/*
 * jPOS Project [http://jpos.org]
 * Copyright (C) 2000-2023 jPOS Software SRL
 *
 * 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 <http://www.gnu.org/licenses/>.
 */

package org.jpos.iso;

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

/**
 * Generic class for handling binary fields in Tag-Len-Value format
 * <code>
 * Format TTLL....
 * Where
 *       TT is the n>0 digit field number (Tag)
 *       LL is the n>=0 digit field length (if n=0 it's means fixed length field with prefixer)
 *       .. is the field content
 * </code>
 * @author joconnor
 * @author Robert Demski
 * @version $Revision: 2854 $ $Date: 2010-01-02 11:34:31 +0100 (sob) $
 */
public class ISOTagBinaryFieldPackager extends ISOBinaryFieldPackager
{
    private Prefixer tagPrefixer;
    private BinaryInterpreter interpreter;
    private Padder padder;
    private Prefixer prefixer;

    /**
     * Constructs a default ISOTagBinaryFieldPackager. There is ASCII tag L prefixer, no padding,
     * no length prefix and a literal binary interpretation. The set methods must be called to
     * make this ISOBaseFieldPackager useful.
     */
    public ISOTagBinaryFieldPackager() {
        super();
        this.tagPrefixer = AsciiPrefixer.L;
        this.interpreter = LiteralBinaryInterpreter.INSTANCE;
        this.padder = NullPadder.INSTANCE;
        this.prefixer = NullPrefixer.INSTANCE;
    }

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

    /**
     * Creates an ISOTagBinaryFieldPackager.
     * @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 tagPrefixer The type of tag prefixer used to encode tag.
     * @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 ISOTagBinaryFieldPackager(int maxLength, String description, Prefixer tagPrefixer,
                                  Padder padder, BinaryInterpreter interpreter, Prefixer prefixer) {
        super(maxLength, description, interpreter, prefixer);
        this.tagPrefixer = tagPrefixer;
        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.
     */
    @Override
    public void setInterpreter(BinaryInterpreter interpreter) {
        this.interpreter = interpreter;
    }

    /**
     * Sets the length prefixer.
     * @param prefixer The length prefixer to use during packing and unpacking.
     */
    @Override
    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()
     */
    @Override
    public int getMaxPackedLength() {
        return tagPrefixer.getPackedLength() + 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[].
     */
    @Override
    public byte[] pack(ISOComponent c) throws ISOException {
        try{
            byte[] data = (byte[])c.getValue();
            if (data.length > getLength())
                throw new ISOException("Field length " + data.length + " too long. Max: " + getLength());

            int tag = (Integer)c.getKey();
            byte[] paddedData = data;
            if (!(padder instanceof NullPadder)) //for save few cycles
              paddedData = ISOUtil.hex2byte(padder.pad(ISOUtil.hexString(data), getLength()));
            byte[] rawData = new byte[tagPrefixer.getPackedLength()+prefixer.getPackedLength()
                    + interpreter.getPackedLength(paddedData.length)];
            tagPrefixer.encodeLength(tag, rawData);
            byte[] rawLen = new byte[prefixer.getPackedLength()];
            prefixer.encodeLength(paddedData.length, rawLen);
            System.arraycopy(rawLen, 0, rawData, tagPrefixer.getPackedLength(), rawLen.length);
            interpreter.interpret(paddedData, rawData, tagPrefixer.getPackedLength()+rawLen.length);
            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.
     */
    @Override
    public int unpack(ISOComponent c, byte[] b, int offset) throws ISOException {
        try{
            int tagLen = tagPrefixer.getPackedLength();
            c.setFieldNumber(tagPrefixer.decodeLength(b, offset));
            int len = prefixer.decodeLength(b, offset + tagLen);
            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();
            byte[] unpacked = interpreter.uninterpret(b, offset + tagLen + lenLen, len);
            c.setValue(unpacked);
            return tagLen + 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.
     */
    @Override
    public void unpack (ISOComponent c, InputStream in) 
        throws IOException, ISOException {
        try{
            int tagLen = tagPrefixer.getPackedLength();
            c.setFieldNumber(tagPrefixer.decodeLength(readBytes (in, tagLen), 0));
            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);
            byte[] unpacked = interpreter.uninterpret(readBytes (in, packedLen), 0, len);
            c.setValue(unpacked);
        } catch(ISOException e){
            throw new ISOException(makeExceptionMessage(c, "unpacking"), e);
        }
    }

}
