package frontend

import (
	"context"
	"embed"
	"io/fs"
	"log"
	"net/http"
	"time"

	"alox.tool/api"
	"alox.tool/eventbus"
	"github.com/gorilla/websocket"
)

//go:embed www
var staticFiles embed.FS

var upgrader = websocket.Upgrader{}

type FServer struct {
	bus eventbus.EventBus
	mux *http.ServeMux
}

func New(bus eventbus.EventBus) *FServer {
	fsrv := &FServer{
		bus: bus,
		mux: http.NewServeMux(),
	}
	fsrv.routes()
	return fsrv
}

func (fsrv *FServer) routes() {
	// Statische Dateien aus dem Embed-FS
	// "www" Präfix entfernen, damit index.html unter / verfügbar ist
	root, _ := fs.Sub(staticFiles, "www")
	fsrv.mux.Handle("/", http.FileServer(http.FS(root)))

	// WebSocket Endpunkt
	fsrv.mux.HandleFunc("/ws", fsrv.handleWS)
}

func (fsrv *FServer) handleWS(w http.ResponseWriter, r *http.Request) {
	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Printf("Upgrade error: %v", err)
		return
	}
	defer conn.Close()

	// Kanäle für die Hardware-Events abonnieren
	rxChan := fsrv.bus.Subscribe(api.TopicUARTRx)
	txChan := fsrv.bus.Subscribe(api.TopicUARTTx)

	// Context nutzen, um Goroutinen zu stoppen, wenn die Verbindung abreißt
	ctx, cancel := context.WithCancel(r.Context())
	defer cancel()

	// WRITER: Send Events to Browser
	go func() {
		for {
			select {
			case <-ctx.Done():
				return
			case f := <-rxChan:
				if err := conn.WriteJSON(map[string]any{"type": "rx", "frame": f}); err != nil {
					return
				}
			case f := <-txChan:
				if err := conn.WriteJSON(map[string]any{"type": "tx", "frame": f}); err != nil {
					return
				}
			}
		}
	}()

	// READER: Commands from Browser
	for {
		var cmd api.FrontendCmd
		if err := conn.ReadJSON(&cmd); err != nil {
			log.Printf("WS Read Error: %v", err)
			break
		}

		fsrv.bus.Publish(api.TopicFrontendCmd, cmd)
		log.Printf("Browser Action: %s auf ID 0x%02X", cmd.Action, cmd.ID)
	}
}

func (fsrv *FServer) Start(addr string) error {
	server := &http.Server{
		Addr:         addr,
		Handler:      fsrv.mux,
		ReadTimeout:  5 * time.Second,
		WriteTimeout: 10 * time.Second,
	}

	log.Printf("Frontend Server gestartet auf %s", addr)
	return server.ListenAndServe()
}