package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"image/color"
	"log"
	"net/url"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"syscall"
	"unsafe"

	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/canvas"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/dialog"
	"fyne.io/fyne/v2/layout"
	"fyne.io/fyne/v2/theme"
	"fyne.io/fyne/v2/widget"
	"fyne.io/fyne/v2"

	"golang.org/x/sys/windows/registry"
)

// Config represents a VPN configuration
type Config struct {
	Title string
	URL   string
}

var (
	currentProcess *exec.Cmd
	configs        []Config // Store all configurations
	activeConfig   int      // Index of the active config (-1 if none)
)

// checkSingBox checks if sing-box.exe exists in the bin folder
func checkSingBox() bool {
	singBoxPath := filepath.Join("bin", "sing-box.exe")
	if _, err := os.Stat(singBoxPath); os.IsNotExist(err) {
		return false
	}
	return true
}

// isValidVLESS checks if the given URL is a valid VLESS URL
func isValidVLESS(vlessURL string) bool {
	// Basic validation for VLESS URL format
	if !strings.HasPrefix(vlessURL, "vless://") {
		return false
	}

	u, err := url.Parse(vlessURL)
	if err != nil {
		return false
	}

	// Check if it's a valid VLESS link
	matched, _ := regexp.MatchString(`^vless://[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}@.*`, vlessURL)
	if !matched {
		return false
	}

	// Additional validation checks can be added here
	return u.Scheme == "vless" && u.Host != ""
}

// addConfig adds a new configuration to the list
func addConfig(title, url string) {
	configs = append(configs, Config{Title: title, URL: url})
}

// updateConfig updates an existing configuration
func updateConfig(index int, title, url string) {
	if index >= 0 && index < len(configs) {
		configs[index].Title = title
		configs[index].URL = url
	}
}

// removeConfig removes a configuration by index
func removeConfig(index int) {
	if index >= 0 && index < len(configs) {
		configs = append(configs[:index], configs[index+1:]...)
		if activeConfig >= index {
			activeConfig--
		}
		if activeConfig >= len(configs) {
			activeConfig = -1
		}
	}
}

// generateAndRunSingBox generates a Sing-box config from VLESS URL and runs sing-box
func generateAndRunSingBox(vlessURL string) error {
	// Generate unique config filename based on timestamp or hash
	configPath := "config.json"

	// Generate the Sing-box configuration from the VLESS URL
	err := generateConfigFromVLESSURL(vlessURL, configPath)
	if err != nil {
		return fmt.Errorf("failed to generate config: %v", err)
	}

	// Run sing-box with the generated config
	return runSingBox(configPath)
}

// runSingBox starts the sing-box process with the given config path
func runSingBox(configPath string) error {
	singBoxPath := filepath.Join("bin", "sing-box.exe")

	if !checkSingBox() {
		return nil
	}

	cmd := exec.Command(singBoxPath, "run", "-c", configPath)

	// Make the process run as hidden
	cmd.SysProcAttr = &syscall.SysProcAttr{
		HideWindow: true,
	}

	err := cmd.Start()
	if err != nil {
		return err
	}

	currentProcess = cmd
	return nil
}

// killCurrentProcess terminates the current sing-box process if running
func killCurrentProcess() {
	if currentProcess != nil && currentProcess.Process != nil {
		currentProcess.Process.Kill()
		currentProcess = nil
	}
}

// VLESSConfig represents parsed VLESS URL data
type VLESSConfig struct {
	UUID       string
	ServerAddr string
	ServerPort int
	Type       string
	SNI        string
	Network    string
	Path       string
	Host       string
	Fingerprint string
	Flow       string
	AllowInsecure bool
}

// parseVLESS parses a VLESS URL and extracts relevant information
func parseVLESS(vlessURL string) (*VLESSConfig, error) {
	u, err := url.Parse(vlessURL)
	if err != nil {
		return nil, err
	}

	// Extract UUID from the user part of the URL
	uuid := u.User.Username()

	// Extract server address and port
	serverAddr := u.Hostname()
	portStr := u.Port()
	if portStr == "" {
		return nil, fmt.Errorf("port not specified in VLESS URL")
	}
	port, err := strconv.Atoi(portStr)
	if err != nil {
		return nil, err
	}

	// Parse query parameters
	params := u.Query()

	vlessConfig := &VLESSConfig{
		UUID:          uuid,
		ServerAddr:    serverAddr,
		ServerPort:    port,
		Type:          params.Get("type"),
		SNI:           params.Get("sni"),
		Network:       params.Get("network"),
		Path:          params.Get("path"),
		Host:          params.Get("host"),
		Fingerprint:   params.Get("fp"),
		Flow:          params.Get("flow"),
		AllowInsecure: params.Get("allowInsecure") == "true",
	}

	// Set default network type if not specified
	if vlessConfig.Network == "" {
		vlessConfig.Network = "tcp"
	}

	return vlessConfig, nil
}

// SingBoxOutbound represents an outbound configuration for Sing-box
type SingBoxOutbound struct {
	Type              string                 `json:"type"`
	Tag               string                 `json:"tag,omitempty"`
	Server            string                 `json:"server"`
	ServerPort        int                    `json:"server_port"`
	UUID              string                 `json:"uuid"`
	Flow              string                 `json:"flow,omitempty"`
	Network           string                 `json:"network,omitempty"`
	TLS               *SingBoxTLS            `json:"tls,omitempty"`
	Transport         map[string]interface{} `json:"transport,omitempty"`
	V2RayTransport    *V2RayTransport        `json:"v2ray_transport,omitempty"`
}

// SingBoxTLS represents TLS configuration for Sing-box
type SingBoxTLS struct {
	Enabled      bool   `json:"enabled"`
	ServerName   string `json:"server_name,omitempty"`
	Insecure     bool   `json:"insecure,omitempty"`
	Fingerprint  string `json:"fingerprint,omitempty"`
	UTLS         *UTLS  `json:"utls,omitempty"`
}

// UTLS represents uTLS configuration
type UTLS struct {
	Enabled     bool   `json:"enabled"`
	Fingerprint string `json:"fingerprint"`
}

// V2RayTransport represents V2Ray transport configuration
type V2RayTransport struct {
	Type        string                 `json:"type"`
	Headers     map[string]string      `json:"headers,omitempty"`
	Host        string                 `json:"host,omitempty"`
	Method      string                 `json:"method,omitempty"`
	Path        string                 `json:"path,omitempty"`
	ServiceName string                 `json:"service_name,omitempty"`
	Metadata    map[string]interface{} `json:"metadata,omitempty"`
}

// SingBoxInbound represents an inbound configuration for Sing-box
type SingBoxInbound struct {
	Type         string `json:"type"`
	Tag          string `json:"tag,omitempty"`
	Listen       string `json:"listen"`
	ListenPort   int    `json:"listen_port"`
	SetSystemProxy bool `json:"set_system_proxy,omitempty"`
}

// SingBoxConfig represents the full Sing-box configuration
type SingBoxConfig struct {
	Log      map[string]interface{}   `json:"log"`
	Inbounds []SingBoxInbound         `json:"inbounds"`
	Outbounds []SingBoxOutbound        `json:"outbounds"`
}

// generateSingBoxConfig generates a Sing-box configuration from VLESSConfig
func generateSingBoxConfig(vlessConfig *VLESSConfig, configPath string) error {
	// Create TLS configuration if SNI is present
	var tlsConfig *SingBoxTLS
	if vlessConfig.SNI != "" || vlessConfig.Fingerprint != "" {
		tlsConfig = &SingBoxTLS{
			Enabled:    true,
			ServerName: vlessConfig.SNI,
			Insecure:   vlessConfig.AllowInsecure,
		}

		if vlessConfig.Fingerprint != "" {
			tlsConfig.Fingerprint = vlessConfig.Fingerprint
			// Enable uTLS if fingerprint is specified
			tlsConfig.UTLS = &UTLS{
				Enabled:     true,
				Fingerprint: vlessConfig.Fingerprint,
			}
		}
	}

	// Create V2Ray transport if specific transport settings are present
	var v2rayTransport *V2RayTransport
	if vlessConfig.Path != "" || vlessConfig.Host != "" {
		v2rayTransport = &V2RayTransport{
			Type: vlessConfig.Network,
		}

		if vlessConfig.Path != "" {
			v2rayTransport.Path = vlessConfig.Path
		}

		if vlessConfig.Host != "" {
			v2rayTransport.Host = vlessConfig.Host
		}

		// For HTTP headers
		if vlessConfig.Host != "" {
			v2rayTransport.Headers = map[string]string{
				"Host": vlessConfig.Host,
			}
		}
	}

	// Create the outbound configuration
	outbound := SingBoxOutbound{
		Type:       "vless",
		Server:     vlessConfig.ServerAddr,
		ServerPort: vlessConfig.ServerPort,
		UUID:       vlessConfig.UUID,
		Flow:       vlessConfig.Flow,
		Network:    vlessConfig.Network,
	}

	if tlsConfig != nil {
		outbound.TLS = tlsConfig
	}

	if v2rayTransport != nil {
		outbound.V2RayTransport = v2rayTransport
	}

	// Special handling for different transport types
	switch vlessConfig.Network {
	case "ws":
		// WebSocket transport
		transport := map[string]interface{}{
			"type": vlessConfig.Network,
		}

		if vlessConfig.Path != "" {
			transport["path"] = vlessConfig.Path
		}

		if vlessConfig.Host != "" {
			headers := map[string]interface{}{
				"Host": vlessConfig.Host,
			}
			transport["headers"] = headers
		}

		outbound.Transport = transport
	case "grpc":
		// gRPC transport
		transport := map[string]interface{}{
			"type": vlessConfig.Network,
		}

		if vlessConfig.Path != "" {
			transport["service_name"] = vlessConfig.Path
		}

		outbound.Transport = transport
	}

	// Create inbounds - mixed (SOCKS5 + HTTP) on port 1080
	inbounds := []SingBoxInbound{
		{
			Type:         "mixed",
			Listen:       "127.0.0.1",
			ListenPort:   1080,
			SetSystemProxy: true,
		},
	}

	// Create the full configuration
	config := SingBoxConfig{
		Log: map[string]interface{}{
			"level": "info",
		},
		Inbounds:  inbounds,
		Outbounds: []SingBoxOutbound{outbound},
	}

	// Convert to JSON
	jsonData, err := json.MarshalIndent(config, "", "  ")
	if err != nil {
		return err
	}

	// Write to file
	err = os.WriteFile(configPath, jsonData, 0644)
	if err != nil {
		return err
	}

	log.Printf("Sing-box configuration written to %s", configPath)
	return nil
}

// generateConfigFromVLESSURL parses a VLESS URL and generates a Sing-box config file
func generateConfigFromVLESSURL(vlessURL, outputPath string) error {
	// Parse the VLESS URL
	vlessConfig, err := parseVLESS(vlessURL)
	if err != nil {
		return err
	}

	// Generate the Sing-box configuration
	err = generateSingBoxConfig(vlessConfig, outputPath)
	if err != nil {
		return err
	}

	return nil
}

// setSystemProxy enables the system proxy with the specified server and port
func setSystemProxy(proxyServer string) error {
	key, err := registry.OpenKey(registry.CURRENT_USER, `Software\Microsoft\Windows\CurrentVersion\Internet Settings`, registry.SET_VALUE)
	if err != nil {
		return fmt.Errorf("failed to open registry key: %v", err)
	}
	defer key.Close()

	// Set ProxyEnable to 1 to enable proxy
	err = key.SetDWordValue("ProxyEnable", 1)
	if err != nil {
		return fmt.Errorf("failed to set ProxyEnable: %v", err)
	}

	// Set ProxyServer to the specified server and port
	err = key.SetStringValue("ProxyServer", proxyServer)
	if err != nil {
		return fmt.Errorf("failed to set ProxyServer: %v", err)
	}

	// Optionally, set ProxyOverride to bypass proxy for local addresses
	err = key.SetStringValue("ProxyOverride", "localhost;127.*;10.*;172.16.*;172.17.*;172.18.*;172.19.*;172.20.*;172.21.*;172.22.*;172.23.*;172.24.*;172.25.*;172.26.*;172.27.*;172.28.*;172.29.*;172.30.*;172.31.*;192.168.*")
	if err != nil {
		return fmt.Errorf("failed to set ProxyOverride: %v", err)
	}

	// Notify Windows that the proxy settings have changed
	notifyProxyChange()

	return nil
}

// disableSystemProxy disables the system proxy
func disableSystemProxy() error {
	key, err := registry.OpenKey(registry.CURRENT_USER, `Software\Microsoft\Windows\CurrentVersion\Internet Settings`, registry.SET_VALUE)
	if err != nil {
		return fmt.Errorf("failed to open registry key: %v", err)
	}
	defer key.Close()

	// Set ProxyEnable to 0 to disable proxy
	err = key.SetDWordValue("ProxyEnable", 0)
	if err != nil {
		return fmt.Errorf("failed to set ProxyEnable: %v", err)
	}

	// Notify Windows that the proxy settings have changed
	notifyProxyChange()

	return nil
}

// notifyProxyChange notifies Windows that proxy settings have changed
func notifyProxyChange() {
	// Use Windows API to notify about proxy change
	// Call InternetSetOption to refresh proxy settings
	procInternetSetOption := syscall.NewLazyDLL("wininet.dll").NewProc("InternetSetOptionW")
	procInternetSetOption.Call(
		0,                // hInternet = NULL
		39,               // INTERNET_OPTION_SETTINGS_CHANGED
		0,                // lpBuffer = NULL
		0,                // dwBufferLength = 0
	)

	// Also send WM_SETTINGCHANGE to broadcast the change
	procSendMessageTimeout := syscall.NewLazyDLL("user32.dll").NewProc("SendMessageTimeoutW")
	procSendMessageTimeout.Call(
		0xFFFF,           // HWND_BROADCAST
		0x001A,           // WM_SETTINGCHANGE
		uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr("Proxy"))),
		0,
		0x0002,           // SMTO_ABORTIFHUNG
		5000,             // timeout
	)
}

func main() {
	myApp := app.New()
	myWindow := myApp.NewWindow("Hamy VPN Client")

	// Set the window size to 200x300 as requested
	myWindow.Resize(fyne.NewSize(200, 300))

	// Initialize active config to -1 (no config selected)
	activeConfig = -1

	// Connection state - true for connected, false for disconnected
	var isConnected bool = false

	// Update connection button text based on connection state
	updateConnectionButtonText := func(button *widget.Button) {
		if isConnected {
			button.SetText("Отключить")
		} else {
			button.SetText("Подключить")
		}
	}

	// Create program title with proper padding
	titleText := canvas.NewText("Hamy VPN", nil)
	titleText.TextStyle.Bold = true
	titleText.TextSize = 16
	titleText.Alignment = fyne.TextAlignLeading

	// Create settings button (gear icon)
	settingsButton := widget.NewButtonWithIcon("", theme.SettingsIcon(), func() {
		// Show settings dialog in a separate fixed-size window
		settingsWindow := myApp.NewWindow("Настройки")
		settingsWindow.Resize(fyne.NewSize(400, 300))
		settingsWindow.SetFixedSize(true)

		// Add content to settings window (for now just a placeholder)
		settingsLabel := widget.NewLabel("Настройки приложения")
		settingsContent := container.NewVBox(
			settingsLabel,
			widget.NewLabel("Добавьте элементы настроек здесь"),
		)

		settingsWindow.SetContent(settingsContent)
		settingsWindow.Show()
	})

	// Create HBox for title and settings button with proper padding
	titleContainer := container.NewBorder(nil, nil, titleText, settingsButton, layout.NewSpacer())

	// Status indicator (bold, smaller padding)
	statusLabel := canvas.NewText("Отключено", color.RGBA{R: 128, G: 128, B: 128, A: 255}) // Gray color
	statusLabel.Alignment = fyne.TextAlignCenter
	statusLabel.TextSize = 14  // Small font
	statusLabel.TextStyle.Bold = true  // Make it bold

	// Connect/Disconnect button (with dynamic text)
	var connectButton *widget.Button
	connectButton = widget.NewButton("Подключить", func() {
		if activeConfig == -1 || len(configs) == 0 {
			dialog.ShowError(errors.New("Выберите конфигурацию"), myWindow)
			return
		}

		// Toggle connection state
		if !isConnected {
			// Connect - generate config and run sing-box
			err := generateAndRunSingBox(configs[activeConfig].URL)
			if err != nil {
				dialog.ShowError(fmt.Errorf("failed to start connection: %v", err), myWindow)
				// Revert connection state on failure
				isConnected = false
				updateConnectionButtonText(connectButton)
				statusLabel.Text = "Отключено"
				statusLabel.Color = color.RGBA{R: 128, G: 128, B: 128, A: 255}
				statusLabel.Refresh()
				return
			}

			// Set proxy to route traffic through VPN
			err = setSystemProxy("127.0.0.1:1080")
			if err != nil {
				log.Printf("Failed to set system proxy: %v", err)
				dialog.ShowError(fmt.Errorf("failed to set system proxy: %v", err), myWindow)
			}

			// Update connection state after successful connection
			isConnected = true
		} else {
			// Disconnect - kill the current process
			killCurrentProcess()

			// Disable proxy when disconnecting from VPN
			err := disableSystemProxy()
			if err != nil {
				log.Printf("Failed to disable system proxy: %v", err)
			}

			// Update connection state after disconnection
			isConnected = false
		}

		// Update button text
		updateConnectionButtonText(connectButton)

		// Update status text
		if isConnected {
			statusLabel.Text = "Подключено"
			statusLabel.Color = color.RGBA{R: 0, G: 128, B: 0, A: 255} // Green color for connected
		} else {
			statusLabel.Text = "Отключено"
			statusLabel.Color = color.RGBA{R: 128, G: 128, B: 128, A: 255} // Gray color for disconnected
		}
		statusLabel.Refresh()
	})
	connectButton.Importance = widget.HighImportance
	if len(configs) == 0 {
		connectButton.Disable() // Disable initially until a config is selected
	} else {
		connectButton.Enable() // Enable if we have configs
	}

	// Configurations button - opens a separate window
	configsButton := widget.NewButton("Конфигурации", func() {
		// Create a separate fixed-size window for configurations
		configWindow := myApp.NewWindow("Конфигурации")
		configWindow.Resize(fyne.NewSize(400, 300))
		configWindow.SetFixedSize(true)

		// Declare variables before use
		var listContainer *widget.List
		var scrollContainer *container.Scroll
		var refreshList func()

		// Entry for importing new configuration - fixed to expand properly
		importEntry := widget.NewEntry()
		importEntry.PlaceHolder = "vless://..."

		// Container for import field and button - use HBox to allow proper expansion
		importButton := widget.NewButtonWithIcon("", theme.ContentAddIcon(), func() {
			url := importEntry.Text
			if url != "" && isValidVLESS(url) {
				title := fmt.Sprintf("Конфиг %d", len(configs)+1)
				addConfig(title, url)
				dialog.ShowInformation("Успешно", "Конфиг добавлен", configWindow)

				// Refresh the list
				refreshList()
				importEntry.SetText("")
			} else if url != "" {
				dialog.ShowError(errors.New("Невалидная ссылка"), configWindow)
			}
		})

		// Fixed the order of operations to avoid nil reference
		refreshList = func() {
			// Create the list first
			newListContainer := widget.NewList(
				func() int {
					return len(configs)
				},
				func() fyne.CanvasObject {
					return container.NewBorder(nil, nil,
						widget.NewLabel("Template"),
						container.NewHBox(
							widget.NewButtonWithIcon("", theme.DocumentCreateIcon(), func() {}),
							widget.NewButtonWithIcon("", theme.DeleteIcon(), func() {}),
						),
					)
				},
				func(id widget.ListItemID, obj fyne.CanvasObject) {
					containerObj := obj.(*fyne.Container)

					// For a container.NewBorder(nil, nil, left, right, nil), the structure is:
					// Objects[0] is the left element (label)
					// Objects[1] is the right element (buttons container)
					titleLabel := containerObj.Objects[0].(*widget.Label)
					buttonsContainer := containerObj.Objects[1].(*fyne.Container)

					editButton := buttonsContainer.Objects[0].(*widget.Button)
					deleteButton := buttonsContainer.Objects[1].(*widget.Button)

					// Update visual indication for active config
					if id == activeConfig {
						titleLabel.SetText(fmt.Sprintf("● %s", configs[id].Title))
					} else {
						titleLabel.SetText(fmt.Sprintf("○ %s", configs[id].Title))
					}

					// Set up edit button
					editButton.OnTapped = func() {
						showEditDialog(configWindow, id)
					}

					// Set up delete button
					deleteButton.OnTapped = func() {
						dialog.ShowConfirm("Удалить конфигурацию",
							fmt.Sprintf("Вы уверены, что хотите удалить конфигурацию '%s'?", configs[id].Title),
							func(confirmed bool) {
								if confirmed {
									removeConfig(id)
									dialog.ShowInformation("Удалено", "Конфигурация удалена", configWindow)

									// Refresh the list
									refreshList()
								}
							},
							configWindow)
					}
				},
			)

			newListContainer.OnSelected = func(id widget.ListItemID) {
				activeConfig = id
				dialog.ShowInformation("Config Selected", fmt.Sprintf("Active config: %s", configs[id].Title), configWindow)
				configWindow.Close()
			}

			// Assign to the variable before using it in the scroll container
			listContainer = newListContainer

			// Create scroll container only once
			if scrollContainer == nil {
				scrollContainer = container.NewScroll(listContainer)
			} else {
				scrollContainer.Content = listContainer
				scrollContainer.Refresh()
			}
		}

		// Call refreshList to initialize the list first
		refreshList()

		// Container for import field and button - use HBox to allow proper expansion
		// Using container.NewBorder to make the entry expand properly
		importContainer := container.NewBorder(nil, nil, nil, importButton, importEntry)

		// Main content for the config window using a border container to properly size the scroll area
		configContent := container.NewBorder(importContainer, nil, nil, nil, scrollContainer)

		configWindow.SetContent(configContent)
		configWindow.Show()
	})

	// Main content container with vertical layout
	contentContainer := container.NewVBox(
		titleContainer,
		layout.NewSpacer(),
		container.NewCenter(statusLabel),
		layout.NewSpacer(),
		container.NewCenter(connectButton),
		layout.NewSpacer(),
		container.NewCenter(configsButton),
		layout.NewSpacer(),
	)

	// Create a top-level container
	mainContainer := container.NewStack(contentContainer)

	// Register an app lifecycle listener to handle cleanup when the app exits
	myApp.Lifecycle().SetOnStopped(func() {
		// Kill the current process if running
		if currentProcess != nil && currentProcess.Process != nil {
			currentProcess.Process.Kill()
		}

		// Disable proxy when the application exits
		err := disableSystemProxy()
		if err != nil {
			log.Printf("Failed to disable system proxy on exit: %v", err)
		}
	})

	// Set the content and show the window
	myWindow.SetContent(mainContainer)

	myWindow.ShowAndRun()
}

// Function to show the edit dialog
func showEditDialog(parentWindow fyne.Window, configIndex int) {
	// Create entry fields for title and URL with existing values
	titleEntry := widget.NewEntry()
	titleEntry.SetText(configs[configIndex].Title)
	titleEntry.PlaceHolder = "Название конфигурации"
	urlEntry := widget.NewEntry()
	urlEntry.SetText(configs[configIndex].URL)
	urlEntry.PlaceHolder = "vless://..."

	// Create a custom dialog
	editDialog := dialog.NewForm("Редактировать конфигурацию", "Сохранить", "Отмена",
		[]*widget.FormItem{
			widget.NewFormItem("Заголовок", titleEntry),
			widget.NewFormItem("Ссылка", urlEntry),
		},
		func(ok bool) {
			if ok {
				title := titleEntry.Text
				url := urlEntry.Text

				if title == "" {
					title = fmt.Sprintf("Конфиг %d", configIndex+1) // Default title
				}

				if isValidVLESS(url) {
					updateConfig(configIndex, title, url)
					dialog.ShowInformation("Успешно", "Конфиг обновлен", parentWindow)
				} else {
					dialog.ShowError(errors.New("Невалидная ссылка"), parentWindow)
				}
			}
		},
		parentWindow,
	)
	editDialog.Show()
}