use quick_xml::events::{BytesStart, Event};

use crate::xml::*;
use anyhow::{anyhow as ffail, Result};

pub const XMLNS: &'static str = "jabber:iq:roster";

#[derive(PartialEq, Eq, Debug)]
pub struct RosterQuery;

pub struct QueryParser(QueryParserInner);

enum QueryParserInner {
    Initial,
    InQuery,
}

impl Parser for QueryParser {
    type Output = Result<RosterQuery>;

    fn consume<'a>(
        self: Self,
        namespace: quick_xml::name::ResolveResult,
        event: &quick_xml::events::Event<'a>,
    ) -> Continuation<Self, Self::Output> {
        match self.0 {
            QueryParserInner::Initial => match event {
                Event::Start(_) => Continuation::Continue(QueryParser(QueryParserInner::InQuery)),
                Event::Empty(_) => Continuation::Final(Ok(RosterQuery)),
                _ => Continuation::Final(Err(ffail!("Unexpected XML event: {event:?}"))),
            },
            QueryParserInner::InQuery => match event {
                Event::End(_) => Continuation::Final(Ok(RosterQuery)),
                _ => Continuation::Final(Err(ffail!("Unexpected XML event: {event:?}"))),
            },
        }
    }
}

impl FromXml for RosterQuery {
    type P = QueryParser;

    fn parse() -> Self::P {
        QueryParser(QueryParserInner::Initial)
    }
}

impl FromXmlTag for RosterQuery {
    const NAME: &'static str = "query";
    const NS: &'static str = XMLNS;
}

impl ToXml for RosterQuery {
    fn serialize(&self, events: &mut Vec<Event<'static>>) {
        events.push(Event::Empty(BytesStart::new(format!(r#"query xmlns="{}""#, XMLNS))));
    }
}