#include <algorithm>
	#include <iostream>
	#include <fstream>
	#include <string>
	#include <numeric>
	#include <regex>
	#include <cmath>
	#include <system_error>
	
	using namespace std;
	
	int main(int argc, char **argv)
	{
	  cout << "Mon RSS Usage Test" << endl;
	

	  if (argc != 2) {
	    cout << "Syntax: "
	         << "ceph_test_mon_rss_usage <mon-memory-target-bytes>"
	         << endl;
	    exit(EINVAL);
	  }
	
	  unsigned long maxallowed = stoul(argv[1], nullptr, 10);
	  // Set max allowed RSS usage to be 125% of mon-memory-target
	  maxallowed *= 1.25;
	
	  string target_directory("/var/log/ceph/");
	  string filePath = target_directory + "ceph-mon-rss-usage.log";
	  ifstream buffer(filePath.c_str());
	  string line;
	  vector<unsigned long> results;

	  while(getline(buffer, line) && !line.empty()) {
	    string rssUsage;
	    size_t pos = line.find(':');
	    if (pos != string::npos) {
	      rssUsage = line.substr(0, pos);
	    }
	    if (!rssUsage.empty()) {
	      results.push_back(stoul(rssUsage));
	    }

	  }
	
	  buffer.close();

	  if (results.empty()) {
	    cout << "Error: No grep results found!" << endl;
	    exit(ENOENT);
	  }
	
	  auto maxe = *(max_element(results.begin(), results.end()));
	  cout << "Stats for mon RSS Memory Usage:" << endl;
	  cout << "Parsed " << results.size() << " entries." << endl;
	  cout << "Max: " << maxe << endl;
	  cout << "Min: " << *(min_element(results.begin(), results.end())) << endl;
	  auto sum = accumulate(results.begin(), results.end(),
	                        static_cast<unsigned long long>(0));
	  auto mean = sum / results.size();
	  cout << "Mean average: " << mean << endl;
	  vector<unsigned long> diff(results.size());
	  transform(results.begin(), results.end(), diff.begin(),
	            [mean](unsigned long x) { return x - mean; });
	  auto sump = inner_product(diff.begin(), diff.end(), diff.begin(), 0.0);
	  auto stdev = sqrt(sump / results.size());

	  cout << fixed <<  "Standard deviation: " << stdev << endl;
	

	  if (maxe > maxallowed) {
	    cout << "Error: Mon RSS memory usage exceeds maximum allowed!" << endl;
	    exit(ENOMEM);
	  }
	
	  cout << "Completed successfully" << endl;

	  return 0;
	}