using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Reflection;
using System.Xml.XPath;
using Microsoft.OpenApi.Any;
using Microsoft.OpenApi.Models;
using Swashbuckle.AspNetCore.SwaggerGen;

namespace FAuth.Extensions
{
    /// <summary>
    /// 通过DescriptionAttribute和summary生成枚举说明
    /// </summary>
    public class SwaggerXmlEnumFilter:IDocumentFilter
    {
        private readonly XPathNavigator _xmlNavigator;

        public static List<Type> AllTypes { get; set; }

        /// <summary>
        /// 通过提供应用程序文档生成枚举说明
        /// </summary>
        /// <param name="xmlPath"></param>
        public SwaggerXmlEnumFilter(string xmlPath) {
            _xmlNavigator = new XPathDocument(xmlPath).CreateNavigator();

            if(AllTypes == null) {
                AllTypes = new List<Type>();
                foreach(var ass in AppDomain.CurrentDomain.GetAssemblies()) {
                    AllTypes.AddRange(ass.GetTypes().Where(m => m.IsEnum));
                }
            }
        }

        public void Apply(OpenApiDocument swaggerDoc,DocumentFilterContext context) {
            var enumList = swaggerDoc.Components.Schemas.Where(m => m.Value.Enum != null && m.Value.Enum.Count > 0);
            foreach(var item in enumList) {
                var key = item.Key;
                var property = item.Value;
                var itemType = AllTypes.Find(m => m.Name == key);
                var list = new List<OpenApiInteger>();
                foreach(var val in property.Enum) {
                    list.Add((OpenApiInteger)val);
                }
                property.Description += describeEnum(itemType,list);
            }
        }

        private string describeEnum(Type type,List<OpenApiInteger> enums) {
            var enumDescriptions = new List<string>();
            foreach(var item in enums) {
                if(type == null)
                    continue;
                var value = Enum.Parse(type,item.Value.ToString());
                var desc = getDescription(type,value);

                if(string.IsNullOrEmpty(desc))
                    enumDescriptions.Add($"{item.Value.ToString()}:{Enum.GetName(type,value)}; ");
                else
                    enumDescriptions.Add($"{item.Value.ToString()}:{Enum.GetName(type,value)},{desc}; ");

            }
            return $"<br/>{Environment.NewLine}{string.Join("<br/>" + Environment.NewLine,enumDescriptions)}";
        }

        private string getDescription(Type t,object value) {
            foreach(var member in t.GetMembers().Where(m => m.Name == t.GetEnumName(value))) {
                foreach(var attr in member.GetCustomAttributes<DescriptionAttribute>()) {
                    return attr.Description;
                }
            }
            var fullName = $"{t.FullName}.{t.GetEnumName(value)}";
            var desc = _xmlNavigator.SelectSingleNode($"doc/members/member[@name='F:{fullName}']/summary")?.InnerXml;
            return desc ?? string.Empty;
        }

    }
}