/*
 * This file is part of PowerDNS or dnsdist.
 * Copyright -- PowerDNS.COM B.V. and its contributors
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * In addition, for the avoidance of any doubt, permission is granted to
 * link this program with OpenSSL and to (re)distribute the binaries
 * produced as the result of such linking.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#pragma once

#include "tcounters.hh"

#include <string>

#include "histogram.hh"
#include "rec-responsestats.hh"
#include "validate.hh"
#include "filterpo.hh"

namespace rec
{

// Simple counters
enum class Counter : uint8_t
{
  outgoingtimeouts,
  outgoing4timeouts,
  outgoing6timeouts,
  throttledqueries,
  dontqueries,
  qnameminfallbacksuccess,
  authzonequeries,
  outqueries,
  tcpoutqueries,
  dotoutqueries,
  unreachables,
  servFails,
  nxDomains,
  noErrors,
  qcounter,
  ipv6qcounter,
  tcpqcounter,
  unauthorizedUDP, // when this is increased, qcounter isn't
  unauthorizedTCP, // when this is increased, qcounter isn't
  sourceDisallowedNotify, // when this is increased, qcounter is also
  zoneDisallowedNotify, // when this is increased, qcounter is also
  policyDrops,
  tcpOverflow,
  tcpClientOverflow,
  clientParseError,
  serverParseError,
  tooOldDrops,
  truncatedDrops,
  queryPipeFullDrops,
  unexpectedCount,
  caseMismatchCount,
  spoofCount,
  resourceLimits,
  overCapacityDrops,
  ipv6queries,
  chainResends,
  nsSetInvalidations,
  ednsPingMatches,
  ednsPingMismatches,
  noPingOutQueries,
  noEdnsOutQueries,
  noPacketError,
  ignoredCount,
  emptyQueriesCount,
  dnssecQueries,
  dnssecAuthenticDataQueries,
  dnssecCheckDisabledQueries,
  variableResponses,
  maxMThreadStackUsage,
  dnssecValidations, // should be the sum of all dnssecResult* stats
  rebalancedQueries,
  proxyProtocolInvalidCount,
  nodLookupsDroppedOversize,
  dns64prefixanswers,
  maintenanceUsec,
  maintenanceCalls,
  nodCount,
  udrCount,
  maxChainLength,
  maxChainWeight,
  chainLimits,
  ecsMissingCount,

  numberOfCounters
};

// double averages times, weighted according to how many packets they processed
enum class DoubleWAvgCounter : uint8_t
{
  avgLatencyUsec,
  avgLatencyOursUsec,
  numberOfCounters
};

// An RCode histogram
enum class RCode : uint8_t
{
  auth,
  numberOfCounters
};

// Recursor Response Stats
enum class ResponseStats : uint8_t
{
  responseStats,
  numberOfCounters
};

// A few other histograms
enum class Histogram : uint8_t
{
  answers,
  auth4Answers,
  auth6Answers,
  ourtime,
  cumulativeAnswers,
  cumulativeAuth4Answers,
  cumulativeAuth6Answers,

  numberOfCounters
};

// DNSSEC validation results
enum class DNSSECHistogram : uint8_t
{
  dnssec,
  xdnssec,

  numberOfCounters
};

// Policy hits
enum class PolicyHistogram : uint8_t
{
  policy,

  numberOfCounters
};

enum class PolicyNameHits : uint8_t
{
  policyName,

  numberOfCounters
};

struct Counters
{
  // An array of simple counters
  std::array<uint64_t, static_cast<size_t>(Counter::numberOfCounters)> uint64Count{};

  struct WeightedAverage
  {
    double avg{};
    uint64_t weight{};

    void add(double value)
    {
      avg = value;
      ++weight;
    }

    void addToRollingAvg(double value, uint64_t rollsize)
    {
      add((1.0 - 1.0 / static_cast<double>(rollsize)) * avg + value / static_cast<double>(rollsize));
    }
  };
  // And an array of weighted averaged values
  std::array<WeightedAverage, static_cast<size_t>(DoubleWAvgCounter::numberOfCounters)> doubleWAvg{};

  struct RCodeCounters
  {
    RCodeCounters& operator+=(const RCodeCounters& rhs)
    {
      for (size_t i = 0; i < rcodeCounters.size(); i++) {
        rcodeCounters.at(i) += rhs.rcodeCounters.at(i);
      }
      return *this;
    }
    static const size_t numberOfRCodes = 16;
    std::array<uint64_t, numberOfRCodes> rcodeCounters;
  };
  // An RCodes histogram
  RCodeCounters auth{};

  std::array<pdns::Histogram, static_cast<size_t>(Histogram::numberOfCounters)> histograms = {
    pdns::Histogram{"answers", {1000, 10000, 100000, 1000000}},
    pdns::Histogram{"auth4answers", {1000, 10000, 100000, 1000000}},
    pdns::Histogram{"auth6answers", {1000, 10000, 100000, 1000000}},
    pdns::Histogram{"ourtime", {1000, 2000, 4000, 8000, 16000, 32000}},
    pdns::Histogram{"cumul-clientanswers-", 10, 19},
    pdns::Histogram{"cumul-authanswers-", 1000, 13},
    pdns::Histogram{"cumul-authanswers-", 1000, 13}};

  // Response stats
  RecResponseStats responseStats{};

  // DNSSEC stats
  struct DNSSECCounters
  {
    DNSSECCounters& operator+=(const DNSSECCounters& rhs)
    {
      for (size_t i = 0; i < counts.size(); i++) {
        counts.at(i) += rhs.counts.at(i);
      }
      return *this;
    }
    uint64_t& at(vState index)
    {
      return counts.at(static_cast<size_t>(index));
    }
    std::array<uint64_t, static_cast<size_t>(vState::BogusInvalidDNSKEYProtocol) + 1> counts;
  };
  std::array<DNSSECCounters, static_cast<size_t>(DNSSECHistogram::numberOfCounters)> dnssecCounters{};

  // Policy histogram
  struct PolicyCounters
  {
    PolicyCounters& operator+=(const PolicyCounters& rhs)
    {
      for (size_t i = 0; i < counts.size(); i++) {
        counts.at(i) += rhs.counts.at(i);
      }
      return *this;
    }
    uint64_t& at(DNSFilterEngine::PolicyKind index)
    {
      return counts.at(static_cast<size_t>(index));
    }
    std::array<uint64_t, static_cast<size_t>(DNSFilterEngine::PolicyKind::Custom) + 1> counts;
  };
  PolicyCounters policyCounters{};

  // Policy hits by name
  struct PolicyNameCounters
  {
    PolicyNameCounters& operator+=(const PolicyNameCounters& rhs)
    {
      for (const auto& [name, count] : rhs.counts) {
        counts[name] += count;
      }
      return *this;
    }
    std::unordered_map<std::string, uint64_t> counts;
  };
  PolicyNameCounters policyNameHits;

  Counters()
  {
    for (auto& elem : uint64Count) {
      elem = 0;
    }
    // doubleWAvg has a default constructor that initializes
    for (auto& elem : auth.rcodeCounters) {
      elem = 0;
    }
    // Histogram has a constructor that initializes
    // RecResponseStats has a default constructor that initializes
    for (auto& histogram : dnssecCounters) {
      for (auto& elem : histogram.counts) {
        elem = 0;
      }
    }
    for (auto& elem : policyCounters.counts) {
      elem = 0;
    }
    // PolicyNameCounters has a default constuctor that initializes
  }

  // Merge a set of counters into an existing set of counters. For simple counters, that will be additions
  // for averages, we should take the weights into account. Histograms need to sum all individual counts.
  Counters& merge(const Counters& data);

  // The following accessors select the right counter type based on the index type
  uint64_t& at(Counter index)
  {
    return uint64Count.at(static_cast<size_t>(index));
  }

  WeightedAverage& at(DoubleWAvgCounter index)
  {
    return doubleWAvg.at(static_cast<size_t>(index));
  }

  RCodeCounters& at(RCode /*unused*/)
  {
    // We only have a single RCode indexed Histogram, so no need to select a specific one
    return auth;
  }

  RecResponseStats& at(ResponseStats /*unused*/)
  {
    // We only have a single ResponseStats indexed RecResponseStats, so no need to select a specific one
    return responseStats;
  }

  pdns::Histogram& at(Histogram index)
  {
    return histograms.at(static_cast<size_t>(index));
  }

  DNSSECCounters& at(DNSSECHistogram index)
  {
    return dnssecCounters.at(static_cast<size_t>(index));
  }

  // We only have a single PolicyHistogram indexed PolicyCounters, so no need to select a specific one
  PolicyCounters& at(PolicyHistogram)
  {
    return policyCounters;
  }

  // We only have a single policyNameHits indexed PolicyNameCounters, so no need to select a specific one
  PolicyNameCounters& at(PolicyNameHits /*unused*/)
  {
    return policyNameHits;
  }

  // Mainly for debugging purposes
  [[nodiscard]] std::string toString() const;
};

// The application specific types, one for thread local, one for the aggregator
using TCounters = pdns::TLocalCounters<Counters>;
using GlobalCounters = pdns::GlobalCounters<Counters>;
}
