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use crate::dvl_error::DvlError;
use crate::errors::ContractError;

pub trait DvlDeserializableInstruction<'a> {
    fn expected_size() -> usize;
    fn expected_version() -> u8;
    #[inline(always)]
    fn check_version(vec: &'a [u8]) -> Result<(), DvlError> {
        // Check the second byte for the version number.
        // The first byte usually contains the command identifier,
        // and the second byte consistently holds the version number of the instruction format.
        if vec[1] != Self::expected_version() {
            return Err(DvlError::new(ContractError::InstructionDataVersion));
        }
        Ok(())
    }

    fn from_vec_le(vec: &'a [u8]) -> Result<&'a Self, DvlError> where Self: Sized {
        if vec.len() != Self::expected_size() {
            return Err(DvlError::new(ContractError::InstructionDataLength));
        }
        Self::check_version(vec)?;
        Ok(unsafe { &*(vec.as_ptr() as *const Self) })
    }
}