// Package tray provides system tray functionality for the application.
// It displays an icon in the Windows notification area with a context menu.
package tray

import (
	"bytes"
	_ "embed"
	"encoding/binary"
	"fmt"
	"os"
	"runtime"
	"strings"
	"sync"

	"wis-free-v3/internal/config"
	"wis-free-v3/internal/logger"
	"wis-free-v3/internal/platform"

	"github.com/getlantern/systray"
)

//go:embed icon.ico
var iconData []byte

//go:embed icon_recording.png
var iconRecordingData []byte

//go:embed icon_transcribing.png
var iconTranscribingData []byte

// App defines the interface required by the tray package to interact with the main application.
type App interface {
	Quit()
	GetConfig() *config.Config
	ShowSettings()
	Version() string
}

// trayLabel is the short product name shown in the tray (includes version when set at link time).
var trayLabel = "wis-free-v3"

// Menu item references for dynamic updates
var statusMenuItem *systray.MenuItem
var triggerCountItem *systray.MenuItem
var triggerCount int

// Start initializes and runs the system tray.
// This function blocks until the tray is terminated.
func Start(app App) {
	// Pin this goroutine to one OS thread for the whole lifetime of systray.Run.
	// getlantern/systray creates the notify icon and runs the Win32 message pump on
	// whichever thread calls Run; if the goroutine migrates between threads, callbacks
	// and the tray context menu break until restart (often seen after sleep/resume).
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()
	systray.Run(
		func() { onReady(app) },
		onExit,
	)
}

func appDisplayName(app App) string {
	v := app.Version()
	if v != "" && v != "dev" {
		return "wis-free-v3 v" + v
	}
	return "wis-free-v3"
}

// onReady is called when the system tray is ready to be configured.
func onReady(app App) {
	trayLabel = appDisplayName(app)

	// Configure tray icon and tooltip
	systray.SetIcon(getDefaultIcon())
	systray.SetTitle(trayLabel)
	systray.SetTooltip(buildTooltip(app))

	// Build menu structure
	statusMenuItem = systray.AddMenuItem("Status: Ready", "Current application status")
	statusMenuItem.Disable()

	triggerCountItem = systray.AddMenuItem("Shortcut detected: 0 times", "Troubleshooting counter")
	triggerCountItem.Disable()

	systray.AddSeparator()

	menuSettings := systray.AddMenuItem("Settings", "Open settings window")
	menuStartup := systray.AddMenuItemCheckbox(
		"Start with system",
		"Automatically start when computer boots",
		platform.IsInStartup(),
	)

	systray.AddSeparator()

	menuExit := systray.AddMenuItem("Exit", "Close the application")

	// Handle menu events in background
	go handleMenuEvents(app, menuSettings, menuStartup, menuExit)
}

// handleMenuEvents processes menu item click events.
func handleMenuEvents(app App, settings, startupItem, exit *systray.MenuItem) {
	for {
		select {
		case <-settings.ClickedCh:
			go app.ShowSettings()

		case <-startupItem.ClickedCh:
			go toggleStartup(startupItem)

		case <-exit.ClickedCh:
			go handleExit(app)
		}
	}
}

// toggleStartup handles the startup toggle menu item.
func toggleStartup(item *systray.MenuItem) {
	if item.Checked() {
		if err := platform.RemoveFromStartup(); err != nil {
			logger.Error("Failed to remove from startup: %v", err)
		} else {
			item.Uncheck()
			logger.Info("Removed from system startup")
		}
	} else {
		if err := platform.AddToStartup(); err != nil {
			logger.Error("Failed to add to startup: %v", err)
		} else {
			item.Check()
			logger.Info("Added to system startup")
		}
	}
}

// handleExit cleanly shuts down the application.
func handleExit(app App) {
	logger.Info("User requested application exit")
	app.Quit()
	systray.Quit()
	os.Exit(0)
}

// buildTooltip creates the tray icon tooltip text.
func buildTooltip(app App) string {
	shortcut := "Ctrl+K"
	if cfg := app.GetConfig(); cfg != nil && cfg.Shortcut != "" {
		shortcut = cfg.Shortcut
	}
	return trayLabel + " - " + shortcut + " to record"
}

var (
	defaultIconOnce  sync.Once
	defaultIconBytes []byte
)

func getDefaultIcon() []byte {
	if runtime.GOOS != "linux" {
		return iconData
	}

	defaultIconOnce.Do(func() {
		pngData, err := icoToPNG(iconData)
		if err != nil {
			logger.Error("Failed to convert tray icon to PNG for Linux: %v", err)
			defaultIconBytes = iconData
			return
		}
		defaultIconBytes = pngData
	})

	if len(defaultIconBytes) == 0 {
		return iconData
	}
	return defaultIconBytes
}

func icoToPNG(data []byte) ([]byte, error) {
	// Try to find a PNG image embedded inside the ICO file and return it.
	// ICO files contain entries that may be BMP/DIB or PNG encoded images.
	if len(data) < 6 {
		return nil, fmt.Errorf("invalid ico data")
	}
	count := int(binary.LittleEndian.Uint16(data[4:6]))
	var bestOffset int
	var bestSize int
	for i := 0; i < count; i++ {
		entry := 6 + i*16
		if entry+16 > len(data) {
			break
		}
		bytesInRes := int(binary.LittleEndian.Uint32(data[entry+8 : entry+12]))
		imageOffset := int(binary.LittleEndian.Uint32(data[entry+12 : entry+16]))
		if bytesInRes == 0 || imageOffset+bytesInRes > len(data) {
			continue
		}
		// PNG files start with the 8-byte signature 89 50 4E 47 0D 0A 1A 0A
		if bytesInRes >= 8 && imageOffset+8 <= len(data) &&
			bytes.Equal(data[imageOffset:imageOffset+8], []byte{0x89, 'P', 'N', 'G', '\r', '\n', 0x1A, '\n'}) {
			if bytesInRes > bestSize {
				bestSize = bytesInRes
				bestOffset = imageOffset
			}
		}
	}
	if bestSize > 0 {
		out := make([]byte, bestSize)
		copy(out, data[bestOffset:bestOffset+bestSize])
		return out, nil
	}
	return nil, fmt.Errorf("no PNG image found in ico")
}

// UpdateStatus updates the status text displayed in the tray menu.
func UpdateStatus(status string) {
	if statusMenuItem != nil {
		statusMenuItem.SetTitle("Status: " + status)
		systray.SetTooltip(trayLabel + " - " + status)

		if strings.Contains(status, "Recording") {
			systray.SetIcon(iconRecordingData)
		} else if strings.Contains(status, "Transcribing") {
			systray.SetIcon(iconTranscribingData)
		} else {
			systray.SetIcon(getDefaultIcon())
		}
	}
}

// IncrementTriggerCount increments the troubleshooting counter in the tray.
func IncrementTriggerCount() {
	triggerCount++
	if triggerCountItem != nil {
		triggerCountItem.SetTitle(fmt.Sprintf("Shortcut detected: %d times", triggerCount))
	}
}

// onExit is called when the system tray is shutting down.
func onExit() {
	logger.Info("System tray terminated")
}