#include <windows.h>

#include "common.h"

/* Win32Error: Exception for Windows API errors. */

Win32Error::Win32Error(const DWORD dwErr) : m_dwErr(dwErr) {}

Win32Error::~Win32Error()
{
	if (m_szMsg)
		HeapFree(GetProcessHeap(), 0, m_szMsg);
	if (m_wszMsg)
		HeapFree(GetProcessHeap(), 0, m_wszMsg);
}

const char* Win32Error::what() const noexcept 
{
	if (!m_szMsg)
		FormatMessageA(
		    FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
		    NULL,
		    m_dwErr,
		    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
		    (char*)&m_szMsg,
		    0, NULL);
	return m_szMsg;
}

const TCHAR* Win32Error::twhat() const noexcept 
{
#ifdef UNICODE
#define M m_wszMsg
#else
#define M m_szMsg
#endif
	if (!M)
		FormatMessage(
		    FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
		    NULL,
		    m_dwErr,
		    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
		    (TCHAR*)&M,
		    0, NULL);
	return M;
#undef M
}

/* Library: Wrapper for loading and freeing dynamically linked libraries. */

Library::Library(const TCHAR* const tszLibrary)
{
	m_hModule = LoadLibrary(tszLibrary);
	if (!m_hModule)
		throw Win32Error(GetLastError());
}

Library::~Library()
{
	FreeLibrary(m_hModule);
}

/* Move message box to center of main window. */
static LRESULT CALLBACK CBTProc(const int nCode, const WPARAM wParam, const LPARAM lParam)
{
	extern HWND g_hWnd;
	if (!g_hWnd || nCode < 0 || nCode != HCBT_ACTIVATE)
		return CallNextHookEx(0, nCode, wParam, lParam);

	HWND hWnd = (HWND)wParam;
	long lStyle = GetWindowLong(hWnd, GWL_STYLE);
	if (!(lStyle & WS_POPUP)) return 0;

	RECT rcMain, rcMsg;
	GetWindowRect(g_hWnd, &rcMain);
	GetWindowRect(hWnd, &rcMsg);
	SetWindowPos(hWnd, NULL,
	    rcMain.left+(rcMain.right-rcMain.left)/2-(rcMsg.right-rcMsg.left)/2,
	    rcMain.top+(rcMain.bottom-rcMain.top)/2-(rcMsg.bottom-rcMsg.top)/2,
	    -1, -1,
	    SWP_NOZORDER|SWP_NOSIZE|SWP_NOACTIVATE);

	return 0;
}

/* Show message box owned by and centered in the main window. */
int EBMessageBox(const TCHAR* const tszText, const TCHAR* const tszCaption, const unsigned uType)
{
	extern HWND g_hWnd;
	HHOOK hHook = SetWindowsHookEx(WH_CBT, CBTProc, 0, GetCurrentThreadId());
	if (!hHook) return 0;
	int r = MessageBox(g_hWnd, tszText, tszCaption, uType);
	UnhookWindowsHookEx(hHook);
	if (!hHook) throw Win32Error(GetLastError());
	return r;
}