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jPOS is an ISO-8583 based financial transaction library/framework that can be customized and extended in order to implement financial interchanges.
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/*
 * jPOS Project [http://jpos.org]
 * Copyright (C) 2000-2015 Alejandro P. Revilla
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see .
 */

package org.jpos.iso;

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

/**
 * @author joconnor
 * @version $Revision$ $Date$
 */
public class ISOAmountFieldPackager extends ISOFieldPackager
{
    private Padder padder;
    private Interpreter interpreter;
    private Prefixer prefixer;

    /**
     * Creates an ISOAmountFieldPackager.
     * @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 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 ISOAmountFieldPackager(int maxLength, String description, Padder padder, 
                                  Interpreter interpreter, Prefixer prefixer)
    {
        super(maxLength, description);
        this.padder = padder;
        this.interpreter = interpreter;
        this.prefixer = prefixer;
    }

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

    /**
     * Constructs an ISOAmountFieldPackager 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 ISOAmountFieldPackager(Padder padder, Interpreter interpreter, Prefixer prefixer)
    {
        super();
        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.
     */
    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;
    }

    /**
	 * Packs 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 sign = data.substring(0, 1);
            String amount = data.substring(1);
            String paddedData = padder.pad(amount, getLength()-1);
            int signLength = interpreter.getPackedLength(1);
            byte[] rawData = new byte[prefixer.getPackedLength()
                    + signLength
                    + interpreter.getPackedLength(paddedData.length())];
            prefixer.encodeLength(paddedData.length(), rawData);
            interpreter.interpret(sign, rawData, prefixer.getPackedLength());
            interpreter.interpret(paddedData, rawData, prefixer.getPackedLength() + signLength);
            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();
            }
            else if (getLength() > 0 && len > getLength())
                throw new ISOException("Field length " + len + " too long. Max: " + getLength());
            int lenLen = prefixer.getPackedLength();
            String unpacked = interpreter.uninterpret(b, offset + lenLen, len);
            c.setValue(unpacked);
            return lenLen + interpreter.getPackedLength(len);
        } 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);
                if (getLength() > 0 && len > 0 && len > getLength())
                    throw new ISOException("Field length " + len + " too long. Max: " + getLength());
            }
            int packedLen = interpreter.getPackedLength(len);
            String unpacked = interpreter.uninterpret(readBytes (in, packedLen), 0, len);
            c.setValue(unpacked);
        } 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());
        }
    }
}