using System.Text.Json;
using System.Text.Json.Serialization;
using System.Text.RegularExpressions;

namespace MMSL.DateTimeConverter
{
    public class MicrosoftDateTimeConverter : JsonConverter<DateTime>
    {
        private static readonly Regex MicrosoftDateRegex = new Regex(@"\\/Date\((\d+)([-+]\d+)?\)\\/", RegexOptions.Compiled);

        public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            string value = reader.GetString();

            if (value != null && value.StartsWith("/Date(") && value.EndsWith(")/"))
            {
                var milliseconds = long.Parse(value[6..^2]);
                return DateTimeOffset.FromUnixTimeMilliseconds(milliseconds).UtcDateTime;
            }

            return DateTime.Parse(value);
        }

        public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)
        {
            var milliseconds = new DateTimeOffset(value).ToUnixTimeMilliseconds();
            writer.WriteStringValue($"/Date({milliseconds})/");
        }
    }
}