// every hardcoded 2 will one day be a constant in a special
// constant file but rn I AM LAZY AND ITS LATE
//
use crate::message::Message;

pub struct MessageReader {
    pub buffer: Vec<u8>,
}

impl MessageReader {
    pub fn new() -> Self {
        Self { buffer: Vec::new() }
    }

    fn can_parse(&self) -> bool {
        if self.buffer.len() < 2 {
            return false;
        }

        let length = u16::from_be_bytes([self.buffer[0], self.buffer[1]]);
        self.buffer.len() >= 2 + length as usize
    }

    fn parse_first(&mut self) -> anyhow::Result<Message> {
        let length = u16::from_be_bytes([self.buffer[0], self.buffer[2]]);
        let message_length = 2 + length as usize;
        let message = self.buffer[..message_length].to_vec();
        self.buffer = self.buffer[message_length..].to_vec();

        Message::decode(&message)
    }

    pub fn read(&mut self, data: &[u8]) -> anyhow::Result<Vec<Message>> {
        self.buffer.extend_from_slice(data);
        let mut data = vec![];

        while self.can_parse() {
            let message = self.parse_first()?;
            data.push(message);
        }

        Ok(data)
    }
}