package org.spongycastle.asn1.cms;

import org.spongycastle.asn1.ASN1Choice;
import org.spongycastle.asn1.ASN1Object;
import org.spongycastle.asn1.ASN1Primitive;
import org.spongycastle.asn1.ASN1TaggedObject;
import org.spongycastle.asn1.DERTaggedObject;

/**
 * <a href="http://tools.ietf.org/html/rfc5544">RFC 5544</a>:
 * Binding Documents with Time-Stamps; Evidence object.
 * <p>
 * <pre>
 * Evidence ::= CHOICE {
 *     tstEvidence    [0] TimeStampTokenEvidence,   -- see RFC 3161
 *     ersEvidence    [1] EvidenceRecord,           -- see RFC 4998
 *     otherEvidence  [2] OtherEvidence
 * }
 * </pre>
 */
public class Evidence
    extends ASN1Object
    implements ASN1Choice
{
    private TimeStampTokenEvidence tstEvidence;

    public Evidence(TimeStampTokenEvidence tstEvidence)
    {
        this.tstEvidence = tstEvidence;
    }

    private Evidence(ASN1TaggedObject tagged)
    {
        if (tagged.getTagNo() == 0)
        {
            this.tstEvidence = TimeStampTokenEvidence.getInstance(tagged, false);
        }
    }

    /**
     * Return an Evidence object from the given object.
     * <p>
     * Accepted inputs:
     * <ul>
     * <li> {@link Evidence} object
     * <li> {@link org.spongycastle.asn1.ASN1TaggedObject#getInstance(java.lang.Object) ASN1TaggedObject} input formats with Evidence data inside
     * </ul>
     *
     * @param obj the object we want converted.
     * @exception IllegalArgumentException if the object cannot be converted.
     */
    public static Evidence getInstance(Object obj)
    {
        if (obj == null || obj instanceof Evidence)
        {
            return (Evidence)obj;
        }
        else if (obj instanceof ASN1TaggedObject)
        {
            return new Evidence(ASN1TaggedObject.getInstance(obj));
        }

        throw new IllegalArgumentException("unknown object in getInstance");
    }

    public TimeStampTokenEvidence getTstEvidence()
    {
        return tstEvidence;
    }

    public ASN1Primitive toASN1Primitive()
    {
       if (tstEvidence != null)
       {
           return new DERTaggedObject(false, 0, tstEvidence);
       }

       return null;
    }
}
