//go:build windows

package win32

import (
	"fmt"
	"log"
	"syscall"
	"unsafe"
)

const (
	WS_MAXIMIZE = 0x01000000

	GWL_STYLE = -16
)

// http://msdn.microsoft.com/en-us/library/windows/desktop/bb773244.aspx
type MARGINS struct {
	CxLeftWidth, CxRightWidth, CyTopHeight, CyBottomHeight int32
}

func ExtendFrameIntoClientArea(hwnd uintptr) {
	// -1: Adds the default frame styling (aero shadow and e.g. rounded corners on Windows 11)
	//     Also shows the caption buttons if transparent ant translucent but they don't work.
	//  0: Adds the default frame styling but no aero shadow, does not show the caption buttons.
	//  1: Adds the default frame styling (aero shadow and e.g. rounded corners on Windows 11) but no caption buttons
	//     are shown if transparent ant translucent.
	margins := &MARGINS{1, 1, 1, 1} // Only extend 1 pixel to have the default frame styling but no caption buttons
	if err := dwmExtendFrameIntoClientArea(hwnd, margins); err != nil {
		log.Fatal(fmt.Errorf("DwmExtendFrameIntoClientArea failed: %s", err))
	}
}

func IsWindowMaximised(hwnd uintptr) bool {
	style := uint32(getWindowLong(hwnd, GWL_STYLE))
	return style&WS_MAXIMIZE != 0
}

func dwmExtendFrameIntoClientArea(hwnd uintptr, margins *MARGINS) error {
	ret, _, _ := procDwmExtendFrameIntoClientArea.Call(
		hwnd,
		uintptr(unsafe.Pointer(margins)))

	if ret != 0 {
		return syscall.GetLastError()
	}

	return nil
}

func getWindowLong(hwnd uintptr, index int) int32 {
	ret, _, _ := procGetWindowLong.Call(
		hwnd,
		uintptr(index))

	return int32(ret)
}