// **********************************************************************
//
// Copyright (c) 2003-2005 ZeroC, Inc. All rights reserved.
//
// This copy of Ice is licensed to you under the terms described in the
// ICE_LICENSE file included in this distribution.
//
// **********************************************************************

using System.Collections;
using System.Diagnostics;
using System.Text;

namespace IceInternal
{
    public abstract class Patcher : Ice.ReadObjectCallback
    {
        public Patcher()
        {
        }

        public Patcher(System.Type type)
        {
            type_ = type;
        }

	public abstract void patch(Ice.Object v);

        public virtual string type()
        {
            Debug.Assert(type_ != null);
            return type_.FullName;
        }

	public virtual void invoke(Ice.Object v)
	{
	    patch(v);
	}

        protected System.Type type_;
    }

    public sealed class ParamPatcher : Patcher
    {
	public ParamPatcher(System.Type type) : base(type)
	{
	}

	public override void patch(Ice.Object v)
	{
            Debug.Assert(type_ != null);
	    if(v != null && !type_.IsInstanceOfType(v))
	    {
                throw new System.InvalidCastException("expected element of type " + type()
                    + " but received " + v.GetType().FullName);
	    }
	    value = v;
	}

	public Ice.Object value;
    }

    public sealed class SequencePatcher : Patcher
    {
	public SequencePatcher(ICollection seq, System.Type type, int index) : base(type)
	{
	    _seq = seq;
	    _index = index;
	}
    
        private static object dummyObject = new object();

	public override void patch(Ice.Object v)
	{
	    Debug.Assert(type_ != null);
	    if(v != null && !type_.IsInstanceOfType(v))
	    {
		throw new System.InvalidCastException("expected element of type " + type() +
						      " but received " + v.GetType().FullName); 
	    }

            try 
            {
                if(_seq is CollectionBase)
                {
                    if(_index >= _seq.Count) // Need to grow the sequence.
                    {
                        for(int i = _seq.Count; i <= _index; i++)
                        {
                            ((IList)_seq).Add(dummyObject); // Broken CollectionBase implementation
                        }
                    }

		    //
		    // Ugly work-around for broken CollectionBase implementation:
		    //
		    // CollectionBase provides implementations of the IList.Add method
		    // and indexer. However, stupidly, these implementations do not permit
		    // null to be added or assigned even though, according to the doc, this should work.
		    // (Attempts to put a null into the collection raise ArgumentNullException.)
		    // That's why the above code grows the sequence by adding a dummy object.
		    //
		    // Furthermore, CollectionBase.Add and the indexer are (incorrectly) non-virtual so,
		    // when we treat _seq as an IList, we always dispatch into the CollectionBase
		    // implementation, not into the implementation of the generated sequence type.
		    // This makes it impossible to assign v to a sequence element if v is null.
		    //
		    // The ugly work-around is to use reflection to ensure that we get the
		    // actual run-time type of the generated sequence, and then
		    // use dynamic invocation to make sure that we dispatch to the generated indexer,
		    // instead of the broken indexer provided by CollectionBase.
		    //
		    if(v == null)
		    {
			object[] ov = new object[2];
			ov[0] = _index;
			ov[1] = null;
			_seq.GetType().GetProperty("Item").GetSetMethod().Invoke(_seq, ov);
		    }
		    else
		    {
			((IList)_seq)[_index] = v;
		    }
                }
                else
                {
                    ((System.Array)_seq).SetValue(v, _index);
                }
            }
            catch(System.Exception ex)
            {
                throw new Ice.MarshalException("Unexpected failure during patching", ex);
            }
	}

	private ICollection _seq;
	private int _index;
    }
}