using System;
using System.Collections.Generic;
using System.Text;
using System.Xml.Serialization;

namespace MyDownloader.Extension.PersistedList
{
    [XmlRoot("dictionary")]
    public class SerializableDictionary<TKey, TValue>
        : Dictionary<TKey, TValue>, IXmlSerializable
    {
        #region Constructor
        public SerializableDictionary()
        {
        }

        public SerializableDictionary(IDictionary<TKey, TValue> dictionary)
            : base(dictionary)
        {
        } 
        #endregion

        #region IXmlSerializable Members

        public System.Xml.Schema.XmlSchema GetSchema()
        {
            return null;
        }

        public void ReadXml(System.Xml.XmlReader reader)
        {
            XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
            XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));
            
            bool wasEmpty = reader.IsEmptyElement;

            reader.Read();

            if (wasEmpty)
                return;
            
            while (reader.NodeType != System.Xml.XmlNodeType.EndElement)
            {
                reader.ReadStartElement("item");
                reader.ReadStartElement("key");
                TKey key = (TKey)keySerializer.Deserialize(reader);
                reader.ReadEndElement();

                reader.ReadStartElement("value");
                TValue value = (TValue)valueSerializer.Deserialize(reader);
                reader.ReadEndElement();

                this.Add(key, value);

                reader.ReadEndElement();
                reader.MoveToContent();
            }

            reader.ReadEndElement();
        }

        public void WriteXml(System.Xml.XmlWriter writer)
        {
            XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
            XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));

            foreach (TKey key in this.Keys)
            {
                writer.WriteStartElement("item");

                writer.WriteStartElement("key");
                keySerializer.Serialize(writer, key);
                writer.WriteEndElement();

                writer.WriteStartElement("value");
                TValue value = this[key];
                valueSerializer.Serialize(writer, value);
                writer.WriteEndElement();

                writer.WriteEndElement();
            }
        }

        #endregion
    }
}