/**
    *
    *  Licensed to the Apache Software Foundation (ASF) under one or more
    *  contributor license agreements.  See the NOTICE file distributed with
    *  this work for additional information regarding copyright ownership.
    *  The ASF licenses this file to You under the Apache License, Version 2.0
    *  (the "License"); you may not use this file except in compliance with
    *  the License.  You may obtain a copy of the License at
    *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   */
  
  package org.apache.geronimo.util.asn1;
  
  import java.io.IOException;
  import java.util.Enumeration;
  import java.util.Vector;
  
  public abstract class ASN1Sequence
      extends DERObject
  {
      private Vector seq = new Vector();
  
      /**
       * return an ASN1Sequence from the given object.
       *
       * @param obj the object we want converted.
       * @exception IllegalArgumentException if the object cannot be converted.
       */
      public static ASN1Sequence getInstance(
          Object  obj)
      {
          if (obj == null || obj instanceof ASN1Sequence)
          {
              return (ASN1Sequence)obj;
          }
  
          throw new IllegalArgumentException("unknown object in getInstance");
      }
  
      /**
       * Return an ASN1 sequence from a tagged object. There is a special
       * case here, if an object appears to have been explicitly tagged on
       * reading but we were expecting it to be implictly tagged in the
       * normal course of events it indicates that we lost the surrounding
       * sequence - so we need to add it back (this will happen if the tagged
       * object is a sequence that contains other sequences). If you are
       * dealing with implicitly tagged sequences you really <b>should</b>
       * be using this method.
       *
       * @param obj the tagged object.
       * @param explicit true if the object is meant to be explicitly tagged,
       *          false otherwise.
       * @exception IllegalArgumentException if the tagged object cannot
       *          be converted.
       */
      public static ASN1Sequence getInstance(
          ASN1TaggedObject    obj,
          boolean             explicit)
      {
          if (explicit)
          {
              if (!obj.isExplicit())
              {
                  throw new IllegalArgumentException("object implicit - explicit expected.");
              }
  
              return (ASN1Sequence)obj.getObject();
          }
          else
          {
              //
              // constructed object which appears to be explicitly tagged
              // when it should be implicit means we have to add the
              // surrounding sequence.
              //
              if (obj.isExplicit())
              {
                  if (obj instanceof BERTaggedObject)
                  {
                      return new BERSequence(obj.getObject());
                  }
                  else
                  {
                      return new DERSequence(obj.getObject());
                  }
              }
              else
              {
                  if (obj.getObject() instanceof ASN1Sequence)
                  {
                      return (ASN1Sequence)obj.getObject();
                  }
             }
         }
 
         throw new IllegalArgumentException(
                 "unknown object in getInstanceFromTagged");
     }
 
     public Enumeration getObjects()
     {
         return seq.elements();
     }
 
     /**
      * return the object at the sequence postion indicated by index.
      *
      * @param index the sequence number (starting at zero) of the object
      * @return the object at the sequence postion indicated by index.
      */
     public DEREncodable getObjectAt(
         int index)
     {
         return (DEREncodable)seq.elementAt(index);
     }
 
     /**
      * return the number of objects in this sequence.
      *
      * @return the number of objects in this sequence.
      */
     public int size()
     {
         return seq.size();
     }
 
     public int hashCode()
     {
         Enumeration             e = this.getObjects();
         int                     hashCode = 0;
 
         while (e.hasMoreElements())
         {
             Object    o = e.nextElement();
 
             if (o != null)
             {
                 hashCode ^= o.hashCode();
             }
         }
 
         return hashCode;
     }
 
     public boolean equals(
         Object  o)
     {
         if (o == null || !(o instanceof ASN1Sequence))
         {
             return false;
         }
 
         ASN1Sequence   other = (ASN1Sequence)o;
 
         if (this.size() != other.size())
         {
             return false;
         }
 
         Enumeration s1 = this.getObjects();
         Enumeration s2 = other.getObjects();
 
         while (s1.hasMoreElements())
         {
             Object  o1 = s1.nextElement();
             Object  o2 = s2.nextElement();
 
             if (o1 != null && o2 != null)
             {
                 if (!o1.equals(o2))
                 {
                     return false;
                 }
             }
             else if (o1 == null && o2 == null)
             {
                 continue;
             }
             else
             {
                 return false;
             }
         }
 
         return true;
     }
 
     protected void addObject(
         DEREncodable obj)
     {
         seq.addElement(obj);
     }
 
     abstract void encode(DEROutputStream out)
         throws IOException;
 }