package main

import (
	_ "embed"
	"fmt"
	"log"
	"net/http"
	"os"
	"path/filepath"

	"github.com/gorilla/websocket"
)

//go:embed ui/index.html
var uiHTML string

var upgrader = websocket.Upgrader{CheckOrigin: func(r *http.Request) bool { return true }}

func startUI(dataDir, nodeID, serverAddr string) {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "text/html")
		fmt.Fprint(w, uiHTML)
	})

	http.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
		conn, err := upgrader.Upgrade(w, r, nil)
		if err != nil {
			log.Printf("UI WS upgrade error: %v", err)
			return
		}
		defer conn.Close()

		for {
			var msg map[string]interface{}
			if err := conn.ReadJSON(&msg); err != nil {
				break
			}
			action, _ := msg["action"].(string)
			switch action {
			case "check":
				act, err := loadActivation(dataDir)
				if err == nil && act.Activated {
					conn.WriteJSON(map[string]interface{}{"action": "activated", "studentName": act.StudentName})
				} else {
					conn.WriteJSON(map[string]interface{}{"action": "not_activated"})
				}
			case "activate":
				code, _ := msg["code"].(string)
				// Forward to server WS
				go func() {
					forwardActivation(serverAddr, nodeID, code, conn)
				}()
			case "instances":
				listInstances(dataDir, conn)
			}
		}
	})

	port := "7070"
	log.Printf("UI starting on http://localhost:%s", port)
	if err := http.ListenAndServe("127.0.0.1:"+port, nil); err != nil {
		log.Fatalf("UI server error: %v", err)
	}
}

func forwardActivation(serverAddr, nodeID, code string, uiConn *websocket.Conn) {
	conn, _, err := websocket.DefaultDialer.Dial(serverAddr, nil)
	if err != nil {
		uiConn.WriteJSON(map[string]interface{}{"action": "activation_failed", "error": err.Error()})
		return
	}
	defer conn.Close()

	conn.WriteJSON(map[string]interface{}{"action": "register", "nodeId": nodeID})
	conn.WriteJSON(map[string]interface{}{"action": "activate", "code": code, "nodeId": nodeID})

	for {
		var msg map[string]interface{}
		if err := conn.ReadJSON(&msg); err != nil {
			break
		}
		action, _ := msg["action"].(string)
		if action == "activated" || action == "activation_failed" {
			uiConn.WriteJSON(msg)
			break
		}
	}
}

func listInstances(dataDir string, conn *websocket.Conn) {
	dir := filepath.Join(dataDir, "instances")
	entries, err := os.ReadDir(dir)
	if err != nil {
		conn.WriteJSON(map[string]interface{}{"action": "instances_list", "instances": []interface{}{}})
		return
	}
	var instances []map[string]interface{}
	for _, e := range entries {
		if e.IsDir() {
			instances = append(instances, map[string]interface{}{"id": e.Name()})
		}
	}
	conn.WriteJSON(map[string]interface{}{"action": "instances_list", "instances": instances})
}