#ifndef SRC_CARES_WRAP_H_
#define SRC_CARES_WRAP_H_

#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#define CARES_STATICLIB

#include "async_wrap.h"
#include "base_object.h"
#include "env.h"
#include "memory_tracker.h"
#include "node.h"
#include "node_internals.h"
#include "util.h"

#include "ares.h"
#include "v8.h"
#include "uv.h"

#include <unordered_set>

#ifdef __POSIX__
# include <netdb.h>
#endif  // __POSIX__

# include <ares_nameser.h>

namespace node {
namespace cares_wrap {

constexpr int ns_t_cname_or_a = -1;
constexpr int DNS_ESETSRVPENDING = -1000;
constexpr uint8_t DNS_ORDER_VERBATIM = 0;
constexpr uint8_t DNS_ORDER_IPV4_FIRST = 1;
constexpr uint8_t DNS_ORDER_IPV6_FIRST = 2;

class ChannelWrap;

inline void safe_free_hostent(struct hostent* host);

using HostEntPointer = DeleteFnPtr<hostent, ares_free_hostent>;
using SafeHostEntPointer = DeleteFnPtr<hostent, safe_free_hostent>;

inline const char* ToErrorCodeString(int status) {
  switch (status) {
#define V(code) case ARES_##code: return #code;
    V(EADDRGETNETWORKPARAMS)
    V(EBADFAMILY)
    V(EBADFLAGS)
    V(EBADHINTS)
    V(EBADNAME)
    V(EBADQUERY)
    V(EBADRESP)
    V(EBADSTR)
    V(ECANCELLED)
    V(ECONNREFUSED)
    V(EDESTRUCTION)
    V(EFILE)
    V(EFORMERR)
    V(ELOADIPHLPAPI)
    V(ENODATA)
    V(ENOMEM)
    V(ENONAME)
    V(ENOTFOUND)
    V(ENOTIMP)
    V(ENOTINITIALIZED)
    V(EOF)
    V(EREFUSED)
    V(ESERVFAIL)
    V(ETIMEOUT)
#undef V
  }

  return "UNKNOWN_ARES_ERROR";
}

inline void cares_wrap_hostent_cpy(
    struct hostent* dest,
    const struct hostent* src) {
  dest->h_addr_list = nullptr;
  dest->h_addrtype = 0;
  dest->h_aliases = nullptr;
  dest->h_length = 0;
  dest->h_name = nullptr;

  /* copy `h_name` */
  size_t name_size = strlen(src->h_name) + 1;
  dest->h_name = node::Malloc<char>(name_size);
  memcpy(dest->h_name, src->h_name, name_size);

  /* copy `h_aliases` */
  size_t alias_count;
  for (alias_count = 0;
      src->h_aliases[alias_count] != nullptr;
      alias_count++) {
  }

  dest->h_aliases = node::Malloc<char*>(alias_count + 1);
  for (size_t i = 0; i < alias_count; i++) {
    const size_t cur_alias_size = strlen(src->h_aliases[i]) + 1;
    dest->h_aliases[i] = node::Malloc(cur_alias_size);
    memcpy(dest->h_aliases[i], src->h_aliases[i], cur_alias_size);
  }
  dest->h_aliases[alias_count] = nullptr;

  /* copy `h_addr_list` */
  size_t list_count;
  for (list_count = 0;
      src->h_addr_list[list_count] != nullptr;
      list_count++) {
  }

  dest->h_addr_list = node::Malloc<char*>(list_count + 1);
  for (size_t i = 0; i < list_count; i++) {
    dest->h_addr_list[i] = node::Malloc(src->h_length);
    memcpy(dest->h_addr_list[i], src->h_addr_list[i], src->h_length);
  }
  dest->h_addr_list[list_count] = nullptr;

  /* work after work */
  dest->h_length = src->h_length;
  dest->h_addrtype = src->h_addrtype;
}


struct NodeAresTask final : public MemoryRetainer {
  ChannelWrap* channel;
  ares_socket_t sock;
  uv_poll_t poll_watcher;

  inline void MemoryInfo(MemoryTracker* trakcer) const override;
  SET_MEMORY_INFO_NAME(NodeAresTask)
  SET_SELF_SIZE(NodeAresTask)

  struct Hash {
    inline size_t operator()(NodeAresTask* a) const {
      return std::hash<ares_socket_t>()(a->sock);
    }
  };

  struct Equal {
    inline bool operator()(NodeAresTask* a, NodeAresTask* b) const {
      return a->sock == b->sock;
    }
  };

  static NodeAresTask* Create(ChannelWrap* channel, ares_socket_t sock);

  using List = std::unordered_set<NodeAresTask*, Hash, Equal>;
};

class ChannelWrap final : public AsyncWrap {
 public:
  ChannelWrap(Environment* env,
              v8::Local<v8::Object> object,
              int timeout,
              int tries,
              int max_timeout);
  ~ChannelWrap() override;

  static void New(const v8::FunctionCallbackInfo<v8::Value>& args);

  void Setup();
  void EnsureServers();
  void StartTimer();
  void CloseTimer();

  void ModifyActivityQueryCount(int count);

  inline uv_timer_t* timer_handle() { return timer_handle_; }
  inline ares_channel cares_channel() { return channel_; }
  inline void set_query_last_ok(bool ok) { query_last_ok_ = ok; }
  inline void set_is_servers_default(bool is_default) {
    is_servers_default_ = is_default;
  }
  inline int active_query_count() { return active_query_count_; }
  inline NodeAresTask::List* task_list() { return &task_list_; }

  void MemoryInfo(MemoryTracker* tracker) const override;
  SET_MEMORY_INFO_NAME(ChannelWrap)
  SET_SELF_SIZE(ChannelWrap)

  static void AresTimeout(uv_timer_t* handle);

 private:
  uv_timer_t* timer_handle_ = nullptr;
  ares_channel channel_ = nullptr;
  bool query_last_ok_ = true;
  bool is_servers_default_ = true;
  bool library_inited_ = false;
  int timeout_;
  int tries_;
  int max_timeout_;
  int active_query_count_ = 0;
  NodeAresTask::List task_list_;
};

class GetAddrInfoReqWrap final : public ReqWrap<uv_getaddrinfo_t> {
 public:
  GetAddrInfoReqWrap(Environment* env,
                     v8::Local<v8::Object> req_wrap_obj,
                     uint8_t order);

  SET_NO_MEMORY_INFO()
  SET_MEMORY_INFO_NAME(GetAddrInfoReqWrap)
  SET_SELF_SIZE(GetAddrInfoReqWrap)

  uint8_t order() const { return order_; }

 private:
  const uint8_t order_;
};

class GetNameInfoReqWrap final : public ReqWrap<uv_getnameinfo_t> {
 public:
  GetNameInfoReqWrap(Environment* env, v8::Local<v8::Object> req_wrap_obj);

  SET_NO_MEMORY_INFO()
  SET_MEMORY_INFO_NAME(GetNameInfoReqWrap)
  SET_SELF_SIZE(GetNameInfoReqWrap)
};

struct ResponseData final {
  int status;
  bool is_host;
  SafeHostEntPointer host;
  MallocedBuffer<unsigned char> buf;
};

template <typename Traits>
class QueryWrap final : public AsyncWrap {
 public:
  QueryWrap(ChannelWrap* channel, v8::Local<v8::Object> req_wrap_obj)
      : AsyncWrap(channel->env(), req_wrap_obj, AsyncWrap::PROVIDER_QUERYWRAP),
        channel_(channel),
        trace_name_(Traits::name) {}

  ~QueryWrap() {
    CHECK_EQ(false, persistent().IsEmpty());

    // Let Callback() know that this object no longer exists.
    if (callback_ptr_ != nullptr)
      *callback_ptr_ = nullptr;
  }

  int Send(const char* name) {
    return Traits::Send(this, name);
  }

  void AresQuery(const char* name,
                 ares_dns_class_t dnsclass,
                 ares_dns_rec_type_t type) {
    channel_->EnsureServers();
    TRACE_EVENT_NESTABLE_ASYNC_BEGIN1(
      TRACING_CATEGORY_NODE2(dns, native), trace_name_, this,
      "name", TRACE_STR_COPY(name));
    ares_query_dnsrec(channel_->cares_channel(),
                      name,
                      dnsclass,
                      type,
                      Callback,
                      MakeCallbackPointer(),
                      nullptr);
  }

  void ParseError(int status) {
    CHECK_NE(status, ARES_SUCCESS);
    v8::HandleScope handle_scope(env()->isolate());
    v8::Context::Scope context_scope(env()->context());
    const char* code = ToErrorCodeString(status);
    v8::Local<v8::Value> arg = OneByteString(env()->isolate(), code);
    TRACE_EVENT_NESTABLE_ASYNC_END1(
        TRACING_CATEGORY_NODE2(dns, native), trace_name_, this,
        "error", status);
    MakeCallback(env()->oncomplete_string(), 1, &arg);
  }

  const BaseObjectPtr<ChannelWrap>& channel() const { return channel_; }

  void AfterResponse() {
    CHECK(response_data_);

    int status = response_data_->status;

    if (status != ARES_SUCCESS)
      return ParseError(status);

    if (!Traits::Parse(this, response_data_).To(&status)) {
      return ParseError(ARES_ECANCELLED);
    }

    if (status != ARES_SUCCESS)
      ParseError(status);
  }

  void* MakeCallbackPointer() {
    CHECK_NULL(callback_ptr_);
    callback_ptr_ = new QueryWrap<Traits>*(this);
    return callback_ptr_;
  }

  static QueryWrap<Traits>* FromCallbackPointer(void* arg) {
    std::unique_ptr<QueryWrap<Traits>*> wrap_ptr {
        static_cast<QueryWrap<Traits>**>(arg)
    };
    QueryWrap<Traits>* wrap = *wrap_ptr.get();
    if (wrap == nullptr) return nullptr;
    wrap->callback_ptr_ = nullptr;
    return wrap;
  }

  static void Callback(void* arg,
                       ares_status_t status,
                       size_t timeouts,
                       const ares_dns_record_t* dnsrec) {
    QueryWrap<Traits>* wrap = FromCallbackPointer(arg);
    if (wrap == nullptr) return;

    unsigned char* buf_copy = nullptr;
    size_t answer_len = 0;
    if (status == ARES_SUCCESS) {
      // No need to explicitly call ares_free_string here,
      // as it is a wrapper around free, which is already
      // invoked when MallocedBuffer is destructed.
      ares_dns_write(dnsrec, &buf_copy, &answer_len);
    }

    wrap->response_data_ = std::make_unique<ResponseData>();
    ResponseData* data = wrap->response_data_.get();
    data->status = status;
    data->is_host = false;
    data->buf = MallocedBuffer<unsigned char>(buf_copy, answer_len);

    wrap->QueueResponseCallback(status);
  }

  static void Callback(
      void* arg,
      int status,
      int timeouts,
      struct hostent* host) {
    QueryWrap<Traits>* wrap = FromCallbackPointer(arg);
    if (wrap == nullptr) return;

    struct hostent* host_copy = nullptr;
    if (status == ARES_SUCCESS) {
      host_copy = node::Malloc<hostent>(1);
      cares_wrap_hostent_cpy(host_copy, host);
    }

    wrap->response_data_ = std::make_unique<ResponseData>();
    ResponseData* data = wrap->response_data_.get();
    data->status = status;
    data->host.reset(host_copy);
    data->is_host = true;

    wrap->QueueResponseCallback(status);
  }

  void QueueResponseCallback(int status) {
    BaseObjectPtr<QueryWrap<Traits>> strong_ref{this};
    env()->SetImmediate([this, strong_ref](Environment*) {
      AfterResponse();

      // Delete once strong_ref goes out of scope.
      Detach();
    });

    channel_->set_query_last_ok(status != ARES_ECONNREFUSED);
    channel_->ModifyActivityQueryCount(-1);
  }

  void CallOnComplete(
      v8::Local<v8::Value> answer,
      v8::Local<v8::Value> extra = v8::Local<v8::Value>()) {
    v8::HandleScope handle_scope(env()->isolate());
    v8::Context::Scope context_scope(env()->context());
    v8::Local<v8::Value> argv[] = {
      v8::Integer::New(env()->isolate(), 0),
      answer,
      extra
    };
    const int argc = arraysize(argv) - extra.IsEmpty();
    TRACE_EVENT_NESTABLE_ASYNC_END0(
        TRACING_CATEGORY_NODE2(dns, native), trace_name_, this);

    MakeCallback(env()->oncomplete_string(), argc, argv);
  }

  void MemoryInfo(MemoryTracker* tracker) const override {
    tracker->TrackField("channel", channel_);
    if (response_data_) {
      tracker->TrackFieldWithSize("response", response_data_->buf.size);
    }
  }

  SET_MEMORY_INFO_NAME(QueryWrap)
  SET_SELF_SIZE(QueryWrap<Traits>)

 private:
  BaseObjectPtr<ChannelWrap> channel_;

  std::unique_ptr<ResponseData> response_data_;
  const char* trace_name_;
  // Pointer to pointer to 'this' that can be reset from the destructor,
  // in order to let Callback() know that 'this' no longer exists.
  QueryWrap<Traits>** callback_ptr_ = nullptr;
};

#define QUERY_TYPES(V)                                                         \
  V(Reverse, reverse, getHostByAddr)                                           \
  V(A, resolve4, queryA)                                                       \
  V(Any, resolveAny, queryAny)                                                 \
  V(Aaaa, resolve6, queryAaaa)                                                 \
  V(Caa, resolveCaa, queryCaa)                                                 \
  V(Cname, resolveCname, queryCname)                                           \
  V(Mx, resolveMx, queryMx)                                                    \
  V(Naptr, resolveNaptr, queryNaptr)                                           \
  V(Ns, resolveNs, queryNs)                                                    \
  V(Ptr, resolvePtr, queryPtr)                                                 \
  V(Srv, resolveSrv, querySrv)                                                 \
  V(Soa, resolveSoa, querySoa)                                                 \
  V(Tlsa, resolveTlsa, queryTlsa)                                              \
  V(Txt, resolveTxt, queryTxt)

// All query type handlers share the same basic structure, so we can simplify
// the code a bit by using a macro to define that structure.
#define TYPE_TRAITS(Name, label)                                               \
  struct Name##Traits final {                                                  \
    static constexpr const char* name = #label;                                \
    static int Send(QueryWrap<Name##Traits>* wrap, const char* name);          \
    static v8::Maybe<int> Parse(                                               \
        QueryWrap<Name##Traits>* wrap,                                         \
        const std::unique_ptr<ResponseData>& response);                        \
  };                                                                           \
  using Query##Name##Wrap = QueryWrap<Name##Traits>;

#define V(NAME, LABEL, _) TYPE_TRAITS(NAME, LABEL)
QUERY_TYPES(V)
#undef V
#undef TYPE_TRAITS
}  // namespace cares_wrap
}  // namespace node

#endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS

#endif  // SRC_CARES_WRAP_H_