// Copyright (C) 2020 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 "aemu/base/events/EventWaiter.h"

namespace android {
namespace base {

EventWaiter::EventWaiter(RegisterCallback add, RemoveCallback remove) : mRemove(remove) {
    add(&EventWaiter::callbackForwarder, this);
}

EventWaiter::~EventWaiter() {
    if (mRemove) {
        mRemove(this);
    }
}

uint64_t EventWaiter::next(std::chrono::milliseconds timeout_ms) {
    uint64_t missed = next(mLastEvent, timeout_ms);
    mLastEvent = current();
    return missed;
}

uint64_t EventWaiter::current() const { return mEventCounter; }

uint64_t EventWaiter::next(uint64_t afterEvent, std::chrono::milliseconds timeout_ms) {
    std::unique_lock<std::mutex> lock(mStreamLock);
    auto future = std::chrono::system_clock::now() + timeout_ms;
    bool timedOut =
        !mCv.wait_until(lock, future, [=, this]() { return mEventCounter > afterEvent; });
    (void)timedOut;

    return afterEvent > mEventCounter ? 0 : mEventCounter - afterEvent;
}

void EventWaiter::newEvent() {
    std::unique_lock<std::mutex> lock(mStreamLock);
    mEventCounter++;
    mCv.notify_all();
}

void EventWaiter::callbackForwarder(void* opaque) {
    reinterpret_cast<EventWaiter*>(opaque)->newEvent();
}

}  // namespace base
}  // namespace android