/*
 * Copyright 2022 The Android Open Source Project
 *
 * 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 "hci/acl_manager/acl_scheduler.h"

#include <gmock/gmock.h>
#include <gtest/gtest.h>

#include <chrono>
#include <future>

#include "hci/address.h"
#include "os/thread.h"

namespace bluetooth {
namespace hci {
namespace acl_manager {
namespace {

const auto address1 = Address::FromString("A1:A2:A3:A4:A5:A6").value();
const auto address2 = Address::FromString("B1:B2:B3:B4:B5:B6").value();
const auto address3 = Address::FromString("C1:C2:C3:C4:C5:C6").value();

const auto timeout = std::chrono::milliseconds(100);

MATCHER(IsSet, "Future is set") {
  if (arg.wait_for(timeout) != std::future_status::ready) {
    return false;
  }
  const_cast<std::future<void>&>(arg).get();
  return true;
}

class AclSchedulerTest : public ::testing::Test {
 protected:
  void SetUp() override {
    fake_registry_.Start<AclScheduler>(&thread_);
    ASSERT_TRUE(fake_registry_.IsStarted<AclScheduler>());

    client_handler_ = fake_registry_.GetTestModuleHandler(&AclScheduler::Factory);
    ASSERT_NE(client_handler_, nullptr);

    acl_scheduler_ = static_cast<AclScheduler*>(fake_registry_.GetModuleUnderTest(&AclScheduler::Factory));

    ::testing::FLAGS_gtest_death_test_style = "threadsafe";
  }

  void TearDown() override {
    fake_registry_.SynchronizeModuleHandler(&AclScheduler::Factory, timeout);
    fake_registry_.StopAll();
  }

  common::ContextualOnceCallback<void(std::string)> impossibleCallbackTakingString() {
    return client_handler_->BindOnce([](std::string /* _ */) { ADD_FAILURE(); });
  }

  common::ContextualOnceCallback<void(std::string)> emptyCallbackTakingString() {
    return client_handler_->BindOnce([](std::string /* _ */) {});
  }

  common::ContextualOnceCallback<void(std::string)> promiseCallbackTakingString(std::promise<void> promise) {
    return client_handler_->BindOnce(
        [](std::promise<void> promise, std::string /* _ */) { promise.set_value(); },
        std::move(promise));
  }

  common::ContextualOnceCallback<void()> impossibleCallback() {
    return client_handler_->BindOnce([] { ADD_FAILURE(); });
  }

  common::ContextualOnceCallback<void()> emptyCallback() {
    return client_handler_->BindOnce([] {});
  }

  common::ContextualOnceCallback<void()> promiseCallback(std::promise<void> promise) {
    return client_handler_->BindOnce([](std::promise<void> promise) { promise.set_value(); }, std::move(promise));
  }

  TestModuleRegistry fake_registry_;
  os::Thread& thread_ = fake_registry_.GetTestThread();
  AclScheduler* acl_scheduler_ = nullptr;
  os::Handler* client_handler_ = nullptr;
};

TEST_F(AclSchedulerTest, SingleConnectionImmediatelyExecuted) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start connection, which should immediately execute
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, promiseCallback(std::move(promise)));

  // it has started
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, ThreeConnectionsQueue) {
  auto promise1 = std::promise<void>{};
  auto future1 = promise1.get_future();
  auto promise2 = std::promise<void>{};
  auto future2 = promise2.get_future();

  // start first connection, which immediately runs
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());
  // start second connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address2, (promiseCallback(std::move(promise1))));
  // start third connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address3, (promiseCallback(std::move(promise2))));

  // the second and third connections are currently queued
  EXPECT_THAT(future1.wait_for(timeout), std::future_status::timeout);

  // first connection fails, so next one should start
  acl_scheduler_->ReportOutgoingAclConnectionFailure();

  // the second connection has started, the third one is queued
  EXPECT_THAT(future1, IsSet());
  EXPECT_THAT(future2.wait_for(timeout), std::future_status::timeout);

  // second connection fails, so third one should start
  acl_scheduler_->ReportOutgoingAclConnectionFailure();

  // the third connection has started
  EXPECT_THAT(future2, IsSet());
}

TEST_F(AclSchedulerTest, SingleConnectionCompletionCallback) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start connection, which immediately runs
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());

  // the outgoing connection completes
  acl_scheduler_->ReportAclConnectionCompletion(
      address1, promiseCallback(std::move(promise)), impossibleCallback(), impossibleCallbackTakingString());

  // the outgoing_connection callback should have executed
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, SingleConnectionCompletionDequeueNext) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start connection, which immediately runs
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());
  // start second connection which should queue
  acl_scheduler_->EnqueueOutgoingAclConnection(address2, promiseCallback(std::move(promise)));

  // complete the first connection
  acl_scheduler_->ReportAclConnectionCompletion(
      address1, emptyCallback(), impossibleCallback(), impossibleCallbackTakingString());

  // the next connection should dequeue now
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, IncomingConnectionCallback) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // an incoming connection arrives
  acl_scheduler_->RegisterPendingIncomingConnection(address1);

  // and completes
  acl_scheduler_->ReportAclConnectionCompletion(
      address1, impossibleCallback(), promiseCallback(std::move(promise)), impossibleCallbackTakingString());

  // the incoming_connection callback should have executed
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, UnknownConnectionCallback) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start outgoing connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());

  // an incoming connection arrives
  acl_scheduler_->RegisterPendingIncomingConnection(address2);

  // then an unknown connection completes
  acl_scheduler_->ReportAclConnectionCompletion(
      address3, impossibleCallback(), impossibleCallback(), (promiseCallbackTakingString(std::move(promise))));

  // the unknown_connection callback should have executed
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, TiebreakForOutgoingConnection) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start outgoing connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());

  // an incoming connection arrives *from the same address*
  acl_scheduler_->RegisterPendingIncomingConnection(address1);

  // then the connection to that address completes
  acl_scheduler_->ReportAclConnectionCompletion(
      address1, promiseCallback(std::move(promise)), impossibleCallback(), impossibleCallbackTakingString());

  // the outgoing_connection callback should have executed, NOT the incoming_connection one
  // this preserves working behavior, it is not based on any principled decision (so if you need to break this test,
  // go for it)
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, QueueWhileIncomingConnectionsPending) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start outgoing connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());
  // queue a second outgoing connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address2, promiseCallback(std::move(promise)));

  // an incoming connection arrives
  acl_scheduler_->RegisterPendingIncomingConnection(address3);

  // then the first outgoing connection completes
  acl_scheduler_->ReportAclConnectionCompletion(
      address1, emptyCallback(), impossibleCallback(), impossibleCallbackTakingString());

  // the outgoing_connection callback should not have executed yet
  EXPECT_THAT(future.wait_for(timeout), std::future_status::timeout);

  // now the incoming connection completes
  acl_scheduler_->ReportAclConnectionCompletion(
      address3, impossibleCallback(), emptyCallback(), impossibleCallbackTakingString());

  // only now does the next outgoing connection start
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, DoNothingWhileIncomingConnectionsExist) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // an incoming connection arrives
  acl_scheduler_->RegisterPendingIncomingConnection(address1);

  // try to start an outgoing connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address2, promiseCallback(std::move(promise)));

  // the outgoing_connection callback should not have executed yet
  EXPECT_THAT(future.wait_for(timeout), std::future_status::timeout);

  // a second incoming connection arrives
  acl_scheduler_->RegisterPendingIncomingConnection(address3);

  // the first incoming connection completes
  acl_scheduler_->ReportAclConnectionCompletion(
      address1, impossibleCallback(), emptyCallback(), impossibleCallbackTakingString());

  // the outgoing_connection callback should *still* not have executed yet
  EXPECT_THAT(future.wait_for(timeout), std::future_status::timeout);

  // the second incoming connection completes, so none are left
  acl_scheduler_->ReportAclConnectionCompletion(
      address3, impossibleCallback(), emptyCallback(), impossibleCallbackTakingString());

  // only now does the outgoing connection start
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, CancelOutgoingConnection) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start an outgoing connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());
  // enqueue a second connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address2, promiseCallback(std::move(promise)));

  // cancel the outgoing connection
  acl_scheduler_->CancelAclConnection(address1, emptyCallback(), impossibleCallback());

  // we expect the second connection to stay queued until the cancel completes
  EXPECT_THAT(future.wait_for(timeout), std::future_status::timeout);

  // now the cancel completes (with a failed status, in reality, but the scheduler doesn't care)
  acl_scheduler_->ReportAclConnectionCompletion(
      address1, emptyCallback(), impossibleCallback(), impossibleCallbackTakingString());

  // so only now do we advance the queue
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, CancelOutgoingConnectionCallback) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start an outgoing connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());

  // cancel the outgoing connection
  acl_scheduler_->CancelAclConnection(address1, promiseCallback(std::move(promise)), impossibleCallback());

  // we expect the cancel_connection callback to be invoked since we are cancelling an actually active connection
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, CancelQueuedConnectionRemoveFromQueue) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start an outgoing connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());
  // start another connection that will queue
  acl_scheduler_->EnqueueOutgoingAclConnection(address2, impossibleCallback());
  // start a third connection that will queue
  acl_scheduler_->EnqueueOutgoingAclConnection(address3, promiseCallback(std::move(promise)));

  // cancel the first queued connection
  acl_scheduler_->CancelAclConnection(address2, impossibleCallback(), emptyCallback());

  // the second queued connection should remain enqueued, since another connection is in progress
  EXPECT_THAT(future.wait_for(timeout), std::future_status::timeout);

  // complete the outgoing connection
  acl_scheduler_->ReportOutgoingAclConnectionFailure();

  // only now can we dequeue the second queued connection
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, CancelQueuedConnectionCallback) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start an outgoing connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());
  // start another connection that will queue
  acl_scheduler_->EnqueueOutgoingAclConnection(address2, emptyCallback());

  // cancel the queued connection
  acl_scheduler_->CancelAclConnection(address2, impossibleCallback(), promiseCallback(std::move(promise)));

  // we expect the cancel_connection_completed callback to be invoked since we are cancelling a connection in the queue
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, RemoteNameRequestImmediatelyExecuted) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start an outgoing request
  acl_scheduler_->EnqueueRemoteNameRequest(address1, promiseCallback(std::move(promise)), emptyCallback());

  // we expect the start callback to be invoked immediately
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, RemoteNameRequestQueuing) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start an outgoing request
  acl_scheduler_->EnqueueRemoteNameRequest(address1, emptyCallback(), impossibleCallback());
  // enqueue a second one
  acl_scheduler_->EnqueueRemoteNameRequest(address2, promiseCallback(std::move(promise)), impossibleCallback());

  // we should still be queued
  EXPECT_THAT(future.wait_for(timeout), std::future_status::timeout);

  // the first request completes
  acl_scheduler_->ReportRemoteNameRequestCompletion(address1);

  // so the second request should now have started
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, RemoteNameRequestCancellationCallback) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start an outgoing request
  acl_scheduler_->EnqueueRemoteNameRequest(address1, emptyCallback(), impossibleCallback());

  // cancel it
  acl_scheduler_->CancelRemoteNameRequest(address1, promiseCallback(std::move(promise)));

  // the cancel callback should be invoked
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, RemoteNameRequestCancellationWhileQueuedCallback) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start an outgoing request
  acl_scheduler_->EnqueueRemoteNameRequest(address1, emptyCallback(), impossibleCallback());
  // enqueue a second one
  acl_scheduler_->EnqueueRemoteNameRequest(address2, impossibleCallback(), promiseCallback(std::move(promise)));

  // cancel the second one
  acl_scheduler_->CancelRemoteNameRequest(address2, impossibleCallback());

  // the cancel_request_completed calback should be invoked
  EXPECT_THAT(future, IsSet());

  // the first request completes
  acl_scheduler_->ReportRemoteNameRequestCompletion(address1);

  // we don't dequeue the second one, since it was cancelled
  // implicitly assert that its callback was never invoked
}

TEST_F(AclSchedulerTest, CancelQueuedRemoteNameRequestRemoveFromQueue) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start an outgoing connection
  acl_scheduler_->EnqueueOutgoingAclConnection(address1, emptyCallback());
  // start another connection that will queue
  acl_scheduler_->EnqueueRemoteNameRequest(address2, impossibleCallback(), emptyCallback());
  // start a third connection that will queue
  acl_scheduler_->EnqueueRemoteNameRequest(address3, promiseCallback(std::move(promise)), impossibleCallback());

  // cancel the first queued connection
  acl_scheduler_->CancelRemoteNameRequest(address2, impossibleCallback());

  // the second queued connection should remain enqueued, since another connection is in progress
  EXPECT_THAT(future.wait_for(timeout), std::future_status::timeout);

  // complete the outgoing connection
  acl_scheduler_->ReportOutgoingAclConnectionFailure();

  // only now can we dequeue the second queued connection
  EXPECT_THAT(future, IsSet());
}

TEST_F(AclSchedulerTest, RemoteNameRequestCancellationShouldDequeueNext) {
  auto promise = std::promise<void>{};
  auto future = promise.get_future();

  // start an outgoing request
  acl_scheduler_->EnqueueRemoteNameRequest(address1, emptyCallback(), impossibleCallback());
  // enqueue a second one
  acl_scheduler_->EnqueueRemoteNameRequest(address2, promiseCallback(std::move(promise)), impossibleCallback());

  // we should still be queued
  EXPECT_THAT(future.wait_for(timeout), std::future_status::timeout);

  // the first request is cancelled
  acl_scheduler_->CancelRemoteNameRequest(address1, emptyCallback());

  // we should still remain queued while we wait for the cancel to complete
  EXPECT_THAT(future.wait_for(timeout), std::future_status::timeout);

  // the cancel completes
  acl_scheduler_->ReportRemoteNameRequestCompletion(address1);

  // so the second request should now have started
  EXPECT_THAT(future, IsSet());
}

}  // namespace
}  // namespace acl_manager
}  // namespace hci
}  // namespace bluetooth