#include "router_contact.hpp"

#include <oxenc/bt_serialize.h>

#include "constants/version.hpp"
#include "crypto/crypto.hpp"
#include "net/net.hpp"
#include "util/bencode.hpp"
#include "util/buffer.hpp"
#include "util/time.hpp"
#include "util/file.hpp"

namespace llarp
{
  static auto logcat = log::Cat("RC");

  NetID&
  NetID::DefaultValue()
  {
    static NetID defaultID(reinterpret_cast<const byte_t*>(llarp::DEFAULT_NETID));
    return defaultID;
  }

  bool RouterContact::BlockBogons = true;

  /// 1 day rc lifespan
  constexpr auto rc_lifetime = 24h;
  /// an RC inserted long enough ago (4 hrs) is considered stale and is removed
  constexpr auto rc_stale_age = 4h;
  /// window of time in which a router wil try to update their RC before it is marked stale
  constexpr auto rc_update_window = 5min;
  /// update RCs shortly before they are about to expire
  constexpr auto rc_update_interval = rc_stale_age - rc_update_window;

  llarp_time_t RouterContact::Lifetime = rc_lifetime;
  llarp_time_t RouterContact::StaleInsertionAge = rc_stale_age;
  llarp_time_t RouterContact::UpdateInterval = rc_update_interval;

  /// how many rc lifetime intervals should we wait until purging an rc
  constexpr auto expiration_lifetime_generations = 10;
  /// the max age of an rc before we want to expire it
  constexpr auto rc_expire_age = rc_lifetime * expiration_lifetime_generations;

  NetID::NetID(const byte_t* val)
  {
    const size_t len = strnlen(reinterpret_cast<const char*>(val), size());
    std::copy(val, val + len, begin());
  }

  NetID::NetID() : NetID(DefaultValue().data())
  {}

  bool
  NetID::operator==(const NetID& other) const
  {
    return ToString() == other.ToString();
  }

  std::string
  NetID::ToString() const
  {
    return {begin(), std::find(begin(), end(), '\0')};
  }

  bool
  NetID::BDecode(llarp_buffer_t* buf)
  {
    Zero();
    llarp_buffer_t strbuf;
    if (!bencode_read_string(buf, &strbuf))
      return false;

    if (strbuf.sz > size())
      return false;

    std::copy(strbuf.base, strbuf.base + strbuf.sz, begin());
    return true;
  }

  bool
  NetID::BEncode(llarp_buffer_t* buf) const
  {
    auto term = std::find(begin(), end(), '\0');
    return bencode_write_bytestring(buf, data(), std::distance(begin(), term));
  }

  RouterContact::RouterContact(std::string buf)
  {
    try
    {
      oxenc::bt_list_consumer btlc{buf};

      signature.from_string(btlc.consume_string());
      signed_bt_dict = btlc.consume_string();

      // TODO: parse bt dict
    }
    catch (...)
    {
      log::warning(llarp_cat, "Error: RouterContact failed to populate bt encoded contents!");
    }
  }

  std::string
  RouterContact::bt_encode() const
  {
    oxenc::bt_list_producer btlp;

    try
    {
      btlp.append(signature.ToView());
      btlp.append(signed_bt_dict);
    }
    catch (...)
    {
      log::warning(llarp_cat, "Error: RouterContact failed to bt encode contents!");
    }

    return std::move(btlp).str();
  }

  void
  RouterContact::bt_encode_subdict(oxenc::bt_list_producer& btlp) const
  {
    btlp.append(signature.ToView());
    btlp.append(signed_bt_dict);
  }

  std::string
  RouterContact::ToTXTRecord() const
  {
    std::string result;
    auto out = std::back_inserter(result);
    fmt::format_to(out, "addr={}; pk={}", addr.to_string(), pubkey);
    fmt::format_to(out, "updated={}; onion_pk={}; ", last_updated.count(), enckey.ToHex());
    if (routerVersion.has_value())
      fmt::format_to(out, "router_version={}; ", *routerVersion);
    return result;
  }

  bool
  RouterContact::FromOurNetwork() const
  {
    return netID == NetID::DefaultValue();
  }

  std::string
  RouterContact::bencode_signed_section() const
  {
    oxenc::bt_dict_producer btdp;

    btdp.append("a", addr.to_string());
    btdp.append("i", netID.ToView());
    btdp.append("k", pubkey.bt_encode());
    btdp.append("p", enckey.ToView());
    btdp.append("r", routerVersion->ToString());

    if (not srvRecords.empty())
    {
      auto sublist = btdp.append_list("s");

      for (auto& s : srvRecords)
        sublist.append(s.bt_encode());
    }

    btdp.append("u", last_updated.count());

    return std::move(btdp).str();
  }

  void
  RouterContact::Clear()
  {
    signature.Zero();
    enckey.Zero();
    pubkey.Zero();
    routerVersion = std::optional<RouterVersion>{};
    last_updated = 0s;
    srvRecords.clear();
    version = llarp::constants::proto_version;
  }

  util::StatusObject
  RouterContact::ExtractStatus() const
  {
    util::StatusObject obj{
        {"lastUpdated", last_updated.count()},
        {"publicRouter", IsPublicRouter()},
        {"identity", pubkey.ToString()},
        {"address", addr.to_string()}};

    if (routerVersion)
    {
      obj["routerVersion"] = routerVersion->ToString();
    }
    std::vector<util::StatusObject> srv;
    for (const auto& record : srvRecords)
    {
      srv.emplace_back(record.ExtractStatus());
    }
    obj["srvRecords"] = srv;
    return obj;
  }

  bool
  RouterContact::BDecode(llarp_buffer_t* buf)
  {
    Clear();

    if (*buf->cur == 'd')  // old format
    {
      return DecodeVersion_0(buf);
    }
    else if (*buf->cur != 'l')  // if not dict, should be new format and start with list
    {
      return false;
    }

    try
    {
      std::string_view buf_view(reinterpret_cast<char*>(buf->cur), buf->size_left());
      oxenc::bt_list_consumer btlist(buf_view);

      uint64_t outer_version = btlist.consume_integer<uint64_t>();

      if (outer_version == 1)
      {
        bool decode_result = DecodeVersion_1(btlist);

        // advance the llarp_buffer_t since lokimq serialization is unaware of it.
        buf->cur += btlist.current_buffer().data() - buf_view.data() + 1;

        return decode_result;
      }
      else
      {
        log::warning(logcat, "Received RouterContact with unkown version ({})", outer_version);
        return false;
      }
    }
    catch (const std::exception& e)
    {
      log::debug(logcat, "RouterContact::BDecode failed: {}", e.what());
    }

    return false;
  }

  bool
  RouterContact::DecodeVersion_0(llarp_buffer_t* buf)
  {
    return bencode_decode_dict(*this, buf);
  }

  bool
  RouterContact::DecodeVersion_1(oxenc::bt_list_consumer& btlist)
  {
    auto signature_string = btlist.consume_string_view();
    signed_bt_dict = btlist.consume_dict_data();

    if (not btlist.is_finished())
    {
      log::debug(logcat, "RouterContact serialized list too long for specified version.");
      return false;
    }

    llarp_buffer_t sigbuf(signature_string.data(), signature_string.size());
    if (not signature.FromBytestring(&sigbuf))
    {
      log::debug(logcat, "RouterContact serialized signature had invalid length.");
      return false;
    }

    llarp_buffer_t data_dict_buf(signed_bt_dict.data(), signed_bt_dict.size());
    return bencode_decode_dict(*this, &data_dict_buf);
  }

  bool
  RouterContact::decode_key(const llarp_buffer_t& key, llarp_buffer_t* buf)
  {
    bool read = false;

    // TOFIX: fuck everything about llarp_buffer_t
    // if (!BEncodeMaybeReadDictEntry("a", addr, read, key, buf))
    //   return false;

    if (!BEncodeMaybeReadDictEntry("i", netID, read, key, buf))
      return false;

    if (!BEncodeMaybeReadDictEntry("k", pubkey, read, key, buf))
      return false;

    if (key.startswith("r"))
    {
      RouterVersion r;
      if (not r.BDecode(buf))
        return false;
      routerVersion = r;
      return true;
    }

    if (not BEncodeMaybeReadDictList("s", srvRecords, read, key, buf))
      return false;

    if (!BEncodeMaybeReadDictEntry("p", enckey, read, key, buf))
      return false;

    if (!BEncodeMaybeReadDictInt("u", last_updated, read, key, buf))
      return false;

    if (!BEncodeMaybeReadDictInt("v", version, read, key, buf))
      return false;

    if (key.startswith("x") and serializeExit)
    {
      return bencode_discard(buf);
    }

    if (!BEncodeMaybeReadDictEntry("z", signature, read, key, buf))
      return false;

    return read or bencode_discard(buf);
  }

  bool
  RouterContact::IsPublicRouter() const
  {
    if (not routerVersion)
      return false;
    return addr.is_addressable();
  }

  bool
  RouterContact::IsExpired(llarp_time_t now) const
  {
    return Age(now) >= rc_expire_age;
  }

  llarp_time_t
  RouterContact::TimeUntilExpires(llarp_time_t now) const
  {
    const auto expiresAt = last_updated + Lifetime;
    return now < expiresAt ? expiresAt - now : 0s;
  }

  llarp_time_t
  RouterContact::Age(llarp_time_t now) const
  {
    return now > last_updated ? now - last_updated : 0s;
  }

  bool
  RouterContact::ExpiresSoon(llarp_time_t now, llarp_time_t dlt) const
  {
    return TimeUntilExpires(now) <= dlt;
  }

  bool
  RouterContact::Sign(const SecretKey& secretkey)
  {
    pubkey = llarp::seckey_topublic(secretkey);
    signature.Zero();
    last_updated = time_now_ms();

    signed_bt_dict = bencode_signed_section();

    return crypto::sign(
        signature,
        secretkey,
        reinterpret_cast<uint8_t*>(signed_bt_dict.data()),
        signed_bt_dict.size());
  }

  bool
  RouterContact::Verify(llarp_time_t now, bool allowExpired) const
  {
    if (netID != NetID::DefaultValue())
    {
      log::error(
          logcat, "netid mismatch: '{}' (theirs) != '{}' (ours)", netID, NetID::DefaultValue());
      return false;
    }

    if (IsExpired(now) and not allowExpired)
      return false;

    // TODO: make net* overridable
    const auto* net = net::Platform::Default_ptr();

    if (net->IsBogon(addr.in4()) && BlockBogons)
    {
      log::error(logcat, "invalid address info: {}", addr);
      return false;
    }

    if (!VerifySignature())
    {
      log::error(logcat, "invalid signature: {}", *this);
      return false;
    }
    return true;
  }

  bool
  RouterContact::VerifySignature() const
  {
    RouterContact copy;
    copy = *this;
    copy.signature.Zero();

    auto bte = copy.bt_encode();
    return crypto::verify(
        pubkey, reinterpret_cast<uint8_t*>(bte.data()), bte.size(), signature);
  }

  static constexpr std::array obsolete_bootstraps = {
      "7a16ac0b85290bcf69b2f3b52456d7e989ac8913b4afbb980614e249a3723218"sv,
      "e6b3a6fe5e32c379b64212c72232d65b0b88ddf9bbaed4997409d329f8519e0b"sv,
  };

  bool
  RouterContact::IsObsoleteBootstrap() const
  {
    for (const auto& k : obsolete_bootstraps)
    {
      if (pubkey.ToHex() == k)
        return true;
    }
    return false;
  }

  bool
  RouterContact::Write(const fs::path& fname) const
  {
    std::array<byte_t, MAX_RC_SIZE> tmp;
    llarp_buffer_t buf(tmp);

    auto bte = bt_encode();
    buf.write(bte.begin(), bte.end());

    try
    {
      util::dump_file(fname, tmp.data(), buf.cur - buf.base);
    }
    catch (const std::exception& e)
    {
      log::error(logcat, "Failed to write RC to {}: {}", fname, e.what());
      return false;
    }
    return true;
  }

  bool
  RouterContact::Read(const fs::path& fname)
  {
    std::array<byte_t, MAX_RC_SIZE> tmp;
    llarp_buffer_t buf(tmp);
    try
    {
      util::slurp_file(fname, tmp.data(), tmp.size());
    }
    catch (const std::exception& e)
    {
      log::error(logcat, "Failed to read RC from {}: {}", fname, e.what());
      return false;
    }
    return BDecode(&buf);
  }

  std::string
  RouterContact::ToString() const
  {
    return fmt::format(
        "[RC k={} updated={} netid={} v={} ai={{{}}} e={} z={}]",
        pubkey,
        last_updated.count(),
        netID,
        version,
        fmt::format("{}", addr),
        enckey,
        signature);
  }

}  // namespace llarp