#include <windows.h>
#include <Shlwapi.h>
#include <iostream>
#include <wuapi.h>
#include <wuerror.h>

#include "thresholds.h"

#include "boost/program_options.hpp"

#define VERSION 1.0

#define CRITERIA L"(IsInstalled = 0 and CategoryIDs contains '0fa1201d-4330-4fa8-8ae9-b877473b6441') or (IsInstalled = 0 and CategoryIDs contains 'E6CF1350-C01B-414D-A61F-263D14D133B4')"

namespace po = boost::program_options;

using std::wcout; using std::endl;
using std::wstring; using std::cout;

struct printInfoStruct {
	BOOL warn, crit;
	LONG numUpdates;
	BOOL important, reboot, careForCanRequest;
};

static int parseArguments(int, wchar_t **, po::variables_map&, printInfoStruct&);
static int printOutput(const printInfoStruct&);
static int check_update(printInfoStruct&);

int main(int argc, wchar_t **argv) 
{
	po::variables_map vm;
	printInfoStruct printInfo = { FALSE, FALSE, 0, FALSE, FALSE, FALSE };

	int ret = parseArguments(argc, argv, vm, printInfo);
	if (ret != -1)
		return ret;
	
	ret = check_update(printInfo);
	if (ret != -1)
		return ret;

	return printOutput(printInfo);
}

int printOutput(const printInfoStruct& printInfo) 
{
	state state = OK;
	wstring output = L"UPDATE ";

	if (printInfo.important)
		state = WARNING;

	if (printInfo.reboot)
		state = CRITICAL;

	switch (state)
	{
	case OK:
		output.append(L"OK ");
		break;
	case WARNING:
		output.append(L"WARNING ");
		break;
	case CRITICAL:
		output.append(L"CRITICAL ");
		break;
	}

	wcout << output << printInfo.numUpdates << L"|update=" << printInfo.numUpdates << L";"
		<< printInfo.warn << L";" << printInfo.crit << L";0" << endl;
	return state;
}

int parseArguments(int ac, wchar_t **av, po::variables_map& vm, printInfoStruct& printInfo) 
{
	wchar_t namePath[MAX_PATH];
	GetModuleFileName(NULL, namePath, MAX_PATH);
	wchar_t *progName = PathFindFileName(namePath);

	po::options_description desc;

	desc.add_options()
		(",h", "print help message and exit")
		("help", "print verbose help and exit")
		("version,v", "print version and exit")
		("warning,w", "warn if there are important updates available")
		("critical,c", "critical if there are important updates that require a reboot")
		("possible-reboot", "treat \"update may need to reboot\" as \"update needs to reboot\"")
		;

	po::basic_command_line_parser<wchar_t> parser(ac, av);

	try {
		po::store(
			parser
			.options(desc)
			.style(
			po::command_line_style::unix_style |
			po::command_line_style::allow_long_disguise)
			.run(),
			vm);
		vm.notify();
	}

	catch (std::exception& e) {
		cout << e.what() << endl << desc << endl;
		return 3;
	}

	if (vm.count("h")) {
		cout << desc << endl;
		return 0;
	} 
	if (vm.count("help")) {
		wcout << progName << " Help\n\tVersion: " << VERSION << endl;
		wprintf(
			L"%s is a simple program to check a machines required updates.\n"
			L"You can use the following options to define its behaviour:\n\n", progName);
		cout << desc;
		wprintf(
			L"\nAfter some time, it will then output a string like this one:\n\n"
			L"\tUPDATE WARNING 8|updates=8;1;1;0\n\n"
			L"\"UPDATE\" being the type of the check, \"WARNING\" the returned status\n"
			L"and \"8\" is the number of important updates updates.\n"
			L"The performance data is found behind the \"|\", in order:\n"
			L"returned value, warning threshold, critical threshold, minimal value and,\n"
			L"if applicable, the maximal value.\n\n"
			L"An update counts as important when it is part of the Security- or\n"
			L"CriticalUpdates group.\n"
			L"Consult the msdn on WSUS Classification GUIDs for more information.\n"
			L"%s' exit codes denote the following:\n"
			L" 0\tOK,\n\tno Thresholds were broken or the programs check part was not executed\n"
			L" 1\tWARNING,\n\tThe warning, but not the critical threshold was broken\n"
			L" 2\tCRITICAL,\n\tThe critical threshold was broken\n"
			L" 3\tUNKNOWN, \n\tThe programme experienced an internal or input error\n\n"
			L"%s works different from other plugins in that you do not set thresholds\n"
			L"but only activate them. Using \"-w\" triggers warning state if there are not\n"
			L"installed and non-optional updates. \"-c\" triggers critical if there are\n"
			L"non-optional updates that require a reboot.\n"
			L"The \"possible-reboot\" option is not recommended since this true for nearly\n"
			L"every update."
			, progName, progName);
		cout << endl;
		return 0;
	}  if (vm.count("version")) {
		cout << "Version: " << VERSION << endl;
		return 0;
	}

	if (vm.count("warning"))
		printInfo.warn = TRUE;

	if (vm.count("critical"))
		printInfo.crit = TRUE;

	if (vm.count("possible-reboot"))
		printInfo.careForCanRequest = TRUE;

	return -1;
}

int check_update(printInfoStruct& printInfo) 
{
	CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
	ISearchResult *pResult;
	IUpdateSession *pSession;
	IUpdateSearcher *pSearcher;

	CoCreateInstance(CLSID_UpdateSession, NULL, CLSCTX_INPROC_SERVER, IID_IUpdateSession, (LPVOID*)&pSession);
	pSession->CreateUpdateSearcher(&pSearcher);


	/*
	 IsInstalled = 0: All updates, including languagepacks and features
	 BrowseOnly = 0: No features or languagepacks, security and unnamed
	 BrowseOnly = 1: Nothing, broken
	 RebootRequired = 1: Reboot required
	*/

	BSTR criteria = SysAllocString(CRITERIA);
	// http://msdn.microsoft.com/en-us/library/windows/desktop/aa386526%28v=vs.85%29.aspx
	// http://msdn.microsoft.com/en-us/library/ff357803%28v=vs.85%29.aspx

	if (pSearcher->Search(criteria, &pResult) != S_OK)
		goto die;
	SysFreeString(criteria);

	IUpdateCollection *pCollection;
	IUpdate *pUpdate;

	LONG updateSize;
	pResult->get_Updates(&pCollection);
	pCollection->get_Count(&updateSize);

	if (updateSize == 0)
		return -1;

	printInfo.numUpdates = updateSize;
	printInfo.important = printInfo.warn;

	if (!printInfo.crit)
		return -1;

	IInstallationBehavior *pIbehav;
	InstallationRebootBehavior updateReboot;

	for (LONG i = 0; i < updateSize; i++)
	{
		pCollection->get_Item(i, &pUpdate);
		pUpdate->get_InstallationBehavior(&pIbehav);
		pIbehav->get_RebootBehavior(&updateReboot);
		if (updateReboot == irbAlwaysRequiresReboot) {
			printInfo.reboot = TRUE;
			continue;
		}
		if (printInfo.careForCanRequest && updateReboot == irbCanRequestReboot)
			printInfo.reboot = TRUE;
	}

	return 0;

die:
	if (criteria)
		SysFreeString(criteria);
	return 3;
}