namespace ServerCore;

//=============================================================================================
// 병렬 프로그래밍 환경에서 상태값을 동기화할 수 있게 지원하는  제네릭 클래스 이다.
//
// author : kangms
// 
//=============================================================================================
public class SyncState<T> where T : notnull
{
    private T m_state;
    private readonly object m_mutex = new object(); // mutex

    public SyncState(T state)
    {
        m_state = state;
    }

    public bool isState(T state)
    {
        lock (m_mutex)
        {
            return (m_state.Equals(state));
        }
    }

    public T setState(T state)
    {
        lock (m_mutex)
        {
            T old_state = m_state;
            m_state = state;
            return old_state;
        }
    }

    public T getState()
    {
        return m_state;
    }

    // 같지 않으면 변경 
    // exchange..(disconnected, out old_state)
    public bool exchangeNotEqual(T to_state, out T old_state)
    {
        lock (m_mutex)
        {
            if (false == m_state.Equals(to_state))
            {
                old_state = m_state;
                m_state = to_state;
                return true;
            }

            old_state = m_state;
            return false;
        }
    }
    // 같지 않으면 변경, 예외인 경우는 변경안함
    // exchange...(disconnected, connecting, out old_state)
    public bool exchangeNotEqualExcept(T to_state, T except_state, out T old_state)
    {
        lock (m_mutex)
        {
            // except state
            if (true == m_state.Equals(except_state))
            {
                old_state = m_state;
                return false;
            }

            if (false == m_state.Equals(to_state))
            {
                old_state = m_state;
                m_state = to_state;
                return true;
            }

            old_state = m_state;
            return false;
        }
    }

    public string? toString()
    {
        return Enum.GetName(typeof(T), m_state);
    }
}

public class AtomicString
{
    private string m_value;

    public AtomicString(string value = "")
    {
        m_value = value;
    }

    public string Value
    {
        get { return m_value; }
    }

    public void set(string newValue)
    {
        Interlocked.Exchange(ref m_value, newValue);
    }

    public bool compareAndSet(string expectedValue, string newValue)
    {
        return Interlocked.CompareExchange(ref m_value, newValue, expectedValue) == expectedValue;
    }
}

public class AtomicInt32
{
    private Int32 m_value;

    public AtomicInt32(Int32 value = 0)
    {
        m_value = value;
    }

    public int Value
    {
        get { return m_value; }
    }

    public void set(int newValue)
    {
        Interlocked.Exchange(ref m_value, newValue);
    }

    public int increment()
    {
        return Interlocked.Increment(ref m_value);
    }

    public int decrement()
    {
        return Interlocked.Decrement(ref m_value);
    }

    public int add(int value)
    {
        return Interlocked.Add(ref m_value, value);
    }

    public bool compareAndSet(int expectedValue, int newValue)
    {
        return Interlocked.CompareExchange(ref m_value, newValue, expectedValue) == expectedValue;
    }
}

public class AtomicBool
{
    private Int32 m_value = 0;

    public AtomicBool(bool value)
    {
        m_value = value ? 1 : 0;
    }

    public bool Value
    {
        get { return m_value == 1; }
    }

    public bool set(bool value)
    {
        var comparand = value ? 0 : 1;
        var in_value = value ? 1 : 0;

        var result = Interlocked.CompareExchange(ref m_value, in_value, comparand);
        
        return comparand == result;
    }
}