// 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: Defines PriorityBinding object, which stores information
//              for creating instances of PriorityBindingExpression objects.
//
// See spec at Data Binding.mht
//
 
using System;
using System.Collections;
using System.Collections.ObjectModel;   // Collection<T>
using System.ComponentModel;
using System.Globalization;
using System.Windows.Markup;
using MS.Internal.Data;
using MS.Utility;
 
namespace System.Windows.Data
{
/// <summary>
///  Describes a collection of bindings attached to a single property.
///     These behave as "priority" bindings, meaning that the property
///     receives its value from the first binding in the collection that
///     can produce a legal value.
/// </summary>
[ContentProperty("Bindings")]
public class PriorityBinding : BindingBase, IAddChild
{
    //------------------------------------------------------
    //
    //  Constructors
    //
    //------------------------------------------------------
 
    /// <summary> Constructor </summary>
    public PriorityBinding() : base()
    {
        _bindingCollection = new BindingCollection(this, new BindingCollectionChangedCallback(OnBindingCollectionChanged));
    }
 
#region IAddChild
 
    ///<summary>
    /// Called to Add the object as a Child.
    ///</summary>
    ///<param name="value">
    /// Object to add as a child - must have type BindingBase
    ///</param>
    void IAddChild.AddChild(Object value)
    {
        BindingBase binding = value as BindingBase;
        if (binding != null)
            Bindings.Add(binding);
        else
            throw new ArgumentException(SR.Format(SR.ChildHasWrongType, this.GetType().Name, "BindingBase", value.GetType().FullName), "value");
    }
 
    ///<summary>
    /// Called when text appears under the tag in markup
    ///</summary>
    ///<param name="text">
    /// Text to Add to the Object
    ///</param>
    void IAddChild.AddText(string text)
    {
        XamlSerializerUtil.ThrowIfNonWhiteSpaceInAddText(text, this);
    }
 
#endregion IAddChild
 
    //------------------------------------------------------
    //
    //  Public Properties
    //
    //------------------------------------------------------
 
    /// <summary> List of inner bindings </summary>
    [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
    public Collection<BindingBase> Bindings
    {
        get { return _bindingCollection; }
    }
 
    /// <summary>
    /// This method is used by TypeDescriptor to determine if this property should
    /// be serialized.
    /// </summary>
    [EditorBrowsable(EditorBrowsableState.Never)]
    public bool ShouldSerializeBindings()
    {
        return (Bindings != null && Bindings.Count > 0);
    }
 
    //------------------------------------------------------
    //
    //  Protected Methods
    //
    //------------------------------------------------------
 
    /// <summary>
    /// Create an appropriate expression for this Binding, to be attached
    /// to the given DependencyProperty on the given DependencyObject.
    /// </summary>
    internal override BindingExpressionBase CreateBindingExpressionOverride(DependencyObject target, DependencyProperty dp, BindingExpressionBase owner)
    {
        return PriorityBindingExpression.CreateBindingExpression(target, dp, this, owner);
    }
 
    internal override BindingBase CreateClone()
    {
        return new PriorityBinding();
    }
 
    internal override void InitializeClone(BindingBase baseClone, BindingMode mode)
    {
        PriorityBinding clone = (PriorityBinding)baseClone;
 
        for (int i=0; i<=_bindingCollection.Count; ++i)
        {
            clone._bindingCollection.Add(_bindingCollection[i].Clone(mode));
        }
 
        base.InitializeClone(baseClone, mode);
    }
 
    private void OnBindingCollectionChanged()
    {
        CheckSealed();
    }
 
    //------------------------------------------------------
    //
    //  Private Fields
    //
    //------------------------------------------------------
 
    BindingCollection       _bindingCollection;
}
}