/*
 * Copyright (C) 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.
 */
#pragma once

#include <set>
#include <string>

#include <fruit/fruit.h>

#include "host/commands/cvd/lock_file.h"

namespace cuttlefish {

// This class is not thread safe.
class InstanceLockFile {
  friend class InstanceLockFileManager;
  using LockFile = cvd_impl::LockFile;

 public:
  int Instance() const;
  Result<InUseState> Status() const;
  Result<void> Status(InUseState);

  bool operator<(const InstanceLockFile&) const;

 private:
  InstanceLockFile(LockFile&& lock_file, const int instance_num);
  LockFile lock_file_;
  const int instance_num_;
};

class InstanceLockFileManager {
  using LockFile = cvd_impl::LockFile;
  using LockFileManager = cvd_impl::LockFileManager;

 public:
  INJECT(InstanceLockFileManager());

  Result<InstanceLockFile> AcquireLock(int instance_num);
  Result<std::set<InstanceLockFile>> AcquireLocks(const std::set<int>& nums);

  Result<std::optional<InstanceLockFile>> TryAcquireLock(int instance_num);
  Result<std::set<InstanceLockFile>> TryAcquireLocks(const std::set<int>& nums);

  // Best-effort attempt to find a free instance id.
  Result<std::optional<InstanceLockFile>> TryAcquireUnusedLock();

  Result<std::vector<InstanceLockFile>> LockAllAvailable();

 private:
  /*
   * Generate value to initialize
   */
  Result<std::set<int>> FindPotentialInstanceNumsFromNetDevices();
  static Result<std::string> LockFilePath(int instance_num);
  std::optional<std::set<int>> all_instance_nums_;
  LockFileManager lock_file_manager_;
};

}  // namespace cuttlefish