pub use super::seg::{MAX_TOTAL_PACKET_SIZE, UP_HEADER_SIZE, DOWN_HEADER_SIZE};

#[derive(Clone, Debug)]
pub enum UpMsg {
    Data {
        payload: Vec<u8>,
        // seg_idx: SegIdx,
        // encoding: SegmentEncoding,
        // is_final_packet: bool,
    },
}

#[derive(Clone, Debug)]
pub enum DownMsg {
    Ack {}, // ackd: SegmentSet
}

#[derive(Error, Debug)]
#[error("deserialization failed; malformed packet")]
pub struct DesError;

pub trait SerDes: Sized {
    // For both methods: `buf.len()` must be >= `MAX_SERIALIZED_SIZE`

    fn des(buf: &[u8]) -> Result<Self, DesError>;
    fn ser_to(&self, buf: &mut [u8]) -> usize;
}

impl SerDes for UpMsg {
    fn des(buf: &[u8]) -> Result<Self, DesError> {
        Ok(UpMsg::Data {
            payload: buf.into(),
        })
    }

    fn ser_to(&self, buf: &mut [u8]) -> usize {
        match self {
            UpMsg::Data { payload, .. } => {
                let len = payload.len();
                buf[..len].copy_from_slice(&payload[..]);
                len
            }
        }
    }
}

impl SerDes for DownMsg {
    fn des(_buf: &[u8]) -> Result<Self, DesError> {
        Ok(DownMsg::Ack {})
    }

    fn ser_to(&self, _buf: &mut [u8]) -> usize {
        1
    }
}