#pragma comment(lib, "comctl32.lib") // for visual styles
#pragma comment(lib, "kernel32.lib") // for visual styles
#pragma comment(linker, "/manifestdependency:\"type='win32' \
name='Microsoft.Windows.Common-Controls' version='6.0.0.0' \
processorArchitecture='*' publicKeyToken='6595b64144ccf1df' \
language='*'\"")
#include <windows.h>
#include <commctrl.h>
#define ID_HOTKEY_UP 200
#define ID_HOTKEY_LEFT 300
#define ID_HOTKEY_RIGHT 400

#include <stdio.h>
#include <crtdbg.h>
#define TRACE(...) \
do{ \
char *__trace = NULL; \
int len = 1+_scprintf(__VA_ARGS__); \
__trace = (char*)malloc(len*sizeof(char)); \
_CrtSetReportMode(_CRT_WARN, _CRTDBG_MODE_DEBUG); \
sprintf_s(__trace, len, __VA_ARGS__); \
_RPT0(_CRT_WARN, __trace); \
if(__trace != NULL) \
free(__trace); \
} while(0)

typedef struct
{
	UINT uNumWindows;
	UINT uListLength;
	UINT uCurrent;
	HWND* list;
} WindowList;

typedef DWORD (WINAPI *PSLWA)(HWND, DWORD, BYTE, DWORD);
PSLWA pSetLayeredWindowAttributes = NULL;
HWND g_hwndMain;
HHOOK g_hHookKeyboard = NULL;

void ClearWindowList(WindowList* wl)
{
	if(wl->list != NULL)
		free(wl->list);
	wl->list = NULL;
	wl->uListLength = 0;
	wl->uNumWindows = 0;
	wl->uCurrent = 0;
}

void EnableWindowAlpha(HWND hwnd)
{
	SetWindowLong(hwnd, GWL_EXSTYLE, GetWindowLong(hwnd, GWL_EXSTYLE) | WS_EX_LAYERED);
}

void DisableWindowAlpha(HWND hwnd)
{
	SetWindowLong(hwnd, GWL_EXSTYLE, GetWindowLong(hwnd, GWL_EXSTYLE) & ~WS_EX_LAYERED);
}

void SetWindowAlpha(HWND hwnd, BYTE alpha)
{	// assumes that EnableWindowAlpha has already been called
	if(pSetLayeredWindowAttributes == NULL)
		return;
	pSetLayeredWindowAttributes(hwnd, 0, alpha, LWA_ALPHA);
}

void MultiDisableWindowAlpha(WindowList wl)
{
	UINT i;
	for(i = 0; i < wl.uNumWindows; ++i)
		DisableWindowAlpha(wl.list[i]);
}

void MultiSetWindowAlpha(WindowList wl, BYTE alpha)
{
	UINT i;
	for(i = 0; i < wl.uNumWindows; ++i)
	{
		EnableWindowAlpha(wl.list[i]);
		SetWindowAlpha(wl.list[i], alpha);
	}
}

void PrintWindowTitle(HWND hwnd)
{
	char title[256];
	GetWindowText(hwnd, title, 256);
	TRACE("Window: %s\n", title);
}

BOOL IsAltTabWindow(HWND hwnd)
{
	TITLEBARINFO ti;
	HWND hwndTry, hwndWalk = NULL;

	if(!IsWindowVisible(hwnd))
		return FALSE;

	hwndTry = GetAncestor(hwnd, GA_ROOTOWNER);
	while(hwndTry != hwndWalk) 
	{
		hwndWalk = hwndTry;
		hwndTry = GetLastActivePopup(hwndWalk);
		if(IsWindowVisible(hwndTry)) 
			break;
	}
	if(hwndWalk != hwnd)
		return FALSE;

	// the following removes some task tray programs and "Program Manager"
	ti.cbSize = sizeof(ti);
	GetTitleBarInfo(hwnd, &ti);
	if(ti.rgstate[0] & STATE_SYSTEM_INVISIBLE)
		return FALSE;

	return TRUE;
}

BOOL CALLBACK EnumVisibleWindowsProc(HWND hwnd, LPARAM lParam)
{	// return TRUE to continue enumeration, FALSE to stop
	WindowList* lpwl = (WindowList*)lParam;
	if(!IsAltTabWindow(hwnd) || IsIconic(hwnd))
		return TRUE;			// skip this window and continue
	if(lpwl->uNumWindows < lpwl->uListLength)
		lpwl->list[lpwl->uNumWindows] = hwnd;
	else
		return FALSE;
	//PrintWindowTitle(hwnd);
	lpwl->uNumWindows++;
	return TRUE;
}

BOOL CALLBACK EnumMinimizedWindowsProc(HWND hwnd, LPARAM lParam)
{	// return TRUE to continue enumeration, FALSE to stop
	WindowList* lpwl = (WindowList*)lParam;
	if(!IsAltTabWindow(hwnd) || !IsIconic(hwnd))
		return TRUE;			// skip this window and continue
	if(lpwl->uNumWindows < lpwl->uListLength)
		lpwl->list[lpwl->uNumWindows] = hwnd;
	else
		return FALSE;
	//PrintWindowTitle(hwnd);
	lpwl->uNumWindows++;
	return TRUE;
}

WindowList GetWindowList(BOOL minimized)
{
	WindowList wl = {0};
	wl.list = (HWND*)malloc(1024*sizeof(HWND));
	wl.uListLength = 1024;
	if(minimized)
		EnumWindows(EnumMinimizedWindowsProc, (LPARAM)(&wl));
	else
		EnumWindows(EnumVisibleWindowsProc, (LPARAM)(&wl));
	TRACE("Found %d windows\n", wl.uNumWindows);
	return wl;
}

// ####################################################################################
// ####################################################################################
// ####################################################################################
// ####################################################################################
// ####################################################################################
// ####################################################################################
// ####################################################################################

void HandleUpKeyPress(WindowList* wl)
{	// TODO: minimize current window in the minimized list
	if(wl->uCurrent < wl->uNumWindows)
	{
		EnableWindowAlpha(wl->list[wl->uCurrent]);
		SetWindowAlpha(wl->list[wl->uCurrent], 45);
		wl->uCurrent++;
	}
}

void HandleLateralKeyPress(WindowList* wl, int left)
{
	if(wl->uNumWindows > 0)
	{
		//ShowWindow(wl->list[wl->uCurrent], SW_HIDE);
		ShowWindow(wl->list[wl->uCurrent], SW_MINIMIZE);
		//ShowWindow(wl->list[wl->uCurrent], SW_SHOW);
		if(left)
			wl->uCurrent = (wl->uCurrent + wl->uNumWindows - 1)%wl->uNumWindows;
		else
			wl->uCurrent = (wl->uCurrent + 1)%wl->uNumWindows;
		//ShowWindow(wl->list[wl->uCurrent], SW_HIDE);
		ShowWindow(wl->list[wl->uCurrent], SW_RESTORE);
		//ShowWindow(wl->list[wl->uCurrent], SW_SHOW);
		BringWindowToTop(wl->list[wl->uCurrent]);
	}
}

LRESULT CALLBACK KeyboardProc(int nCode, WPARAM wParam, LPARAM lParam)
{
	if((wParam == VK_LWIN || wParam == VK_RWIN))
		TRACE("HOOK KEY\n");
	if((wParam == VK_LWIN || wParam == VK_RWIN) && (lParam & 0x80000000))
	{
		TRACE("HOOK UP\n");
		SendMessage(g_hwndMain, WM_KEYUP, wParam, lParam);
	}
	return CallNextHookEx(g_hHookKeyboard, nCode, wParam, lParam);
}


LRESULT CALLBACK MainWndProc(HWND hwnd, UINT uMsg, 
    WPARAM wParam, LPARAM lParam)
{
	static int hotkeydown = 0;
	static UINT CURRENT_LIST = 0;
	static WindowList wlVisible = {0};
	static WindowList wlMinimized = {0};

	switch(uMsg)
	{
	case WM_HOTKEY:
		if(wParam == ID_HOTKEY_UP)
		{
			if(wlVisible.list == NULL)
				wlVisible = GetWindowList(0);
			hotkeydown = 1;
			CURRENT_LIST = 0;
			HandleUpKeyPress(&wlVisible);
			SetFocus(hwnd);
		}
		if(wParam == ID_HOTKEY_RIGHT || wParam == ID_HOTKEY_LEFT)
		{
			if(wlMinimized.list == NULL)
				wlMinimized = GetWindowList(1);
			hotkeydown = 1;
			CURRENT_LIST = 1;
			HandleLateralKeyPress(&wlMinimized, wParam == ID_HOTKEY_LEFT);
			SetFocus(hwnd);
		}
		break;

	case WM_KEYDOWN:
		if(wParam == VK_DOWN && hotkeydown == 1 && wlVisible.uCurrent > 0)
		{
			CURRENT_LIST = 0;
			wlVisible.uCurrent--;
			DisableWindowAlpha(wlVisible.list[wlVisible.uCurrent]);
		}
		break;
	case WM_KEYUP:
		if(hotkeydown == 1 && (wParam == VK_LWIN || wParam == VK_RWIN))
		{
			hotkeydown = 0;
			MultiDisableWindowAlpha(wlVisible);

			TRACE("Num Minimized: %d\n", wlMinimized.uNumWindows);

			if(CURRENT_LIST == 0)
			{
				if(wlMinimized.uNumWindows > 0)
					ShowWindow(wlMinimized.list[wlMinimized.uCurrent], SW_MINIMIZE);
				BringWindowToTop(wlVisible.list[wlVisible.uCurrent]);
				SetFocus(wlVisible.list[wlVisible.uCurrent]);
			}
			else if(wlMinimized.uNumWindows > 0)
			{
				TRACE("FINALLY\n");
				PrintWindowTitle(wlMinimized.list[wlMinimized.uCurrent]);
				BringWindowToTop(wlMinimized.list[wlMinimized.uCurrent]);
				SetFocus(wlMinimized.list[wlMinimized.uCurrent]);
			}
			ClearWindowList(&wlVisible);
			ClearWindowList(&wlMinimized);
		}
		break;
	case WM_CLOSE:
		DestroyWindow(hwnd);
		break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	}
	return DefWindowProc(hwnd, uMsg, wParam, lParam);
}


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, 
    LPSTR lpszArgument, int nCmdShow)
{
	MSG msg;
	HWND hwnd;
	WNDCLASSEX wcx = {0};
	HMODULE hDLL = LoadLibrary("user32");

	pSetLayeredWindowAttributes = (PSLWA)GetProcAddress(hDLL, "SetLayeredWindowAttributes");
	InitCommonControls();   // enable visual styles

	wcx.cbSize = sizeof(wcx);
	wcx.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	wcx.hCursor = LoadCursor(NULL, IDC_ARROW); 
	wcx.style = CS_HREDRAW | CS_VREDRAW; 
	wcx.lpszClassName = "TaskSwitcherClass";
	wcx.lpfnWndProc = MainWndProc;
	wcx.hInstance = hInstance;
	RegisterClassEx(&wcx);

	hwnd = CreateWindowEx(WS_EX_CLIENTEDGE, "TaskSwitcherClass", 
	"Task Switcher", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 
	CW_USEDEFAULT, 300, 200, NULL, NULL, hInstance, NULL);

	g_hwndMain = hwnd;
	g_hHookKeyboard = SetWindowsHookEx(WH_KEYBOARD, KeyboardProc, hInstance, 0);

	RegisterHotKey(hwnd, ID_HOTKEY_UP, MOD_WIN, VK_UP);
	RegisterHotKey(hwnd, ID_HOTKEY_LEFT, MOD_WIN, VK_LEFT);
	RegisterHotKey(hwnd, ID_HOTKEY_RIGHT, MOD_WIN, VK_RIGHT);

	while(GetMessage(&msg, NULL, 0, 0))
	{
		// TODO: process hotkey messages here, get rid of window
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	return 0;
}