using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.ModelBinding.Binders;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using NewLife.Collections;
using NewLife.Cube.Common;
using NewLife.Cube.Extensions;
using NewLife.Log;
using NewLife.Reflection;
using NewLife.Serialization;
using XCode;

namespace NewLife.Cube
{
    /// <summary>实体模型绑定器</summary>
    class EntityModelBinder : ComplexTypeModelBinder
    {
        /// <summary>实例化实体模型绑定器</summary>
        /// <param name="propertyBinders"></param>
        /// <param name="loggerFactory"></param>
        public EntityModelBinder(IDictionary<ModelMetadata, IModelBinder> propertyBinders, ILoggerFactory loggerFactory)
            : base(propertyBinders, loggerFactory) { }

        /// <summary>创建模型。对于有Key的请求，使用FindByKeyForEdit方法先查出来数据，而不是直接反射实例化实体对象</summary>
        /// <param name="bindingContext"></param>
        /// <returns></returns>
        protected override Object CreateModel(ModelBindingContext bindingContext)
        {
            var modelType = bindingContext.ModelType;
            if (!modelType.As<IEntity>()) return base.CreateModel(bindingContext);

            var fact = EntityFactory.CreateOperate(modelType);

            if (fact == null) return base.CreateModel(bindingContext);

            // 尝试从body读取json格式的参数
            var ctx = bindingContext.HttpContext;
            var request = ctx.Request;
            if (request.GetRequestBody<Object>() != null)
            {
                ctx.Items["EntityBody"] = ctx.Items["RequestBody"];
                var cubeBodyValueProvider = new CubeBodyValueProvider(bindingContext.ValueProvider,
                    ctx.Items["EntityBody"] as NullableDictionary<String, Object>);

                // 添加body提供者，从body中取值，只取第一层，
                // 下面的BindProperty方法，以前从body中并没有处理值的格式，
                // 强行绑定会出错记录在ModelState，在api中返回400错误，mvc不会
                bindingContext.ValueProvider = cubeBodyValueProvider;
            }

            var pks = fact.Table.PrimaryKeys;
            var uk = fact.Unique;

            IEntity entity = null;
            if (uk != null)
            {
                // 查询实体对象用于编辑
                var id = bindingContext.ValueProvider.GetValue(uk.Name);
                if (id != ValueProviderResult.None) entity = fact.FindByKeyForEdit(id.ToString());
            }
            else if (pks.Length > 0)
            {
                // 查询实体对象用于编辑
                var exp = new WhereExpression();
                foreach (var item in pks)
                {
                    var v = bindingContext.ValueProvider.GetValue(item.Name);
                    if(v == ValueProviderResult.None) continue;
                    exp &= item.Equal(v.ChangeType(item.Type));
                }

                entity = fact.Find(exp);
            }

            return entity ?? fact.Create(true);
        }

        protected override Boolean CanBindProperty(ModelBindingContext bindingContext, ModelMetadata propertyMetadata)
        {
            // 不要绑定复杂类型，那是扩展属性
            if (propertyMetadata.ModelType.GetTypeCode() == TypeCode.Object) return false;

            return base.CanBindProperty(bindingContext, propertyMetadata);
        }

        /// <summary>
        /// 绑定属性，在这里赋值
        /// </summary>
        /// <param name="bindingContext"></param>
        /// <returns></returns>
        protected override Task BindProperty(ModelBindingContext bindingContext)
        {
            var metadata = bindingContext.ModelMetadata;

            switch (metadata.ModelType.GetTypeCode())
            {
                case TypeCode.DateTime:
                    // 客户端可能提交空时间，不要绑定属性，以免出现空时间验证失败
                    //if (result.Model is not DateTime) return Task.CompletedTask;
                    var dt = bindingContext.ValueProvider.GetValue(metadata.Name).Values;
                    if (dt.Count == 0 || dt.ToString().IsNullOrEmpty()) return Task.CompletedTask;

                    break;
            }

            return base.BindProperty(bindingContext);
        }

        /// <summary>
        /// 设置属性，二次处理
        /// </summary>
        /// <param name="bindingContext"></param>
        /// <param name="modelName"></param>
        /// <param name="propertyMetadata"></param>
        /// <param name="result"></param>
        protected override void SetProperty(ModelBindingContext bindingContext, String modelName, ModelMetadata propertyMetadata, ModelBindingResult result)
        {
            switch (propertyMetadata.ModelType.GetTypeCode())
            {
                case TypeCode.String:
                    // 如果有多个值，则修改结果，避免 3,2,5 变成只有3
                    var vs = bindingContext.ValueProvider.GetValue(modelName).Values;
                    if (vs.Count > 1) result = ModelBindingResult.Success(vs.ToString());
                    break;
            }

            base.SetProperty(bindingContext, modelName, propertyMetadata, result);
        }
    }

    /// <summary>实体模型绑定器提供者，为所有XCode实体类提供实体模型绑定器</summary>
    public class EntityModelBinderProvider : IModelBinderProvider
    {
        /// <summary>获取绑定器</summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public IModelBinder GetBinder(ModelBinderProviderContext context)
        {
            if (context == null) throw new ArgumentNullException(nameof(context));

            if (!context.Metadata.ModelType.As<IEntity>()) return null;

            var loggerFactory = context.Services.GetRequiredService<ILoggerFactory>();
            var propertyBinders = new Dictionary<ModelMetadata, IModelBinder>();
            foreach (var property in context.Metadata.Properties)
            {
                propertyBinders.Add(property, context.CreateBinder(property));
            }

            return new EntityModelBinder(propertyBinders, loggerFactory);
        }

        /// <summary>实例化</summary>
        public EntityModelBinderProvider() => XTrace.WriteLine("注册实体模型绑定器：{0}", typeof(EntityModelBinderProvider).FullName);
    }
}