#include <windows.h>

#include "common.h"

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

Win32Error::Win32Error() : dwErr(GetLastError()) {}
Win32Error::Win32Error(const DWORD dwErr) : 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,
		    dwErr,
		    MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
		    (char*)&m_szMsg,
		    0, NULL);
	return m_szMsg;
}

const wchar_t* Win32Error::WhatW() const noexcept
{
	if (!m_wszMsg)
		FormatMessage(
		    FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
		    NULL,
		    dwErr,
		    MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
		    (wchar_t*)&m_wszMsg,
		    0, NULL);
	return m_wszMsg;
}

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

Library::Library(const wchar_t* const wszLibrary)
{
	m_hModule = LoadLibrary(wszLibrary);
	if (!m_hModule)
		throw Win32Error();
}

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

/* Convert narrow unmanaged string to wide managed string. */
std::wstring WstrFromSz(const char* sz, int iCp)
{
	int cbMultiByte = strlen(sz)+1;
	int cchWideChar = MultiByteToWideChar(iCp, 0, sz, cbMultiByte, NULL, 0);
	std::wstring wstr(cchWideChar, 0);
	if (!MultiByteToWideChar(iCp, 0, sz, cbMultiByte, wstr.data(), cchWideChar))
		throw Win32Error(GetLastError());
	return wstr;
}

/* Move message box to center of main window. */
static LRESULT CALLBACK CBTProc(const int nCode, const WPARAM wParam, const LPARAM lParam) noexcept
{
	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 wchar_t* const wszText, const wchar_t* const wszCaption, const unsigned uType)
{
	extern HWND g_hWnd;
	HHOOK hHook = require(SetWindowsHookEx(WH_CBT, CBTProc, (HINSTANCE)NULL, GetCurrentThreadId()));
	int r = MessageBox(g_hWnd, wszText, wszCaption, uType);
	require(UnhookWindowsHookEx(hHook));
	return r;
}