//------------------------------------------------------------------------------
// <copyright file="StringSource.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>                                                                
//------------------------------------------------------------------------------
 
namespace System.Windows.Forms {
 
    using System.Runtime.InteropServices.ComTypes;
    using System.Runtime.InteropServices;
    using System.Collections;
    using System.Diagnostics.CodeAnalysis;
 
    
    /// <include file='doc\StringSource.uex' path='docs/doc[@for="StringSource"]/*' />
    /// <devdoc>
    ///    <para> 
    ///       Represents an internal class that is used bu ComboBox and TextBox AutoCompleteCustomSoucr property.
    ///       This class is reponsible for initializing the SHAutoComplete COM object and setting options in it.
    ///       The StringSource contains an array of Strings which is passed to the COM object as the custom source.
    ///    </para>
    /// </devdoc>
    internal class StringSource : IEnumString {
 
        private string[] strings;
        private int current;
        private int size;
        private UnsafeNativeMethods.IAutoComplete2 autoCompleteObject2;
        
        /// <include file='doc\StringSource.uex' path='docs/doc[@for="StringSource"]/*' />
        /// <devdoc>
        ///    <para> 
        ///       SHAutoComplete COM object CLSID.
        ///    </para>
        /// </devdoc>
        private static Guid   autoCompleteClsid = new Guid("{00BB2763-6A77-11D0-A535-00C04FD7D062}");
 
        /// <include file='doc\StringSource.uex' path='docs/doc[@for="StringSource.StringSource"]/*' />
        /// <devdoc>
        ///    <para> 
        ///       Constructor.
        ///    </para>
        /// </devdoc>
        public StringSource(string[] strings) {
            Array.Clear(strings,0, size);
    
            if (strings != null) {
                this.strings = strings;
            }
            current = 0;
            size = (strings == null ) ? 0 : strings.Length;
 
            Guid iid_iunknown = typeof(UnsafeNativeMethods.IAutoComplete2).GUID;
            object obj = UnsafeNativeMethods.CoCreateInstance(ref autoCompleteClsid, null, NativeMethods.CLSCTX_INPROC_SERVER, ref iid_iunknown);
 
            autoCompleteObject2 = (UnsafeNativeMethods.IAutoComplete2)obj;
        }
 
        /// <include file='doc\StringSource.uex' path='docs/doc[@for="StringSource.Bind"]/*' />
        /// <devdoc>
        ///    <para> 
        ///       This is the method that binds the custom source with the IAutoComplete interface.The "hWndEdit" is the handle 
        ///       to the edit Control and the "options' are the options that need to be set in the AUTOCOMPLETE mode.
        ///    </para>
        /// </devdoc>
        public bool Bind(HandleRef edit, int options) {
            
            bool retVal = false;
            
            if (autoCompleteObject2 != null) {
                try
                {
                    autoCompleteObject2.SetOptions(options);
                    autoCompleteObject2.Init(edit, (IEnumString)this, null, null);
                    retVal = true;
                }
                catch
                {
                    retVal = false;
                }
            }
            return retVal;
        }
	[SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands")]
        public void ReleaseAutoComplete()
        {
            if (autoCompleteObject2 != null)
            {
                Marshal.ReleaseComObject(autoCompleteObject2);
                autoCompleteObject2 = null;
            }
        }
 
        public void RefreshList(string[] newSource)
        {
            Array.Clear(strings,0, size);
    
            if (strings != null) {
                this.strings = newSource;
            }
            current = 0;
            size = (strings == null ) ? 0 : strings.Length;
        }
 
        #region IEnumString Members
 
        void IEnumString.Clone(out IEnumString ppenum)
        {
            ppenum = new StringSource(strings);
        }
 
        int IEnumString.Next(int celt, string[] rgelt, IntPtr pceltFetched)
        {
            if (celt < 0)
            {
                return NativeMethods.E_INVALIDARG;
            }
            int fetched = 0;
 
            while (current < size && celt > 0)
            {
                rgelt[fetched] = strings[current];
                current++;
                fetched++;
                celt--;
            }
 
            if (pceltFetched != IntPtr.Zero)
            {
                Marshal.WriteInt32(pceltFetched, fetched);
            }
            return celt == 0 ? NativeMethods.S_OK : NativeMethods.S_FALSE;
        }
 
        void IEnumString.Reset()
        {
            current = 0;
        }
 
        int IEnumString.Skip(int celt)
        {
            current += celt;
            if (current >= size)
            {
                return (NativeMethods.S_FALSE);
            }
            return NativeMethods.S_OK;
        }
 
        #endregion
    }
}