//------------------------------------------------------------------------------
// <copyright file="ReadOnlyDataSource.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
//------------------------------------------------------------------------------

namespace System.Web.UI.WebControls {

    using System;
    using System.Collections;
    using System.ComponentModel;
    using System.Web;
    using System.Web.UI;
    using System.Web.Util;


    /// <devdoc>
    /// Helper class for data bound controls to wrap an generic data source
    /// with a strongly typed IDataSource. This class automatically handles
    /// other IDataSources, IEnumerable, and IListSource objects.
    /// This class uses ReadOnlyDataSourceView to represent individual views.
    /// </devdoc>
    internal sealed class ReadOnlyDataSource : IDataSource {

        private static string[] ViewNames = new string[0];

        private string _dataMember;
        private object _dataSource;

        public ReadOnlyDataSource(object dataSource, string dataMember) {
            Debug.Assert(dataSource == null || (dataSource is IEnumerable || dataSource is IDataSource || dataSource is IListSource), "Expected dataSource to be either null, an IEnumerable, an IDataSource, or an IListSource.");
            _dataSource = dataSource;
            _dataMember = dataMember;
        }

        #region Implementation of IDataSource
        event EventHandler IDataSource.DataSourceChanged {
            add {
            }
            remove {
            }
        }

        /// <devdoc>
        /// Check for IDataSource, IListSource, and IEnumerable, and return an
        /// approprite DataSourceView.
        /// </devdoc>
        DataSourceView IDataSource.GetView(string viewName) {
            // Check first for IDataSource
            IDataSource ds = _dataSource as IDataSource;
            if (ds != null) {
                return ds.GetView(viewName);
            }

            IEnumerable enumerable = DataSourceHelper.GetResolvedDataSource(_dataSource, _dataMember);
            return new ReadOnlyDataSourceView(this, _dataMember, enumerable);
        }

        ICollection IDataSource.GetViewNames() {
            return ViewNames;
        }
        #endregion
    }
}