package main

// HTTP handlers and hub run loop integration for RadChat.
//
// This file contains:
// - WebSocket and HTTP endpoints (username check, user count, file upload/download)
// - Helpers to send messages to specific clients and broadcast user lists
// - The hub Run loop that manages registration, unregistration, and broadcasting
//
// The actual Hub/Client definitions live in the server package. Here we glue
// them to HTTP.
import (
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"radchat/server"
	"strings"
	"time"
)

// IsUsernameTaken returns true if the given username already exists among connected clients (case-insensitive).
func IsUsernameTaken(h *server.Hub, username string) bool {
	h.Mutex.RLock()
	defer h.Mutex.RUnlock()

	for client := range h.Clients {
		if client.Username == username {
			return true
		}
	}
	return false
}

// HandleUserCountCheck responds with the current number of connected users.
func HandleUserCountCheck(hub *server.Hub, w http.ResponseWriter, r *http.Request) {
	if r.Method != "GET" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	response := map[string]any{
		"userCount": int64(len(hub.Clients)),
	}

	err := json.NewEncoder(w).Encode(response)
	if err != nil {
		return
	}
}

// HandleUsernameCheck validates a requested username and checks for collisions.
func HandleUsernameCheck(hub *server.Hub, w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var request struct {
		Username string `json:"username"`
	}

	if err := json.NewDecoder(r.Body).Decode(&request); err != nil {
		http.Error(w, "Invalid JSON", http.StatusBadRequest)
		return
	}

	w.Header().Set("Content-Type", "application/json")

	// Check if username is taken
	errorString := ""
	isTaken := IsUsernameTaken(hub, request.Username)
	if isTaken {
		errorString = "Username is already taken. Please choose a different username."
	}
	isValid := IsUsernameValid(request.Username)
	if !isValid {
		errorString = "Invalid username. Please use 3-24 characters, letters, numbers, underscores, or hyphens."
	}

	response := map[string]any{
		"available": isValid && !isTaken,
		"username":  request.Username,
		"error":     errorString,
	}

	err := json.NewEncoder(w).Encode(response)
	if err != nil {
		return
	}
}

func SendUsersList(h *server.Hub) {
	h.Mutex.RLock()
	users := make([]map[string]string, 0)
	for client := range h.Clients {
		if client.Username != "" {
			users = append(users, map[string]string{
				"id":       client.Id,
				"username": client.Username,
			})
		}
	}
	h.Mutex.RUnlock()

	msg := Message{
		Type: "users_list",
		Data: users,
	}

	data, err := json.Marshal(msg)
	if err != nil {
		return
	}

	select {
	case h.Broadcast <- data:
	default:
	}
}

func SendToClient(h *server.Hub, targetID string, message []byte) {
	h.Mutex.RLock()
	defer h.Mutex.RUnlock()

	for client := range h.Clients {
		if client.Id == targetID {
			select {
			case client.Send <- message:
			default:
				close(client.Send)
				delete(h.Clients, client)
			}
			return
		}
	}
}

func HandleWebSocket(hub *server.Hub, w http.ResponseWriter, r *http.Request) {
	conn, err := hub.Upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Println("WebSocket upgrade error:", err)
		return
	}

	clientID := r.URL.Query().Get("client_id")

	if clientID == "" {
		clientID = GenerateId()
		log.Println("Client joined. Generated new client ID:", clientID)
	} else {
		log.Println("Client joined. Used existing client ID:", clientID)
	}

	client := &server.Client{
		Conn: conn,
		Id:   clientID,
		Hub:  hub,
		Send: make(chan []byte, 256),
	}

	userIdMsg := map[string]string{
		"type":     "client_id",
		"clientId": clientID,
	}

	if msgBytes, err := json.Marshal(userIdMsg); err == nil {
		client.Send <- msgBytes
	}

	client.Hub.Register <- client

	go WritePump(client)
	go ReadPump(client)
}

func HandleFileUpload(h *server.Hub, filesDir string, fileTimeout time.Duration, w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	err := r.ParseMultipartForm(256 << 20)
	if err != nil {
		http.Error(w, "Error parsing form", http.StatusBadRequest)
		return
	}

	// Get all files
	files := r.MultipartForm.File

	_ = r.ParseForm()
	username := r.FormValue("username")
	clientId := r.FormValue("client_id")

	var uploadedFiles []string

	for _, fileHeaders := range files {
		for _, fileHeader := range fileHeaders {
			file, err := fileHeader.Open()
			if err != nil {
				continue
			}

			fileBytes, err := io.ReadAll(file)
			if err != nil {
				_ = file.Close()
				continue
			}

			filename := SanitizeFilename(fileHeader.Filename)

			// get filename before the extension

			fileExt := filepath.Ext(filename)
			fileName := strings.TrimSuffix(filename, fileExt)
			fileFullName := fileName + "_" + time.Now().Format("20060102150405") + fileExt

			filePath := filepath.Join(filesDir, fileFullName)

			err = os.WriteFile(filePath, fileBytes, 0644)
			if err != nil {
				_ = file.Close()
				continue
			}

			uploadedFiles = append(uploadedFiles, fileFullName)

			fileFullName = url.PathEscape(fileFullName)
			fileLocation := filepath.Join(r.URL.Path, fileFullName)

			scheme := GetScheme(r)

			fileLink := scheme + "://" + filepath.Join(r.Host, fileLocation)

			// find our client and send a message as them
			clients := h.Clients
			for client := range clients {
				if client.Id == clientId {
					broadcastMsg := Message{
						Type:     "chat_message",
						Username: username,
						Data: map[string]any{
							"message":   fileLink,
							"timestamp": time.Now().UnixMilli(),
						},
					}
					data, _ := json.Marshal(broadcastMsg)
					h.Broadcast <- data
					break
				}
			}

			go func() {
				time.Sleep(fileTimeout)
				err := os.Remove(filename)
				if err != nil {
					return
				}
			}()

			_ = file.Close()
		}
	}

	// Respond with success
	response := map[string]interface{}{
		"success":        true,
		"uploaded_files": uploadedFiles,
		"count":          len(uploadedFiles),
	}

	w.Header().Set("Content-Type", "application/json")

	err = json.NewEncoder(w).Encode(response)
	if err != nil {
		return
	}
}

func HandleFileDownload(filesDir string, w http.ResponseWriter, r *http.Request) {
	if r.Method != "GET" {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	path := strings.TrimPrefix(r.URL.Path, "/")
	segments := strings.Split(path, "/")

	if len(segments) < 2 {
		http.Error(w, "Filename required", http.StatusBadRequest)
		return
	}

	filename := segments[len(segments)-1]

	filename = SanitizeFilename(filename)
	if filename == "" {
		http.Error(w, "Invalid filename", http.StatusBadRequest)
		return
	}

	filePath := filepath.Join(filesDir, filename)

	absUploadsDir, err := filepath.Abs(filesDir)
	if err != nil {
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	absFilePath, err := filepath.Abs(filePath)
	if err != nil {
		http.Error(w, "Invalid file path", http.StatusBadRequest)
		return
	}

	if !strings.HasPrefix(absFilePath, absUploadsDir) {
		http.Error(w, "Access denied", http.StatusForbidden)
		return
	}

	if _, err := os.Stat(filePath); os.IsNotExist(err) {
		http.Error(w, "File not found", http.StatusNotFound)
		return
	}

	http.ServeFile(w, r, filePath)
}

func Run(h *server.Hub) {
	log.Println("Hub started and running...")
	for {
		select {
		case client := <-h.Register:
			h.Mutex.Lock()
			h.Clients[client] = true
			h.Mutex.Unlock()
			SendUsersList(h)

		case client := <-h.Unregister:
			var messageJson []byte
			messageJson, _ = json.Marshal(Message{
				Type:     "system_message",
				Data:     fmt.Sprintf("%s left the voice chat", client.Username),
				DataType: "system_message_leave",
				// FIX: Please...
				// Using CONFIG.APP.SYSTEM_MSG_DEFAULT_TIMEOUT from javascript config
				// Hard coding it here for now
				DataTime: 5000,
			})

			for cli := range client.Hub.Clients {
				SendToClient(client.Hub, cli.Id, messageJson)
			}

			h.Mutex.Lock()
			if _, ok := h.Clients[client]; ok {
				delete(h.Clients, client)
				close(client.Send)
			}
			h.Mutex.Unlock()

			log.Println("Client left. Client ID:", client.Id)

			SendUsersList(h)

		case message := <-h.Broadcast:
			h.Mutex.RLock()
			successCount := 0
			for client := range h.Clients {
				select {
				case client.Send <- message:
					successCount++
				default:
					close(client.Send)
					delete(h.Clients, client)
				}
			}
			h.Mutex.RUnlock()
		}
	}
}