using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.IO;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Json;

using System.Globalization;

namespace SharpLib.Utils

{

    /// <summary>

    /// Allow serialization into JSON.

    /// Most useful to be able to save complex settings for instance.

    /// Usage:

    /// ...

    /// [TypeConverter(typeof(TypeConverterJson<PersistantObject>))]

    /// [DataContract]

    /// public class PersistantObject

    /// ...

    /// </summary>

    /// <typeparam name="T"></typeparam>

    public class TypeConverterJson<T> : TypeConverter where T : class

    {

        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)

        {

            if (sourceType == typeof(string))

                return true;

            else

                return base.CanConvertFrom(context, sourceType);

        }

        /// <summary>

        /// Internalize

        /// </summary>

        /// <param name="context"></param>

        /// <param name="culture"></param>

        /// <param name="value"></param>

        /// <returns></returns>

        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)

        {

            string stringValue = value as string;

            if (stringValue != null)

            {

                //try

                //{

                    //Load object form JSON string

                    byte[] byteArray = Encoding.UTF8.GetBytes(stringValue);

                    MemoryStream stream = new MemoryStream(byteArray);

                    DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T),

                        new DataContractJsonSerializerSettings()

                        {

                            UseSimpleDictionaryFormat = true

                        });

                    T settings = (T)ser.ReadObject(stream);

                    return settings;

                //}

                //catch (Exception ex)

                //{

                    //That's not helping with partial loading

                //    Trace.WriteLine("WARNING: Internalize exception -" + ex.ToString() );

                //    return null;

                //}

            }

            else

            {

                return base.ConvertFrom(context, culture, value);

            }

        }

        /// <summary>

        /// Externalize

        /// </summary>

        /// <param name="context"></param>

        /// <param name="culture"></param>

        /// <param name="value"></param>

        /// <param name="destinationType"></param>

        /// <returns></returns>

        public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)

        {

            if (destinationType == typeof(string))

            {

                //Save settings into JSON string

                MemoryStream stream = new MemoryStream();

                DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T), new DataContractJsonSerializerSettings()

                {

                    UseSimpleDictionaryFormat = true

                });

                ser.WriteObject(stream, value);

                // convert stream to string

                stream.Position = 0;

                StreamReader reader = new StreamReader(stream);

                string text = reader.ReadToEnd();

                return text;

            }

            else

            {

                return base.ConvertTo(context,culture,value,destinationType);

            }

        }

    }

}