#include "nix-daemon-proto.hh"

#include <filesystem>
#include <sstream>

#include <absl/strings/str_cat.h>
#include <absl/strings/str_format.h>
#include <google/protobuf/empty.pb.h>
#include <google/protobuf/util/time_util.h>
#include <grpcpp/impl/codegen/server_context.h>
#include <grpcpp/impl/codegen/status.h>
#include <grpcpp/impl/codegen/status_code_enum.h>

#include "libmain/shared.hh"
#include "libproto/worker.grpc.pb.h"
#include "libproto/worker.pb.h"
#include "libstore/derivations.hh"
#include "libstore/local-store.hh"
#include "libstore/store-api.hh"
#include "libutil/archive.hh"
#include "libutil/hash.hh"
#include "libutil/serialise.hh"
#include "libutil/types.hh"

namespace nix::daemon {

using ::grpc::Status;
using ::nix::proto::BuildStatus;
using ::nix::proto::PathInfo;
using ::nix::proto::StorePath;
using ::nix::proto::StorePaths;
using ::nix::proto::WorkerService;

class AddToStoreRequestSource final : public Source {
  using Reader = grpc::ServerReader<nix::proto::AddToStoreRequest>;

 public:
  explicit AddToStoreRequestSource(Reader* reader) : reader_(reader) {}

  size_t read(unsigned char* data, size_t len) override {
    auto got = buffer_.sgetn(reinterpret_cast<char*>(data), len);
    if (got < len) {
      proto::AddToStoreRequest msg;
      if (!reader_->Read(&msg)) {
        return got;
      }
      if (msg.add_oneof_case() != proto::AddToStoreRequest::kData) {
        // TODO(grfn): Make Source::read return a StatusOr and get rid of this
        // throw
        throw Error(
            "Invalid AddToStoreRequest: all messages except the first must "
            "contain data");
      }
      buffer_.sputn(msg.data().data(), msg.data().length());
      return got + read(data + got, len - got);
    }
    return got;
  };

 private:
  std::stringbuf buffer_;
  Reader* reader_;
};

// TODO(grfn): Make this some sort of pipe so we don't have to store data in
// memory
/* If the NAR archive contains a single file at top-level, then save
   the contents of the file to `s'.  Otherwise barf. */
struct RetrieveRegularNARSink : ParseSink {
  bool regular{true};
  std::string s;

  RetrieveRegularNARSink() {}

  void createDirectory(const Path& path) override { regular = false; }

  void receiveContents(unsigned char* data, unsigned int len) override {
    s.append((const char*)data, len);
  }

  void createSymlink(const Path& path, const std::string& target) override {
    regular = false;
  }
};

#define ASSERT_INPUT_STORE_PATH(path)                                          \
  if (!store_->isStorePath(path)) {                                            \
    return Status(grpc::StatusCode::INVALID_ARGUMENT,                          \
                  absl::StrFormat("path '%s' is not in the Nix store", path)); \
  }

class WorkerServiceImpl final : public WorkerService::Service {
 public:
  WorkerServiceImpl(nix::Store& store) : store_(&store) {}

  Status IsValidPath(grpc::ServerContext* context, const StorePath* request,
                     nix::proto::IsValidPathResponse* response) override {
    return HandleExceptions(
        [&]() -> Status {
          const auto& path = request->path();
          response->set_is_valid(store_->isValidPath(path));

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status HasSubstitutes(grpc::ServerContext* context, const StorePath* request,
                        nix::proto::HasSubstitutesResponse* response) override {
    return HandleExceptions(
        [&]() -> Status {
          const auto& path = request->path();
          ASSERT_INPUT_STORE_PATH(path);
          PathSet res = store_->querySubstitutablePaths({path});
          response->set_has_substitutes(res.find(path) != res.end());

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status QueryReferrers(grpc::ServerContext* context, const StorePath* request,
                        StorePaths* response) override {
    return HandleExceptions(
        [&]() -> Status {
          const auto& path = request->path();
          ASSERT_INPUT_STORE_PATH(path);

          PathSet paths;
          store_->queryReferrers(path, paths);

          for (const auto& path : paths) {
            response->add_paths(path);
          }

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status AddToStore(grpc::ServerContext* context,
                    grpc::ServerReader<nix::proto::AddToStoreRequest>* reader,
                    nix::proto::StorePath* response) override {
    return HandleExceptions(
        [&]() -> Status {
          proto::AddToStoreRequest metadata_request;
          auto has_metadata = reader->Read(&metadata_request);

          if (!has_metadata || metadata_request.has_meta()) {
            return Status(grpc::StatusCode::INVALID_ARGUMENT,
                          "Metadata must be set before sending file content");
          }

          auto meta = metadata_request.meta();
          AddToStoreRequestSource source(reader);
          auto opt_hash_type = hash_type_from(meta.hash_type());
          if (!opt_hash_type) {
            return Status(grpc::StatusCode::INVALID_ARGUMENT,
                          "Invalid hash type");
          }

          std::string* data;
          RetrieveRegularNARSink nar;
          TeeSource saved_nar(source);

          if (meta.recursive()) {
            // TODO(grfn): Don't store the full data in memory, instead just
            // make addToStoreFromDump take a Source
            ParseSink sink;
            parseDump(sink, saved_nar);
            data = &(*saved_nar.data);
          } else {
            parseDump(nar, source);
            if (!nar.regular) {
              return Status(grpc::StatusCode::INVALID_ARGUMENT,
                            "Regular file expected");
            }
            data = &nar.s;
          }

          auto local_store = store_.dynamic_pointer_cast<LocalStore>();
          if (!local_store) {
            return Status(grpc::StatusCode::FAILED_PRECONDITION,
                          "operation is only supported by LocalStore");
          }

          auto path = local_store->addToStoreFromDump(
              *data, meta.base_name(), meta.recursive(), opt_hash_type.value());

          response->set_path(path);

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status AddTextToStore(grpc::ServerContext*,
                        const nix::proto::AddTextToStoreRequest* request,
                        nix::proto::StorePath* response) override {
    PathSet references;
    for (const auto& ref : request->references()) {
      references.insert(ref);
    }
    auto path =
        store_->addTextToStore(request->name(), request->content(), references);
    response->set_path(path);
    return Status::OK;
  }

  Status BuildPaths(grpc::ServerContext*,
                    const nix::proto::BuildPathsRequest* request,
                    google::protobuf::Empty*) override {
    PathSet drvs;
    for (const auto& drv : request->drvs()) {
      drvs.insert(drv);
    }
    auto mode = BuildModeFrom(request->mode());

    if (!mode.has_value()) {
      return Status(grpc::StatusCode::INTERNAL, "Invalid build mode");
    }

    // TODO(grfn): If mode is repair and not trusted, we need to return an error
    // here (but we can't yet because we don't know anything about trusted
    // users)
    store_->buildPaths(drvs, mode.value());

    return Status::OK;
  }

  Status AddIndirectRoot(grpc::ServerContext*,
                         const nix::proto::StorePath* request,
                         google::protobuf::Empty*) override {
    auto path = std::filesystem::canonical(request->path());
    ASSERT_INPUT_STORE_PATH(path);

    return HandleExceptions(
        [&]() -> Status {
          store_->addIndirectRoot(path);
          return Status::OK;
        },
        __FUNCTION__);
  }

  Status SyncWithGC(grpc::ServerContext*, const google::protobuf::Empty*,
                    google::protobuf::Empty*) override {
    return HandleExceptions(
        [&]() -> Status {
          store_->syncWithGC();
          return Status::OK;
        },
        __FUNCTION__);
  }

  Status QuerySubstitutablePathInfos(
      grpc::ServerContext*, const StorePaths* request,
      nix::proto::SubstitutablePathInfos* response) override {
    return HandleExceptions(
        [&]() -> Status {
          SubstitutablePathInfos infos;
          PathSet paths;
          for (const auto& path : request->paths()) {
            paths.insert(path);
          }
          store_->querySubstitutablePathInfos(paths, infos);
          for (const auto& [path, path_info] : infos) {
            auto proto_path_info = response->add_path_infos();
            proto_path_info->mutable_path()->set_path(path);
            proto_path_info->mutable_deriver()->set_path(path_info.deriver);
            for (const auto& ref : path_info.references) {
              proto_path_info->add_references(ref);
            }
            proto_path_info->set_download_size(path_info.downloadSize);
            proto_path_info->set_nar_size(path_info.narSize);
          }

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status QueryValidDerivers(grpc::ServerContext* context,
                            const StorePath* request,
                            StorePaths* response) override {
    return HandleExceptions(
        [&]() -> Status {
          const auto& path = request->path();
          ASSERT_INPUT_STORE_PATH(path);

          PathSet paths = store_->queryValidDerivers(path);

          for (const auto& path : paths) {
            response->add_paths(path);
          }

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status QueryDerivationOutputs(grpc::ServerContext* context,
                                const StorePath* request,
                                StorePaths* response) override {
    return HandleExceptions(
        [&]() -> Status {
          const auto& path = request->path();
          ASSERT_INPUT_STORE_PATH(path);

          PathSet paths = store_->queryDerivationOutputs(path);

          for (const auto& path : paths) {
            response->add_paths(path);
          }

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status QueryAllValidPaths(grpc::ServerContext* context,
                            const google::protobuf::Empty* request,
                            StorePaths* response) override {
    return HandleExceptions(
        [&]() -> Status {
          const auto paths = store_->queryAllValidPaths();
          for (const auto& path : paths) {
            response->add_paths(path);
          }

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status QueryPathInfo(grpc::ServerContext* context, const StorePath* request,
                       PathInfo* response) override {
    return HandleExceptions(
        [&]() -> Status {
          auto path = request->path();
          ASSERT_INPUT_STORE_PATH(path);

          response->mutable_path()->set_path(path);
          try {
            auto info = store_->queryPathInfo(path);
            response->mutable_deriver()->set_path(info->deriver);
            response->set_nar_hash(
                reinterpret_cast<const char*>(&info->narHash.hash[0]),
                info->narHash.hashSize);

            for (const auto& reference : info->references) {
              response->add_references(reference);
            }

            *response->mutable_registration_time() =
                google::protobuf::util::TimeUtil::TimeTToTimestamp(
                    info->registrationTime);

            response->set_nar_size(info->narSize);
            response->set_ultimate(info->ultimate);

            for (const auto& sig : info->sigs) {
              response->add_sigs(sig);
            }

            response->set_ca(info->ca);

            return Status::OK;
          } catch (InvalidPath&) {
            return Status(grpc::StatusCode::INVALID_ARGUMENT,
                          "Invalid store path");
          }
        },
        __FUNCTION__);
  }

  Status QueryDerivationOutputNames(
      grpc::ServerContext* context, const StorePath* request,
      nix::proto::DerivationOutputNames* response) override {
    return HandleExceptions(
        [&]() -> Status {
          auto path = request->path();
          ASSERT_INPUT_STORE_PATH(path);
          auto names = store_->queryDerivationOutputNames(path);
          for (const auto& name : names) {
            response->add_names(name);
          }

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status QueryPathFromHashPart(grpc::ServerContext* context,
                               const nix::proto::HashPart* request,
                               StorePath* response) override {
    return HandleExceptions(
        [&]() -> Status {
          auto hash_part = request->hash_part();
          auto path = store_->queryPathFromHashPart(hash_part);
          ASSERT_INPUT_STORE_PATH(path);
          response->set_path(path);
          return Status::OK;
        },
        __FUNCTION__);
  }

  Status QueryValidPaths(grpc::ServerContext* context,
                         const StorePaths* request,
                         StorePaths* response) override {
    return HandleExceptions(
        [&]() -> Status {
          std::set<Path> paths;
          for (const auto& path : request->paths()) {
            ASSERT_INPUT_STORE_PATH(path);
            paths.insert(path);
          }

          auto res = store_->queryValidPaths(paths);

          for (const auto& path : res) {
            response->add_paths(path);
          }

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status QuerySubstitutablePaths(grpc::ServerContext* context,
                                 const StorePaths* request,
                                 StorePaths* response) override {
    return HandleExceptions(
        [&]() -> Status {
          std::set<Path> paths;
          for (const auto& path : request->paths()) {
            ASSERT_INPUT_STORE_PATH(path);
            paths.insert(path);
          }

          auto res = store_->querySubstitutablePaths(paths);

          for (const auto& path : res) {
            response->add_paths(path);
          }

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status OptimiseStore(grpc::ServerContext* context,
                       const google::protobuf::Empty* request,
                       google::protobuf::Empty* response) override {
    return HandleExceptions(
        [&]() -> Status {
          store_->optimiseStore();
          return Status::OK;
        },
        __FUNCTION__);
  }

  Status VerifyStore(grpc::ServerContext* context,
                     const nix::proto::VerifyStoreRequest* request,
                     nix::proto::VerifyStoreResponse* response) override {
    return HandleExceptions(
        [&]() -> Status {
          auto errors =
              store_->verifyStore(request->check_contents(),
                                  static_cast<RepairFlag>(request->repair()));

          response->set_errors(errors);

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status BuildDerivation(
      grpc::ServerContext* context,
      const nix::proto::BuildDerivationRequest* request,
      nix::proto::BuildDerivationResponse* response) override {
    return HandleExceptions(
        [&]() -> Status {
          auto drv_path = request->drv_path().path();
          ASSERT_INPUT_STORE_PATH(drv_path);
          auto drv =
              BasicDerivation::from_proto(&request->derivation(), *store_);

          auto build_mode = nix::BuildModeFrom(request->build_mode());
          if (!build_mode) {
            return Status(grpc::StatusCode::INTERNAL, "Invalid build mode");
          }

          auto res = store_->buildDerivation(drv_path, drv, *build_mode);

          response->set_status(res.status_to_proto());
          response->set_error_message(res.errorMsg);

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status AddSignatures(grpc::ServerContext* context,
                       const nix::proto::AddSignaturesRequest* request,
                       google::protobuf::Empty* response) override {
    return HandleExceptions(
        [&]() -> Status {
          auto path = request->path().path();
          ASSERT_INPUT_STORE_PATH(path);

          StringSet sigs;
          sigs.insert(request->sigs().sigs().begin(),
                      request->sigs().sigs().end());

          store_->addSignatures(path, sigs);

          return Status::OK;
        },
        __FUNCTION__);
  }

  Status QueryMissing(grpc::ServerContext* context, const StorePaths* request,
                      nix::proto::QueryMissingResponse* response) override {
    return HandleExceptions(
        [&]() -> Status {
          std::set<Path> targets;
          for (auto& path : request->paths()) {
            ASSERT_INPUT_STORE_PATH(path);
            targets.insert(path);
          }
          PathSet will_build;
          PathSet will_substitute;
          PathSet unknown;
          // TODO(grfn): Switch to concrete size type
          unsigned long long download_size;
          unsigned long long nar_size;

          store_->queryMissing(targets, will_build, will_substitute, unknown,
                               download_size, nar_size);
          for (auto& path : will_build) {
            response->add_will_build(path);
          }
          for (auto& path : will_substitute) {
            response->add_will_substitute(path);
          }
          for (auto& path : unknown) {
            response->add_unknown(path);
          }
          response->set_download_size(download_size);
          response->set_nar_size(nar_size);

          return Status::OK;
        },
        __FUNCTION__);
  };

 private:
  Status HandleExceptions(std::function<Status(void)> fn,
                          absl::string_view methodName) {
    try {
      return fn();
    } catch (Unsupported& e) {
      return Status(grpc::StatusCode::UNIMPLEMENTED,
                    absl::StrCat(methodName, " is not supported: ", e.what()));
    } catch (Error& e) {
      return Status(grpc::StatusCode::INTERNAL, e.what());
    }
    // add more specific Error-Status mappings above
  }

  ref<nix::Store> store_;
};

WorkerService::Service* NewWorkerService(nix::Store& store) {
  return new WorkerServiceImpl(store);
}

}  // namespace nix::daemon