// Copyright 2020 The Pigweed Authors
//
// 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.

#include "pw_rpc/internal/method.h"

#include <array>

#include "gtest/gtest.h"
#include "pb_encode.h"
#include "pw_rpc/server_context.h"
#include "pw_rpc/service.h"
#include "pw_rpc_private/internal_test_utils.h"
#include "pw_rpc_test_protos/test.pb.h"

namespace pw::rpc::internal {
namespace {

using std::byte;

#define ENCODE_PB(proto, result, ...) \
  _ENCODE_PB_EXPAND(proto, result, __LINE__, __VA_ARGS__)

#define _ENCODE_PB_EXPAND(proto, result, unique, ...) \
  _ENCODE_PB_IMPL(proto, result, unique, __VA_ARGS__)

#define _ENCODE_PB_IMPL(proto, result, unique, ...)               \
  std::array<pb_byte_t, 2 * sizeof(proto)> _pb_buffer_##unique{}; \
  const std::span result = EncodeProtobuf<proto, proto##_fields>( \
      proto{__VA_ARGS__}, _pb_buffer_##unique)

template <typename T, auto fields>
std::span<const byte> EncodeProtobuf(const T& protobuf,
                                     std::span<pb_byte_t> buffer) {
  auto output = pb_ostream_from_buffer(buffer.data(), buffer.size());
  EXPECT_TRUE(pb_encode(&output, fields, &protobuf));
  return std::as_bytes(buffer.first(output.bytes_written));
}

template <typename Implementation>
class FakeGeneratedService : public Service {
 public:
  constexpr FakeGeneratedService(uint32_t id) : Service(id, kMethods) {}

  static Status DoNothing(ServerCall& call,
                          const pw_rpc_test_Empty& request,
                          pw_rpc_test_Empty& response) {
    return static_cast<Implementation&>(call.service())
        .DoNothing(call.context(), request, response);
  }

  static Status AddFive(ServerCall& call,
                        const pw_rpc_test_TestRequest& request,
                        pw_rpc_test_TestResponse& response) {
    return static_cast<Implementation&>(call.service())
        .AddFive(call.context(), request, response);
  }

  static void StartStream(ServerCall& call,
                          const pw_rpc_test_TestRequest& request,
                          ServerWriter<pw_rpc_test_TestResponse>& writer) {
    static_cast<Implementation&>(call.service())
        .StartStream(call.context(), request, writer);
  }

  static constexpr std::array<Method, 3> kMethods = {
      Method::Unary<DoNothing>(
          10u, pw_rpc_test_Empty_fields, pw_rpc_test_Empty_fields),
      Method::Unary<AddFive>(
          11u, pw_rpc_test_TestRequest_fields, pw_rpc_test_TestResponse_fields),
      Method::ServerStreaming<StartStream>(
          12u, pw_rpc_test_TestRequest_fields, pw_rpc_test_TestResponse_fields),
  };
};

pw_rpc_test_TestRequest last_request;
ServerWriter<pw_rpc_test_TestResponse> last_writer;

class FakeGeneratedServiceImpl
    : public FakeGeneratedService<FakeGeneratedServiceImpl> {
 public:
  FakeGeneratedServiceImpl(uint32_t id) : FakeGeneratedService(id) {}

  Status AddFive(ServerContext&,
                 const pw_rpc_test_TestRequest& request,
                 pw_rpc_test_TestResponse& response) {
    last_request = request;
    response.value = request.integer + 5;
    return Status::UNAUTHENTICATED;
  }

  Status DoNothing(ServerContext&,
                   const pw_rpc_test_Empty&,
                   pw_rpc_test_Empty&) {
    return Status::UNKNOWN;
  }

  void StartStream(ServerContext&,
                   const pw_rpc_test_TestRequest& request,
                   ServerWriter<pw_rpc_test_TestResponse>& writer) {
    last_request = request;
    last_writer = std::move(writer);
  }
};

TEST(Method, UnaryRpc_SendsResponse) {
  ENCODE_PB(pw_rpc_test_TestRequest, request, .integer = 123, .status_code = 0);

  const Method& method = std::get<1>(FakeGeneratedServiceImpl::kMethods);
  ServerContextForTest<FakeGeneratedServiceImpl> context(method);
  method.Invoke(context.get(), context.packet(request));

  const Packet& response = context.output().sent_packet();
  EXPECT_EQ(response.status(), Status::UNAUTHENTICATED);

  // Field 1 (encoded as 1 << 3) with 128 as the value.
  constexpr std::byte expected[]{
      std::byte{0x08}, std::byte{0x80}, std::byte{0x01}};

  EXPECT_EQ(sizeof(expected), response.payload().size());
  EXPECT_EQ(0,
            std::memcmp(expected, response.payload().data(), sizeof(expected)));

  EXPECT_EQ(123, last_request.integer);
}

TEST(Method, UnaryRpc_InvalidPayload_SendsError) {
  std::array<byte, 8> bad_payload{byte{0xFF}, byte{0xAA}, byte{0xDD}};

  const Method& method = std::get<0>(FakeGeneratedServiceImpl::kMethods);
  ServerContextForTest<FakeGeneratedServiceImpl> context(method);
  method.Invoke(context.get(), context.packet(bad_payload));

  const Packet& packet = context.output().sent_packet();
  EXPECT_EQ(PacketType::SERVER_ERROR, packet.type());
  EXPECT_EQ(Status::DATA_LOSS, packet.status());
  EXPECT_EQ(context.kServiceId, packet.service_id());
  EXPECT_EQ(method.id(), packet.method_id());
}

TEST(Method, UnaryRpc_BufferTooSmallForResponse_SendsInternalError) {
  constexpr int64_t value = 0x7FFFFFFF'FFFFFF00ll;
  ENCODE_PB(
      pw_rpc_test_TestRequest, request, .integer = value, .status_code = 0);

  const Method& method = std::get<1>(FakeGeneratedServiceImpl::kMethods);
  // Output buffer is too small for the response, but can fit an error packet.
  ServerContextForTest<FakeGeneratedServiceImpl, 22> context(method);
  ASSERT_LT(context.output().buffer_size(),
            context.packet(request).MinEncodedSizeBytes() + request.size() + 1);

  method.Invoke(context.get(), context.packet(request));

  const Packet& packet = context.output().sent_packet();
  EXPECT_EQ(PacketType::SERVER_ERROR, packet.type());
  EXPECT_EQ(Status::INTERNAL, packet.status());
  EXPECT_EQ(context.kServiceId, packet.service_id());
  EXPECT_EQ(method.id(), packet.method_id());

  EXPECT_EQ(value, last_request.integer);
}

TEST(Method, ServerStreamingRpc_SendsNothingWhenInitiallyCalled) {
  ENCODE_PB(pw_rpc_test_TestRequest, request, .integer = 555, .status_code = 0);

  const Method& method = std::get<2>(FakeGeneratedServiceImpl::kMethods);
  ServerContextForTest<FakeGeneratedServiceImpl> context(method);

  method.Invoke(context.get(), context.packet(request));

  EXPECT_EQ(0u, context.output().packet_count());
  EXPECT_EQ(555, last_request.integer);
}

TEST(Method, ServerWriter_SendsResponse) {
  const Method& method = std::get<2>(FakeGeneratedServiceImpl::kMethods);
  ServerContextForTest<FakeGeneratedServiceImpl> context(method);

  method.Invoke(context.get(), context.packet({}));

  EXPECT_EQ(Status::OK, last_writer.Write({.value = 100}));

  ENCODE_PB(pw_rpc_test_TestResponse, payload, .value = 100);
  std::array<byte, 128> encoded_response = {};
  auto encoded = context.packet(payload).Encode(encoded_response);
  ASSERT_EQ(Status::OK, encoded.status());

  ASSERT_EQ(encoded.size(), context.output().sent_data().size());
  EXPECT_EQ(0,
            std::memcmp(encoded_response.data(),
                        context.output().sent_data().data(),
                        encoded.size()));
}

TEST(Method, ServerStreamingRpc_ServerWriterBufferTooSmall_InternalError) {
  const Method& method = std::get<2>(FakeGeneratedServiceImpl::kMethods);

  constexpr size_t kNoPayloadPacketSize = 2 /* type */ + 2 /* channel */ +
                                          5 /* service */ + 5 /* method */ +
                                          2 /* payload */ + 2 /* status */;

  // Make the buffer barely fit a packet with no payload.
  ServerContextForTest<FakeGeneratedServiceImpl, kNoPayloadPacketSize> context(
      method);

  // Verify that the encoded size of a packet with an empty payload is correct.
  std::array<byte, 128> encoded_response = {};
  auto encoded = context.packet({}).Encode(encoded_response);
  ASSERT_EQ(Status::OK, encoded.status());
  ASSERT_EQ(kNoPayloadPacketSize, encoded.size());

  method.Invoke(context.get(), context.packet({}));

  EXPECT_EQ(Status::OK, last_writer.Write({}));                  // Barely fits
  EXPECT_EQ(Status::INTERNAL, last_writer.Write({.value = 1}));  // Too big
}

}  // namespace
}  // namespace pw::rpc::internal