package org.bouncycastle.asn1;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

/**
 * Base class for objects which can be written directly to ASN.1 output streams.
 */
public abstract class ASN1Encodable
    implements DEREncodable
{
    public static final String DER = "DER";
    public static final String BER = "BER";

    /**
     * Return the default BER or DER encoding for this object.
     *
     * @return BER/DER byte encoded object.
     * @throws IOException on encoding error.
     */
    public byte[] getEncoded() 
        throws IOException
    {
        ByteArrayOutputStream   bOut = new ByteArrayOutputStream();
        ASN1OutputStream        aOut = new ASN1OutputStream(bOut);
        
        aOut.writeObject(this);
        
        return bOut.toByteArray();
    }

    /**
     * Return either the default for "BER" or a DER encoding if "DER" is specified.
     *
     * @param encoding name of encoding to use.
     * @return byte encoded object.
     * @throws IOException on encoding error.
     */
    public byte[] getEncoded(
        String encoding) 
        throws IOException
    {
        if (encoding.equals(DER))
        {
            ByteArrayOutputStream   bOut = new ByteArrayOutputStream();
            DEROutputStream         dOut = new DEROutputStream(bOut);
            
            dOut.writeObject(this);
            
            return bOut.toByteArray();
        }
        
        return this.getEncoded();
    }
    
    /**
     * Return the DER encoding of the object, null if the DER encoding can not be made.
     * 
     * @return a DER byte array, null otherwise.
     */
    public byte[] getDEREncoded()
    {
        try
        {
            return this.getEncoded(DER);
        }
        catch (IOException e)
        {
            return null;
        }
    }
    
    public int hashCode()
    {
        return this.toASN1Object().hashCode();
    }

    public boolean equals(
        Object  o)
    {
        if (this == o)
        {
            return true;
        }
        
        if (!(o instanceof DEREncodable))
        {
            return false;
        }

        DEREncodable other = (DEREncodable)o;

        return this.toASN1Object().equals(other.getDERObject());
    }

    public DERObject getDERObject()
    {        
        return this.toASN1Object();
    }

    public abstract DERObject toASN1Object();
}
