using System;
using System.Xml.Linq;

namespace Nitride.Feeds.Structure
{
    /// <summary>
    /// The type-safe structure for a entry's category element.
    /// </summary>
    [WithProperties]
    public partial class AtomCategory
    {
        /// <summary>
        /// Gets or sets the label associated with the category.
        /// </summary>
        public string? Label { get; set; }

        /// <summary>
        /// Gets or sets the scheme associated with the category.
        /// </summary>
        public Uri? Scheme { get; set; }

        /// <summary>
        /// Gets or sets the term of the category.
        /// </summary>
        public string? Term { get; set; }

        /// <summary>
        /// Creates an XML element out of the feed along with all items inside
        /// the feed.
        /// </summary>
        /// <returns></returns>
        public XElement ToXElement()
        {
            if (this.Term == null)
            {
                throw new NullReferenceException(
                    "Category term cannot be null.");
            }

            var elem = new XElement(
                XmlConstants.AtomNamespace + "category",
                new XAttribute("term", this.Term));

            if (this.Scheme != null)
            {
                elem.Add(new XAttribute("scheme", this.Scheme.ToString()));
            }

            if (!string.IsNullOrEmpty(this.Label))
            {
                elem.Add(new XAttribute("label", this.Label));
            }

            return elem;
        }
    }
}