/**
 * Copyright (c) 2014 Digi International Inc.,
 * All rights not expressly granted are reserved.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Digi International Inc. 11001 Bren Road East, Minnetonka, MN 55343
 * =======================================================================
 */
package com.digi.xbee.api.connection.serial;

import java.io.IOException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.digi.xbee.api.connection.IConnectionInterface;
import com.digi.xbee.api.exceptions.ConnectionException;
import com.digi.xbee.api.exceptions.InvalidConfigurationException;

/**
 * Abstract class that provides common functionality to work with serial ports.
 */
public abstract class AbstractSerialPort implements IConnectionInterface {
        
        // Constants.
        /**
         * Default receive timeout: {@value} seconds.
         * 
         * <p>When the specified number of milliseconds have elapsed, read will 
         * return immediately.</p>
         */
        public static final int DEFAULT_PORT_TIMEOUT = 10;
        
        /**
         * Default number of data bits: {@value}.
         */
        public static final int DEFAULT_DATA_BITS = 8;
        
        /**
         * Default number of stop bits: {@value}.
         */
        public static final int DEFAULT_STOP_BITS = 1;
        
        /**
         * Default parity: {@value} (None).
         */
        public static final int DEFAULT_PARITY = 0;
        
        /**
         * Default flow control: {@value} (None).
         */
        public static final int DEFAULT_FLOW_CONTROL = 0;
        
        protected static final int FLOW_CONTROL_HW = 3;
        
        protected static final String PORT_ALIAS = "Serial Port";
        
        // Variables.
        protected String port;
        
        protected int baudRate;
        protected int receiveTimeout;
        
        protected SerialPortParameters parameters;
        
        protected boolean connectionOpen = false;
        
        private Logger logger;
        
        /**
         * Class constructor. Instantiates a new {@code AbstractSerialPort} object
         * with the given parameters.
         * 
         * @param port COM port name to use.
         * @param parameters Serial port connection parameters.
         * 
         * @throws NullPointerException if {@code port == null} or
         *                              if {@code parameters == null}.
         * 
         * @see #AbstractSerialPort(String, int)
         * @see #AbstractSerialPort(String, int, int)
         * @see #AbstractSerialPort(String, SerialPortParameters, int)
         * @see SerialPortParameters
         */
        protected AbstractSerialPort(String port, SerialPortParameters parameters) {
                this(port, parameters, DEFAULT_PORT_TIMEOUT);
        }
        
        /**
         * Class constructor. Instantiates a new {@code AbstractSerialPort} object 
         * with the given parameters.
         * 
         * @param port COM port name to use.
         * @param baudRate Serial connection baud rate, the rest of parameters will 
         *                 be set by default.
         * 
         * @throws NullPointerException if {@code port == null}.
         * 
         * @see #DEFAULT_DATA_BITS
         * @see #DEFAULT_FLOW_CONTROL
         * @see #DEFAULT_PARITY
         * @see #DEFAULT_STOP_BITS
         * @see #DEFAULT_PORT_TIMEOUT
         * @see #AbstractSerialPort(String, int, int)
         * @see #AbstractSerialPort(String, SerialPortParameters)
         * @see #AbstractSerialPort(String, SerialPortParameters, int)
         */
        protected AbstractSerialPort(String port, int baudRate) {
                this(port, new SerialPortParameters(baudRate, DEFAULT_DATA_BITS, DEFAULT_STOP_BITS, DEFAULT_PARITY, DEFAULT_FLOW_CONTROL), DEFAULT_PORT_TIMEOUT);
        }
        
        /**
         * Class constructor. Instantiates a new {@code AbstractSerialPort} object
         * with the given parameters.
         * 
         * @param port COM port name to use.
         * @param baudRate Serial port baud rate, the rest of parameters will be 
         *        set by default.
         * @param receiveTimeout Receive timeout in milliseconds.
         * 
         * @throws IllegalArgumentException if {@code receiveTimeout < 0}.
         * @throws NullPointerException if {@code port == null}.
         * 
         * @see DEFAULT_DATA_BITS
         * @see DEFAULT_FLOW_CONTROL
         * @see DEFAULT_PARITY
         * @see DEFAULT_STOP_BITS
         * @see #AbstractSerialPort(String, int)
         * @see #AbstractSerialPort(String, SerialPortParameters)
         * @see #AbstractSerialPort(String, SerialPortParameters, int)
         */
        protected AbstractSerialPort(String port, int baudRate, int receiveTimeout) {
                this(port, new SerialPortParameters(baudRate, DEFAULT_DATA_BITS, DEFAULT_STOP_BITS, DEFAULT_PARITY, DEFAULT_FLOW_CONTROL), receiveTimeout);
        }
        
        /**
         * Class constructor. Instantiates a new {@code AbstractSerialPort} object
         * with the given parameters.
         * 
         * @param port COM port name to use.
         * @param parameters Serial port connection parameters.
         * @param receiveTimeout Serial connection receive timeout in milliseconds.
         * 
         * @throws IllegalArgumentException if {@code receiveTimeout < 0}.
         * @throws NullPointerException if {@code port == null} or
         *                              if {@code parameters == null}.
         *
         * @see #AbstractSerialPort(String, int)
         * @see #AbstractSerialPort(String, int, int)
         * @see #AbstractSerialPort(String, SerialPortParameters)
         * @see SerialPortParameters
         */
        protected AbstractSerialPort(String port, SerialPortParameters parameters, int receiveTimeout) {
                if (port == null)
                        throw new NullPointerException("Serial port cannot be null");

                if (parameters == null)
                        throw new NullPointerException("SerialPortParameters cannot be null");

                if (receiveTimeout < 0)
                        throw new IllegalArgumentException("Receive timeout cannot be less than 0");

                this.port = port;
                this.baudRate = parameters.baudrate;
                this.receiveTimeout = receiveTimeout;
                this.parameters = parameters;
                this.logger = LoggerFactory.getLogger(AbstractSerialPort.class);
        }
        
        /*
         * (non-Javadoc)
         * @see com.digi.xbee.api.connection.IConnectionInterface#isOpen()
         */
        @Override
        public boolean isOpen() {
                return connectionOpen;
        }
        
        /**
         * Returns the name of the serial port.
         * 
         * @return Port name.
         */
        public String getPort() {
                return port;
        }
        
        /**
         * Sets the state of the DTR.
         * 
         * @param state {@code true} to set the line status high, {@code false} to 
         *              set it low.
         * 
         * @see #isCD()
         * @see #isCTS()
         * @see #isDSR()
         * @see #setRTS(boolean)
         */
        public abstract void setDTR(boolean state);
        
        /**
         * Sets the state of the RTS line.
         * 
         * @param state {@code true} to set the line status high, {@code false} to 
         *              set it low.
         * 
         * @see #isCD()
         * @see #isCTS()
         * @see #isDSR()
         * @see #setDTR(boolean)
         */
        public abstract void setRTS(boolean state);
        
        /**
         * Returns the state of the CTS line.
         * 
         * @return {@code true} if the line is high, {@code false} otherwise.
         * 
         * @see #isCD()
         * @see #isDSR()
         * @see #setDTR(boolean)
         * @see #setRTS(boolean)
         */
        public abstract boolean isCTS();
        
        /**
         * Returns the state of the DSR line.
         * 
         * @return {@code true} if the line is high, {@code false} otherwise.
         * 
         * @see #isCD()
         * @see #isCTS()
         * @see #setDTR(boolean)
         * @see #setRTS(boolean)
         */
        public abstract boolean isDSR();
        
        /**
         * Returns the state of the CD line.
         * 
         * @return {@code true} if the line is high, {@code false} otherwise.
         * 
         * @see #isCTS()
         * @see #isDSR()
         * @see #setDTR(boolean)
         * @see #setRTS(boolean)
         */
        public abstract boolean isCD();
        
        /**
         * Returns whether or not the port's flow control is configured in 
         * hardware mode.
         *  
         * @return {@code true} if the flow control is hardware, {@code false} 
         *         otherwise.
         * 
         * @see #getPortParameters()
         * @see #setPortParameters(SerialPortParameters)
         * @see #setPortParameters(int, int, int, int, int)
         */
        public boolean isHardwareFlowControl() {
                return parameters.flowControl == FLOW_CONTROL_HW;
        }
        
        /**
         * Sets the new parameters of the serial port.
         * 
         * @param baudRate The new value of baud rate.
         * @param dataBits The new value of data bits.
         * @param stopBits The new value of stop bits.
         * @param parity The new value of parity.
         * @param flowControl The new value of flow control.
         * 
         * @throws ConnectionException if any error occurs when setting the serial 
         *                             port parameters
         * @throws IllegalArgumentException if {@code baudRate < 0} or
         *                                  if {@code dataBits < 0} or
         *                                  if {@code stopBits < 0} or
         *                                  if {@code parity < 0} or
         *                                  if {@code flowControl < 0}.
         * @throws InvalidConfigurationException if the configuration is invalid.
         * 
         * @see #getPortParameters()
         * @see #setPortParameters(SerialPortParameters)
         */
        public void setPortParameters(int baudRate, int dataBits, int stopBits, int parity, int flowControl) throws InvalidConfigurationException, ConnectionException {
                SerialPortParameters parameters = new SerialPortParameters(baudRate, dataBits, stopBits, parity, flowControl);
                setPortParameters(parameters);
        }
        
        /**
         * Sets the new parameters of the serial port as 
         * {@code SerialPortParameters}.
         * 
         * @param parameters The new serial port parameters.
         * 
         * @throws ConnectionException if any error occurs when setting the serial 
         *                             port parameters.
         * @throws InvalidConfigurationException if the configuration is invalid.
         * @throws NullPointerException if {@code parameters == null}.
         * 
         * @see #getPortParameters()
         * @see #setPortParameters(int, int, int, int, int)
         * @see SerialPortParameters
         */
        public void setPortParameters(SerialPortParameters parameters) throws InvalidConfigurationException, ConnectionException {
                if (parameters == null)
                        throw new NullPointerException("Serial port parameters cannot be null.");
                
                baudRate = parameters.baudrate;
                this.parameters = parameters;
                if (isOpen()) {
                        close();
                        open();
                }
        }
        
        /**
         * Enables or disables the break line.
         * 
         * @param enabled {@code true} to enable the Break line, {@code false} to 
         *                disable it.
         * 
         * @see #sendBreak(int)
         */
        public abstract void setBreak(boolean enabled);
        
        /**
         * Sends a break signal to the serial port with the given duration
         * (in milliseconds).
         * 
         * @param duration Duration of the break signal in milliseconds.
         * 
         * @see #setBreak(boolean)
         */
        public abstract void sendBreak(int duration);
        
        /**
         * Sets the read timeout of the serial port (in milliseconds).
         * 
         * @param timeout The new read timeout of the serial port in milliseconds.
         * 
         * @see #getReadTimeout()
         */
        public abstract void setReadTimeout(int timeout);
        
        /**
         * Returns the read timeout of the serial port (in milliseconds).
         * 
         * @return The read timeout of the serial port in milliseconds.
         * 
         * @see #setReadTimeout(int)
         */
        public abstract int getReadTimeout();
        
        /**
         * Purges the serial port removing all the data from the input stream.
         * 
         * @see #flush()
         */
        public void purge() {
                if (getInputStream() != null) {
                        try {
                                byte[] availableBytes = new byte[getInputStream().available()];
                                if (getInputStream().available() > 0)
                                        getInputStream().read(availableBytes, 0, getInputStream().available());
                        } catch (IOException e) {
                                logger.error(e.getMessage(), e);
                        }
                }
        }
        
        /**
         * Flushes the available data of the output stream.
         * 
         * @see #purge()
         */
        public void flush() {
                if (getOutputStream() != null) {
                        try {
                                getOutputStream().flush();
                        } catch (IOException e) {
                                logger.error(e.getMessage(), e);
                        }
                }
        }
        
        /*
         * (non-Javadoc)
         * @see com.digi.xbee.api.connection.IConnectionInterface#writeData(byte[])
         */
        @Override
        public void writeData(byte[] data) throws IOException {
                if (data == null)
                        throw new NullPointerException("Data to be sent cannot be null.");
                
                if (getOutputStream() != null) {
                        // Writing data in ports without any device connected and configured with 
                        // hardware flow-control causes the majority of serial libraries to hang.
                        
                        // Before writing any data, check if the port is configured with hardware 
                        // flow-control and, if so, try to write the data up to 3 times verifying 
                        // that the CTS line is high (there is a device connected to the other side 
                        // ready to receive data).
                        if (isHardwareFlowControl()) {
                                int tries = 0;
                                while (tries < 3 && !isCTS()) {
                                        try {
                                                Thread.sleep(100);
                                        } catch (InterruptedException e) { }
                                        tries += 1;
                                }
                                if (isCTS()) {
                                        getOutputStream().write(data);
                                        getOutputStream().flush();
                                }
                        } else {
                                getOutputStream().write(data);
                                getOutputStream().flush();
                        }
                }
        }
        
        /*
         * (non-Javadoc)
         * @see com.digi.xbee.api.connection.IConnectionInterface#writeData(byte[], int, int)
         */
        @Override
        public void writeData(byte[] data, int offset, int length) throws IOException {
                if (data == null)
                        throw new NullPointerException("Data to be sent cannot be null.");
                if (offset < 0)
                        throw new IllegalArgumentException("Offset cannot be less than 0.");
                if (length < 1)
                        throw new IllegalArgumentException("Length cannot be less than 0.");
                if (offset >= data.length)
                        throw new IllegalArgumentException("Offset must be less than the data length.");
                if (offset + length > data.length)
                        throw new IllegalArgumentException("Offset + length cannot be great than the data length.");
                
                if (getOutputStream() != null) {
                        // Writing data in ports without any device connected and configured with 
                        // hardware flow-control causes the majority of serial libraries to hang.
                        
                        // Before writing any data, check if the port is configured with hardware 
                        // flow-control and, if so, try to write the data up to 3 times verifying 
                        // that the CTS line is high (there is a device connected to the other side 
                        // ready to receive data).
                        if (isHardwareFlowControl()) {
                                int tries = 0;
                                while (tries < 3 && !isCTS()) {
                                        try {
                                                Thread.sleep(100);
                                        } catch (InterruptedException e) { }
                                        tries += 1;
                                }
                                if (isCTS()) {
                                        getOutputStream().write(data, offset, length);
                                        getOutputStream().flush();
                                }
                        } else {
                                getOutputStream().write(data, offset, length);
                                getOutputStream().flush();
                        }
                }
        }
        
        /*
         * (non-Javadoc)
         * @see com.digi.xbee.api.connection.IConnectionInterface#readData(byte[])
         */
        @Override
        public int readData(byte[] data) throws IOException {
                if (data == null)
                        throw new NullPointerException("Buffer cannot be null.");
                
                int readBytes = 0;
                if (getInputStream() != null)
                        readBytes = getInputStream().read(data);
                return readBytes;
        }
        
        /*
         * (non-Javadoc)
         * @see com.digi.xbee.api.connection.IConnectionInterface#readData(byte[], int, int)
         */
        @Override
        public int readData(byte[] data, int offset, int length) throws IOException {
                if (data == null)
                        throw new NullPointerException("Buffer cannot be null.");
                if (offset < 0)
                        throw new IllegalArgumentException("Offset cannot be less than 0.");
                if (length < 1)
                        throw new IllegalArgumentException("Length cannot be less than 0.");
                if (offset >= data.length)
                        throw new IllegalArgumentException("Offset must be less than the buffer length.");
                if (offset + length > data.length)
                        throw new IllegalArgumentException("Offset + length cannot be great than the buffer length.");
                
                int readBytes = 0;
                if (getInputStream() != null)
                        readBytes = getInputStream().read(data, offset, length);
                return readBytes;
        }
        
        /**
         * Returns the XBee serial port parameters.
         * 
         * @return The XBee serial port parameters.
         * 
         * @see #setPortParameters(SerialPortParameters)
         * @see #setPortParameters(int, int, int, int, int)
         * @see SerialPortParameters
         */
        public SerialPortParameters getPortParameters() {
                if (parameters != null)
                        return parameters;
                return new SerialPortParameters(baudRate, DEFAULT_DATA_BITS, 
                                DEFAULT_STOP_BITS, DEFAULT_PARITY, DEFAULT_FLOW_CONTROL);
        }
        
        /**
         * Returns the serial port receive timeout (in milliseconds).
         * 
         * @return The serial port receive timeout in milliseconds.
         * 
         * @see #getReadTimeout()
         * @see #setReadTimeout(int)
         */
        public int getReceiveTimeout() {
                return receiveTimeout;
        }
        
        /*
         * (non-Javadoc)
         * @see java.lang.Object#toString()
         */
        @Override
        public String toString() {
                if (parameters != null) {
                        String parity = "N";
                        String flowControl = "N";
                        if (parameters.parity == 1)
                                parity = "O";
                        else if (parameters.parity == 2)
                                parity = "E";
                        else if (parameters.parity == 3)
                                parity = "M";
                        else if (parameters.parity == 4)
                                parity = "S";
                        if (parameters.flowControl == 1 
                                        || parameters.flowControl == 2
                                        || parameters.flowControl == 3)
                                flowControl = "H";
                        else if (parameters.flowControl == 4 
                                        || parameters.flowControl == 8
                                        || parameters.flowControl == 12)
                                flowControl = "S";
                        return "[" + port + " - " + baudRate + "/" + parameters.dataBits + 
                                        "/"  + parity + "/" + parameters.stopBits + "/" + flowControl + "] ";
                } else
                        return "[" + port + " - " + baudRate + "/8/N/1/N] ";
        }
}