package org.bouncycastle.asn1;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Vector;

ASN.1 OctetStrings, with indefinite length rules, and constructed form support.

The Basic Encoding Rules (BER) format allows encoding using so called "constructed form",
which DER and CER formats forbid allowing only "primitive form".

This class always produces the constructed form with underlying segments
in an indefinite length array.  If the input wasn't the same, then this output
is not faithful reproduction.

 See ASN1OctetString for X.690 encoding rules of OCTET-STRING objects. 
/**
 * ASN.1 OctetStrings, with indefinite length rules, and <i>constructed form</i> support.
 * <p>
 * The Basic Encoding Rules (BER) format allows encoding using so called "<i>constructed form</i>",
 * which DER and CER formats forbid allowing only "primitive form".
 * </p><p>
 * This class <b>always</b> produces the constructed form with underlying segments
 * in an indefinite length array.  If the input wasn't the same, then this output
 * is not faithful reproduction.
 * </p>
 * <p>
 * See {@link ASN1OctetString} for X.690 encoding rules of OCTET-STRING objects.
 * </p>
 */
public class BEROctetString
    extends ASN1OctetString
{
    private static final int DEFAULT_LENGTH = 1000;

    private final int chunkSize;
    private final ASN1OctetString[] octs;

    
Convert a vector of octet strings into a single byte string
/**
     * Convert a vector of octet strings into a single byte string
     */
    static private byte[] toBytes(
        ASN1OctetString[]  octs)
    {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();

        for (int i = 0; i != octs.length; i++)
        {
            try
            {
                DEROctetString o = (DEROctetString)octs[i];

                bOut.write(o.getOctets());
            }
            catch (ClassCastException e)
            {
                throw new IllegalArgumentException(octs[i].getClass().getName() + " found in input should only contain DEROctetString");
            }
            catch (IOException e)
            {
                throw new IllegalArgumentException("exception converting octets " + e.toString());
            }
        }

        return bOut.toByteArray();
    }

    
Create an OCTET-STRING object from a byte[]
Params:
string – the octets making up the octet string./**
     * Create an OCTET-STRING object from a byte[]
     * @param string the octets making up the octet string.
     */
    public BEROctetString(
        byte[] string)
    {
        this(string, DEFAULT_LENGTH);
    }

    
Multiple ASN1OctetString data blocks are input, the result is constructed form.
Params:
octs – an array of OCTET STRING to construct the BER OCTET STRING from./**
     * Multiple {@link ASN1OctetString} data blocks are input,
     * the result is <i>constructed form</i>.
     *
     * @param octs an array of OCTET STRING to construct the BER OCTET STRING from.
     */
    public BEROctetString(
        ASN1OctetString[] octs)
    {
        this(octs, DEFAULT_LENGTH);
    }

    
Create an OCTET-STRING object from a byte[]
Params:
string – the octets making up the octet string.
chunkSize – the number of octets stored in each DER encoded component OCTET STRING./**
     * Create an OCTET-STRING object from a byte[]
     * @param string the octets making up the octet string.
     * @param chunkSize the number of octets stored in each DER encoded component OCTET STRING.
     */
    public BEROctetString(
        byte[] string,
        int    chunkSize)
    {
        this(string, null, chunkSize);
    }

    
Multiple ASN1OctetString data blocks are input, the result is constructed form.
Params:
octs – an array of OCTET STRING to construct the BER OCTET STRING from.
chunkSize – the number of octets stored in each DER encoded component OCTET STRING./**
     * Multiple {@link ASN1OctetString} data blocks are input,
     * the result is <i>constructed form</i>.
     *
     * @param octs an array of OCTET STRING to construct the BER OCTET STRING from.
     * @param chunkSize the number of octets stored in each DER encoded component OCTET STRING.
     */
    public BEROctetString(
        ASN1OctetString[] octs,
        int chunkSize)
    {
        this(toBytes(octs), octs, chunkSize);
    }

    private BEROctetString(byte[] string, ASN1OctetString[] octs, int chunkSize)
    {
        super(string);
        this.octs = octs;
        this.chunkSize = chunkSize;
    }

    
Return a concatenated byte array of all the octets making up the constructed OCTET STRING
Returns:
the full OCTET STRING./**
     * Return a concatenated byte array of all the octets making up the constructed OCTET STRING
     * @return the full OCTET STRING.
     */
    public byte[] getOctets()
    {
        return string;
    }

    
Return the OCTET STRINGs that make up this string.
Returns:
an Enumeration of the component OCTET STRINGs./**
     * Return the OCTET STRINGs that make up this string.
     *
     * @return an Enumeration of the component OCTET STRINGs.
     */
    public Enumeration getObjects()
    {
        if (octs == null)
        {
            return generateOcts().elements();
        }

        return new Enumeration()
        {
            int counter = 0;

            public boolean hasMoreElements()
            {
                return counter < octs.length;
            }

            public Object nextElement()
            {
                return octs[counter++];
            }
        };
    }

    private Vector generateOcts()
    { 
        Vector vec = new Vector();
        for (int i = 0; i < string.length; i += chunkSize)
        { 
            int end; 

            if (i + chunkSize > string.length)
            { 
                end = string.length; 
            } 
            else 
            { 
                end = i + chunkSize;
            } 

            byte[] nStr = new byte[end - i]; 

            System.arraycopy(string, i, nStr, 0, nStr.length);

            vec.addElement(new DEROctetString(nStr));
         } 
        
         return vec; 
    }

    boolean isConstructed()
    {
        return true;
    }

    int encodedLength()
        throws IOException
    {
        int length = 0;
        for (Enumeration e = getObjects(); e.hasMoreElements();)
        {
            length += ((ASN1Encodable)e.nextElement()).toASN1Primitive().encodedLength();
        }

        return 2 + length + 2;
    }

    public void encode(
        ASN1OutputStream out)
        throws IOException
    {
        out.write(BERTags.CONSTRUCTED | BERTags.OCTET_STRING);

        out.write(0x80);

        //
        // write out the octet array
        //
        for (Enumeration e = getObjects(); e.hasMoreElements();)
        {
            out.writeObject((ASN1Encodable)e.nextElement());
        }

        out.write(0x00);
        out.write(0x00);
    }

    static BEROctetString fromSequence(ASN1Sequence seq)
    {
        ASN1OctetString[]     v = new ASN1OctetString[seq.size()];
        Enumeration e = seq.getObjects();
        int                   index = 0;

        while (e.hasMoreElements())
        {
            v[index++] = (ASN1OctetString)e.nextElement();
        }

        return new BEROctetString(v);
    }
}