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// Copyright (C) 2019-2022 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 super::*;

impl<N: Network> FromBytes for Block<N> {
    /// Reads the block from the buffer.
    #[inline]
    fn read_le<R: Read>(mut reader: R) -> IoResult<Self> {
        // Read the version.
        let version = u16::read_le(&mut reader)?;
        // Ensure the version is valid.
        if version != 0 {
            return Err(error("Invalid block version"));
        }

        // Read the block.
        let block_hash: N::BlockHash = FromBytes::read_le(&mut reader)?;
        let previous_hash = FromBytes::read_le(&mut reader)?;
        let header = FromBytes::read_le(&mut reader)?;
        let transactions = FromBytes::read_le(&mut reader)?;
        let signature = FromBytes::read_le(&mut reader)?;

        // Construct the block.
        let block = Self::from(previous_hash, header, transactions, signature).map_err(|e| error(e.to_string()))?;
        // Ensure the block hash matches.
        match block_hash == block.hash() {
            true => Ok(block),
            false => Err(error("Mismatching block hash, possible data corruption")),
        }
    }
}

impl<N: Network> ToBytes for Block<N> {
    /// Writes the block to the buffer.
    #[inline]
    fn write_le<W: Write>(&self, mut writer: W) -> IoResult<()> {
        // Write the version.
        0u16.write_le(&mut writer)?;

        // Write the block.
        self.block_hash.write_le(&mut writer)?;
        self.previous_hash.write_le(&mut writer)?;
        self.header.write_le(&mut writer)?;
        self.transactions.write_le(&mut writer)?;
        self.signature.write_le(&mut writer)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use console::network::Testnet3;

    type CurrentNetwork = Testnet3;

    #[test]
    fn test_bytes() -> Result<()> {
        for expected in [crate::ledger::test_helpers::sample_genesis_block()].into_iter() {
            // Check the byte representation.
            let expected_bytes = expected.to_bytes_le()?;
            assert_eq!(expected, Block::read_le(&expected_bytes[..])?);
            assert!(Block::<CurrentNetwork>::read_le(&expected_bytes[1..]).is_err());
        }
        Ok(())
    }
}