// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
//
// Description: Undo unit for TextContainer.ExtractElement calls.
//
 
namespace System.Windows.Documents
{
    // Undo unit for TextContainer.ExtractElement calls.
    internal class TextTreeExtractElementUndoUnit : TextTreeUndoUnit
    {
        //------------------------------------------------------
        //
        //  Constructors
        //
        //------------------------------------------------------
 
        #region Constructors
 
        // Creates a new undo unit instance.
        internal TextTreeExtractElementUndoUnit(TextContainer tree, TextTreeTextElementNode elementNode)
            : base(tree, elementNode.GetSymbolOffset(tree.Generation))
        {
            _symbolCount = elementNode.SymbolCount;
            _type = elementNode.TextElement.GetType();
            _localValues = GetPropertyRecordArray(elementNode.TextElement);
            _resources = elementNode.TextElement.Resources;
 
            // Table requires additional work for storing its Columns collection
            if (elementNode.TextElement is Table)
            {
                _columns = TextTreeDeleteContentUndoUnit.SaveColumns((Table)elementNode.TextElement);
            }
        }
 
        #endregion Constructors
 
        //------------------------------------------------------
        //
        //  Public Methods
        //
        //------------------------------------------------------
 
        #region Public Methods
 
        // Called by the undo manager.  Restores tree state to its condition
        // when the unit was created.  Assumes the tree state matches conditions
        // just after the unit was created.
        public override void DoCore()
        {
            TextPointer start;
            TextPointer end;
            TextElement element;
 
            VerifyTreeContentHashCode();
 
            start = new TextPointer(this.TextContainer, this.SymbolOffset, LogicalDirection.Forward);
            end = new TextPointer(this.TextContainer, this.SymbolOffset + _symbolCount - 2, LogicalDirection.Forward);
 
            // Insert a new element.
            element = (TextElement)Activator.CreateInstance(_type);
            element.Reposition(start, end);
 
            // Restore local resources
            element.Resources = _resources;
 
            // Move end into the scope of the new element.
            end.MoveToNextContextPosition(LogicalDirection.Backward);
            // Then restore local property values.
            // Shouldn't we call this with deferLoad=true and call EndDeferLoad after all parameters set?
            this.TextContainer.SetValues(end, ArrayToLocalValueEnumerator(_localValues));
 
            if (element is Table)
            {
                TextTreeDeleteContentUndoUnit.RestoreColumns((Table)element, _columns);
            }
        }
 
        #endregion Public Methods        
 
        //------------------------------------------------------
        //
        //  Private Fields
        //
        //------------------------------------------------------
 
        #region Private Fields
 
        // Count of symbols covered by the extracted TextElement, including its 2 edges.
        private readonly int _symbolCount;
 
        // Type of the extracted TextElement.
        private readonly Type _type;
 
        // Collection of all local property values set on the extracted TextElement.
        private readonly PropertyRecord []_localValues;
 
        // Resources defined locally on the TextElement
        private readonly ResourceDictionary _resources;
 
        // TableColumns collection
        private readonly TableColumn[] _columns;
 
        #endregion Private Fields
    }
}