package wingui

import (
	"syscall"
	"unsafe"
)

const (
	WM_PAINT = 15

	BI_RGB = 0

	DIB_PAL_COLORS = 1
	DIB_RGB_COLORS = 0

	SRCCOPY = 0xCC0020
)

type RECT struct {
	Left   int32
	Top    int32
	Right  int32
	Bottom int32
}

type PAINTSTRUCT struct {
	HDC         uint32
	Erase       int32 // bool
	RcPaint     RECT
	Restore     int32 // bool
	IncUpdate   int32 // bool
	rgbReserved [32]byte
}

type BITMAP struct {
	Type       int32
	Width      int32
	Height     int32
	WidthBytes int32
	Planes     uint16
	BitsPixel  uint16
	Bits       *byte
}

type BITMAPINFOHEADER struct {
	Size          uint32
	Width         int32
	Height        int32
	Planes        uint16
	BitCount      uint16
	Compression   uint32
	SizeImage     uint32
	XPelsPerMeter int32
	YPelsPerMeter int32
	ClrUsed       uint32
	ClrImportant  uint32
}

type BITMAPINFO struct {
	Header BITMAPINFOHEADER
	Colors [1]RGBQUAD
}

type RGBQUAD struct {
	Blue     byte
	Green    byte
	Red      byte
	Reserved byte
}

var (
	modgdi32 = loadDll("gdi32.dll")

	procGetDC                  = getSysProcAddr(moduser32, "GetDC")
	procCreateCompatibleDC     = getSysProcAddr(modgdi32, "CreateCompatibleDC")
	procGetObject              = getSysProcAddr(modgdi32, "GetObjectW")
	procSelectObject           = getSysProcAddr(modgdi32, "SelectObject")
	procBeginPaint             = getSysProcAddr(moduser32, "BeginPaint")
	procEndPaint               = getSysProcAddr(moduser32, "EndPaint")
	procCreateCompatibleBitmap = getSysProcAddr(modgdi32, "CreateCompatibleBitmap")
	procCreateDIBSection       = getSysProcAddr(modgdi32, "CreateDIBSection")
	procBitBlt                 = getSysProcAddr(modgdi32, "BitBlt")
)

func GetDC(hwnd uint32) (hdc uint32) {
	r0, _, _ := syscall.Syscall(procGetDC, 1, uintptr(hwnd), 0, 0)
	hdc = uint32(r0)
	return hdc
}

func CreateCompatibleDC(hwnd uint32) (hdc uint32) {
	r0, _, _ := syscall.Syscall(procCreateCompatibleDC, 1, uintptr(hwnd), 0, 0)
	hdc = uint32(r0)
	return hdc
}

func GetObject(hgdiobj uint32, cbBuffer int, object uintptr) (size uint32) {
	r0, _, _ := syscall.Syscall(procGetObject, 3, uintptr(hgdiobj), uintptr(cbBuffer), object)
	size = uint32(r0)
	return size
}

func SelectObject(hdc uint32, hgdiobj uint32) uint32 {
	r0, _, _ := syscall.Syscall(procSelectObject, 2, uintptr(hdc), uintptr(hgdiobj), 0)
	return uint32(r0)
}

func BeginPaint(hwnd uint32, ps *PAINTSTRUCT) (hdc uint32) {
	r0, _, _ := syscall.Syscall(procBeginPaint, 2, uintptr(hwnd), uintptr(unsafe.Pointer(ps)), 0)
	hdc = uint32(r0)
	return hdc
}

func EndPaint(hwnd uint32, ps *PAINTSTRUCT) bool {
	syscall.Syscall(procEndPaint, 2, uintptr(hwnd), uintptr(unsafe.Pointer(ps)), 0)
	return true
}

func CreateCompatibleBitmap(hdc uint32, width, height int) (hbitmap uint32) {
	r0, _, _ := syscall.Syscall(procCreateCompatibleBitmap, 3, uintptr(hdc), uintptr(width), uintptr(height))
	return uint32(r0)
}

func CreateDIBSection(hdc uint32, pbmi *BITMAPINFO, iUsage uint, ppvBits uintptr, hSection uint32, dwOffset uint32) (hbitmap uint32) {
	r0, _, _ := syscall.Syscall6(procCreateDIBSection, 6, uintptr(hdc), uintptr(unsafe.Pointer(pbmi)), uintptr(iUsage), ppvBits, uintptr(hSection), uintptr(dwOffset))
	return uint32(r0)
}

func BitBlt(hdc uint32, nXDest, nYDest, nWidth, nHeight int, hdcSrc uint32, nXSrc, nYSrc int, dwRop uint32) bool {
	r0, _, _ := syscall.Syscall9(procBitBlt, 9, uintptr(hdc), uintptr(nXDest), uintptr(nYDest), uintptr(nWidth), uintptr(nHeight), uintptr(hdcSrc), uintptr(nXSrc), uintptr(nYSrc), uintptr(dwRop))
	return r0 != 0
}