package org.bouncycastle.asn1;

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

/**
 * BER TaggedObject - in ASN.1 notation this is any object preceded by
 * a [n] where n is some number - these are assumed to follow the construction
 * rules (as with sequences).
 */
public class BERTaggedObject
    extends ASN1TaggedObject
{
    /**
     * @param tagNo the tag number for this object.
     * @param obj the tagged object.
     */
    public BERTaggedObject(
        int             tagNo,
        ASN1Encodable    obj)
    {
        super(true, tagNo, obj);
    }

    /**
     * @param explicit true if an explicitly tagged object.
     * @param tagNo the tag number for this object.
     * @param obj the tagged object.
     */
    public BERTaggedObject(
        boolean         explicit,
        int             tagNo,
        ASN1Encodable    obj)
    {
        super(explicit, tagNo, obj);
    }

    /**
     * create an implicitly tagged object that contains a zero
     * length sequence.
     */
    public BERTaggedObject(
        int             tagNo)
    {
        super(false, tagNo, new BERSequence());
    }

    boolean isConstructed()
    {
        if (!empty)
        {
            if (explicit)
            {
                return true;
            }
            else
            {
                ASN1Primitive primitive = obj.toASN1Primitive().toDERObject();

                return primitive.isConstructed();
            }
        }
        else
        {
            return true;
        }
    }

    int encodedLength()
        throws IOException
    {
        if (!empty)
        {
            ASN1Primitive primitive = obj.toASN1Primitive();
            int length = primitive.encodedLength();

            if (explicit)
            {
                return StreamUtil.calculateTagLength(tagNo) + StreamUtil.calculateBodyLength(length) + length;
            }
            else
            {
                // header length already in calculation
                length = length - 1;

                return StreamUtil.calculateTagLength(tagNo) + length;
            }
        }
        else
        {
            return StreamUtil.calculateTagLength(tagNo) + 1;
        }
    }

    void encode(
        ASN1OutputStream out)
        throws IOException
    {
        out.writeTag(BERTags.CONSTRUCTED | BERTags.TAGGED, tagNo);
        out.write(0x80);

        if (!empty)
        {
            if (!explicit)
            {
                Enumeration e;
                if (obj instanceof ASN1OctetString)
                {
                    if (obj instanceof BEROctetString)
                    {
                        e = ((BEROctetString)obj).getObjects();
                    }
                    else
                    {
                        ASN1OctetString             octs = (ASN1OctetString)obj;
                        BEROctetString berO = new BEROctetString(octs.getOctets());
                        e = berO.getObjects();
                    }
                }
                else if (obj instanceof ASN1Sequence)
                {
                    e = ((ASN1Sequence)obj).getObjects();
                }
                else if (obj instanceof ASN1Set)
                {
                    e = ((ASN1Set)obj).getObjects();
                }
                else
                {
                    throw new RuntimeException("not implemented: " + obj.getClass().getName());
                }

                while (e.hasMoreElements())
                {
                    out.writeObject((ASN1Encodable)e.nextElement());
                }
            }
            else
            {
                out.writeObject(obj);
            }
        }

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