// Copyright 2021 gRPC 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
//
//     http://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 "absl/log/check.h"

#include <grpc/grpc.h>

#include "src/core/ext/transport/binder/transport/binder_transport.h"
#include "src/core/lib/config/core_configuration.h"
#include "src/core/lib/iomgr/executor.h"
#include "src/core/lib/slice/slice_internal.h"
#include "src/core/server/server.h"
#include "src/libfuzzer/libfuzzer_macro.h"
#include "test/core/test_util/test_config.h"
#include "test/core/transport/binder/end2end/fuzzers/binder_transport_fuzzer.pb.h"
#include "test/core/transport/binder/end2end/fuzzers/fuzzer_utils.h"

bool squelch = true;
bool leak_check = true;

static void* tag(intptr_t t) { return reinterpret_cast<void*>(t); }

DEFINE_PROTO_FUZZER(const binder_transport_fuzzer::Input& input) {
  if (squelch) {
    grpc_disable_all_absl_logs();
  }
  grpc_init();
  {
    // Copied and modified from grpc/test/core/end2end/fuzzers/server_fuzzer.cc
    grpc_core::ExecCtx exec_ctx;
    grpc_core::Executor::SetThreadingAll(false);

    grpc_server* server = grpc_server_create(nullptr, nullptr);
    grpc_completion_queue* cq = grpc_completion_queue_create_for_next(nullptr);
    grpc_server_register_completion_queue(server, cq, nullptr);
    // TODO(ctiller): add more registered methods (one for POST, one for PUT)
    grpc_server_register_method(server, "/reg", nullptr, {}, 0);
    grpc_server_start(server);
    grpc_core::Transport* server_transport =
        grpc_create_binder_transport_server(
            std::make_unique<grpc_binder::fuzzing::BinderForFuzzing>(
                input.incoming_parcels()),
            std::make_shared<
                grpc::experimental::binder::UntrustedSecurityPolicy>());
    grpc_core::ChannelArgs channel_args = grpc_core::CoreConfiguration::Get()
                                              .channel_args_preconditioning()
                                              .PreconditionChannelArgs(nullptr);
    (void)grpc_core::Server::FromC(server)->SetupTransport(
        server_transport, nullptr, channel_args, nullptr);
    grpc_call* call1 = nullptr;
    grpc_call_details call_details1;
    grpc_metadata_array request_metadata1;
    grpc_call_details_init(&call_details1);
    grpc_metadata_array_init(&request_metadata1);
    int requested_calls = 0;

    CHECK(GRPC_CALL_OK ==
          grpc_server_request_call(server, &call1, &call_details1,
                                   &request_metadata1, cq, cq, tag(1)));
    requested_calls++;

    grpc_event ev;
    while (true) {
      grpc_core::ExecCtx::Get()->Flush();
      ev = grpc_completion_queue_next(cq, gpr_inf_past(GPR_CLOCK_REALTIME),
                                      nullptr);
      switch (ev.type) {
        case GRPC_QUEUE_TIMEOUT:
          goto done;
        case GRPC_QUEUE_SHUTDOWN:
          break;
        case GRPC_OP_COMPLETE:
          if (ev.tag == tag(1)) {
            requested_calls--;
            // TODO(ctiller): keep reading that call!
          }
          break;
      }
    }

  done:
    grpc_binder::fuzzing::JoinFuzzingThread();
    if (call1 != nullptr) grpc_call_unref(call1);
    grpc_call_details_destroy(&call_details1);
    grpc_metadata_array_destroy(&request_metadata1);
    grpc_server_shutdown_and_notify(server, cq, tag(0xdead));
    grpc_server_cancel_all_calls(server);
    grpc_core::Timestamp deadline =
        grpc_core::Timestamp::Now() + grpc_core::Duration::Seconds(5);
    for (int i = 0; i <= requested_calls; i++) {
      // A single grpc_completion_queue_next might not be sufficient for getting
      // the tag from shutdown, because we might potentially get blocked by
      // an operation happening on the timer thread.
      // For example, the deadline timer might expire, leading to the timer
      // thread trying to cancel the RPC and thereby acquiring a few references
      // to the call. This will prevent the shutdown to complete till the timer
      // thread releases those references.
      // As a solution, we are going to keep performing a cq_next for a
      // liberal period of 5 seconds for the timer thread to complete its work.
      do {
        ev = grpc_completion_queue_next(cq, gpr_inf_past(GPR_CLOCK_REALTIME),
                                        nullptr);
        grpc_core::ExecCtx::Get()->InvalidateNow();
      } while (ev.type != GRPC_OP_COMPLETE &&
               grpc_core::Timestamp::Now() < deadline);
      CHECK(ev.type == GRPC_OP_COMPLETE);
    }
    grpc_completion_queue_shutdown(cq);
    for (int i = 0; i <= requested_calls; i++) {
      do {
        ev = grpc_completion_queue_next(cq, gpr_inf_past(GPR_CLOCK_REALTIME),
                                        nullptr);
        grpc_core::ExecCtx::Get()->InvalidateNow();
      } while (ev.type != GRPC_QUEUE_SHUTDOWN &&
               grpc_core::Timestamp::Now() < deadline);
      CHECK(ev.type == GRPC_QUEUE_SHUTDOWN);
    }
    grpc_server_destroy(server);
    grpc_completion_queue_destroy(cq);
  }
  grpc_shutdown();
}
