package org.bouncycastle.asn1;

import java.io.IOException;

ASN.1 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).
/**
 * ASN.1 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 abstract class ASN1TaggedObject
    extends ASN1Object
    implements ASN1TaggedObjectParser
{
    int             tagNo;
    boolean         empty = false;
    boolean         explicit = true;
    DEREncodable    obj = null;

    static public ASN1TaggedObject getInstance(
        ASN1TaggedObject    obj,
        boolean             explicit)
    {
        if (explicit)
        {
            return (ASN1TaggedObject)obj.getObject();
        }

        throw new IllegalArgumentException("implicitly tagged tagged object");
    }

    static public ASN1TaggedObject getInstance(
        Object obj) 
    {
        if (obj == null || obj instanceof ASN1TaggedObject) 
        {
                return (ASN1TaggedObject)obj;
        }

        throw new IllegalArgumentException("unknown object in getInstance: " + obj.getClass().getName());
    }

    
Create a tagged object in the explicit style.
Params:
tagNo – the tag number for this object.
obj – the tagged object./**
     * Create a tagged object in the explicit style.
     * 
     * @param tagNo the tag number for this object.
     * @param obj the tagged object.
     */
    public ASN1TaggedObject(
        int             tagNo,
        DEREncodable    obj)
    {
        this.explicit = true;
        this.tagNo = tagNo;
        this.obj = obj;
    }

    
Create a tagged object with the style given by the value of explicit.

If the object implements ASN1Choice the tag style will always be changed
to explicit in accordance with the ASN.1 encoding rules.

Params:
explicit – true if the object is explicitly tagged.
tagNo – the tag number for this object.
obj – the tagged object./**
     * Create a tagged object with the style given by the value of explicit.
     * <p>
     * If the object implements ASN1Choice the tag style will always be changed
     * to explicit in accordance with the ASN.1 encoding rules.
     * </p>
     * @param explicit true if the object is explicitly tagged.
     * @param tagNo the tag number for this object.
     * @param obj the tagged object.
     */
    public ASN1TaggedObject(
        boolean         explicit,
        int             tagNo,
        DEREncodable    obj)
    {
        if (obj instanceof ASN1Choice)
        {
            this.explicit = true;
        }
        else
        {
            this.explicit = explicit;
        }
        
        this.tagNo = tagNo;
        this.obj = obj;
    }
    
    boolean asn1Equals(
        DERObject o)
    {
        if (!(o instanceof ASN1TaggedObject))
        {
            return false;
        }
        
        ASN1TaggedObject other = (ASN1TaggedObject)o;
        
        if (tagNo != other.tagNo || empty != other.empty || explicit != other.explicit)
        {
            return false;
        }
        
        if(obj == null)
        {
            if (other.obj != null)
            {
                return false;
            }
        }
        else
        {
            if (!(obj.getDERObject().equals(other.obj.getDERObject())))
            {
                return false;
            }
        }
        
        return true;
    }
    
    public int hashCode()
    {
        int code = tagNo;

        // TODO: actually this is wrong - the problem is that a re-encoded
        // object may end up with a different hashCode due to implicit
        // tagging. As implicit tagging is ambiguous if a sequence is involved
        // it seems the only correct method for both equals and hashCode is to
        // compare the encodings...
        if (obj != null)
        {
            code ^= obj.hashCode();
        }

        return code;
    }

    public int getTagNo()
    {
        return tagNo;
    }

    
return whether or not the object may be explicitly tagged. 

Note: if the object has been read from an input stream, the only
time you can be sure if isExplicit is returning the true state of
affairs is if it returns false. An implicitly tagged object may appear
to be explicitly tagged, so you need to understand the context under
which the reading was done as well, see getObject below.
/**
     * return whether or not the object may be explicitly tagged. 
     * <p>
     * Note: if the object has been read from an input stream, the only
     * time you can be sure if isExplicit is returning the true state of
     * affairs is if it returns false. An implicitly tagged object may appear
     * to be explicitly tagged, so you need to understand the context under
     * which the reading was done as well, see getObject below.
     */
    public boolean isExplicit()
    {
        return explicit;
    }

    public boolean isEmpty()
    {
        return empty;
    }

    
return whatever was following the tag.

Note: tagged objects are generally context dependent if you're
trying to extract a tagged object you should be going via the
appropriate getInstance method.
/**
     * return whatever was following the tag.
     * <p>
     * Note: tagged objects are generally context dependent if you're
     * trying to extract a tagged object you should be going via the
     * appropriate getInstance method.
     */
    public DERObject getObject()
    {
        if (obj != null)
        {
            return obj.getDERObject();
        }

        return null;
    }

    
Return the object held in this tagged object as a parser assuming it has
the type of the passed in tag. If the object doesn't have a parser
associated with it, the base object is returned.
/**
     * Return the object held in this tagged object as a parser assuming it has
     * the type of the passed in tag. If the object doesn't have a parser
     * associated with it, the base object is returned.
     */
    public DEREncodable getObjectParser(
        int     tag,
        boolean isExplicit)
    {
        switch (tag)
        {
        case DERTags.SET:
            return ASN1Set.getInstance(this, isExplicit).parser();
        case DERTags.SEQUENCE:
            return ASN1Sequence.getInstance(this, isExplicit).parser();
        case DERTags.OCTET_STRING:
            return ASN1OctetString.getInstance(this, isExplicit).parser();
        }

        if (isExplicit)
        {
            return getObject();
        }

        throw new RuntimeException("implicit tagging not implemented for tag: " + tag);
    }

    public DERObject getLoadedObject()
    {
        return this.getDERObject();
    }
    
    abstract void encode(DEROutputStream  out)
        throws IOException;

    public String toString()
    {
        return "[" + tagNo + "]" + obj;
    }
}