package main

import (
	"fmt"
	"os"
	"runtime"
	"syscall"
	"unsafe"

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

// ── 윈도우 핸들 (진행 창에서 사용) ──────────────────────────

var (
	wndProcCb         uintptr
	titleLabelHwnd    uintptr
	progressLabelHwnd uintptr
	progressBarHwnd   uintptr
	hBrushBg          uintptr
)

func init() {
	wndProcCb = syscall.NewCallback(progressWndProc)
}

// ── DPI ──────────────────────────────────────────────────────

// enableDPIAwareness Per-Monitor V2 DPI 인식을 선언한다.
func enableDPIAwareness() {
	// DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2 = -4 (Windows 10 1703+)
	setProcessDpiAwarenessContextProc.Call(^uintptr(3))
}

func getSystemDPI() uint32 {
	dpi, _, _ := getDpiForSystemProc.Call()
	if dpi == 0 {
		return 96
	}
	return uint32(dpi)
}

// dpiScale 96 DPI 기준 픽셀 값을 현재 DPI에 맞게 변환한다.
func dpiScale(px int, dpi uint32) uintptr {
	return uintptr(int(float64(px)*float64(dpi)/96.0 + 0.5))
}

// ── 폰트 ─────────────────────────────────────────────────────

func createUIFont(pointSize int, dpi uint32, bold bool) uintptr {
	weight := int32(400) // FW_NORMAL
	if bold {
		weight = 700 // FW_BOLD
	}
	lf := logFontW{
		lfHeight:  -int32(pointSize) * int32(dpi) / 72,
		lfWeight:  weight,
		lfCharSet: 1, // DEFAULT_CHARSET
		lfQuality: 5, // CLEARTYPE_QUALITY
	}
	face, _ := windows.UTF16FromString("Segoe UI")
	copy(lf.lfFaceName[:], face)
	font, _, _ := createFontIndirectWProc.Call(uintptr(unsafe.Pointer(&lf)))
	return font
}

// ── 메시지 박스 ──────────────────────────────────────────────

// exitWithError 오류 메시지를 표시하고 프로그램을 종료한다.
func exitWithError(msg string) {
	msgBox("One of the plans 런처 - 오류", msg, mbOK|mbError)
	os.Exit(1)
}

func msgBox(title, text string, flags uintptr) int {
	t, err := windows.UTF16PtrFromString(title)
	if err != nil {
		return 0
	}
	m, err := windows.UTF16PtrFromString(text)
	if err != nil {
		return 0
	}
	ret, _, _ := messageBoxWProc.Call(0, uintptr(unsafe.Pointer(m)), uintptr(unsafe.Pointer(t)), flags)
	return int(ret)
}

// ── 단일 인스턴스 ────────────────────────────────────────────

func acquireSingleInstance() bool {
	name, _ := windows.UTF16PtrFromString("Global\\A301LauncherMutex")
	_, _, err := createMutexWProc.Call(0, 0, uintptr(unsafe.Pointer(name)))
	// ERROR_ALREADY_EXISTS = 183
	if errno, ok := err.(syscall.Errno); ok && errno == 183 {
		return false
	}
	return true
}

func activateExistingWindow() {
	className, _ := windows.UTF16PtrFromString("A301Progress")
	hwnd, _, _ := findWindowWProc.Call(uintptr(unsafe.Pointer(className)), 0)
	if hwnd != 0 {
		setForegroundWindowProc.Call(hwnd)
	}
}

// ── 진행 창 (프로그레스 윈도우) ──────────────────────────────

func initCommonControls() {
	icc := initCommonControlsExS{
		dwSize: uint32(unsafe.Sizeof(initCommonControlsExS{})),
		dwICC:  iccProgressClass,
	}
	initCommonControlsExProc.Call(uintptr(unsafe.Pointer(&icc)))
}

// progressWndProc 진행 창의 메시지 처리 프로시저.
func progressWndProc(hwnd, uMsg, wParam, lParam uintptr) uintptr {
	switch uint32(uMsg) {
	case wmClose:
		ret := msgBox("One of the plans 런처", "다운로드를 취소하시겠습니까?", mbYesNo|mbQ)
		if ret == idYes {
			downloadCancelled.Store(true)
			destroyWindowProc.Call(hwnd)
		}
		return 0
	case wmDestroy:
		postQuitMsgProc.Call(0)
		return 0
	case wmAppDone:
		destroyWindowProc.Call(hwnd)
		return 0
	case wmCtlColorStatic:
		hdc := wParam
		setBkModeProc.Call(hdc, setBkModeTransparent)
		if lParam == titleLabelHwnd {
			setTextColorProc.Call(hdc, colorAccent)
		} else {
			setTextColorProc.Call(hdc, colorText)
		}
		return hBrushBg
	}
	ret, _, _ := defWindowProcWProc.Call(hwnd, uMsg, wParam, lParam)
	return ret
}

// setProgress 진행 창의 텍스트와 퍼센트를 갱신한다.
func setProgress(text string, pct int) {
	if text != "" {
		t, err := windows.UTF16PtrFromString(text)
		if err == nil {
			sendMessageWProc.Call(progressLabelHwnd, uintptr(wmSetText), 0, uintptr(unsafe.Pointer(t)))
		}
	}
	if pct >= 0 {
		sendMessageWProc.Call(progressBarHwnd, uintptr(pbmSetPos), uintptr(pct), 0)
	}
}

// createProgressWindow 다크 테마 진행 창을 생성하고 핸들을 반환한다.
func createProgressWindow(dpi uint32) (hwnd uintptr, err error) {
	s := func(px int) uintptr { return dpiScale(px, dpi) }

	hBrushBg, _, _ = createSolidBrushProc.Call(colorBg)
	hInstance, _, _ := getModuleHandleWProc.Call(0)

	className, _ := windows.UTF16PtrFromString("A301Progress")
	wc := wndClassExW{
		cbSize:        uint32(unsafe.Sizeof(wndClassExW{})),
		lpfnWndProc:   wndProcCb,
		hInstance:     hInstance,
		lpszClassName: className,
		hbrBackground: hBrushBg,
	}
	atom, _, _ := registerClassExWProc.Call(uintptr(unsafe.Pointer(&wc)))
	if atom == 0 {
		return 0, fmt.Errorf("윈도우 클래스 등록 실패")
	}

	// 화면 중앙에 배치
	screenW, _, _ := getSystemMetricsProc.Call(smCxScreen)
	screenH, _, _ := getSystemMetricsProc.Call(smCyScreen)
	winW := s(440)
	winH := s(152)
	x := (screenW - winW) / 2
	y := (screenH - winH) / 2

	titleStr, _ := windows.UTF16PtrFromString("One of the plans 런처")
	hwnd, _, _ = createWindowExWProc.Call(
		0,
		uintptr(unsafe.Pointer(className)),
		uintptr(unsafe.Pointer(titleStr)),
		wsPopup|wsCaption|wsSysMenu|wsVisible,
		x, y, winW, winH,
		0, 0, hInstance, 0,
	)
	if hwnd == 0 {
		return 0, fmt.Errorf("다운로드 창 생성 실패")
	}

	// 폰트
	titleFont := createUIFont(13, dpi, true)
	statusFont := createUIFont(9, dpi, false)

	// 타이틀 라벨
	staticClass, _ := windows.UTF16PtrFromString("STATIC")
	titleText, _ := windows.UTF16PtrFromString("One of the plans")
	titleLabelHwnd, _, _ = createWindowExWProc.Call(
		0,
		uintptr(unsafe.Pointer(staticClass)),
		uintptr(unsafe.Pointer(titleText)),
		wsChild|wsVisible|ssCenter,
		s(20), s(14), winW-s(40), s(28),
		hwnd, 0, hInstance, 0,
	)
	sendMessageWProc.Call(titleLabelHwnd, uintptr(wmSetFont), titleFont, 1)

	// 상태 라벨
	initText, _ := windows.UTF16PtrFromString("게임 파일을 다운로드하는 중...")
	progressLabelHwnd, _, _ = createWindowExWProc.Call(
		0,
		uintptr(unsafe.Pointer(staticClass)),
		uintptr(unsafe.Pointer(initText)),
		wsChild|wsVisible|ssCenter,
		s(20), s(52), winW-s(40), s(20),
		hwnd, 0, hInstance, 0,
	)
	sendMessageWProc.Call(progressLabelHwnd, uintptr(wmSetFont), statusFont, 1)

	// 프로그레스바
	progressClass, _ := windows.UTF16PtrFromString("msctls_progress32")
	progressBarHwnd, _, _ = createWindowExWProc.Call(
		0,
		uintptr(unsafe.Pointer(progressClass)),
		0,
		wsChild|wsVisible|pbsSmooth,
		s(20), s(82), winW-s(40), s(18),
		hwnd, 0, hInstance, 0,
	)
	sendMessageWProc.Call(progressBarHwnd, uintptr(pbmSetRange32), 0, 100)

	// 비주얼 스타일 비활성화 후 커스텀 색상 적용
	empty, _ := windows.UTF16PtrFromString("")
	setWindowThemeProc.Call(progressBarHwnd, uintptr(unsafe.Pointer(empty)), uintptr(unsafe.Pointer(empty)))
	sendMessageWProc.Call(progressBarHwnd, uintptr(pbmSetBarColor), 0, colorAccent)
	sendMessageWProc.Call(progressBarHwnd, uintptr(pbmSetBkColor), 0, colorProgressBg)

	showWindowProc.Call(hwnd, swShow)
	updateWindowProc.Call(hwnd)

	return hwnd, nil
}

// downloadWithProgress 진행 창을 표시하면서 파일을 다운로드하고 추출한다.
// Win32 메시지 루프를 사용하므로 반드시 메인 고루틴에서 호출해야 한다.
func downloadWithProgress(downloadURL, destDir string) error {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	initCommonControls()
	dpi := getSystemDPI()

	hwnd, err := createProgressWindow(dpi)
	if err != nil {
		return err
	}
	defer deleteObjectProc.Call(hBrushBg)

	downloadCancelled.Store(false)

	// 별도 고루틴에서 다운로드, 완료 시 wmAppDone 메시지로 창 닫기
	errCh := make(chan error, 1)
	go func() {
		errCh <- doDownload(downloadURL, destDir)
		postMessageWProc.Call(hwnd, uintptr(wmAppDone), 0, 0)
	}()

	// Win32 메시지 루프
	var m msgW
	for {
		ret, _, _ := getMessageWProc.Call(uintptr(unsafe.Pointer(&m)), 0, 0, 0)
		if ret == 0 || ret == ^uintptr(0) {
			break
		}
		translateMsgProc.Call(uintptr(unsafe.Pointer(&m)))
		dispatchMsgWProc.Call(uintptr(unsafe.Pointer(&m)))
	}

	return <-errCh
}