using System;
using System.Text.RegularExpressions;
using System.Web.Script.Serialization;


namespace Neo.Legitimate.WinService.SystemTriggers
{
    /// <summary>
    /// Contains JSON extension methods.
    /// </summary>
    public static partial class Extensions
    {
        const string DatePattern = @"\\\/(Date\(-?\d+\))\\\/";
        readonly static JavaScriptSerializer Serializer = new JavaScriptSerializer()
        {
            MaxJsonLength = Int32.MaxValue,
            RecursionLimit = 100
        };

        /// <summary>
        /// Converts the given object to a JSON string.
        /// <remarks>
        /// To avoid circular reference issues, use ScriptIgnore 
        /// attribute on properties that reference a parent instance
        /// </remarks>
        /// </summary>
        /// <param name="data">The object to be converted.</param>
        /// <param name="options">The serialization options.</param>
        /// <returns>A JSON representation of the object.</returns>
        public static string ToJson(this object data, JsonSerializerOptions options = JsonSerializerOptions.None)
        {
            var jsonSerialized = Serializer.Serialize(data);

            if((options & JsonSerializerOptions.All) == JsonSerializerOptions.All)
            {
                if(jsonSerialized.Contains("/Date("))
                {
                    jsonSerialized = Regex.Replace(jsonSerialized, DatePattern, new MatchEvaluator(JsonDateConverter));
                }

                //Replace single \ with double \ to escape JSON correctly so it can be parsed by underlying window.JSON.parse()
                jsonSerialized = jsonSerialized.Replace(@"\", @"\\");

                //Replace single \ with double \ to escape JSON correctly so it can be parsed by underlying window.JSON.parse()
                jsonSerialized = jsonSerialized.Replace("\\\"", "\"");
            }

            if((options & JsonSerializerOptions.FormatDateTime) == JsonSerializerOptions.FormatDateTime)
            {
                if(jsonSerialized.Contains("/Date("))
                {
                    jsonSerialized = Regex.Replace(jsonSerialized, DatePattern, new MatchEvaluator(JsonDateConverter));
                }
            }

            if((options & JsonSerializerOptions.EscapeBackSlash) == JsonSerializerOptions.EscapeBackSlash)
            {
                //Replace single \ with double \ to escape JSON correctly so it can be parsed by underlying window.JSON.parse()
                jsonSerialized = jsonSerialized.Replace(@"\", @"\\");
            }

            if((options & JsonSerializerOptions.EscapeDoubleSlashQuotes) == JsonSerializerOptions.EscapeDoubleSlashQuotes)
            {
                //Replace single \ with double \ to escape JSON correctly so it can be parsed by underlying window.JSON.parse()
                jsonSerialized = jsonSerialized.Replace("\\\"", "\"");
            }

            return jsonSerialized;
        }

        /// <summary>
        /// Converts the given JSON string to an object of the given type.
        /// </summary>
        /// <param name="json">The JSON string to be converted.</param>
        /// <param name="targetType">The type of the target object.</param>
        /// <returns>An object of the given type.</returns>
        public static object ParseJson(this string json, Type targetType)
        {
            return Serializer.Deserialize(json, targetType);
        }

        static string JsonDateConverter(Match regexDateMatch)
        {
            var matchDateTicks = regexDateMatch.ToString().Replace(@"\/Date(", "").Replace(@")\/", "");
            var dateString = @"""\/Date(" + matchDateTicks + @")\/""";
            var date = (DateTime)Serializer.Deserialize(dateString, typeof(DateTime));

            date = date.AddMinutes(TimeZone.CurrentTimeZone.GetUtcOffset(DateTime.Now).TotalMinutes);

            return date.ToString();
        }
    }
}