using System;
using System.Xml;
using Chernobyl.Collections.Generic.Event;

namespace Chernobyl.Reflection.Template.Xml
{
    /// <summary>
    /// A class which can be passed to the last <see cref="Action{T}"/>
    /// parameter of the 
    /// <see cref="XmlAttribute.Create(IEventCollection{object}, XmlReader, Action{XmlAttribute})"/> 
    /// method. This class will use the value of the XML "id" attribute to name
    /// the <see cref="IComponent"/> given to it.
    /// </summary>
    public class XmlIdAttributeProcessor
    {
        /// <summary>
        /// Initializes a new instance of the
        /// <see cref="XmlIdAttributeProcessor"/> class.
        /// </summary>
        /// <param name="component">The component that is to be given the name 
        /// of the XML ID attributes value.</param>
        public XmlIdAttributeProcessor(IComponent component)
        {
            Component = component;
        }

        /// <summary>
        /// Performs an implicit conversion from
        /// <see cref="XmlIdAttributeProcessor"/> to 
        /// <see cref="Action{XmlAttribute}"/>.
        /// </summary>
        /// <param name="processor">The <see cref="XmlIdAttributeProcessor"/> to
        /// convert to an <see cref="Action{XmlAttribute}"/>.</param>
        /// <returns>The result of the conversion.</returns>
        public static implicit operator Action<XmlAttribute>(XmlIdAttributeProcessor processor)
        {
            return processor.AttributeProcessor;
        }

        /// <summary>
        /// The name used by XML's id attribute, which is "id".
        /// </summary>
        public const string AttributeName = "id";

        /// <summary>
        /// The URI used by XML attributes, which is 
        /// "http://www.w3.org/XML/1998/namespace".
        /// </summary>
        public const string AttributeUri = "http://www.w3.org/XML/1998/namespace";

        /// <summary>
        /// Passed to the <see cref="XmlAttribute.Create(IEventCollection{object}, XmlReader, Action{XmlAttribute})"/> 
        /// method to grab the value from the "id" attribute so that it can be 
        /// used as a name on the <see cref="IComponent"/> passed to this class.
        /// </summary>
        /// <param name="xmlAttribute">The <see cref="XmlAttribute"/> to process.</param>
        void AttributeProcessor(XmlAttribute xmlAttribute)
        {
            if (xmlAttribute.Name == AttributeName &&
                xmlAttribute.Prefix == AttributeUri)
                Component.Name = xmlAttribute.Value;
        }

        /// <summary>
        /// The component that is to be given the name of the XML ID attributes
        /// value.
        /// </summary>
        IComponent Component { get; set; }
    }
}