using System;
using System.Collections.Generic;
using System.Xml;
using Chernobyl.Collections.Generic.Event;
using Chernobyl.Reflection.Template.Attribution;
using Attribute = Chernobyl.Reflection.Template.Attribution.Attribute;

namespace Chernobyl.Reflection.Template.Xml
{
    /// <summary>
    /// An <see cref="IAttribute"/> that is generated from or can be written to 
    /// an XML stream.
    /// </summary>
    public class XmlAttribute : Attribute
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="XmlAttribute"/> class.
        /// </summary>
        /// <param name="services">The <see cref="IEventCollection{T}"/> instance that 
        /// takes and sets service.</param>
        /// <param name="xmlr">The XmlReader to read the attribute from. Note 
        /// that, the <see cref="XmlReader"/> is expected to be on an XML 
        /// attribute node or an exception will be thrown.</param>
        /// <exception cref="System.ArgumentException">The <see cref="XmlReader"/>  
        /// passed in is not on an XML attribute node.</exception>
        /// <exception cref="System.ArgumentException">Thrown if the 
        /// <paramref name="xmlr"/> is not positioned on an
        /// <see cref="XmlNodeType"/> (see <see cref="XmlReader.NodeType"/>) of
        /// <see cref="XmlNodeType.Attribute"/>.</exception>
        public XmlAttribute(IEventCollection<object> services, XmlReader xmlr) : base(services, string.Empty, string.Empty, string.Empty)
        {
            if (xmlr.NodeType != XmlNodeType.Attribute)
                throw new ArgumentException("Unable to extract the XML attribute data because " +
                "The XmlReader passed into this constructor is not positioned on an " +
                "XML attribute. Please ensure the XmlReader is positioned correctly.");

            Prefix = xmlr.NamespaceURI;
            Name = xmlr.LocalName;
            Value = xmlr.Value;
        }

        /// <summary>
        /// Creates a collection of <see cref="XmlAttribute"/> instances by  
        /// reading them from an <see cref="XmlReader"/>.
        /// </summary>
        /// <param name="services">The <see cref="IEventCollection{T}"/> instance that 
        /// takes and sets service.</param>
        /// <param name="xmlr">The <see cref="XmlReader"/> to read the XML 
        /// attributes from.</param>
        /// <returns>The list of <see cref="XmlAttribute"/>s that were read in.</returns>
        public static IList<IAttribute> Create(IEventCollection<object> services, XmlReader xmlr)
        {
            return Create(services, xmlr, xmlAttribute => { /* no-op */ });
        }

        /// <summary>
        /// Creates a collection of <see cref="XmlAttribute"/> instances by  
        /// reading them from an <see cref="XmlReader"/>.
        /// </summary>
        /// <param name="services">The <see cref="IEventCollection{T}"/> instance that 
        /// takes and sets service.</param>
        /// <param name="xmlr">The <see cref="XmlReader"/> to read the XML 
        /// attributes from.</param>
        /// <param name="processor">A method that will be invoked for each XML 
        /// attribute read in. This method can be used to process the XML attributes.</param>
        /// <returns>The list of <see cref="XmlAttribute"/>s that were read in.</returns>
        public static IList<IAttribute> Create(IEventCollection<object> services, XmlReader xmlr, Action<XmlAttribute> processor)
        {
            List<IAttribute> attributes = new List<IAttribute>();
            
            while (xmlr.MoveToNextAttribute() == true)
            {
                XmlAttribute xmlAttribute = new XmlAttribute(services, xmlr);
                processor(xmlAttribute);
                attributes.Add(xmlAttribute);
            }

            return attributes;
        }
    }
}