SendData.java

/**
 * Copyright (c) 2010-2016 by the respective copyright holders.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.openhab.binding.lcn.connection;

import java.io.UnsupportedEncodingException;
import java.nio.BufferOverflowException;
import java.nio.ByteBuffer;

import org.openhab.binding.lcn.common.LcnAddr;
import org.openhab.binding.lcn.common.LcnDefs;
import org.openhab.binding.lcn.common.PckGenerator;

/**
 * A packet to be send to LCN-PCHK.
 *
 * @author Tobias J�ttner
 */
abstract class SendData {

    /**
     * Writes the packet's data into the given buffer.
     * Called right before the packet is actually sent to LCN-PCHK.
     * 
     * @param buffer the target buffer
     * @param localSegId the local segment id
     * @return true if everything was set-up correctly and data was written
     * @throws UnsupportedEncodingException if text could not be encoded for LCN-PCHK
     * @throws BufferOverflowException if target buffer has not enough space left (buffer will not be altered)
     */
    abstract boolean write(ByteBuffer buffer, int localSegId)
            throws UnsupportedEncodingException, BufferOverflowException;

    /** A plain text to be send to LCN-PCHK. */
    static class PlainText extends SendData {

        /** The text. */
        private final String text;

        /**
         * Constructor.
         * 
         * @param text the text
         */
        PlainText(String text) {
            this.text = text;
        }

        /**
         * Gets the text.
         * 
         * @return the text
         */
        String getText() {
            return this.text;
        }

        /** {@inheritDoc} */
        @Override
        boolean write(ByteBuffer buffer, int localSegId) throws UnsupportedEncodingException, BufferOverflowException {
            buffer.put((this.text + PckGenerator.TERMINATION).getBytes(LcnDefs.LCN_ENCODING));
            return true;
        }

    }

    /**
     * A PCK command to be send to LCN-PCHK.
     * It is already encoded as bytes to allow different text-encodings (ANSI, UTF-8).
     */
    static class PckSendData extends SendData {

        /** The target LCN address. */
        private final LcnAddr addr;

        /** true to acknowledge the command on receipt. */
        private final boolean wantsAck;

        /** PCK command (without address header) encoded as bytes. */
        private final ByteBuffer data;

        /**
         * Constructor.
         * 
         * @param addr the target LCN address
         * @param wantsAck true to claim receipt
         * @param data the PCK command encoded as bytes
         */
        PckSendData(LcnAddr addr, boolean wantsAck, ByteBuffer data) {
            this.addr = addr;
            this.wantsAck = wantsAck;
            this.data = data;
        }

        /**
         * Gets the PCK command.
         * 
         * @return the PCK command encoded as bytes
         */
        ByteBuffer getData() {
            return this.data;
        }

        /** {@inheritDoc} */
        @Override
        boolean write(ByteBuffer buffer, int localSegId) throws UnsupportedEncodingException, BufferOverflowException {
            if (this.addr.getSegId() != 3 && localSegId == -1) { // Always allow commands to all segments (3)
                return false;
            }
            buffer.put(PckGenerator.generateAddressHeader(this.addr, localSegId, this.wantsAck)
                    .getBytes(LcnDefs.LCN_ENCODING));
            buffer.put(this.data);
            buffer.put(PckGenerator.TERMINATION.getBytes(LcnDefs.LCN_ENCODING));
            return true;
        }

    }

}