using Microsoft.AspNetCore.WebUtilities;
using System.ComponentModel;
using System.Text.Json.Serialization;
using System.Text.Json;

namespace Nuuru.Server.Utilities
{
    [TypeConverter(typeof(ShortGuidTypeConverter))]
    [JsonConverter(typeof(ShortGuidJsonConverter))]
    public readonly struct ShortGuid
    {
        private readonly Guid? _value;

        public ShortGuid(Guid? value) => _value = value;

        public static implicit operator Guid?(ShortGuid shortGuid) => shortGuid._value;
        public static implicit operator ShortGuid(Guid? guid) => new(guid);

        public static ShortGuid? Parse(string? input)
        {
            if (string.IsNullOrEmpty(input))
                return null;

            try
            {
                return new ShortGuid(new Guid(WebEncoders.Base64UrlDecode(input)));
            }
            catch
            {
                return null;
            }
        }

        public override string? ToString()
        {
            if (!_value.HasValue)
                return null;

            Span<byte> bytes = stackalloc byte[16];
            _value.Value.TryWriteBytes(bytes);
            return WebEncoders.Base64UrlEncode(bytes);
        }

        private sealed class ShortGuidTypeConverter : TypeConverter
        {
            public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
                => sourceType == typeof(string);

            public override object? ConvertFrom(ITypeDescriptorContext? context, System.Globalization.CultureInfo? culture, object value)
                => value is string str ? Parse(str) : null;

            public override bool CanConvertTo(ITypeDescriptorContext? context, Type destinationType)
                => destinationType == typeof(string);

            public override object? ConvertTo(ITypeDescriptorContext? context, System.Globalization.CultureInfo? culture, object? value, Type destinationType)
                => value is ShortGuid shortGuid ? shortGuid.ToString() : null;
        }

        private sealed class ShortGuidJsonConverter : JsonConverter<ShortGuid>
        {
            public override ShortGuid Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
            {
                var str = reader.GetString();
                if (str == null)
                    return new ShortGuid(null);

                var parsed = Parse(str);
                return parsed ?? new ShortGuid(null);
            }

            public override void Write(Utf8JsonWriter writer, ShortGuid value, JsonSerializerOptions options)
            {
                var str = value.ToString();
                if (str == null)
                    writer.WriteNullValue();
                else
                    writer.WriteStringValue(str);
            }
        }
    }
}