package org.bouncycastle.asn1;

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

abstract public class ASN1Set
    extends ASN1Object
{
    protected Vector set = new Vector();

    
return an ASN1Set from the given object.
Params:
obj – the object we want converted.
Throws:
IllegalArgumentException – if the object cannot be converted./**
     * return an ASN1Set from the given object.
     *
     * @param obj the object we want converted.
     * @exception IllegalArgumentException if the object cannot be converted.
     */
    public static ASN1Set getInstance(
        Object  obj)
    {
        if (obj == null || obj instanceof ASN1Set)
        {
            return (ASN1Set)obj;
        }

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

    
Return an ASN1 set 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 implicitly tagged in the 
normal course of events it indicates that we lost the surrounding
set - 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 sets you really should
be using this method.
Params:
obj – the tagged object.
explicit – true if the object is meant to be explicitly tagged
         false otherwise.
Throws:
IllegalArgumentException – if the tagged object cannot
         be converted./**
     * Return an ASN1 set 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 implicitly tagged in the 
     * normal course of events it indicates that we lost the surrounding
     * set - 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 sets 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 ASN1Set getInstance(
        ASN1TaggedObject    obj,
        boolean             explicit)
    {
        if (explicit)
        {
            if (!obj.isExplicit())
            {
                throw new IllegalArgumentException("object implicit - explicit expected.");
            }

            return (ASN1Set)obj.getObject();
        }
        else
        {
            //
            // constructed object which appears to be explicitly tagged
            // and it's really implicit means we have to add the
            // surrounding sequence.
            //
            if (obj.isExplicit())
            {
                ASN1Set    set = new DERSet(obj.getObject());

                return set;
            }
            else
            {
                if (obj.getObject() instanceof ASN1Set)
                {
                    return (ASN1Set)obj.getObject();
                }

                //
                // in this case the parser returns a sequence, convert it
                // into a set.
                //
                ASN1EncodableVector  v = new ASN1EncodableVector();

                if (obj.getObject() instanceof ASN1Sequence)
                {
                    ASN1Sequence s = (ASN1Sequence)obj.getObject();
                    Enumeration e = s.getObjects();

                    while (e.hasMoreElements())
                    {
                        v.add((DEREncodable)e.nextElement());
                    }

                    return new DERSet(v, false);
                }
            }
        }

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

    public ASN1Set()
    {
    }

    public Enumeration getObjects()
    {
        return set.elements();
    }

    
return the object at the set position indicated by index.
Params:
index – the set number (starting at zero) of the object
Returns:
the object at the set position indicated by index./**
     * return the object at the set position indicated by index.
     *
     * @param index the set number (starting at zero) of the object
     * @return the object at the set position indicated by index.
     */
    public DEREncodable getObjectAt(
        int index)
    {
        return (DEREncodable)set.elementAt(index);
    }

    
return the number of objects in this set.
Returns:
the number of objects in this set./**
     * return the number of objects in this set.
     *
     * @return the number of objects in this set.
     */
    public int size()
    {
        return set.size();
    }

    public ASN1Encodable[] toArray()
    {
        ASN1Encodable[] values = new ASN1Encodable[this.size()];

        for (int i = 0; i != this.size(); i++)
        {
            values[i] = (ASN1Encodable)this.getObjectAt(i);
        }

        return values;
    }

    public ASN1SetParser parser()
    {
        final ASN1Set outer = this;

        return new ASN1SetParser()
        {
            private final int max = size();

            private int index;

            public DEREncodable readObject() throws IOException
            {
                if (index == max)
                {
                    return null;
                }

                DEREncodable obj = getObjectAt(index++);
                if (obj instanceof ASN1Sequence)
                {
                    return ((ASN1Sequence)obj).parser();
                }
                if (obj instanceof ASN1Set)
                {
                    return ((ASN1Set)obj).parser();
                }

                return obj;
            }

            public DERObject getLoadedObject()
            {
                return outer;
            }

            public DERObject getDERObject()
            {
                return outer;
            }
        };
    }

    public int hashCode()
    {
        Enumeration             e = this.getObjects();
        int                     hashCode = size();

        while (e.hasMoreElements())
        {
            Object o = getNext(e);
            hashCode *= 17;

            hashCode ^= o.hashCode();
        }

        return hashCode;
    }

    boolean asn1Equals(
        DERObject  o)
    {
        if (!(o instanceof ASN1Set))
        {
            return false;
        }

        ASN1Set   other = (ASN1Set)o;

        if (this.size() != other.size())
        {
            return false;
        }

        Enumeration s1 = this.getObjects();
        Enumeration s2 = other.getObjects();

        while (s1.hasMoreElements())
        {
            DEREncodable  obj1 = getNext(s1);
            DEREncodable  obj2 = getNext(s2);

            DERObject  o1 = obj1.getDERObject();
            DERObject  o2 = obj2.getDERObject();

            if (o1 == o2 || o1.equals(o2))
            {
                continue;
            }

            return false;
        }

        return true;
    }

    private DEREncodable getNext(Enumeration e)
    {
        DEREncodable encObj = (DEREncodable)e.nextElement();

        // unfortunately null was allowed as a substitute for DER null
        if (encObj == null)
        {
            return DERNull.INSTANCE;
        }

        return encObj;
    }

    
return true if a <= b (arrays are assumed padded with zeros).
/**
     * return true if a <= b (arrays are assumed padded with zeros).
     */
    private boolean lessThanOrEqual(
         byte[] a,
         byte[] b)
    {
        int len = Math.min(a.length, b.length);
        for (int i = 0; i != len; ++i)
        {
            if (a[i] != b[i])
            {
                return (a[i] & 0xff) < (b[i] & 0xff);
            }
        }
        return len == a.length;
    }

    private byte[] getEncoded(
        DEREncodable obj)
    {
        ByteArrayOutputStream   bOut = new ByteArrayOutputStream();
        ASN1OutputStream        aOut = new ASN1OutputStream(bOut);

        try
        {
            aOut.writeObject(obj);
        }
        catch (IOException e)
        {
            throw new IllegalArgumentException("cannot encode object added to SET");
        }

        return bOut.toByteArray();
    }

    protected void sort()
    {
        if (set.size() > 1)
        {
            boolean    swapped = true;
            int        lastSwap = set.size() - 1;

            while (swapped)
            {
                int    index = 0;
                int    swapIndex = 0;
                byte[] a = getEncoded((DEREncodable)set.elementAt(0));
                
                swapped = false;

                while (index != lastSwap)
                {
                    byte[] b = getEncoded((DEREncodable)set.elementAt(index + 1));

                    if (lessThanOrEqual(a, b))
                    {
                        a = b;
                    }
                    else
                    {
                        Object  o = set.elementAt(index);

                        set.setElementAt(set.elementAt(index + 1), index);
                        set.setElementAt(o, index + 1);

                        swapped = true;
                        swapIndex = index;
                    }

                    index++;
                }

                lastSwap = swapIndex;
            }
        }
    }

    protected void addObject(
        DEREncodable obj)
    {
        set.addElement(obj);
    }

    abstract void encode(DEROutputStream out)
            throws IOException;

    public String toString() 
    {
      return set.toString();
    }
}