                            Some(val_neg) => Some(val_neg),
                            None => return Err(SignedIntegerError::Overflow) // -0 should fail
                        }
                    }
                    None => None,
                };

                // calculate two's complement
                let bits = self.bits.neg(cs)?;

                Ok(Self {
                    bits,
                    value,
                })
            }
        }
    )*)
}

neg_int_impl!(Int8 Int16 Int32 Int64 Int128);