use crate::message::proto_message::ProtoMessage;
use crate::reader::errors::ProtoReadError;
use crate::reader::protoreader::ProtoReader;
use crate::reader::utils::AsyncPeek;
use async_trait::async_trait;
use tokio::io::{AsyncBufRead, AsyncReadExt};

#[async_trait]
pub trait OneWayProtoReader<T>
where
    T: ProtoMessage,
{
    async fn read_proto(&mut self) -> Result<T, ProtoReadError>;
}

#[async_trait]
impl<R, T> OneWayProtoReader<T> for ProtoReader<R>
where
    R: AsyncBufRead + AsyncPeek + Unpin + Send,
    T: ProtoMessage,
{
    async fn read_proto(&mut self) -> Result<T, ProtoReadError> {
        let variant = self.inner.read_u8().await?;
        let length = self.inner.read_i32().await?;

        if length < 4 {
            return Err(ProtoReadError::InvalidLength(length));
        }
        if length > self.msg_len_limit {
            return Err(ProtoReadError::LengthOverflow {
                limit: self.msg_len_limit as usize,
                actual: length as usize,
            });
        }

        let mut data = vec![0u8; (length - 4) as usize];
        self.inner.read_exact(&mut data).await?;

        Ok(T::deserialize(variant, &data)?)
    }
}