//---------------------------------------------------------------------
// <copyright file="ChangeNode.cs" company="Microsoft">
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
//
// @owner [....]
// @backupOwner [....]
//---------------------------------------------------------------------

using System.Data.Metadata.Edm;
using System.Collections.Generic;
using System.Text;
using System.Globalization;
namespace System.Data.Mapping.Update.Internal
{
    /// <summary>
    /// This class encapsulates changes propagated to a node in an update mapping view.
    /// It contains lists of deleted and inserted rows. Key intersections betweens rows
    /// in the two sets are treated as updates in the store.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Additional tags indicating the roles of particular values (e.g., concurrency, undefined,
    /// etc.) are stored within each row: where appropriate, constants appearing
    /// within a row are associated with a <see cref="PropagatorResult" /> through the <see cref=
    /// "UpdateTranslator" />.
    /// </para> 
    /// <para>
    /// The 'leaves' of an update mapping view (UMV) are extent expressions. A change node
    /// associated with an extent expression is simply the list of changes to the C-Space
    /// requested by a caller. As changes propagate 'up' the UMV expression tree, we recursively
    /// apply transformations such that the change node associated with the root of the UMV
    /// represents changes to apply in the S-Space.
    /// </para>
    /// </remarks>
    internal class ChangeNode
    {
        #region Constructors
        /// <summary>
        /// Constructs a change node containing changes belonging to the specified collection
        /// schema definition.
        /// </summary>
        /// <param name="elementType">Sets <see cref="ElementType" /> property.</param>
        internal ChangeNode(TypeUsage elementType)
        {
            m_elementType = elementType;
        }
        #endregion

        #region Fields
        private TypeUsage m_elementType;
        private List<PropagatorResult> m_inserted = new List<PropagatorResult>();
        private List<PropagatorResult> m_deleted = new List<PropagatorResult>();
        private PropagatorResult m_placeholder;
        #endregion

        #region Properties
        /// <summary>
        /// Gets the type of the rows contained in this node. This type corresponds (not coincidentally)
        /// to the type of an expression in an update mapping view.
        /// </summary>
        internal TypeUsage ElementType { get { return m_elementType; } }

        /// <summary>
        /// Gets a list of rows to be inserted.
        /// </summary>
        internal List<PropagatorResult> Inserted { get { return m_inserted; } }

        /// <summary>
        /// Gets a list of rows to be deleted.
        /// </summary>
        internal List<PropagatorResult> Deleted { get { return m_deleted; } }

        /// <summary>
        /// Gets or sets a version of a record at this node with default record. The record has the type 
        /// of the node we are visiting.
        /// </summary>
        internal PropagatorResult Placeholder
        {
            get { return m_placeholder; }
            set { m_placeholder = value; }
        }
        #endregion

#if DEBUG
        public override string ToString()
        {
            StringBuilder builder = new StringBuilder();

            builder.AppendLine("{");
            builder.AppendFormat(CultureInfo.InvariantCulture, "    ElementType = {0}", ElementType).AppendLine();
            builder.AppendLine("    Inserted = {");
            foreach (PropagatorResult insert in Inserted)
            {
                builder.Append("        ").AppendLine(insert.ToString());
            }
            builder.AppendLine("    }");
            builder.AppendLine("    Deleted = {");
            foreach (PropagatorResult delete in Deleted)
            {
                builder.Append("        ").AppendLine(delete.ToString());
            }
            builder.AppendLine("    }");
            builder.AppendFormat(CultureInfo.InvariantCulture, "    PlaceHolder = {0}", Placeholder).AppendLine();

            builder.Append("}");
            return builder.ToString();
        }
#endif
    }
}