/**
 * =========================================================================
 * File        : wutil.cpp
 * Project     : 0 A.D.
 * Description : various Windows-specific utilities
 * =========================================================================
 */

// license: GPL; see lib/license.txt

#include "precompiled.h"
#include "wutil.h"

#include <stdio.h>
#include <stdlib.h>	// __argc

#include "lib/path_util.h"
#include "lib/posix/posix.h"
#include "win.h"
#include "winit.h"

WINIT_REGISTER_EARLY_INIT(wutil_Init);
WINIT_REGISTER_LATE_SHUTDOWN(wutil_Shutdown);


//-----------------------------------------------------------------------------
// safe allocator

//
// safe allocator that may be used independently of libc malloc
// (in particular, before _cinit and while calling static dtors).
// used by wpthread critical section code.
//

void* win_alloc(size_t size)
{
	const DWORD flags = HEAP_ZERO_MEMORY;
	return HeapAlloc(GetProcessHeap(), flags, size);
}

void win_free(void* p)
{
	const DWORD flags = 0;
	HeapFree(GetProcessHeap(), flags, p);
}


//-----------------------------------------------------------------------------
// locks

// several init functions are before called before _cinit.
// POSIX static mutex init may not have been done by then,
// so we need our own lightweight functions.

static CRITICAL_SECTION cs[NUM_CS];
static bool cs_valid;

void win_lock(WinLockId id)
{
	if(!cs_valid)
		return;
	EnterCriticalSection(&cs[id]);
}

void win_unlock(WinLockId id)
{
	if(!cs_valid)
		return;
	LeaveCriticalSection(&cs[id]);
}

bool win_is_locked(WinLockId id)
{
	if(!cs_valid)
		return false;
	const BOOL successfullyEntered = TryEnterCriticalSection(&cs[id]);
	if(!successfullyEntered)
		return true;	// still locked
	LeaveCriticalSection(&cs[id]);
	return false;	// probably not locked
}


static void InitLocks()
{
	for(int i = 0; i < NUM_CS; i++)
		InitializeCriticalSection(&cs[i]);

	cs_valid = true;
}

static void ShutdownLocks()
{
	cs_valid = false;

	for(int i = 0; i < NUM_CS; i++)
		DeleteCriticalSection(&cs[i]);
	memset(cs, 0, sizeof(cs));
}


//-----------------------------------------------------------------------------
// error codes

// only call after a Win32 function indicates failure.
LibError LibError_from_GLE(bool warn_if_failed)
{
	LibError err = ERR::FAIL;
	switch(GetLastError())
	{
	case ERROR_OUTOFMEMORY:
		err = ERR::NO_MEM; break;

	case ERROR_INVALID_PARAMETER:
		err = ERR::INVALID_PARAM; break;
	case ERROR_INSUFFICIENT_BUFFER:
		err = ERR::BUF_SIZE; break;

/*
	case ERROR_ACCESS_DENIED:
		err = ERR::FILE_ACCESS; break;
	case ERROR_FILE_NOT_FOUND:
	case ERROR_PATH_NOT_FOUND:
		err = ERR::TNODE_NOT_FOUND; break;
*/
	}

	if(warn_if_failed)
		DEBUG_WARN_ERR(err);
	return err;
}


// return the LibError equivalent of GetLastError(), or ERR::FAIL if
// there's no equal.
// you should SetLastError(0) before calling whatever will set ret
// to make sure we do not return any stale errors.
LibError LibError_from_win32(DWORD ret, bool warn_if_failed)
{
	if(ret != FALSE)
		return INFO::OK;
	return LibError_from_GLE(warn_if_failed);
}


//-----------------------------------------------------------------------------
// command line

// copy of GetCommandLine string. will be tokenized and then referenced by
// the argv pointers.
static char* argvContents;

int wutil_argc = 0;
char** wutil_argv = 0;

static void ReadCommandLine()
{
	const char* commandLine = GetCommandLine();
	// (this changes as quotation marks are removed)
	size_t numChars = strlen(commandLine);
	argvContents = (char*)HeapAlloc(GetProcessHeap(), HEAP_GENERATE_EXCEPTIONS, numChars+1);
	strcpy_s(argvContents, numChars+1, commandLine);

	// first pass: tokenize string and count number of arguments
	bool ignoreSpace = false;
	for(size_t i = 0; i < numChars; i++)
	{
		switch(argvContents[i])
		{
		case '"':
			ignoreSpace = !ignoreSpace;
			// strip the " character
			memmove(argvContents+i, argvContents+i+1, numChars-i);
			numChars--;
			i--;
			break;

		case ' ':
			if(!ignoreSpace)
			{
				argvContents[i] = '\0';
				wutil_argc++;
			}
			break;
		}
	}
	wutil_argc++;

	// have argv entries point into the tokenized string
	wutil_argv = (char**)HeapAlloc(GetProcessHeap(), HEAP_GENERATE_EXCEPTIONS, wutil_argc*sizeof(char*));
	char* nextArg = argvContents;
	for(int i = 0; i < wutil_argc; i++)
	{
		wutil_argv[i] = nextArg;
		nextArg += strlen(nextArg)+1;
	}
}


static void FreeCommandLine()
{
	HeapFree(GetProcessHeap(), 0, wutil_argv);
	HeapFree(GetProcessHeap(), 0, argvContents);
}


bool wutil_HasCommandLineArgument(const char* arg)
{
	for(int i = 0; i < wutil_argc; i++)
	{
		if(!strcmp(wutil_argv[i], arg))
			return true;
	}

	return false;
}


//-----------------------------------------------------------------------------
// directories

char win_sys_dir[MAX_PATH+1];
char win_exe_dir[MAX_PATH+1];

static void GetDirectories()
{
	GetSystemDirectory(win_sys_dir, sizeof(win_sys_dir));

	const DWORD len = GetModuleFileName(GetModuleHandle(0), win_exe_dir, MAX_PATH);
	debug_assert(len != 0);
	// strip EXE filename and trailing slash
	char* slash = strrchr(win_exe_dir, '\\');
	if(slash)
		*slash = '\0';
	else
		debug_assert(0);	// directory name invalid?!
}


//-----------------------------------------------------------------------------
// user32 fix

// HACK: make sure a reference to user32 is held, even if someone
// decides to delay-load it. this fixes bug #66, which was the
// Win32 mouse cursor (set via user32!SetCursor) appearing as a
// black 32x32(?) rectangle. underlying cause was as follows:
// powrprof.dll was the first client of user32, causing it to be
// loaded. after we were finished with powrprof, we freed it, in turn
// causing user32 to unload. later code would then reload user32,
// which apparently terminally confused the cursor implementation.
//
// since we hold a reference here, user32 will never unload.
// of course, the benefits of delay-loading are lost for this DLL,
// but that is unavoidable. it is safer to force loading it, rather
// than documenting the problem and asking it not be delay-loaded.
static HMODULE hUser32Dll;

static void ForciblyLoadUser32Dll()
{
	hUser32Dll = LoadLibrary("user32.dll");
}

// avoids Boundschecker warning
static void FreeUser32Dll()
{
	FreeLibrary(hUser32Dll);
}


//-----------------------------------------------------------------------------
// memory

static void EnableLowFragmentationHeap()
{
#if WINVER >= 0x0501
	const HMODULE hKernel32Dll = GetModuleHandle("kernel32.dll");
	typedef BOOL (WINAPI* PHeapSetInformation)(HANDLE, HEAP_INFORMATION_CLASS, void*, size_t);
	PHeapSetInformation pHeapSetInformation = (PHeapSetInformation)GetProcAddress(hKernel32Dll, "HeapSetInformation");
	if(!pHeapSetInformation)
		return;

	ULONG flags = 2;	// enable LFH
	pHeapSetInformation(GetProcessHeap(), HeapCompatibilityInformation, &flags, sizeof(flags));
#endif	// #if WINVER >= 0x0501
}


//-----------------------------------------------------------------------------
// version

static char windowsVersionString[20];
static size_t windowsVersion;	// see WUTIL_VERSION_*

static void DetectWindowsVersion()
{
	// note: don't use GetVersion[Ex] because it gives the version of the
	// emulated OS when running an app with compatibility shims enabled.
	HKEY hKey;
	if(RegOpenKeyEx(HKEY_LOCAL_MACHINE, "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion", 0, KEY_QUERY_VALUE, &hKey) == ERROR_SUCCESS)
	{
		DWORD size = ARRAY_SIZE(windowsVersionString);
		(void)RegQueryValueEx(hKey, "CurrentVersion", 0, 0, (LPBYTE)windowsVersionString, &size);

		size_t major = 0, minor = 0;
		int ret = sscanf(windowsVersionString, "%d.%d", &major, &minor);
		debug_assert(ret == 2);
		debug_assert(major <= 0xFF && minor <= 0xFF);
		windowsVersion = (major << 8) | minor;

		RegCloseKey(hKey);
	}
	else
		debug_assert(0);
}


const char* wutil_WindowsFamily()
{
	debug_assert(windowsVersion != 0);
	switch(windowsVersion)
	{
	case WUTIL_VERSION_2K:
		return "Win2k";
	case WUTIL_VERSION_XP:
		return "WinXP";
	case WUTIL_VERSION_XP64:
		return "WinXP64";
	case WUTIL_VERSION_VISTA:
		return "Vista";
	default:
		return "Windows";
	}
}


const char* wutil_WindowsVersionString()
{
	debug_assert(windowsVersionString[0] != '\0');
	return windowsVersionString;
}

size_t wutil_WindowsVersion()
{
	debug_assert(windowsVersion != 0);
	return windowsVersion;
}


//-----------------------------------------------------------------------------
// Wow64

// Wow64 'helpfully' redirects all 32-bit apps' accesses of
// %windir%\\system32\\drivers to %windir%\\system32\\drivers\\SysWOW64.
// that's bad, because the actual drivers are not in the subdirectory. to
// work around this, provide for temporarily disabling redirection.

typedef BOOL (WINAPI *PIsWow64Process)(HANDLE, PBOOL);
typedef BOOL (WINAPI *PWow64DisableWow64FsRedirection)(PVOID*);
typedef BOOL (WINAPI *PWow64RevertWow64FsRedirection)(PVOID);
static PIsWow64Process pIsWow64Process;
static PWow64DisableWow64FsRedirection pWow64DisableWow64FsRedirection;
static PWow64RevertWow64FsRedirection pWow64RevertWow64FsRedirection;

static bool isWow64;

static void ImportWow64Functions()
{
	const HMODULE hKernel32Dll = GetModuleHandle("kernel32.dll");
	pIsWow64Process = (PIsWow64Process)GetProcAddress(hKernel32Dll, "IsWow64Process"); 
	pWow64DisableWow64FsRedirection = (PWow64DisableWow64FsRedirection)GetProcAddress(hKernel32Dll, "Wow64DisableWow64FsRedirection");
	pWow64RevertWow64FsRedirection = (PWow64RevertWow64FsRedirection)GetProcAddress(hKernel32Dll, "Wow64RevertWow64FsRedirection");
}

static void DetectWow64()
{
	// function not found => running on 32-bit Windows
	if(!pIsWow64Process)
	{
		isWow64 = false;
		return;
	}

	BOOL isWow64Process = FALSE;
	const BOOL ok = pIsWow64Process(GetCurrentProcess(), &isWow64Process);
	WARN_IF_FALSE(ok);
	isWow64 = (isWow64Process == TRUE);
}

bool wutil_IsWow64()
{
	return isWow64;
}


WinScopedDisableWow64Redirection::WinScopedDisableWow64Redirection()
{
	// note: don't just check if the function pointers are valid. 32-bit
	// Vista includes them but isn't running Wow64, so calling the functions
	// would fail. since we have to check if actually on Wow64, there's no
	// more need to verify the pointers (their existence is implied).
	if(!wutil_IsWow64())
		return;
	BOOL ok = pWow64DisableWow64FsRedirection(&m_wasRedirectionEnabled);
	WARN_IF_FALSE(ok);
}

WinScopedDisableWow64Redirection::~WinScopedDisableWow64Redirection()
{
	if(!wutil_IsWow64())
		return;
	BOOL ok = pWow64RevertWow64FsRedirection(m_wasRedirectionEnabled);
	WARN_IF_FALSE(ok);
}


//-----------------------------------------------------------------------------
// module handle

#ifndef LIB_STATIC_LINK

HMODULE wutil_LibModuleHandle;

BOOL WINAPI DllMain(HINSTANCE hInstance, DWORD reason, LPVOID reserved)
{
	DisableThreadLibraryCalls(hInstance);
	wutil_LibModuleHandle = hInstance;
	return TRUE;	// success (ignored unless reason == DLL_PROCESS_ATTACH)
}

#else

HMODULE wutil_LibModuleHandle = GetModuleHandle(0);

#endif


//-----------------------------------------------------------------------------
// find main window

// this is required by the error dialog and clipboard code.
// note that calling from wutil_Init won't work, because the app will not
// have created its window by then.

static HWND hAppWindow;

static BOOL CALLBACK FindAppWindowByPid(HWND hWnd, LPARAM UNUSED(lParam))
{
	DWORD pid;
	const DWORD tid = GetWindowThreadProcessId(hWnd, &pid);
	UNUSED2(tid);	// the function can't fail

	if(pid == GetCurrentProcessId())
	{
		hAppWindow = hWnd;
		return FALSE;	// done
	}

	return TRUE;	// keep calling
}

HWND wutil_AppWindow()
{
	if(!hAppWindow)
	{
		const DWORD ret = EnumWindows(FindAppWindowByPid, 0);
		// the callback returns FALSE when it has found the window
		// (so as not to waste time); EnumWindows then returns 0.
		// we therefore cannot check for errors.
		UNUSED2(ret);
	}

	return hAppWindow;
}


//-----------------------------------------------------------------------------

static LibError wutil_Init()
{
	InitLocks();

	ForciblyLoadUser32Dll();

	EnableLowFragmentationHeap();

	ReadCommandLine();

	GetDirectories();

	DetectWindowsVersion();

	ImportWow64Functions();
	DetectWow64();

	return INFO::OK;
}


static LibError wutil_Shutdown()
{
	FreeCommandLine();

	FreeUser32Dll();

	ShutdownLocks();

	return INFO::OK;
}