using System;
using System.IO;
using System.Linq;
using System.Xml;
using Chernobyl.Collections.Generic.Event;
using Chernobyl.Reflection.Template;
using Chernobyl.Reflection.Template.Xml;
using Chernobyl.Resources;

namespace Chernobyl.Reflection.Resources
{
    /// <summary>
    /// Loads declarative XML components that describes how .NET types should be
    /// configured and initialized.
    /// </summary>
    public class XmlContentResourceProcessor : ResourceProcessor<IComponent>
    {
        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="services">The services instance to use when injecting
        /// or receiving dependencies from created instances.</param>
        public XmlContentResourceProcessor(IEventCollection<object> services)
        {
            Services = services;
        }

        /// <summary>
        /// Reads in the declarative instance content to the stream specified.
        /// </summary>
        /// <param name="callback">The callback that will be invoked when the
        /// resource has been loaded.</param>
        /// <param name="readFrom">The stream to load the resource from.</param>
        /// <param name="options">Options for the loading or processing of the
        /// resource.</param>
        public override void From(ResourceProcessCallback<IComponent> callback, Stream readFrom, params IOption[] options)
        {
            // create a reader and move to the first bit of content
            using(XmlReader xmlr = XmlReader.Create(readFrom))
            {
                if (xmlr.MoveToContent() != XmlNodeType.None)
                    callback(new ResourceProcessResult<IComponent>(XmlInstance.Create(Services, xmlr).First(), null, true, true));
                else
                    CheckedNextFrom(callback, readFrom, options);
            }
        }

        /// <summary>
        /// Writes out the declarative instance content to the stream specified.
        /// </summary>
        /// <param name="resource">The <see cref="IComponent"/> instance to 
        /// write out to the stream specified.</param>
        /// <param name="writeTo">The stream to write the instances to.</param>
        /// <param name="options">Options for controlling the writing out of the
        /// instance data. This resource processor does currently use any options.</param>
        public override void To(IComponent resource, Stream writeTo, params IOption[] options)
        {
            throw new NotImplementedException();
        }

        /// <summary>
        /// The services instance to use when injecting or receiving 
        /// dependencies from created instances.
        /// </summary>
        IEventCollection<object> Services { get; set; }
    }
}