#include <absl/strings/match.h>
#include <absl/strings/str_cat.h>
#include <glog/logging.h>

#include "libstore/derivations.hh"
#include "libstore/remote-store.hh"
#include "libstore/serve-protocol.hh"
#include "libstore/ssh.hh"
#include "libstore/store-api.hh"
#include "libstore/worker-protocol.hh"
#include "libutil/archive.hh"
#include "libutil/pool.hh"

namespace nix {

constexpr std::string_view kUriScheme = "ssh://";

struct LegacySSHStore : public Store {
  const Setting<int> maxConnections{
      this, 1, "max-connections",
      "maximum number of concurrent SSH connections"};
  const Setting<Path> sshKey{this, "", "ssh-key", "path to an SSH private key"};
  const Setting<bool> compress{this, false, "compress",
                               "whether to compress the connection"};
  const Setting<Path> remoteProgram{
      this, "nix-store", "remote-program",
      "path to the nix-store executable on the remote system"};
  const Setting<std::string> remoteStore{
      this, "", "remote-store", "URI of the store on the remote system"};

  // Hack for getting remote build log output.
  const Setting<int> logFD{
      this, -1, "log-fd", "file descriptor to which SSH's stderr is connected"};

  struct Connection {
    std::unique_ptr<SSHMaster::Connection> sshConn;
    FdSink to;
    FdSource from;
    int remoteVersion;
    bool good = true;
  };

  std::string host;

  ref<Pool<Connection>> connections;

  SSHMaster master;

  LegacySSHStore(const std::string& host, const Params& params)
      : Store(params),
        host(host),
        connections(make_ref<Pool<Connection>>(
            std::max(1, (int)maxConnections),
            [this]() { return openConnection(); },
            [](const ref<Connection>& r) { return r->good; })),
        master(host, sshKey,
               // Use SSH master only if using more than 1 connection.
               connections->capacity() > 1, compress, logFD) {}

  ref<Connection> openConnection() {
    auto conn = make_ref<Connection>();
    conn->sshConn = master.startCommand(
        fmt("%s --serve --write", remoteProgram) +
        (remoteStore.get().empty()
             ? ""
             : " --store " + shellEscape(remoteStore.get())));
    conn->to = FdSink(conn->sshConn->in.get());
    conn->from = FdSource(conn->sshConn->out.get());

    try {
      conn->to << SERVE_MAGIC_1 << SERVE_PROTOCOL_VERSION;
      conn->to.flush();

      unsigned int magic = readInt(conn->from);
      if (magic != SERVE_MAGIC_2) {
        throw Error("protocol mismatch with 'nix-store --serve' on '%s'", host);
      }
      conn->remoteVersion = readInt(conn->from);
      if (GET_PROTOCOL_MAJOR(conn->remoteVersion) != 0x200) {
        throw Error("unsupported 'nix-store --serve' protocol version on '%s'",
                    host);
      }

    } catch (EndOfFile& e) {
      throw Error("cannot connect to '%1%'", host);
    }

    return conn;
  };

  std::string getUri() override { return absl::StrCat(kUriScheme, host); }

  void queryPathInfoUncached(
      const Path& path,
      Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept override {
    try {
      auto conn(connections->get());

      DLOG(INFO) << "querying remote host '" << host << "' for info on '"
                 << path << "'";

      conn->to << cmdQueryPathInfos << PathSet{path};
      conn->to.flush();

      auto info = std::make_shared<ValidPathInfo>();
      conn->from >> info->path;
      if (info->path.empty()) {
        return callback(nullptr);
      }
      assert(path == info->path);

      PathSet references;
      conn->from >> info->deriver;
      info->references = readStorePaths<PathSet>(*this, conn->from);
      readLongLong(conn->from);  // download size
      info->narSize = readLongLong(conn->from);

      if (GET_PROTOCOL_MINOR(conn->remoteVersion) >= 4) {
        auto s = readString(conn->from);
        if (s.empty()) {
          info->narHash = Hash();
        } else {
          auto hash_ = Hash::deserialize(s);
          info->narHash = Hash::unwrap_throw(hash_);
        }
        conn->from >> info->ca;
        info->sigs = readStrings<StringSet>(conn->from);
      }

      auto s = readString(conn->from);
      assert(s.empty());

      callback(std::move(info));
    } catch (...) {
      callback.rethrow();
    }
  }

  void addToStore(const ValidPathInfo& info, Source& source, RepairFlag repair,
                  CheckSigsFlag checkSigs,
                  std::shared_ptr<FSAccessor> accessor) override {
    DLOG(INFO) << "adding path '" << info.path << "' to remote host '" << host
               << "'";

    auto conn(connections->get());

    if (GET_PROTOCOL_MINOR(conn->remoteVersion) >= 5) {
      conn->to << cmdAddToStoreNar << info.path << info.deriver
               << info.narHash.to_string(Base16, false) << info.references
               << info.registrationTime << info.narSize
               << static_cast<uint64_t>(info.ultimate) << info.sigs << info.ca;
      try {
        copyNAR(source, conn->to);
      } catch (...) {
        conn->good = false;
        throw;
      }
      conn->to.flush();

    } else {
      conn->to << cmdImportPaths << 1;
      try {
        copyNAR(source, conn->to);
      } catch (...) {
        conn->good = false;
        throw;
      }
      conn->to << exportMagic << info.path << info.references << info.deriver
               << 0 << 0;
      conn->to.flush();
    }

    if (readInt(conn->from) != 1) {
      throw Error(
          "failed to add path '%s' to remote host '%s', info.path, host");
    }
  }

  void narFromPath(const Path& path, Sink& sink) override {
    auto conn(connections->get());

    conn->to << cmdDumpStorePath << path;
    conn->to.flush();
    copyNAR(conn->from, sink);
  }

  Path queryPathFromHashPart(const std::string& hashPart) override {
    unsupported("queryPathFromHashPart");
  }

  Path addToStore(const std::string& name, const Path& srcPath, bool recursive,
                  HashType hashAlgo, PathFilter& filter,
                  RepairFlag repair) override {
    unsupported("addToStore");
  }

  Path addTextToStore(const std::string& name, const std::string& s,
                      const PathSet& references, RepairFlag repair) override {
    unsupported("addTextToStore");
  }

  BuildResult buildDerivation(const Path& drvPath, const BasicDerivation& drv,
                              BuildMode buildMode) override {
    auto conn(connections->get());

    conn->to << cmdBuildDerivation << drvPath << drv << settings.maxSilentTime
             << settings.buildTimeout;
    if (GET_PROTOCOL_MINOR(conn->remoteVersion) >= 2) {
      conn->to << settings.maxLogSize;
    }
    if (GET_PROTOCOL_MINOR(conn->remoteVersion) >= 3) {
      conn->to << settings.buildRepeat
               << static_cast<uint64_t>(settings.enforceDeterminism);
    }

    conn->to.flush();

    BuildResult status;
    status.status = static_cast<BuildResult::Status>(readInt(conn->from));
    conn->from >> status.errorMsg;

    if (GET_PROTOCOL_MINOR(conn->remoteVersion) >= 3) {
      conn->from >> status.timesBuilt >> status.isNonDeterministic >>
          status.startTime >> status.stopTime;
    }

    return status;
  }

  void ensurePath(const Path& path) override { unsupported("ensurePath"); }

  void computeFSClosure(const PathSet& paths, PathSet& out,
                        bool flipDirection = false, bool includeOutputs = false,
                        bool includeDerivers = false) override {
    if (flipDirection || includeDerivers) {
      Store::computeFSClosure(paths, out, flipDirection, includeOutputs,
                              includeDerivers);
      return;
    }

    auto conn(connections->get());

    conn->to << cmdQueryClosure << static_cast<uint64_t>(includeOutputs)
             << paths;
    conn->to.flush();

    auto res = readStorePaths<PathSet>(*this, conn->from);

    out.insert(res.begin(), res.end());
  }

  PathSet queryValidPaths(const PathSet& paths, SubstituteFlag maybeSubstitute =
                                                    NoSubstitute) override {
    auto conn(connections->get());

    conn->to << cmdQueryValidPaths << 0u  // lock
             << maybeSubstitute << paths;
    conn->to.flush();

    return readStorePaths<PathSet>(*this, conn->from);
  }

  void connect() override { auto conn(connections->get()); }

  unsigned int getProtocol() override {
    auto conn(connections->get());
    return conn->remoteVersion;
  }
};

static RegisterStoreImplementation regStore(
    [](const std::string& uri,
       const Store::Params& params) -> std::shared_ptr<Store> {
      if (!absl::StartsWith(uri, kUriScheme)) {
        return nullptr;
      }
      return std::make_shared<LegacySSHStore>(
          std::string(uri, kUriScheme.size()), params);
    });

}  // namespace nix