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// Copyright (C) 2019-2023 Aleo Systems Inc.
// This file is part of the snarkVM library.

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
// http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

pub trait ToBits: Sized {
    /// Returns `self` as a boolean array in little-endian order.
    fn to_bits_le(&self) -> Vec<bool>;

    /// Returns `self` as a boolean array in big-endian order.
    fn to_bits_be(&self) -> Vec<bool>;
}

/********************/
/****** Tuples ******/
/********************/

/// A helper macro to implement `ToBits` for a tuple of `ToBits` circuits.
macro_rules! to_bits_tuple {
    (($t0:ident, $i0:tt), $(($ty:ident, $idx:tt)),+) => {
        impl<$t0: ToBits, $($ty: ToBits),+> ToBits for ($t0, $($ty),+) {
            /// A helper method to return a concatenated list of little-endian bits from the circuits.
            #[inline]
            fn to_bits_le(&self) -> Vec<bool> {
                // The tuple is order-preserving, meaning the first circuit in is the first circuit bits out.
                self.$i0.to_bits_le().into_iter()
                    $(.chain(self.$idx.to_bits_le().into_iter()))+
                    .collect()
            }

            /// A helper method to return a concatenated list of big-endian bits from the circuits.
            #[inline]
            fn to_bits_be(&self) -> Vec<bool> {
                // The tuple is order-preserving, meaning the first circuit in is the first circuit bits out.
                self.$i0.to_bits_be().into_iter()
                    $(.chain(self.$idx.to_bits_be().into_iter()))+
                    .collect()
            }
        }

        impl<'a, $t0: ToBits, $($ty: ToBits),+> ToBits for &'a ($t0, $($ty),+) {
            /// A helper method to return a concatenated list of little-endian bits from the circuits.
            #[inline]
            fn to_bits_le(&self) -> Vec<bool> {
                // The tuple is order-preserving, meaning the first circuit in is the first circuit bits out.
                self.$i0.to_bits_le().into_iter()
                    $(.chain(self.$idx.to_bits_le().into_iter()))+
                    .collect()
            }

            /// A helper method to return a concatenated list of big-endian bits from the circuits.
            #[inline]
            fn to_bits_be(&self) -> Vec<bool> {
                // The tuple is order-preserving, meaning the first circuit in is the first circuit bits out.
                self.$i0.to_bits_be().into_iter()
                    $(.chain(self.$idx.to_bits_be().into_iter()))+
                    .collect()
            }
        }
    }
}

to_bits_tuple!((C0, 0), (C1, 1));
to_bits_tuple!((C0, 0), (C1, 1), (C2, 2));
to_bits_tuple!((C0, 0), (C1, 1), (C2, 2), (C3, 3));
to_bits_tuple!((C0, 0), (C1, 1), (C2, 2), (C3, 3), (C4, 4));
to_bits_tuple!((C0, 0), (C1, 1), (C2, 2), (C3, 3), (C4, 4), (C5, 5));
to_bits_tuple!((C0, 0), (C1, 1), (C2, 2), (C3, 3), (C4, 4), (C5, 5), (C6, 6));
to_bits_tuple!((C0, 0), (C1, 1), (C2, 2), (C3, 3), (C4, 4), (C5, 5), (C6, 6), (C7, 7));
to_bits_tuple!((C0, 0), (C1, 1), (C2, 2), (C3, 3), (C4, 4), (C5, 5), (C6, 6), (C7, 7), (C8, 8));
to_bits_tuple!((C0, 0), (C1, 1), (C2, 2), (C3, 3), (C4, 4), (C5, 5), (C6, 6), (C7, 7), (C8, 8), (C9, 9));
to_bits_tuple!((C0, 0), (C1, 1), (C2, 2), (C3, 3), (C4, 4), (C5, 5), (C6, 6), (C7, 7), (C8, 8), (C9, 9), (C10, 10));

/********************/
/****** Arrays ******/
/********************/

impl<C: ToBits> ToBits for Vec<C> {
    /// A helper method to return a concatenated list of little-endian bits.
    #[inline]
    fn to_bits_le(&self) -> Vec<bool> {
        // The vector is order-preserving, meaning the first variable in is the first variable bits out.
        self.as_slice().to_bits_le()
    }

    /// A helper method to return a concatenated list of big-endian bits.
    #[inline]
    fn to_bits_be(&self) -> Vec<bool> {
        // The vector is order-preserving, meaning the first variable in is the first variable bits out.
        self.as_slice().to_bits_be()
    }
}

impl<C: ToBits, const N: usize> ToBits for [C; N] {
    /// A helper method to return a concatenated list of little-endian bits.
    #[inline]
    fn to_bits_le(&self) -> Vec<bool> {
        // The slice is order-preserving, meaning the first variable in is the first variable bits out.
        self.as_slice().to_bits_le()
    }

    /// A helper method to return a concatenated list of big-endian bits.
    #[inline]
    fn to_bits_be(&self) -> Vec<bool> {
        // The slice is order-preserving, meaning the first variable in is the first variable bits out.
        self.as_slice().to_bits_be()
    }
}

impl<C: ToBits> ToBits for &[C] {
    /// A helper method to return a concatenated list of little-endian bits.
    #[inline]
    fn to_bits_le(&self) -> Vec<bool> {
        // The slice is order-preserving, meaning the first variable in is the first variable bits out.
        self.iter().flat_map(|c| c.to_bits_le()).collect()
    }

    /// A helper method to return a concatenated list of big-endian bits.
    #[inline]
    fn to_bits_be(&self) -> Vec<bool> {
        // The slice is order-preserving, meaning the first variable in is the first variable bits out.
        self.iter().flat_map(|c| c.to_bits_be()).collect()
    }
}