package dart

import (
	"fmt"
	"net/http"
	"sync"

	"github.com/gorilla/websocket"
)

type WebsocketManager struct {
	conns map[string]map[*websocket.Conn]bool
	mutex sync.RWMutex
}

func (wm *WebsocketManager) createHandler() Handler {
	return func(ctx *Context) error {
		upgrader := websocket.Upgrader{
			CheckOrigin: func(r *http.Request) bool { return true },
		}
		conn, err := upgrader.Upgrade(ctx.response, ctx.request, nil)
		if err != nil {
			return err
		}

		wm.register(ctx.request.URL.Path, conn)

		for {
			if _, _, err := conn.NextReader(); err != nil {
				break
			}
		}

		wm.unregister(ctx.request.URL.Path, conn)
		conn.Close()
		return nil
	}
}

func (wm *WebsocketManager) register(path string, conn *websocket.Conn) {
	wm.mutex.Lock()
	defer wm.mutex.Unlock()

	if _, exists := wm.conns[path]; !exists {
		wm.conns[path] = make(map[*websocket.Conn]bool)
	}
	wm.conns[path][conn] = true
}

func (wm *WebsocketManager) unregister(path string, conn *websocket.Conn) {
	wm.mutex.Lock()
	defer wm.mutex.Unlock()

	if conns, exists := wm.conns[path]; exists {
		delete(conns, conn)
		if len(conns) == 0 {
			delete(wm.conns, path)
		}
	}
}

func (wm *WebsocketManager) Broadcast(path string, msg []byte) error {
	wm.mutex.RLock()
	conns, exists := wm.conns[path]
	wm.mutex.RUnlock()

	if !exists {
		return fmt.Errorf("there is no websocket on path '%s'", path)
	}

	for conn := range conns {
		go func(c *websocket.Conn) {
			if err := c.WriteMessage(websocket.TextMessage, msg); err != nil {
				wm.unregister(path, conn)
				conn.Close()
			}
		}(conn)
	}

	return nil
}