#include <utility>
#include <windows.h>

#include "win.h"

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::What() 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;
}

std::optional<Library> Library::Maybe(const wchar_t* const lib)
{
	HMODULE hModule = LoadLibrary(lib);
	if (!hModule) return {};
	return Library(hModule);
}

Library::Library(const HMODULE hModule) : m_hModule(hModule) {}

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

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

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;
}

int GetRelativeCursorPos(HWND hWnd, POINT* pt)
{
	RECT rc;
	if (!GetClientRect(hWnd, &rc)) return 0;
	SetLastError(ERROR_SUCCESS);
	if (!MapWindowPoints(hWnd, NULL, (POINT*)&rc, 2)) return 0;

	POINT ptMouse;
	if (!GetCursorPos(&ptMouse)) return 0;
	pt->x = ptMouse.x-rc.left;
	pt->y = ptMouse.y-rc.top;
	return 1;
}