// Copyright 2024 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_async2/pendable_as_task.h"

#include "pw_async2/dispatcher.h"
#include "pw_unit_test/framework.h"

namespace {

using ::pw::async2::Context;
using ::pw::async2::Dispatcher;
using ::pw::async2::PendableAsTask;
using ::pw::async2::Pending;
using ::pw::async2::Poll;
using ::pw::async2::Ready;
using ::pw::async2::WaitReason;
using ::pw::async2::Waker;

struct StructWithPendMethod {
  StructWithPendMethod(int& poll_count, bool& allow_completion, Waker& waker)
      : poll_count_(poll_count),
        allow_completion_(allow_completion),
        waker_(waker) {}

  Poll<> Pend(Context& cx) {
    ++poll_count_;
    if (allow_completion_) {
      return Ready();
    }
    waker_ = cx.GetWaker(WaitReason::Unspecified());
    return Pending();
  }

  int& poll_count_;
  bool& allow_completion_;
  Waker& waker_;
};

TEST(PendableAsTask, PendDelegatesToPendable) {
  Dispatcher dispatcher;

  int poll_count = 0;
  bool allow_completion = false;
  Waker waker;
  StructWithPendMethod pendable(poll_count, allow_completion, waker);
  PendableAsTask task(std::move(pendable));

  dispatcher.Post(task);

  EXPECT_EQ(poll_count, 0);
  EXPECT_EQ(dispatcher.RunUntilStalled(), Pending());
  EXPECT_EQ(poll_count, 1);

  // Unwoken task is not polled.
  EXPECT_EQ(dispatcher.RunUntilStalled(), Pending());
  EXPECT_EQ(poll_count, 1);

  std::move(waker).Wake();
  allow_completion = true;
  EXPECT_EQ(dispatcher.RunUntilStalled(), Ready());
  EXPECT_EQ(poll_count, 2);
}

TEST(PendableAsTask, PendDelegatesToPendablePtr) {
  Dispatcher dispatcher;

  int poll_count = 0;
  bool allow_completion = false;
  Waker waker;
  StructWithPendMethod pendable(poll_count, allow_completion, waker);
  // Note the lack of `std::move` or a copy-- we pass a ptr.
  PendableAsTask task(&pendable);

  dispatcher.Post(task);

  EXPECT_EQ(poll_count, 0);
  EXPECT_EQ(dispatcher.RunUntilStalled(), Pending());
  EXPECT_EQ(poll_count, 1);

  // Unwoken task is not polled.
  EXPECT_EQ(dispatcher.RunUntilStalled(), Pending());
  EXPECT_EQ(poll_count, 1);

  std::move(waker).Wake();
  allow_completion = true;
  EXPECT_EQ(dispatcher.RunUntilStalled(), Ready());
  EXPECT_EQ(poll_count, 2);
}

}  // namespace