package org.bouncycastle.asn1.x509;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;

import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERBoolean;
import org.bouncycastle.asn1.DEREncodable;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERObjectIdentifier;
import org.bouncycastle.asn1.DERSequence;

public class X509Extensions
    implements DEREncodable
{
    /**
     * Subject Key Identifier 
     */
    public static final DERObjectIdentifier SubjectKeyIdentifier = new DERObjectIdentifier("2.5.29.14");

    /**
     * Key Usage 
     */
    public static final DERObjectIdentifier KeyUsage = new DERObjectIdentifier("2.5.29.15");

    /**
     * Private Key Usage Period 
     */
    public static final DERObjectIdentifier PrivateKeyUsagePeriod = new DERObjectIdentifier("2.5.29.16");

    /**
     * Subject Alternative Name 
     */
    public static final DERObjectIdentifier SubjectAlternativeName = new DERObjectIdentifier("2.5.29.17");

    /**
     * Issuer Alternative Name 
     */
    public static final DERObjectIdentifier IssuerAlternativeName = new DERObjectIdentifier("2.5.29.18");

    /**
     * Basic Constraints 
     */
    public static final DERObjectIdentifier BasicConstraints = new DERObjectIdentifier("2.5.29.19");

    /**
     * CRL Number 
     */
    public static final DERObjectIdentifier CRLNumber = new DERObjectIdentifier("2.5.29.20");

    /**
     * Reason code 
     */
    public static final DERObjectIdentifier ReasonCode = new DERObjectIdentifier("2.5.29.21");

    /**
     * Hold Instruction Code 
     */
    public static final DERObjectIdentifier InstructionCode = new DERObjectIdentifier("2.5.29.23");

    /**
     * Invalidity Date 
     */
    public static final DERObjectIdentifier InvalidityDate = new DERObjectIdentifier("2.5.29.24");

    /**
     * Delta CRL indicator 
     */
    public static final DERObjectIdentifier DeltaCRLIndicator = new DERObjectIdentifier("2.5.29.27");

    /**
     * Issuing Distribution Point 
     */
    public static final DERObjectIdentifier IssuingDistributionPoint = new DERObjectIdentifier("2.5.29.28");

    /**
     * Certificate Issuer 
     */
    public static final DERObjectIdentifier CertificateIssuer = new DERObjectIdentifier("2.5.29.29");

    /**
     * Name Constraints 
     */
    public static final DERObjectIdentifier NameConstraints = new DERObjectIdentifier("2.5.29.30");

    /**
     * CRL Distribution Points 
     */
    public static final DERObjectIdentifier CRLDistributionPoints = new DERObjectIdentifier("2.5.29.31");

    /**
     * Certificate Policies 
     */
    public static final DERObjectIdentifier CertificatePolicies = new DERObjectIdentifier("2.5.29.32");

    /**
     * Policy Mappings 
     */
    public static final DERObjectIdentifier PolicyMappings = new DERObjectIdentifier("2.5.29.33");

    /**
     * Authority Key Identifier 
     */
    public static final DERObjectIdentifier AuthorityKeyIdentifier = new DERObjectIdentifier("2.5.29.35");

    /**
     * Policy Constraints 
     */
    public static final DERObjectIdentifier PolicyConstraints = new DERObjectIdentifier("2.5.29.36");

    /**
     * Extended Key Usage 
     */
    public static final DERObjectIdentifier ExtendedKeyUsage = new DERObjectIdentifier("2.5.29.37");

    /**
     * Inhibit Any Policy
     */
    public static final DERObjectIdentifier InhibitAnyPolicy = new DERObjectIdentifier("2.5.29.54");

    private Hashtable               extensions = new Hashtable();
    private Vector                  ordering = new Vector();

    public static X509Extensions getInstance(
        ASN1TaggedObject obj,
        boolean          explicit)
    {
        return getInstance(ASN1Sequence.getInstance(obj, explicit));
    }

    public static X509Extensions getInstance(
        Object  obj)
    {
        if (obj == null || obj instanceof X509Extensions)
        {
            return (X509Extensions)obj;
        }

        if (obj instanceof ASN1Sequence)
        {
            return new X509Extensions((ASN1Sequence)obj);
        }

        if (obj instanceof ASN1TaggedObject)
        {
            return getInstance(((ASN1TaggedObject)obj).getObject());
        }

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

    /**
     * Constructor from ASN1Sequence.
     *
     * the extensions are a list of constructed sequences, either with (OID, OctetString) or (OID, Boolean, OctetString)
     */
    public X509Extensions(
        ASN1Sequence  seq)
    {
        Enumeration e = seq.getObjects();

        while (e.hasMoreElements())
        {
            ASN1Sequence            s = (ASN1Sequence)e.nextElement();

            if (s.size() == 3)
            {
                extensions.put(s.getObjectAt(0), new X509Extension((DERBoolean)s.getObjectAt(1), (ASN1OctetString)s.getObjectAt(2)));
            }
            else
            {
                extensions.put(s.getObjectAt(0), new X509Extension(false, (ASN1OctetString)s.getObjectAt(1)));
            }

            ordering.addElement(s.getObjectAt(0));
        }
    }

    /**
     * constructor from a table of extensions.
     * <p>
     * it's is assumed the table contains OID/String pairs.
     */
    public X509Extensions(
        Hashtable  extensions)
    {
        this(null, extensions);
    }

    /**
     * constructor from a table of extensions with ordering
     * <p>
     * it's is assumed the table contains OID/String pairs.
     */
    public X509Extensions(
        Vector      ordering,
        Hashtable   extensions)
    {
        Enumeration e;

        if (ordering == null)
        {
            e = extensions.keys();
        }
        else
        {
            e = ordering.elements();
        }

        while (e.hasMoreElements())
        {
            this.ordering.addElement(e.nextElement()); 
        }

        e = this.ordering.elements();

        while (e.hasMoreElements())
        {
            DERObjectIdentifier     oid = (DERObjectIdentifier)e.nextElement();
            X509Extension           ext = (X509Extension)extensions.get(oid);

            this.extensions.put(oid, ext);
        }
    }

    /**
     * return an Enumeration of the extension field's object ids.
     */
    public Enumeration oids()
    {
        return ordering.elements();
    }

    /**
     * return the extension represented by the object identifier
     * passed in.
     *
     * @return the extension if it's present, null otherwise.
     */
    public X509Extension getExtension(
        DERObjectIdentifier oid)
    {
        return (X509Extension)extensions.get(oid);
    }

    public DERObject getDERObject()
    {
        ASN1EncodableVector     vec = new ASN1EncodableVector();
        Enumeration             e = ordering.elements();

        while (e.hasMoreElements())
        {
            DERObjectIdentifier     oid = (DERObjectIdentifier)e.nextElement();
            X509Extension           ext = (X509Extension)extensions.get(oid);
            ASN1EncodableVector     v = new ASN1EncodableVector();

            v.add(oid);

            if (ext.isCritical())
            {
                v.add(new DERBoolean(true));
            }

            v.add(ext.getValue());

            vec.add(new DERSequence(v));
        }

        return new DERSequence(vec);
    }

    public int hashCode()
    {
        Enumeration     e = extensions.keys();
        int             hashCode = 0;

        while (e.hasMoreElements())
        {
            Object  o = e.nextElement();

            hashCode ^= o.hashCode();
            hashCode ^= extensions.get(o).hashCode();
        }

        return hashCode;
    }

    public boolean equals(
        Object o)
    {
        if (o == null || !(o instanceof X509Extensions))
        {
            return false;
        }

        X509Extensions  other = (X509Extensions)o;

        Enumeration     e1 = extensions.keys();
        Enumeration     e2 = other.extensions.keys();

        while (e1.hasMoreElements() && e2.hasMoreElements())
        {
            Object  o1 = e1.nextElement();
            Object  o2 = e2.nextElement();
            
            if (!o1.equals(o2))
            {
                return false;
            }
        }

        if (e1.hasMoreElements() || e2.hasMoreElements())
        {
            return false;
        }

        return true;
    }
}
