#include <exception>
#include <windows.h>
#include <wininet.h>
#include <libxml/xmlerror.h>

#include "err.h"
#include "util.h"
#include "win32.h"

/* Strip trailing punctuation. */
static void Strip(wchar_t* s, size_t len = -1)
{
	for (int i = len-1; i >= 0; i--)
		if (s[i] == '\r' || s[i] == '\n' || s[i] == '.')
			s[i] = 0;
}

Err::Err(ErrType t, const wchar_t* fmt)
{
	switch (t) {
	case GENERIC:
		assert(wcscmp(fmt, L"%s.") != 0);
		what = fmt;
		break;
	case WINDOWS:
	    {
		wchar_t* msg;
		DWORD lenMsg = FormatMessageW(
		    FORMAT_MESSAGE_ALLOCATE_BUFFER
		    |FORMAT_MESSAGE_FROM_SYSTEM
		    |FORMAT_MESSAGE_IGNORE_INSERTS,
		    nullptr,
		    GetLastError(),
		    MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
		    (wchar_t*)&msg,
		    0, nullptr);
		Strip(msg, lenMsg);
		what = std::wstring(lenMsg+wcslen(fmt), 0);
		Swprintf(what, fmt, msg);
		HeapFree(GetProcessHeap(), 0, msg);
		break;
	    }
	case WININET:
	    {
		DWORD code = GetLastError();
		if (code == ERROR_INTERNET_EXTENDED_ERROR) {
			DWORD lenMsg;
			InternetGetLastResponseInfo(&code, nullptr, &lenMsg);
			std::wstring msg(lenMsg, 0);
			if (InternetGetLastResponseInfoW(&code, msg.data(), &lenMsg)) {
				what = std::wstring(lenMsg+wcslen(fmt), 0);
				Swprintf(what, fmt, msg.c_str());
			} else
				what = Err(WINDOWS, fmt).what;
		} else {
			wchar_t* msg;
			DWORD lenMsg = FormatMessageW(
			    FORMAT_MESSAGE_ALLOCATE_BUFFER
			    |FORMAT_MESSAGE_FROM_SYSTEM
			    |FORMAT_MESSAGE_FROM_HMODULE
			    |FORMAT_MESSAGE_IGNORE_INSERTS,
			    GetModuleHandle(L"wininet.dll"),
			    code,
			    MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
			    (wchar_t*)&msg,
			    0, nullptr);
			Strip(msg, lenMsg);
			what = std::wstring(lenMsg+wcslen(fmt), 0);
			Swprintf(what, fmt, msg);
			HeapFree(GetProcessHeap(), 0, msg);
		}
		break;
	    }
	case LIBXML2:
	    {
		std::wstring msg = WideFromNarrow(xmlGetLastError()->message);
		what = std::wstring(msg.size()+wcslen(fmt), 0);
		Swprintf(what, fmt, msg.c_str());
		break;
	    }
	}
}

std::wstring What(std::exception_ptr ex)
{
	try {
		std::rethrow_exception(ex);
	} catch (const Err& e) {
		return e.what;
	} catch (const std::exception& e) {
		return WideFromNarrow(e.what());
	} catch (...) {
		return L"Unknown exception";
	}
}

void OnTerminate()
{
	EBMessageBox(What(), L"Fatal Error", MB_ICONERROR);
}