package ws

import (
	"encoding/json"
	"sync"

	"github.com/gorilla/websocket"
)

type Client struct {
	Conn *websocket.Conn
	Send chan []byte
}

type Subscription struct {
	Client *Client
	Room   string
	done   chan struct{} // used by RegisterSync to wait for completion
}

type RoomMessage struct {
	Room    string
	Message []byte
}

type Hub struct {
	rooms      map[string]map[*Client]bool
	register   chan *Subscription
	unregister chan *Subscription
	broadcast  chan *RoomMessage
	mu         sync.RWMutex
}

func NewHub() *Hub {
	return &Hub{
		rooms:      make(map[string]map[*Client]bool),
		register:   make(chan *Subscription, 10),
		unregister: make(chan *Subscription, 10),
		broadcast:  make(chan *RoomMessage, 100),
	}
}

func (h *Hub) Run() {
	for {
		select {
		case sub := <-h.register:
			h.mu.Lock()
			if h.rooms[sub.Room] == nil {
				h.rooms[sub.Room] = make(map[*Client]bool)
			}
			h.rooms[sub.Room][sub.Client] = true
			h.mu.Unlock()
			if sub.done != nil {
				close(sub.done)
			}

		case sub := <-h.unregister:
			h.mu.Lock()
			if clients, ok := h.rooms[sub.Room]; ok {
				if _, exists := clients[sub.Client]; exists {
					delete(clients, sub.Client)
					close(sub.Client.Send)
				}
			}
			h.mu.Unlock()

		case msg := <-h.broadcast:
			h.mu.RLock()
			if clients, ok := h.rooms[msg.Room]; ok {
				for client := range clients {
					select {
					case client.Send <- msg.Message:
					default:
						close(client.Send)
						delete(clients, client)
					}
				}
			}
			h.mu.RUnlock()
		}
	}
}

func (h *Hub) Register(sub *Subscription) {
	h.register <- sub
}

// RegisterSync registers a subscription and blocks until the Hub has processed it,
// ensuring the client is in the room before returning.
func (h *Hub) RegisterSync(sub *Subscription) {
	sub.done = make(chan struct{})
	h.register <- sub
	<-sub.done
}

func (h *Hub) Unregister(sub *Subscription) {
	h.unregister <- sub
}

func (h *Hub) BroadcastToRoom(room string, data interface{}) {
	jsonData, err := json.Marshal(data)
	if err != nil {
		return
	}
	h.broadcast <- &RoomMessage{Room: room, Message: jsonData}
}