/*

 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#pragma once

#include <AK/Forward.h>

#include <AK/HashTable.h>

#include <AK/Random.h>

namespace AK {

// This class manages a pool of random ID's in the range N (default of 1) to INT32_MAX

class IDAllocator {

public:

    IDAllocator() = default;

    explicit IDAllocator(int minimum_value)

        : m_minimum_value(minimum_value)

    {

    }

    ~IDAllocator() = default;

    int allocate()

    {

        VERIFY(m_allocated_ids.size() < (INT32_MAX - 2));

        int id = 0;

        for (;;) {

            id = static_cast<int>(get_random_uniform(NumericLimits<int>::max()));

            if (id < m_minimum_value)

                continue;

            if (m_allocated_ids.set(id) == AK::HashSetResult::InsertedNewEntry)

                break;

        }

        return id;

    }

    void deallocate(int id)

    {

        m_allocated_ids.remove(id);

    }

private:

    HashTable<int> m_allocated_ids;

    int m_minimum_value { 1 };

};

}

#if USING_AK_GLOBALLY

using AK::IDAllocator;

#endif