package httpserver

import (
	"net/http"
	"time"

	"github.com/gorilla/websocket"

	"github.com/tim/md-hub-secure/apps/server/internal/realtime"
)

const (
	wsWriteWait  = 10 * time.Second
	wsPongWait   = 60 * time.Second
	wsPingPeriod = 45 * time.Second
)

var wsUpgrader = websocket.Upgrader{
	ReadBufferSize:  1024,
	WriteBufferSize: 1024,
	CheckOrigin: func(r *http.Request) bool {
		origin := r.Header.Get("Origin")
		if origin == "" {
			return true
		}
		return origin == "http://"+r.Host || origin == "https://"+r.Host
	},
}

func (s *Server) handleWebSocket(w http.ResponseWriter, r *http.Request) {
	conn, err := wsUpgrader.Upgrade(w, r, nil)
	if err != nil {
		s.logger.Warn("upgrade websocket", "error", err)
		return
	}

	client := s.hub.NewClient(16)
	s.hub.Register(client)

	go s.readWebSocket(conn, client)
	s.writeWebSocket(conn, client)
}

func (s *Server) readWebSocket(conn *websocket.Conn, client *realtime.Client) {
	defer func() {
		s.hub.Unregister(client)
		_ = conn.Close()
	}()
	conn.SetReadLimit(1024)
	_ = conn.SetReadDeadline(time.Now().Add(wsPongWait))
	conn.SetPongHandler(func(string) error {
		return conn.SetReadDeadline(time.Now().Add(wsPongWait))
	})

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

func (s *Server) writeWebSocket(conn *websocket.Conn, client *realtime.Client) {
	ticker := time.NewTicker(wsPingPeriod)
	defer func() {
		ticker.Stop()
		s.hub.Unregister(client)
		_ = conn.Close()
	}()

	for {
		select {
		case message, ok := <-client.Send():
			_ = conn.SetWriteDeadline(time.Now().Add(wsWriteWait))
			if !ok {
				_ = conn.WriteMessage(websocket.CloseMessage, []byte{})
				return
			}
			if err := conn.WriteMessage(websocket.TextMessage, message); err != nil {
				return
			}
		case <-ticker.C:
			_ = conn.SetWriteDeadline(time.Now().Add(wsWriteWait))
			if err := conn.WriteMessage(websocket.PingMessage, nil); err != nil {
				return
			}
		}
	}
}