pub mod header;
pub mod payload;

use header::{MessageHeader, HEADER_LENGTH};
use payload::MessagePayload;

pub const PROTOCOL_VERSION: u8 = 0;

#[derive(thiserror::Error, Debug)]
pub enum DecodeError {
    #[error("invalid version {0} (expected {1})")]
    InvalidVersion(u8, u8),
    #[error("invalid paylaod type {0}")]
    InvalidPayloadType(u8),
    #[error("invalid boolean {0}")]
    InvalidBoolean(u8),
}

#[derive(Debug, PartialEq)]
pub struct Message {
    //header: MessageHeader,
    payload: MessagePayload,
}

impl Message {
    pub fn new(payload: MessagePayload) -> Message {
        Message { payload }
    }

    pub fn encode(&self) -> Vec<u8> {
        let payload_type = (&self.payload).into();
        let payload_bytes = self.payload.encode();

        let header = MessageHeader::new(payload_type, payload_bytes.len() as u32);
        let header_bytes = header.encode();

        let mut buf = vec![];
        buf.extend(header_bytes);
        buf.extend(payload_bytes);
        buf
    }

    pub fn decode(buf: &mut impl std::io::Read) -> Result<Message, Box<dyn std::error::Error>> {
        let mut header_bytes = [0; HEADER_LENGTH];
        buf.read_exact(&mut header_bytes)?;
        let header = MessageHeader::decode(header_bytes)?;

        let mut payload_bytes = vec![0; header.payload_length as usize];
        buf.read_exact(&mut payload_bytes)?;
        let mut payload_reader = std::io::Cursor::new(payload_bytes);
        let payload = MessagePayload::decode(header.payload_type, &mut payload_reader)?;

        Ok(Message { payload })
    }
}

#[test]
fn test_round_trip_message_authentication() {
    let sent_message = Message::new(MessagePayload::Authentication {
        key: "this_is_a_key".to_owned(),
    });

    let sent_message_bytes = sent_message.encode();

    let mut reader = std::io::Cursor::new(sent_message_bytes);
    let received_message = Message::decode(&mut reader).unwrap();

    assert_eq!(sent_message, received_message);
}