using Estsh.Core.Model.Result;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using System;
using System.Net;
using System.Text;
using System.Threading.Tasks;

namespace Estsh.Core.Util
{
    /// <summary>
    /// 全局异常处理中间件
    /// </summary>
    public class GlobalExceptionHandler
    {
        #region 属性及其构造函数

        private readonly RequestDelegate _next;  //上下文请求 
        private readonly ILogger<GlobalExceptionHandler> _logger;

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="next">上下文请求</param>
        /// <param name="logger">日志对象</param>
        public GlobalExceptionHandler(RequestDelegate next, ILogger<GlobalExceptionHandler> logger)
        {
            _next = next;
            _logger = logger;
        }

        #endregion

        #region 处理上下文请求

        /// <summary>
        /// 处理上下文请求
        /// </summary>
        /// <param name="httpContext">http会话对象</param>
        /// <returns></returns>
        public async Task InvokeAsync(HttpContext httpContext)
        {
            try
            {
                //_logger.LogInformation(httpContext.Request.Path);
                await _next(httpContext); //处理上下文请求
            }
            catch (Exception ex)
            {
                await HandleExceptionAsync(httpContext, ex); //捕获异常,在HandleExceptionAsync中处理
            }
        }

        #endregion

        #region 全局统一异常处理

        /// <summary>
        /// 全局统一异常处理
        /// </summary>
        /// <param name="context">http会话对象</param>
        /// <param name="exception">全局异常处理</param>
        /// <returns></returns>
        private async Task HandleExceptionAsync(HttpContext context, Exception exception)
        {
            context.Response.ContentType = "application/json";  //返回json 类型
            var response = context.Response;

            var errorResult = new ErrorResult { Success = false };

            // 自定义的异常错误信息类型
            switch (exception)
            {
                case ApplicationException ex:
                    response.StatusCode = (int)HttpStatusCode.BadRequest;
                    errorResult.Message = ex.Message;
                    break;
                case Exception ex:
                    response.StatusCode = (int)HttpStatusCode.InternalServerError;
                    errorResult.Message = ex.Message;
                    break;
                default:
                    response.StatusCode = (int)HttpStatusCode.InternalServerError;
                    errorResult.Message = "Internal Server Error";
                    break;
            }

            //错误日志控制台输出
            _logger.LogError(exception.Message);

            //错误日志文件输出
            var errorInfo = new StringBuilder();
            errorInfo.AppendLine("Time:" + DateTime.Now);
            errorInfo.AppendLine("StackTrace:" + (exception.StackTrace == null ? "" : exception.StackTrace));
            errorInfo.AppendLine("Source:" + (exception.Source == null ? "" : exception.Source));
            errorInfo.AppendLine("Message:" + exception.Message);
            errorInfo.AppendLine("InnerExceptionMessage:" + (exception.InnerException == null ? "" : exception.InnerException.Message));
            LogHelper.Error(errorInfo.ToString());

            //返回统一异常
            await context.Response.WriteAsync(errorResult.ToJson());
        }

        #endregion
    }
}