using System;
using System.IO;
using System.Text;
using System.Xml;
using System.Linq;
using System.Xml.Linq;

namespace ConsoleOutputExample
{
    public class XmlFileWriter : TextWriter
    {
        private readonly Stream _stream;
        private readonly XDocument _writer;
        private readonly XElement _header;

        private void WriteEntry(object item)
        {
            _header.Add(
                    new XElement("Entry", 
                        new XElement("Date", DateTime.UtcNow), 
                        new XElement("Message", new XCData(item.ToString()))
                                )
                        );


            _writer.Save(_stream);
        }

        public XmlFileWriter(Stream writerStream)
        {
            _writer = new XDocument();
            _header = new XElement("Entries");
            _writer.Add(_header);

            _stream = writerStream;
        }

        public override Encoding Encoding { get; }

        /*
    You'll want to override the rest of the Write, WriteLine, WriteAsync, and WriteLineAsync.
    Any of these can be called, and if they aren't overridden, then the message will not appear in the logs.
    */

        public override void Write(string value) => WriteEntry(value);
        public override void WriteLine(string value) => WriteEntry(value);

        public override void Write(string format, object arg0, object arg1)
        {
            var formatted = String.Format(format, arg0, arg1);
            WriteEntry(formatted);
        }

        public override void Write(string format, object arg0)
        {
            var formatted = string.Format(format, arg0);
            WriteEntry(formatted);
        }

        public override void Write(string format, object arg0, object arg1, object arg2)
        {
            var formatted = String.Format(format, arg0, arg1, arg2);
            WriteEntry(formatted);
        }

        public override void Write(string format, params object[] arg)
        {
            var formatted = String.Format(format, arg);
            WriteEntry(formatted);
        }

        public override void Write(char[] buffer, int index, int count)
        {
            var arrayPart = new char[count];
            Array.Copy(buffer, index, arrayPart, 0, count);

            WriteEntry(String.Join("", arrayPart));
        }

    }
}