use serde_json;
use serde::{Serialize, Deserialize};

use anyhow::bail;

#[derive(Debug, Serialize, Deserialize)]
pub enum Header {
    State(StateMeta),
    Cursor,
    Join,
    Leave,
    UsersInfo{my_uid: u64, others: Vec<u64>},
}

#[derive(Debug, Default, Serialize, Deserialize)]
pub struct StateMeta {
    pub sender_power: u64,
    pub generation: u64,
}

pub fn parse_header(m: &str) -> anyhow::Result<Header>{
    let zero = m.find('\0').unwrap_or(m.len());
    Ok(serde_json::from_str::<Header>(&m[..zero])?)
}

pub fn parse_uid_header(m: &str) -> anyhow::Result<(u64, Header)>{
    if let Some(zero) = m.find('\0') {
        let uid = m[..zero].parse::<u64>()?;
        Ok((uid, parse_header(&m[zero+1..])?))
    }
    else { bail!("no \\0 message, wanted to split off uid."); }
}

fn main(){
    let h = Header::State(StateMeta{sender_power: 345, generation: 1});
    let j = serde_json::to_string_pretty(&h).unwrap();
    println!("{}", j);
}