CC-Tweaked/src/main/java/dan200/computercraft/shared/peripheral/modem/ModemState.java

/*
 * This file is part of ComputerCraft - http://www.computercraft.info
 * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
 * Send enquiries to dratcliffe@gmail.com
 */

package dan200.computercraft.shared.peripheral.modem;

import dan200.computercraft.api.lua.LuaException;
import it.unimi.dsi.fastutil.ints.IntOpenHashSet;
import it.unimi.dsi.fastutil.ints.IntSet;

import java.util.concurrent.atomic.AtomicBoolean;

public class ModemState
{
    private final Runnable onChanged;
    private final AtomicBoolean changed = new AtomicBoolean( true );

    private boolean open = false;
    private final IntSet channels = new IntOpenHashSet();

    public ModemState()
    {
        this.onChanged = null;
    }

    public ModemState( Runnable onChanged )
    {
        this.onChanged = onChanged;
    }

    private void setOpen( boolean open )
    {
        if( this.open == open ) return;
        this.open = open;
        if( !changed.getAndSet( true ) && onChanged != null ) onChanged.run();
    }

    public boolean pollChanged()
    {
        return changed.getAndSet( false );
    }

    public boolean isOpen()
    {
        return open;
    }

    public boolean isOpen( int channel )
    {
        synchronized( channels )
        {
            return channels.contains( channel );
        }
    }

    public void open( int channel ) throws LuaException
    {
        synchronized( channels )
        {
            if( !channels.contains( channel ) )
            {
                if( channels.size() >= 128 ) throw new LuaException( "Too many open channels" );
                channels.add( channel );
                setOpen( true );
            }
        }
    }

    public void close( int channel )
    {
        synchronized( channels )
        {
            channels.remove( channel );
            if( channels.isEmpty() ) setOpen( false );
        }
    }

    public void closeAll()
    {
        synchronized( channels )
        {
            channels.clear();
            setOpen( false );
        }
    }
}