using System;
using System.Collections;
using System.Runtime.InteropServices;
using System.Text;

namespace Intel.Management.Wsman
{
    class WsmanItem : IWsmanItem
    {
        private object _object;
   
        internal class ObjectAndRef
        {
            public IManagedInstance _inst;
            public IManagedReference _ref;
            public ObjectAndRef(IManagedInstance instObj, IManagedReference refObj)
            {
                _inst = instObj;
                _ref = refObj;
            }
        }

        internal class NullObject {}

        internal class ItemEnumerator : IEnumerator
        {
            WsmanItem _item;
            int _index;
            public ItemEnumerator(WsmanItem item)
            {
                _item = item;
                _index = -1;
            }

            public bool HasNext
            {
                get
                {
                    // can't enumerator a null object
                    if (_item.IsNull || _item.InternalArray == null)
                        return false;
                    if (_item.IsArray)
                        return (_index + 1) < _item.InternalArray.Length;
                    
                    return _index < 0;
                }
            }

            public object Current
            {
                get
                {
                    if (_index<0)
                        throw new InvalidOperationException();

                    if (_item.IsArray)
                    {
                        if (_item.InternalArray == null || _index>=_item.InternalArray.Length)
                             throw new InvalidOperationException();

                        return _item.InternalArray[_index];
                    }

                    if (_index>0)
                        throw new InvalidOperationException();

                    return _item;
                }
            }

            public bool MoveNext()
            {

                if (_item.IsNull)
                    return false;

                _index++;

                if (_item.IsArray)
                {
                    if (_item.InternalArray == null)
                        return false;
                    return _index < _item.InternalArray.Length;
                }

                return _index < 1;
            }

            public void Reset()
            {
                _index = -1;
            }
        } // end WsmanEnumerator


        public WsmanItem(IManagedInstance instObj,IManagedReference refObj)
        {
            _object = new ObjectAndRef(instObj, refObj);
        }

        public WsmanItem()
        {
            _object = new NullObject();
        }

        public WsmanItem(object obj)
        {
            _object = obj;
        }

        public object TypedObject
        {
            get
            {
                return null;
            }
        }

        public IManagedInstance Object
        {
            get
            {
                if (IsObjectAndRef)
                    return ((ObjectAndRef)_object)._inst;

                return (IManagedInstance)_object;
            }
        }

        public IManagedReference Ref
        {
            get
            {
                if (IsObjectAndRef)
                    return ((ObjectAndRef)_object)._ref;

                if (IsRef)
                    return (IManagedReference)_object;
                return null;
            }
        }

        public bool IsArray
        {
            get
            {
                return _object.GetType().IsArray;
            }
        }

        public bool IsTyped
        {
            get
            {
                return false;
            }
        }

        public bool IsObject
        {
            get
            {
                return _object is IManagedInstance;
            }
        }

        public bool IsRef
        {
            get
            {

                return _object is IManagedReference;
            }
        }

        public bool IsObjectAndRef
        {
            get
            {
                return _object is ObjectAndRef;
            }
        }

        public bool IsString
        {
            get
            {
                return _object is string;
            }
        }

        public bool IsNull
        {
            get
            {
                return _object is NullObject;
            }
        }

        public int Count
        {
            get
            {
                if (IsArray)
                    return ((IWsmanItem[])_object).Length;

                if (_object is NullObject)
                    return 0;
                return 1;
            }
        }


        public IWsmanItem Item(int index)
        {
            if (index >= Count)
                throw new IndexOutOfRangeException();

            if (IsArray)
                return ((IWsmanItem[])_object)[index];

            return this;
        }

        [DispId(-4)]
        public IEnumerator GetEnumerator()
        {
            return new ItemEnumerator(this);
        }


        public override string ToString()
        {
            return _object.ToString();
        }

        public bool IsA(string typeName)
        {
            bool result=false;
            if (IsObject)
            {
                if (Object.SimpleName.Equals(typeName) ||
                    Object.ResourceUri.Equals(typeName))
                    result = true;
            }
            else if (IsRef)
            {
                if (Ref.SimpleName.Equals(typeName) ||
                   Ref.ResourceUri.Equals(typeName) )
                    result = true;
            }
            return result;
        }

        public object[] InternalArray
        {
            get
            {
                return _object as object[];
            }
        }

        public object InternalObject
        {
            get
            {
                return _object;
            }
        }

    }
}