package lobby

import (
	"context"

	"git.sunturtle.xyz/studio/shotgun/player"
	"github.com/google/uuid"
)

type match struct {
	dealer player.ID
	chall  chan player.ID
	match  chan GameID
}

// Queue waits for a match.
// This may cause a new match to be created.
func (l *Lobby) Queue(ctx context.Context, p player.ID) GameID {
	select {
	case <-ctx.Done():
		return GameID{}
	case m := <-l.matches:
		// We found a dealer waiting for a match.
		// We don't need to check the context here because the challenger
		// channel is buffered and we have exclusive send access on it.
		m.chall <- p
		// We do need to check the context here in case they disappeared.
		select {
		case <-ctx.Done():
			return GameID{}
		case id := <-m.match:
			return id
		}
	default: // do nothing
	}
	// We're a new dealer.
	m := match{
		dealer: p,
		chall:  make(chan player.ID, 1),
		match:  make(chan GameID, 1),
	}
	select {
	case <-ctx.Done():
		return GameID{}
	case l.matches <- m:
		// Our match is submitted. Move on.
	case m := <-l.matches:
		// We might have become a dealer at the same time someone else did.
		// We created our match, but we can try to get theirs as well and
		// never send ours, since l.matches is unbuffered.
		m.chall <- p
		select {
		case <-ctx.Done():
			return GameID{}
		case id := <-m.match:
			return id
		}
	}
	select {
	case <-ctx.Done():
		return GameID{}
	case chall := <-m.chall:
		// Got our challenger. Create the game and send the ID back.
		id := uuid.New()
		l.Start(id, p, chall)
		// Don't need to check context because the match channel is buffered.
		m.match <- id
		return id
	}
}