use crate::engine::packet::Packet;
use crate::engine::session::{SessionState, SessionStore, TransportType};

pub async fn handle_upgrade_probe(
    store: &SessionStore,
    sid: &str,
) -> Result<Packet, UpgradeError> {
    let session = store.get(sid).ok_or(UpgradeError::SessionNotFound)?;
    let mut session = session.write().await;

    if session.state == SessionState::Closed {
        return Err(UpgradeError::SessionClosed);
    }

    session.set_state(SessionState::Upgrading);
    Ok(Packet::pong("probe"))
}

pub async fn handle_upgrade_complete(
    store: &SessionStore,
    sid: &str,
    new_transport: TransportType,
) -> Result<(), UpgradeError> {
    let session = store.get(sid).ok_or(UpgradeError::SessionNotFound)?;
    let mut session = session.write().await;

    session.set_transport(new_transport);
    session.set_state(SessionState::Open);

    Ok(())
}

pub async fn send_noop_to_pending_polling(
    store: &SessionStore,
    sid: &str,
) -> Result<(), UpgradeError> {
    let session = store.get(sid).ok_or(UpgradeError::SessionNotFound)?;
    let mut session = session.write().await;

    session.buffer_packet(Packet::noop());

    Ok(())
}

#[derive(Debug, thiserror::Error)]
pub enum UpgradeError {
    #[error("session not found")]
    SessionNotFound,
    #[error("session closed")]
    SessionClosed,
    #[error("invalid state for upgrade")]
    InvalidState,
}