using System.ComponentModel;
using System.Text.Json.Nodes;
using Microsoft.AspNetCore.OpenApi;
using Microsoft.OpenApi;

namespace StopShopping.Api.Extensions;

/// <summary>
/// 处理enum类型openapi显示
/// </summary>
public class EnumOpenApiSchemaTransformer : IOpenApiSchemaTransformer
{
    public Task TransformAsync(OpenApiSchema schema, OpenApiSchemaTransformerContext context, CancellationToken cancellationToken)
    {
        if (context.JsonTypeInfo.Type.IsEnum)
        {
            schema.Type = JsonSchemaType.Integer;

            var enumValues = Enum.GetValues(context.JsonTypeInfo.Type)
                .Cast<object>()
                .Select(v => JsonNode.Parse(Convert.ToInt32(v).ToString())!)
                .ToList();

            schema.Enum = enumValues;

            var enumNames = Enum.GetNames(context.JsonTypeInfo.Type);
            schema.Extensions ??= new Dictionary<string, IOpenApiExtension>();
            var namesExtension = new JsonNodeExtension(new JsonArray(
                        enumNames
                        .Select(n => (JsonNode)n)
                        .ToArray()));
            schema.Extensions.Add("x-enumNames", namesExtension);

            var descMap = new JsonObject();
            foreach (var name in enumNames)
            {
                if (context.JsonTypeInfo.Type.GetField(name)
                    ?.GetCustomAttributes(typeof(DescriptionAttribute), false)
                    .FirstOrDefault() is DescriptionAttribute attr)
                {
                    descMap[name] = attr.Description;
                }
            }
            schema.Extensions.Add("x-enumDescriptions", new JsonNodeExtension(descMap));
        }

        return Task.CompletedTask;
    }
}