#include <windows.h>

#include "common.h"

/* wstring_owner: Simple wrapper for wide C strings. */

wstring_owner::wstring_owner() {}

wstring_owner::wstring_owner(wchar_t* const s) : p(s) {}

wstring_owner& wstring_owner::operator=(wchar_t* const s)
{
	if (p != s) {
		delete p;
		p = s;
	}
	return *this;
}

wstring_owner::wstring_owner(wstring_owner&& other) noexcept : p(std::exchange(other.p, nullptr)) {}

wstring_owner& wstring_owner::operator=(wstring_owner&& other) noexcept
{
	std::swap(p, other.p);
	return *this;
}

/* Return pointer, releasing ownership. */
wchar_t* wstring_owner::release()
{
	wchar_t* p2 = p;
	p = nullptr;
	return p2;
}

wstring_owner::operator bool() const
{
	return p;
}

wstring_owner::~wstring_owner()
{
	delete p;
}

wstring_owner WsoFromSz(const char* const src, const int cp)
{
	int cbMultiByte = strlen(src)+1;
	int cchWideChar = MultiByteToWideChar(cp, 0, src, cbMultiByte, NULL, 0);
	wchar_t* dst = new wchar_t[cchWideChar];
	if (!MultiByteToWideChar(cp, 0, src, cbMultiByte, dst, cchWideChar)) {
		delete dst;
		throw Win32Error();
	}
	return dst;
}

wstring_owner WsoCopy(const wchar_t* const src)
{
	const int cb = wcslen(src)+1;
	wchar_t* dst = new wchar_t[cb];
	memcpy(dst, src, cb*sizeof(wchar_t));
	return dst;
}

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

Win32Error::Win32Error() : code(GetLastError()) {}
Win32Error::Win32Error(const DWORD code) : code(code) {}

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,
		    code,
		    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,
		    code,
		    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 lib)
{
	m_hModule = LoadLibrary(lib);
	if (!m_hModule)
		throw Win32Error();
}

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

/* 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;

	auto proc = [](const int nCode, const WPARAM wParam, const LPARAM lParam) noexcept
		-> LRESULT CALLBACK
	{
		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;
	};

	HHOOK hHook = require(SetWindowsHookEx(WH_CBT, proc, (HINSTANCE)NULL, GetCurrentThreadId()));
	int r = MessageBox(g_hWnd, wszText, wszCaption, uType);
	require(UnhookWindowsHookEx(hHook));
	return r;
}