using System;
using System.Collections.Generic;
using System.IO;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Windows;
using XP.ImageProcessing.RoiControl.Models;

namespace XP.ImageProcessing.RoiControl
{
    /// <summary>
    /// ROI序列化工具类
    /// </summary>
    public static class ROISerializer
    {
        private static readonly JsonSerializerOptions Options = new JsonSerializerOptions
        {
            WriteIndented = true,
            Converters = { new PointConverter(), new ROIShapeConverter() }
        };

        /// <summary>
        /// 保存ROI列表到JSON文件
        /// </summary>
        public static void SaveToFile(IEnumerable<ROIShape> roiList, string filePath)
        {
            var json = JsonSerializer.Serialize(roiList, Options);
            File.WriteAllText(filePath, json);
        }

        /// <summary>
        /// 从JSON文件加载ROI列表
        /// </summary>
        public static List<ROIShape> LoadFromFile(string filePath)
        {
            var json = File.ReadAllText(filePath);
            return JsonSerializer.Deserialize<List<ROIShape>>(json, Options) ?? new List<ROIShape>();
        }

        /// <summary>
        /// 序列化ROI列表为JSON字符�?
        /// </summary>
        public static string Serialize(IEnumerable<ROIShape> roiList)
        {
            return JsonSerializer.Serialize(roiList, Options);
        }

        /// <summary>
        /// 从JSON字符串反序列化ROI列表
        /// </summary>
        public static List<ROIShape> Deserialize(string json)
        {
            return JsonSerializer.Deserialize<List<ROIShape>>(json, Options) ?? new List<ROIShape>();
        }
    }

    /// <summary>
    /// Point类型的JSON转换�?
    /// </summary>
    public class PointConverter : JsonConverter<Point>
    {
        public override Point Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            if (reader.TokenType != JsonTokenType.StartObject)
                throw new JsonException();

            double x = 0, y = 0;

            while (reader.Read())
            {
                if (reader.TokenType == JsonTokenType.EndObject)
                    return new Point(x, y);

                if (reader.TokenType == JsonTokenType.PropertyName)
                {
                    string? propertyName = reader.GetString();
                    reader.Read();

                    switch (propertyName)
                    {
                        case "X":
                            x = reader.GetDouble();
                            break;

                        case "Y":
                            y = reader.GetDouble();
                            break;
                    }
                }
            }

            throw new JsonException();
        }

        public override void Write(Utf8JsonWriter writer, Point value, JsonSerializerOptions options)
        {
            writer.WriteStartObject();
            writer.WriteNumber("X", value.X);
            writer.WriteNumber("Y", value.Y);
            writer.WriteEndObject();
        }
    }

    /// <summary>
    /// ROIShape多态类型的JSON转换�?
    /// </summary>
    public class ROIShapeConverter : JsonConverter<ROIShape>
    {
        public override ROIShape? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            using (JsonDocument doc = JsonDocument.ParseValue(ref reader))
            {
                var root = doc.RootElement;

                if (!root.TryGetProperty("ROIType", out var typeElement))
                    throw new JsonException("Missing ROIType property");

                var roiType = (ROIType)typeElement.GetInt32();

                return roiType switch
                {
                    ROIType.Polygon => JsonSerializer.Deserialize<PolygonROI>(root.GetRawText(), options),
                    _ => throw new JsonException($"Unknown ROIType: {roiType}")
                };
            }
        }

        public override void Write(Utf8JsonWriter writer, ROIShape value, JsonSerializerOptions options)
        {
            JsonSerializer.Serialize(writer, value, value.GetType(), options);
        }
    }
}