// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Provides a class to marshall protobufs in and out of the sandbox

#ifndef SANDBOXED_API_VAR_PROTO_H_
#define SANDBOXED_API_VAR_PROTO_H_

#include <cinttypes>
#include <cstdint>
#include <ctime>
#include <memory>
#include <string>
#include <type_traits>
#include <utility>
#include <vector>

#include "absl/base/attributes.h"
#include "absl/base/macros.h"
#include "absl/log/log.h"
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/utility/utility.h"
#include "sandboxed_api/proto_helper.h"
#include "sandboxed_api/util/status_macros.h"
#include "sandboxed_api/var_lenval.h"
#include "sandboxed_api/var_ptr.h"

namespace sapi::v {

template <typename T>
class Proto : public Var {
 public:
  class PrivateToken {
   private:
    explicit PrivateToken() = default;
    friend class Proto;
  };

  static_assert(std::is_base_of<google::protobuf::MessageLite, T>::value,
                "Template argument must be a proto message");

  Proto(PrivateToken, std::vector<uint8_t> data)
      : wrapped_var_(std::move(data)) {}

  ABSL_DEPRECATED("Use Proto<>::FromMessage() instead")
  explicit Proto(const T& proto)
      : wrapped_var_(SerializeProto(proto).value()) {}

  static absl::StatusOr<Proto<T>> FromMessage(const T& proto) {
    SAPI_ASSIGN_OR_RETURN(std::vector<uint8_t> len_val, SerializeProto(proto));
    return absl::StatusOr<Proto<T>>(absl::in_place, PrivateToken{},
                                    std::move(len_val));
  }

  size_t GetSize() const final { return wrapped_var_.GetSize(); }
  Type GetType() const final { return Type::kProto; }
  std::string GetTypeString() const final { return "Protobuf"; }
  std::string ToString() const final { return "Protobuf"; }

  void* GetRemote() const override { return wrapped_var_.GetRemote(); }
  void* GetLocal() const override { return wrapped_var_.GetLocal(); }

  // Returns a copy of the stored protobuf object.
  absl::StatusOr<T> GetMessage() const {
    return DeserializeProto<T>(
        reinterpret_cast<const char*>(wrapped_var_.GetData()),
        wrapped_var_.GetDataSize());
  }

  ABSL_DEPRECATED("Use GetMessage() instead")
  std::unique_ptr<T> GetProtoCopy() const {
    if (auto proto = GetMessage(); proto.ok()) {
      return std::make_unique<T>(*std::move(proto));
    }
    return nullptr;
  }

  void SetRemote(void* /* remote */) override {
    // We do not support that much indirection (pointer to a pointer to a
    // protobuf) as it is unlikely that this is wanted behavior. If you expect
    // this to work, please get in touch with us.
    LOG(FATAL) << "SetRemote not supported on protobufs.";
  }

 protected:
  // Forward a couple of function calls to the actual var.
  absl::Status Allocate(RPCChannel* rpc_channel, bool automatic_free) override {
    return wrapped_var_.Allocate(rpc_channel, automatic_free);
  }

  absl::Status Free(RPCChannel* rpc_channel) override {
    return absl::OkStatus();
  }

  absl::Status TransferToSandboxee(RPCChannel* rpc_channel,
                                   pid_t pid) override {
    return wrapped_var_.TransferToSandboxee(rpc_channel, pid);
  }

  absl::Status TransferFromSandboxee(RPCChannel* rpc_channel,
                                     pid_t pid) override {
    return wrapped_var_.TransferFromSandboxee(rpc_channel, pid);
  }

 private:
  // The management of reading/writing the data to the sandboxee is handled by
  // the LenVal class.
  LenVal wrapped_var_;
};

}  // namespace sapi::v

#endif  // SANDBOXED_API_VAR_PROTO_H_