/**
 * Copyright (c) 2010-2017 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.dscalarm.internal.discovery;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;

import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import gnu.io.CommPort;
import gnu.io.CommPortIdentifier;
import gnu.io.PortInUseException;
import gnu.io.SerialPort;
import gnu.io.UnsupportedCommOperationException;

/**
 * This class is responsible for discovering the DSC IT100 RS232 Serial interface.
 *
 * @author Russell Stephens - Initial Contribution
 *
 */
public class IT100BridgeDiscovery {
    private final static Logger logger = LoggerFactory.getLogger(IT100BridgeDiscovery.class);

    static final int BAUD_RATE = 9600;
    static final int RECEIVE_TIMEOUT = 15000;
    static final String IT100_SEND_STRING = "00090\r\n";
    static final String IT100_DISCOVERY_RESPONSE = "500";

    private DSCAlarmBridgeDiscovery dscAlarmBridgeDiscovery = null;

    /**
     * Constructor.
     */
    public IT100BridgeDiscovery(DSCAlarmBridgeDiscovery dscAlarmBridgeDiscovery) {
        this.dscAlarmBridgeDiscovery = dscAlarmBridgeDiscovery;
    }

    /**
     * Method for Bridge Discovery.
     */
    public synchronized void discoverBridge() {
        logger.debug("Starting IT-100 Bridge Discovery.");

        Enumeration<?> ports = CommPortIdentifier.getPortIdentifiers();

        while (ports.hasMoreElements()) {
            CommPortIdentifier portIdentifier = (CommPortIdentifier) ports.nextElement();

            if (portIdentifier.getPortType() == CommPortIdentifier.PORT_SERIAL) {
                SerialPort serialPort = null;
                OutputStreamWriter serialOutput = null;
                BufferedReader serialInput = null;

                try {
                    CommPort commPort = portIdentifier.open(this.getClass().getName(), 2000);
                    serialPort = (SerialPort) commPort;
                    serialPort.setSerialPortParams(BAUD_RATE, SerialPort.DATABITS_8, SerialPort.STOPBITS_1,
                            SerialPort.PARITY_NONE);
                    serialPort.enableReceiveThreshold(1);

                    serialOutput = new OutputStreamWriter(serialPort.getOutputStream(), "US-ASCII");
                    serialInput = new BufferedReader(new InputStreamReader(serialPort.getInputStream()));

                    serialPort.enableReceiveTimeout(RECEIVE_TIMEOUT);
                    String message = "";

                    serialOutput.write(IT100_SEND_STRING);
                    serialOutput.flush();

                    try {
                        message = serialInput.readLine();
                    } catch (IOException e) {
                        logger.debug("discoverBridge(): No Message Read from Serial Port '{}'",
                                portIdentifier.getName());
                        continue;
                    }

                    if (message.substring(0, 3).equals(IT100_DISCOVERY_RESPONSE)) {
                        logger.debug("discoverBridge(): Serial Port '{}' Found!", portIdentifier.getName());
                        dscAlarmBridgeDiscovery.addIT100Bridge(portIdentifier.getName());
                    } else {
                        logger.debug("discoverBridge(): Incorrect Response from Serial Port! '{}' - {}",
                                portIdentifier.getName(), message);
                    }

                } catch (UnsupportedCommOperationException e) {
                    logger.debug("discoverBridge(): Unsupported Comm Operation Exception - '{}': {}",
                            portIdentifier.getName(), e.toString());
                } catch (PortInUseException e) {
                    logger.debug("discoverBridge(): Port in Use Exception - '{}': {}", portIdentifier.getName(),
                            e.toString());
                } catch (UnsupportedEncodingException e) {
                    logger.debug("discoverBridge(): Unsupported Encoding Exception - '{}': {}",
                            portIdentifier.getName(), e.toString());
                } catch (IOException e) {
                    logger.debug("discoverBridge(): IO Exception - '{}': ", portIdentifier.getName(), e.toString());
                } finally {
                    if (serialInput != null) {
                        IOUtils.closeQuietly(serialInput);
                        serialInput = null;
                    }

                    if (serialOutput != null) {
                        IOUtils.closeQuietly(serialOutput);
                        serialOutput = null;
                    }

                    if (serialPort != null) {
                        serialPort.close();
                        serialPort = null;
                    }
                }
            }
        }
    }
}
