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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.

use super::*;

impl<N: Network> FromBytes for Identifier<N> {
    /// Reads in an identifier from a buffer.
    fn read_le<R: Read>(mut reader: R) -> IoResult<Self> {
        // Read the number of bytes.
        let size = u8::read_le(&mut reader)?;

        // Read the identifier bytes.
        let mut buffer = vec![0u8; size as usize];
        reader.read_exact(&mut buffer)?;

        // from_str the identifier.
        Self::from_str(&String::from_utf8(buffer).map_err(|e| error(format!("Failed to decode identifier: {e}")))?)
            .map_err(|e| error(format!("{e}")))
    }
}

impl<N: Network> ToBytes for Identifier<N> {
    /// Writes an identifier to a buffer.
    fn write_le<W: Write>(&self, mut writer: W) -> IoResult<()> {
        // Convert the identifier to a string.
        let string = self.to_string();
        if string.len() != self.1 as usize {
            return Err(error("Identifier length does not match expected size"));
        }

        // Ensure identifier fits within the data capacity of the base field.
        let max_bytes = Field::<N>::size_in_data_bits() / 8; // Note: This intentionally rounds down.
        if string.len() > max_bytes {
            return Err(error(format!("Identifier is too large. Identifiers must be <= {max_bytes} bytes long")));
        }

        // Write the identifier to a buffer.
        u8::try_from(string.len()).or_halt_with::<N>("Invalid identifier length").write_le(&mut writer)?;
        string.as_bytes().write_le(&mut writer)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::data::identifier::tests::sample_identifier;
    use snarkvm_console_network::Testnet3;

    type CurrentNetwork = Testnet3;

    const ITERATIONS: u64 = 1000;

    #[test]
    fn test_bytes() -> Result<()> {
        let mut rng = TestRng::default();

        for _ in 0..ITERATIONS {
            // Sample a random fixed-length alphanumeric identifier, that always starts with an alphabetic character.
            let expected = sample_identifier::<CurrentNetwork>(&mut rng)?;

            // Check the byte representation.
            let expected_bytes = expected.to_bytes_le()?;
            assert_eq!(expected, Identifier::read_le(&expected_bytes[..])?);
            assert!(Identifier::<CurrentNetwork>::read_le(&expected_bytes[1..]).is_err());
        }
        Ok(())
    }
}