RssCodec.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
using System.Xml;
using Waher.Content.Xml.Text;
using Waher.Runtime.Inventory;
 
namespace Waher.Content.Rss
{
    public class RssCodec : IContentDecoder, IContentEncoder
    {
        public const string ContentType = "application/rss+xml";
 
        public const string FileExtension = "rss";
 
        private static readonly string[] contentTypes = new string[] { ContentType };
        private static readonly string[] fileExtensions = new string[] { FileExtension };
 
        public string[] ContentTypes => contentTypes;
 
        public string[] FileExtensions => fileExtensions;
 
        public bool TryGetContentType(string FileExtension, out string ContentType)
        {
            if (string.Compare(FileExtension, RssCodec.FileExtension, true) == 0)
            {
                ContentType = RssCodec.ContentType;
                return true;
            }
            else
            {
                ContentType = null;
                return false;
            }
        }
 
        public bool TryGetFileExtension(string ContentType, out string FileExtension)
        {
            if (string.Compare(ContentType, RssCodec.ContentType, true) == 0)
            {
                FileExtension = RssCodec.FileExtension;
                return true;
            }
            else
            {
                FileExtension = null;
                return false;
            }
        }
 
        public bool Decodes(string ContentType, out Grade Grade)
        {
            if (string.Compare(ContentType, RssCodec.ContentType, true) == 0)
            {
                Grade = Grade.Excellent;
                return true;
            }
            else
            {
                Grade = Grade.NotAtAll;
                return false;
            }
        }
 
        public bool Encodes(object Object, out Grade Grade, params string[] AcceptedContentTypes)
        {
            if (Object is RssDocument)
            {
                if (InternetContent.IsAccepted(contentTypes, AcceptedContentTypes))
                {
                    Grade = Grade.Excellent;
                    return true;
                }
            }
 
            Grade = Grade.NotAtAll;
            return false;
        }
 
        public Task<object> DecodeAsync(string ContentType, byte[] Data, Encoding Encoding, KeyValuePair<string, string>[] Fields, Uri BaseUri)
        {
            string Xml = CommonTypes.GetString(Data, Encoding);
            XmlDocument Doc = new XmlDocument()
            {
                PreserveWhitespace = true
            };
 
            Doc.LoadXml(Xml);
 
            return Task.FromResult<object>(new RssDocument(Doc, BaseUri));
        }
 
        public Task<KeyValuePair<byte[], string>> EncodeAsync(object Object, Encoding Encoding, params string[] AcceptedContentTypes)
        {
            if (!(Object is RssDocument Doc) ||
                !InternetContent.IsAccepted(contentTypes, out string ContentType, AcceptedContentTypes))
            {
                throw new ArgumentException("Unable to encode object, or content type not accepted.", nameof(Object));
            }
 
            return XmlCodec.EncodeXmlAsync(Doc.Xml, Encoding, ContentType);
        }
    }
}