#include "statistics.h"

#include "libreichwein/file.h"
#include "libreichwein/tempfile.h"

#include <boost/algorithm/string/predicate.hpp>
#include <boost/algorithm/string/split.hpp>
#include <boost/coroutine2/coroutine.hpp>
#include <boost/process.hpp>

#include <algorithm>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <string>
#include <unordered_map>

using namespace std::string_literals;
namespace bp = boost::process;
namespace fs = std::filesystem;
using namespace Reichwein;

namespace {

 // Used to return errors by generating response page and HTTP status code
 std::string HttpStatus(std::string status, std::string message, std::function<plugin_interface_setter_type>& SetResponseHeader)
 {
  SetResponseHeader("status", status);
  SetResponseHeader("content_type", "text/html");

  return status + " " + message;
 }

 std::string statsPng(std::function<std::string(const std::string& key)>& GetServerParam,
                      std::function<plugin_interface_setter_type>& SetResponseHeader)
 {
  // Create PNG statistics via Gnuplot
  std::string statistics{GetServerParam("statistics")};

  Tempfile tempStats{".txt"}; // input data
  File::setFile(tempStats.getPath(), statistics);
  
  Tempfile tempPng{".png"}; // output
  
  Tempfile tempGnuplot{".gnuplot"};
  std::stringstream s;
  s << "set terminal png truecolor\n";
  s << "set output " << tempPng.getPath() << "\n"; // quotes added automatically for paths
  s << "set title \"Webserver Throughput\"\n";
  s << "set xlabel \"Time\"\n";
  s << "set timefmt \"%s\"\n";
  s << "set format x \"%Y-%m-%d\"\n";
  s << "set xdata time\n";
  s << "set xtics rotate by 45 right\n";
  s << "set ylabel \"Bytes\"\n";
  s << "set datafile separator \",\"\n";
  s << "set grid\n";
  s << "set style fill solid\n";
  s << "plot " << tempStats.getPath() << " using 1:($4+$5) with boxes title \"Bytes I/O\" lt rgb \"#1132A7\"\n";
  File::setFile(tempGnuplot.getPath(), s.str());

  int exit_code{system(("gnuplot "s + tempGnuplot.getPath().generic_string()).c_str())};
  if (exit_code) {
   std::cerr << "Error: gnuplot returned " << std::to_string(exit_code) << std::endl;
   return HttpStatus("500", "Statistics error"s, SetResponseHeader);
  }
  
  SetResponseHeader("content_type", "image/png");
  return File::getFile(tempPng.getPath());
 }

 // returns sum over specified column
 uint64_t getSum(const std::string& stats, size_t column)
 {
  uint64_t result{0};

  std::istringstream is{stats};
  std::string line;

  while (std::getline(is, line) && !is.eof()) {

   std::vector<std::string> elements;
   boost::algorithm::split(elements, line, [](char c){ return c == ','; });

   if (column >= elements.size()) {
    std::cerr << "Error: No column " << column << " found." << std::endl;
    return 0;
   }

   try {
    result += stoull(elements[column]);
   } catch(...) {
    std::cerr << "Error: Stats value " << elements[column] << " malformed." << std::endl;
   }
  }

  return result;
 }

} // anonymous namespace

std::string statistics_plugin::name()
{
 return "statistics";
}

statistics_plugin::statistics_plugin()
{
 //std::cout << "Plugin constructor" << std::endl;
}

statistics_plugin::~statistics_plugin()
{
 //std::cout << "Plugin destructor" << std::endl;
}

std::string statistics_plugin::generate_page(
  std::function<std::string(const std::string& key)>& GetServerParam,
  std::function<std::string(const std::string& key)>& GetRequestParam, // request including body (POST...)
  std::function<void(const std::string& key, const std::string& value)>& SetResponseHeader // to be added to result string
)
{
 try {
  // Request path must not contain "..".
  std::string rel_target{GetRequestParam("rel_target")};
  size_t query_pos{rel_target.find("?")};
  if (query_pos != rel_target.npos)
   rel_target = rel_target.substr(0, query_pos);

  std::string target{GetRequestParam("target")};
  if (rel_target.find("..") != std::string::npos) {
   return HttpStatus("400", "Illegal request: "s + target, SetResponseHeader);
  }

  // Build the path to the requested file
  std::string doc_root{GetRequestParam("doc_root")};
  fs::path path {fs::path{doc_root} / rel_target};
  if (target.size() && target.back() != '/' && fs::is_directory(path)) {
   std::string location{GetRequestParam("location") + "/"s};
   SetResponseHeader("location", location);
   return HttpStatus("301", "Correcting directory path", SetResponseHeader); // 301 Moved Permanently
  }

  if (path.filename() == "stats.png")
   return statsPng(GetServerParam, SetResponseHeader);

  try {
   SetResponseHeader("content_type", "text/html");

   std::string header {"<!DOCTYPE html><html><head>"
             "<meta charset=\"utf-8\"/>"
             "<title>Webserver Statistics</title>"
             "</head><body>"};
   std::string footer{"<br/><br/><br/></body></html>"};

   std::string result{header};

   std::string statistics{GetServerParam("statistics")};
   double ipv6_fraction_by_requests {double(getSum(statistics, 5)) / getSum(statistics, 1)};
   double ipv6_fraction_by_bytes {double(getSum(statistics, 7) + getSum(statistics, 8)) / (getSum(statistics, 3) + getSum(statistics, 4))};
   double https_fraction_by_requests {double(getSum(statistics, 9)) / getSum(statistics, 1)};
   double https_fraction_by_bytes {double(getSum(statistics, 11) + getSum(statistics, 12)) / (getSum(statistics, 3) + getSum(statistics, 4))};

   result += "<h1>Webserver Statistics</h1>";
   result += "<p>Host uptime: "s + GetServerParam("uptime_host") + "</p>";
   result += "<p>Webserver uptime: "s + GetServerParam("uptime_webserver") + "</p>";
   result += "<p>IPv6 fraction by requests: "s + std::to_string(ipv6_fraction_by_requests * 100) + "%</p>";
   result += "<p>IPv6 fraction by bytes: "s + std::to_string(ipv6_fraction_by_bytes * 100) + "%</p>";
   result += "<p>HTTPS fraction by requests: "s + std::to_string(https_fraction_by_requests * 100) + "%</p>";
   result += "<p>HTTPS fraction by bytes: "s + std::to_string(https_fraction_by_bytes * 100) + "%</p>";
   result += "<p><img src=\"stats.png\"/></p>";
   result += "<pre>"s + statistics + "</pre>"s;

   result += footer;
   
   return result;
  } catch (const std::exception& ex) {
   return HttpStatus("500", "Statistics error: "s + ex.what(), SetResponseHeader);
  }

 } catch (const std::exception& ex) {
  return HttpStatus("500", "Unknown Error: "s + ex.what(), SetResponseHeader);
 }
}

bool statistics_plugin::has_own_authentication()
{
 return false;
}