TeleportFling/internal/gui/gui.go

// Package gui provides the Fyne desktop app: a settings window and a system
// tray that start/stop the flinger engine.
//
// The engine itself lives in internal/flinger and is GUI-free, so the tray
// can control streaming without any UI dependency. This package wires the two
// together: config persistence, the settings form, and the tray menu.
package gui

import (
	"errors"
	"log"
	"strconv"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/dialog"
	"fyne.io/fyne/v2/driver/desktop"
	"fyne.io/fyne/v2/widget"

	"teleportfling/internal/config"
	"teleportfling/internal/flinger"
)

// errInvalidPort is returned when the port field contains a non-numeric or
// out-of-range value.
var errInvalidPort = errors.New("port must be 1–65535")

func itoa(v int) string { return strconv.Itoa(v) }

func atoi(s string) (int, error) { return strconv.Atoi(s) }

// appID is the Fyne application ID used for preferences/settings storage.
const appID = "io.teleportfling"

// App is the desktop application shell.
type App struct {
	fyneApp fyne.App
	win     fyne.Window

	cfg  config.Config
	eng  *flinger.Engine
	lock bool // serialises start/stop against UI actions

	// UI state.
	startBtn   *widget.Button
	statusLab  *widget.Label
	portEnt    *widget.Entry
	qualitySel *widget.Select
	fpsSel     *widget.Select
	nameEnt    *widget.Entry
	audioChk   *widget.Check
	srcSel     *widget.Select
}

// Run starts the GUI and blocks until the app exits.
func Run() {
	g := &App{}

	g.fyneApp = app.NewWithID(appID)
	g.win = g.fyneApp.NewWindow("TeleportFling")

	// Load persisted settings (falling back to defaults).
	g.cfg = mustLoadConfig()

	g.buildUI()

	// Closing the window hides it (tray keeps the app alive) rather than
	// quitting, which is the expected behaviour for a tray app.
	g.win.SetCloseIntercept(func() {
		g.win.Hide()
	})

	g.setupTray()

	g.win.ShowAndRun()
}

// mustLoadConfig loads the config, logging and falling back to defaults.
func mustLoadConfig() config.Config {
	c, err := config.Load()
	if err != nil {
		log.Printf("gui: config load: %v (using defaults)", err)
		return config.Default()
	}
	return c
}

// buildUI creates the settings form and wires its widgets to cfg.
func (g *App) buildUI() {
	// Stream identity.
	g.nameEnt = widget.NewEntry()
	g.nameEnt.SetPlaceHolder("Stream name (default: hostname)")
	g.nameEnt.SetText(g.cfg.Name)

	// Port.
	g.portEnt = widget.NewEntry()
	g.portEnt.SetText(itoa(g.cfg.Port))
	g.portEnt.Validator = func(s string) error {
		n, err := atoi(s)
		if err != nil || n < 1 || n > 65535 {
			return errInvalidPort
		}
		return nil
	}

	// Source.
	g.srcSel = widget.NewSelect([]string{"screen", "pattern"}, func(string) {})
	g.srcSel.SetSelected(g.cfg.Source)

	// Quality.
	g.qualitySel = widget.NewSelect([]string{"50", "60", "70", "80", "90", "100"}, func(string) {})
	g.qualitySel.SetSelected(itoa(g.cfg.Quality))

	// FPS.
	g.fpsSel = widget.NewSelect([]string{"15", "30", "60"}, func(string) {})
	g.fpsSel.SetSelected(itoa(g.cfg.FPS))

	// Audio.
	g.audioChk = widget.NewCheck("Capture system audio", nil)
	g.audioChk.SetChecked(g.cfg.Audio)

	// Status label.
	g.statusLab = widget.NewLabel("Stopped")
	g.statusLab.Importance = widget.MediumImportance

	// Start/stop toggle.
	g.startBtn = widget.NewButton("Start", g.toggleStream)
	g.startBtn.Importance = widget.HighImportance

	form := &widget.Form{
		Items: []*widget.FormItem{
			{Text: "Name", Widget: g.nameEnt},
			{Text: "Port", Widget: g.portEnt},
			{Text: "Source", Widget: g.srcSel},
			{Text: "Quality", Widget: g.qualitySel},
			{Text: "Frame rate", Widget: g.fpsSel},
			{Text: "", Widget: g.audioChk},
		},
	}

	content := container.NewVBox(
		widget.NewLabelWithStyle("TeleportFling", fyne.TextAlignCenter, fyne.TextStyle{Bold: true}),
		form,
		g.statusLab,
		g.startBtn,
	)

	g.win.SetContent(container.NewBorder(nil, content, nil, nil, nil))
	g.win.Resize(fyne.NewSize(380, 0))
}

// toggleStream starts or stops the engine based on current UI state.
func (g *App) toggleStream() {
	if g.lock {
		return
	}
	if g.eng != nil {
		g.stop()
		return
	}
	g.start()
}

// start reads the form into cfg, saves it, and boots the engine.
func (g *App) start() {
	port, _ := atoi(g.portEnt.Text)
	quality, _ := atoi(g.qualitySel.Selected)
	fps, _ := atoi(g.fpsSel.Selected)

	g.cfg = config.Config{
		Name:        g.nameEnt.Text,
		Port:        port,
		Quality:     quality,
		FPS:         fps,
		Source:      g.srcSel.Selected,
		Audio:       g.audioChk.Checked,
		StreamIndex: g.cfg.StreamIndex,
	}
	if err := config.Save(g.cfg); err != nil {
		log.Printf("gui: config save: %v", err)
	}

	eng, err := flinger.New(g.cfg.ToFlinger())
	if err != nil {
		dialog.ShowError(err, g.win)
		return
	}
	g.eng = eng
	g.eng.Start()

	g.startBtn.SetText("Stop")
	g.startBtn.Importance = widget.DangerImportance
	g.statusLab.SetText("Streaming (port " + itoa(g.cfg.Port) + ")")
	g.statusLab.Importance = widget.SuccessImportance
	g.refresh()
}

// stop halts the engine and returns the UI to the stopped state.
func (g *App) stop() {
	if g.eng != nil {
		g.eng.Stop()
		g.eng = nil
	}
	g.startBtn.SetText("Start")
	g.startBtn.Importance = widget.HighImportance
	g.statusLab.SetText("Stopped")
	g.statusLab.Importance = widget.MediumImportance
	g.refresh()
}

// refresh forces the window to repaint (state/importance changed).
func (g *App) refresh() {
	g.startBtn.Refresh()
	g.statusLab.Refresh()
}

// setupTray registers the system tray menu and window. If the platform driver
// does not support a tray (older Fyne/desktops), this is a no-op and the
// window close intercept simply won't hide.
func (g *App) setupTray() {
	desk, ok := g.fyneApp.(desktop.App)
	if !ok {
		log.Printf("gui: system tray not supported on this desktop")
		return
	}

	m := fyne.NewMenu("TeleportFling",
		fyne.NewMenuItem("Show", func() {
			// Show is a no-op if the window is already visible, so also raise
			// and focus it to bring it to the foreground.
			g.win.Show()
			g.win.RequestFocus()
		}),
		fyne.NewMenuItemSeparator(),
		fyne.NewMenuItem("Start", g.toggleStream),
		fyne.NewMenuItem("Stop", func() {
			if g.eng != nil {
				g.stop()
			}
		}),
		fyne.NewMenuItemSeparator(),
		fyne.NewMenuItem("Quit", func() {
			if g.eng != nil {
				g.eng.Stop()
			}
			g.fyneApp.Quit()
		}),
	)
	desk.SetSystemTrayMenu(m)
	// Left-clicking the tray icon shows the settings window.
	desk.SetSystemTrayWindow(g.win)
	g.win.SetOnClosed(func() { g.fyneApp.Quit() })
}