using System;
using System.Collections;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace MacUistin.Serialization
{
  // I wrote this to help when creating new JsonConverter
	public static class JsonSerializationHelper
	{
		#region Retrieve values

    /*
      Can simplify the code for retreiving and defaulting values:

      public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
      {
        if (reader.TokenType == JsonToken.StartObject)
        {
          JObject item = JObject.Load(reader);

          if (item["Items"] == null)
            return null;

          var items = item.GetValueOrDefault<MyCustomList>("Items", serializer);
          string listField1 = item.GetValueOrDefault("ListField1", "xyz");
          int listField2 = item.GetValueOrDefault("ListField2", 123);

          return new MyCustomList(items, listField1, listField2);
        }

        throw new JsonSerializationException($"Unexpected format deserializing MyCustomList. Token type: {reader.TokenType}");
      }
    */

		public static T GetValueOrDefault<T>(this JObject jObject, string key, JsonSerializer serializer, T defaultValue = null) where T : class
		{
			var value = jObject[key];

			if (value == null)
				return defaultValue ?? new T();

			try
			{
				return value.ToObject<T>();
			}
			catch
			{
				return defaultValue ?? new T();
			}
		}

		public static string GetValueOrDefault(this JObject jObject, string key, string defaultValue = "")
		{
			var value = jObject[key];

			if (value == null)
				return defaultValue;

			try
			{
				return value.Value<string>();
			}
			catch
			{
				return defaultValue;
			}
		}

		public static T GetValueOrDefault<T>(this JObject jObject, string key, T defaultValue = default(T)) where T : struct
		{
			var value = jObject[key];

			if (value == null)
				return defaultValue;

			try
			{
				return value.Value<T>();
			}
			catch
			{
				return defaultValue;
			}
		}

		#endregion Retrieve values

		#region Set values

    /*
      Can simplify the writing of values to JSON:

      public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
      {
        var items = (MyCustomList)value;

        writer.WriteObject(() =>
        {
          writer.WriteField("ListField1", items.ListField1);
          writer.WriteField("ListField2", items.ListField2);

          writer.WriteArray("Items", items, serializer);
        });
      }

    */

		public static void WriteField<T>(this JsonWriter writer, string fieldName, T fieldValue)
		{
			writer.WritePropertyName(fieldName);
			writer.WriteValue(fieldValue);
		}

		public static void WriteArray(this JsonWriter writer, string fieldName, Action action)
		{
			writer.WritePropertyName(fieldName);
			writer.WriteStartArray();
			action();
			writer.WriteEndArray();
		}

		public static void WriteArray(this JsonWriter writer, string fieldName, IEnumerable enumerable, JsonSerializer serializer)
		{
			writer.WriteArray(fieldName, () =>
			{
				foreach (var item in enumerable)
				{
					serializer.Serialize(writer, item);
				}
			});
		}

		public static void WriteObject(this JsonWriter writer, Action action)
		{
			writer.WriteStartObject();
			action();
			writer.WriteEndObject();
		}

		#endregion Set values
	}
}