/*************************************************************************
 * ModernUO                                                              *
 * Copyright 2019-2020 - ModernUO Development Team                       *
 * Email: hi@modernuo.com                                                *
 * File: Point3DConverter.cs                                             *
 *                                                                       *
 * This program is free software: you can redistribute it and/or modify  *
 * it under the terms of the GNU General Public License as published by  *
 * the Free Software Foundation, either version 3 of the License, or     *
 * (at your option) any later version.                                   *
 *                                                                       *
 * You should have received a copy of the GNU General Public License     *
 * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 *************************************************************************/

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

namespace Server.Json
{
    public class Point3DConverter : JsonConverter<Point3D>
    {
        private Point3D DeserializeArray(ref Utf8JsonReader reader)
        {
            Span<int> data = stackalloc int[3];
            var count = 0;

            while (true)
            {
                reader.Read();
                if (reader.TokenType == JsonTokenType.EndArray)
                {
                    break;
                }

                if (reader.TokenType == JsonTokenType.Number)
                {
                    if (count < 3)
                    {
                        data[count] = reader.GetInt32();
                    }

                    count++;
                }
            }

            if (count > 3)
            {
                throw new JsonException("Point3D must be an array of x, y, z");
            }

            return new Point3D(data[0], data[1], data[2]);
        }

        private Point3D DeserializeObj(ref Utf8JsonReader reader)
        {
            Span<int> data = stackalloc int[3];

            while (true)
            {
                reader.Read();
                if (reader.TokenType == JsonTokenType.EndObject)
                {
                    break;
                }

                if (reader.TokenType != JsonTokenType.PropertyName)
                {
                    throw new JsonException("Invalid json structure for Point3D object");
                }

                var key = reader.GetString();

                var i = key switch
                {
                    "x" => 0,
                    "y" => 1,
                    "z" => 2,
                    _   => throw new JsonException($"Invalid property {key} for Point3D")
                };

                reader.Read();

                if (reader.TokenType != JsonTokenType.Number)
                {
                    throw new JsonException($"Value for {key} must be a number");
                }

                data[i] = reader.GetInt32();
            }

            return new Point3D(data[0], data[1], data[2]);
        }

        public override Point3D Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) =>
            reader.TokenType switch
            {
                JsonTokenType.StartArray  => DeserializeArray(ref reader),
                JsonTokenType.StartObject => DeserializeObj(ref reader),
                _                         => throw new JsonException("Invalid Json for Point3D")
            };

        public override void Write(Utf8JsonWriter writer, Point3D value, JsonSerializerOptions options)
        {
            writer.WriteStartArray();
            writer.WriteNumberValue(value.X);
            writer.WriteNumberValue(value.Y);
            writer.WriteNumberValue(value.Z);
            writer.WriteEndArray();
        }
    }
}