/*
 * Copyright (c) 2000 jPOS.org.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *    "This product includes software developed by the jPOS project 
 *    (http://www.jpos.org/)". Alternately, this acknowledgment may 
 *    appear in the software itself, if and wherever such third-party 
 *    acknowledgments normally appear.
 *
 * 4. The names "jPOS" and "jPOS.org" must not be used to endorse 
 *    or promote products derived from this software without prior 
 *    written permission. For written permission, please contact 
 *    license@jpos.org.
 *
 * 5. Products derived from this software may not be called "jPOS",
 *    nor may "jPOS" appear in their name, without prior written
 *    permission of the jPOS project.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  
 * IN NO EVENT SHALL THE JPOS PROJECT OR ITS CONTRIBUTORS BE LIABLE FOR 
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the jPOS Project.  For more
 * information please see <http://www.jpos.org/>.
 */
package org.jpos.iso;

import java.io.IOException;
import java.io.InputStream;

/**
 * @author joconnor
 * @version $Revision: 1.1 $ $Date: 2003/11/17 11:58:14 $
 */
public class ISOFilledStringFieldPackager extends ISOFieldPackager
{
    private Interpreter interpreter;
    private Padder padder;
    private Prefixer prefixer;

    /**
     * Constructs a default ISOFilledStringFieldPackager. There is no padding,
     * no length prefix and a literal interpretation. The set methods must be called to
     * make this useful.
     */
    public ISOFilledStringFieldPackager()
    {
        super();
        this.padder = NullPadder.INSTANCE;
        this.interpreter = LiteralInterpreter.INSTANCE;
        this.prefixer = NullPrefixer.INSTANCE;
    }

    /**
     * Constructs an ISOFilledStringFieldPackager with a specific Padder, Interpreter and Prefixer.
     * The length and description should be set with setLength() and setDescription methods.
     * @param padder The type of padding used.
     * @param interpreter The interpreter used to encode the field.
     * @param prefixer The type of length prefixer used to encode this field.
     */
    public ISOFilledStringFieldPackager(Padder padder, Interpreter interpreter, Prefixer prefixer)
    {
        super();
        this.padder = padder;
        this.interpreter = interpreter;
        this.prefixer = prefixer;
    }

    /**
     * Creates an ISOFilledStringFieldPackager.
     * @param maxLength The maximum length of the field in characters or bytes depending on the datatype.
     * @param description The description of the field. For human readable output.
     * @param interpreter The interpreter used to encode the field.
     * @param padder The type of padding used.
     * @param prefixer The type of length prefixer used to encode this field.
     */
    public ISOFilledStringFieldPackager(int maxLength, String description, Padder padder,
                                  Interpreter interpreter, Prefixer prefixer)
    {
        super(maxLength, description);
        this.padder = padder;
        this.interpreter = interpreter;
        this.prefixer = prefixer;
    }

    /**
     * Sets the Padder.
     * @param padder The padder to use during packing and unpacking.
     */
    public void setPadder(Padder padder)
    {
        this.padder = padder;
    }

    /**
     * Sets the Interpreter.
     * @param interpreter The interpreter to use in packing and unpacking.
     */
    public void setInterpreter(Interpreter interpreter)
    {
        this.interpreter = interpreter;
    }

    /**
     * Sets the length prefixer.
     * @param prefixer The length prefixer to use during packing and unpacking.
     */
    public void setPrefixer(Prefixer prefixer)
    {
        this.prefixer = prefixer;
    }

    /**
     * Returns the prefixer's packed length and the interpreter's packed length.
	 * @see org.jpos.iso.ISOFieldPackager#getMaxPackedLength()
	 */
    public int getMaxPackedLength()
    {
        return prefixer.getPackedLength() + interpreter.getPackedLength(getLength());
    }

    /** Create a nice readable message for errors */
    private String makeExceptionMessage(ISOComponent c, String operation) {
        Object fieldKey = "unknown";
        if (c != null)
        {
            try
            {
                fieldKey = c.getKey();
            } catch (Exception ignore)
            {
            }
        }
        return this.getClass().getName() + ": Problem " + operation + " field " + fieldKey;
    }

    /**
	 * Convert the component into a byte[].
	 */
    public byte[] pack(ISOComponent c) throws ISOException
    {
        try
        {
            String data = (String)c.getValue();
            if (data.length() > getLength())
            {
                throw new ISOException("Field length " + data.length() + " too long. Max: " + getLength());
            }
            String paddedData = padder.pad(data, getLength());
            byte[] rawData = new byte[prefixer.getPackedLength()
                    + interpreter.getPackedLength(paddedData.length())];
            prefixer.encodeLength(data.length(), rawData);
            interpreter.interpret(paddedData, rawData, prefixer.getPackedLength());
            return rawData;
        } catch(Exception e)
        {
            throw new ISOException(makeExceptionMessage(c, "packing"), e);
        }
    }

    /**
     * Unpacks the byte array into the component.
     * @param c The component to unpack into.
     * @param b The byte array to unpack.
     * @param offset The index in the byte array to start unpacking from.
     * @return The number of bytes consumed unpacking the component.
     */
    public int unpack(ISOComponent c, byte[] b, int offset) throws ISOException
    {
        try
        {
            int len = prefixer.decodeLength(b, offset);
            if (len == -1)
            {
                // The prefixer doesn't know how long the field is, so use
    			// maxLength instead
                len = getLength();
            }
            int lenLen = prefixer.getPackedLength();
            String unpacked = interpreter.uninterpret(b, offset + lenLen, len);
            c.setValue(unpacked);
            return lenLen + interpreter.getPackedLength(getLength());
        } catch(Exception e)
        {
            throw new ISOException(makeExceptionMessage(c, "unpacking"), e);
        }
    }

    /**
     * Unpack the input stream into the component.
     * @param c  The Component to unpack into.
     * @param in Input stream where the packed bytes come from.
     * @exception IOException Thrown if there's a problem reading the input stream.
     */
    public void unpack (ISOComponent c, InputStream in) 
        throws IOException, ISOException
    {
        try
        {
            int lenLen = prefixer.getPackedLength ();
            int len;
            if (lenLen == 0)
            {
                len = getLength();
            } else
            {
                len = prefixer.decodeLength (readBytes (in, lenLen), 0);
            }
            int packedLen = interpreter.getPackedLength(len);
            String unpacked = interpreter.uninterpret(readBytes (in, packedLen), 0, len);
            c.setValue(unpacked);
            in.skip(interpreter.getPackedLength(getLength()) - packedLen);
        } catch(ISOException e)
        {
            throw new ISOException(makeExceptionMessage(c, "unpacking"), e);
        }
    }

    /**
     * Checks the length of the data against the maximum, and throws an IllegalArgumentException.
     * This is designed to be called from field Packager constructors and the setLength()
     * method.
     * @param len The length of the data for this field packager.
     * @param maxLength The maximum length allowed for this type of field packager.
     *          This depends on the prefixer that is used.
     * @throws IllegalArgumentException If len > maxLength.
     */
    protected void checkLength(int len, int maxLength) throws IllegalArgumentException
    {
        if (len > maxLength)
        {
            throw new IllegalArgumentException("Length " + len + " too long for " + getClass().getName());
        }
    }
}