/*
 * 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 "dolog.hh"
#include "dnsdist.hh"
#include "dnsparser.hh"
#include <random>

struct ResponseConfig
{
  boost::optional<bool> setAA{boost::none};
  boost::optional<bool> setAD{boost::none};
  boost::optional<bool> setRA{boost::none};
  uint32_t ttl{60};
};
void setResponseHeadersFromConfig(dnsheader& dh, const ResponseConfig& config);

class SpoofAction : public DNSAction
{
public:
  SpoofAction(const vector<ComboAddress>& addrs): d_addrs(addrs)
  {
    for (const auto& addr : d_addrs) {
      if (addr.isIPv4()) {
        d_types.insert(QType::A);
      }
      else if (addr.isIPv6()) {
        d_types.insert(QType::AAAA);
      }
    }

    if (!d_addrs.empty()) {
      d_types.insert(QType::ANY);
    }
  }

  SpoofAction(const DNSName& cname): d_cname(cname)
  {
  }

  SpoofAction(const char* rawresponse, size_t len): d_raw(rawresponse, rawresponse + len)
  {
  }

  SpoofAction(const vector<std::string>& raws): d_rawResponses(raws)
  {
  }

  DNSAction::Action operator()(DNSQuestion* dq, string* ruleresult) const override;

  string toString() const override
  {
    string ret = "spoof in ";
    if (!d_cname.empty()) {
      ret += d_cname.toString() + " ";
    }
    if (d_rawResponses.size() > 0) {
      ret += "raw bytes ";
    }
    else {
      for(const auto& a : d_addrs)
        ret += a.toString()+" ";
    }
    return ret;
  }


  ResponseConfig d_responseConfig;
private:
  static thread_local std::default_random_engine t_randomEngine;
  std::vector<ComboAddress> d_addrs;
  std::unordered_set<uint16_t> d_types;
  std::vector<std::string> d_rawResponses;
  PacketBuffer d_raw;
  DNSName d_cname;
};

class LimitTTLResponseAction : public DNSResponseAction, public boost::noncopyable
{
public:
  LimitTTLResponseAction() {}

  LimitTTLResponseAction(uint32_t min, uint32_t max = std::numeric_limits<uint32_t>::max(), const std::unordered_set<QType>& types = {}) : d_types(types), d_min(min), d_max(max)
  {
  }

  DNSResponseAction::Action operator()(DNSResponse* dr, std::string* ruleresult) const override
  {
    auto visitor = [&](uint8_t section, uint16_t qclass, uint16_t qtype, uint32_t ttl) {
      if (!d_types.empty() && qclass == QClass::IN && d_types.count(qtype) == 0) {
        return ttl;
      }

      if (d_min > 0) {
        if (ttl < d_min) {
          ttl = d_min;
        }
      }
      if (ttl > d_max) {
        ttl = d_max;
      }
      return ttl;
    };
    editDNSPacketTTL(reinterpret_cast<char *>(dr->getMutableData().data()), dr->getData().size(), visitor);
    return DNSResponseAction::Action::None;
  }

  std::string toString() const override
  {
    std::string result = "limit ttl (" + std::to_string(d_min) + " <= ttl <= " + std::to_string(d_max);
    if (!d_types.empty()) {
      bool first = true;
      result += ", types in [";
      for (const auto& type : d_types) {
        if (first) {
          first = false;
        }
        else {
          result += " ";
        }
        result += type.toString();
      }
      result += "]";
    }
    result += + ")";
    return result;
  }

private:
  std::unordered_set<QType> d_types;
  uint32_t d_min{0};
  uint32_t d_max{std::numeric_limits<uint32_t>::max()};
};

template <class T> using LuaArray = std::vector<std::pair<int, T>>;
template <class T> using LuaAssociativeTable = std::unordered_map<std::string, T>;
template <class T> using LuaTypeOrArrayOf = boost::variant<T, LuaArray<T>>;

using luadnsrule_t = boost::variant<string, LuaArray<std::string>, std::shared_ptr<DNSRule>, DNSName, LuaArray<DNSName>>;
using luaruleparams_t = LuaAssociativeTable<std::string>;
using nmts_t = NetmaskTree<DynBlock, AddressAndPortRange>;

std::shared_ptr<DNSRule> makeRule(const luadnsrule_t& var);
void parseRuleParams(boost::optional<luaruleparams_t>& params, boost::uuids::uuid& uuid, std::string& name, uint64_t& creationOrder);
void checkParameterBound(const std::string& parameter, uint64_t value, size_t max = std::numeric_limits<uint16_t>::max());

vector<std::function<void(void)>> setupLua(LuaContext& luaCtx, bool client, bool configCheck, const std::string& config);
void setupLuaActions(LuaContext& luaCtx);
void setupLuaBindings(LuaContext& luaCtx, bool client);
void setupLuaBindingsDNSCrypt(LuaContext& luaCtx, bool client);
void setupLuaBindingsDNSParser(LuaContext& luaCtx);
void setupLuaBindingsDNSQuestion(LuaContext& luaCtx);
void setupLuaBindingsKVS(LuaContext& luaCtx, bool client);
void setupLuaBindingsNetwork(LuaContext& luaCtx, bool client);
void setupLuaBindingsPacketCache(LuaContext& luaCtx, bool client);
void setupLuaBindingsProtoBuf(LuaContext& luaCtx, bool client, bool configCheck);
void setupLuaBindingsRings(LuaContext& luaCtx, bool client);
void setupLuaRules(LuaContext& luaCtx);
void setupLuaInspection(LuaContext& luaCtx);
void setupLuaVars(LuaContext& luaCtx);
void setupLuaWeb(LuaContext& luaCtx);
void setupLuaLoadBalancingContext(LuaContext& luaCtx);

/**
 * getOptionalValue(vars, key, value)
 *
 * Attempts to extract value for key in vars.
 * Erases the key from vars.
 *
 * returns: -1 if type wasn't compatible, 0 if not found or number of element(s) found
 */
template<class G, class T, class V>
static inline int getOptionalValue(boost::optional<V>& vars, const std::string& key, T& value, bool warnOnWrongType = true) {
  /* nothing found, nothing to return */
  if (!vars) {
    return 0;
  }

  if (vars->count(key)) {
    try {
      value = boost::get<G>((*vars)[key]);
    } catch (const boost::bad_get& e) {
      /* key is there but isn't compatible */
      if (warnOnWrongType) {
        warnlog("Invalid type for key '%s' - ignored", key);
        vars->erase(key);
      }
      return -1;
    }
  }
  return vars->erase(key);
}

template<class T, class V>
static inline int getOptionalIntegerValue(const std::string& func, boost::optional<V>& vars, const std::string& key, T& value) {
  std::string valueStr;
  auto ret = getOptionalValue<std::string>(vars, key, valueStr, true);
  if (ret == 1) {
    try {
      value = std::stoi(valueStr);
    }
    catch (const std::exception& e) {
      warnlog("Parameter '%s' of '%s' must be integer, not '%s' - ignoring", func, key, valueStr);
      return -1;
    }
  }
  return ret;
}

template<class V>
static inline void checkAllParametersConsumed(const std::string& func, const boost::optional<V>& vars) {
  /* no vars */
  if (!vars) {
    return;
  }
  for (const auto& [key, value] : *vars) {
    warnlog("%s: Unknown key '%s' given - ignored", func, key);
  }
}