using System;
using System.IO;
using System.Web;
using System.Web.Mvc;
using Newtonsoft.Json;

namespace WebInterface.Helpers
{
    /// <summary>
    /// Custom JSON action result using JSON.NET library
    /// </summary>
    public class JsonNetResult : JsonResult
    {
        /// <summary>
        /// Serialization settings
        /// </summary>
        public JsonSerializerSettings Settings { get; }

        /// <summary>
        /// Constructor
        /// </summary>
        public JsonNetResult()
        {
            Settings = new JsonSerializerSettings
            {
                ReferenceLoopHandling = ReferenceLoopHandling.Error
            };
        }

        
        /// <summary>
        /// Generates the resulting JSON output
        /// </summary>
        /// <param name="context">Controller context for outputting</param>
        public override void ExecuteResult(ControllerContext context)
        {
            //Verify context is valid before continuing
            if (context == null)
            {
                throw new ArgumentNullException(nameof(context));
            }
            //Verify HTTP method is valid before continuing
            if (JsonRequestBehavior == JsonRequestBehavior.DenyGet && string.Equals(context.HttpContext.Request.HttpMethod, "GET", StringComparison.OrdinalIgnoreCase))
            {
                throw new InvalidOperationException("JSON GET is not allowed");
            }

            //Write response
            HttpResponseBase response = context.HttpContext.Response;
            response.ContentType = string.IsNullOrEmpty(ContentType) ? "application/json" : ContentType;

            if (ContentEncoding != null)
                response.ContentEncoding = ContentEncoding;
            if (Data == null)
                return;

            var scriptSerializer = JsonSerializer.Create(Settings);

            using (var sw = new StringWriter())
            {
                scriptSerializer.Serialize(sw, Data);
                response.Write(sw.ToString());
            }
        }
    }
}