package middleware

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"time"

	"github.com/go-kratos/kratos/v2/log"
	"github.com/go-kratos/kratos/v2/middleware"
	"github.com/go-kratos/kratos/v2/transport"
	kratoshttp "github.com/go-kratos/kratos/v2/transport/http"
)

// EmailSender 邮件发送接口
type EmailSender interface {
	SendError(subject, body string) error
}

// ErrorToEmail 错误邮件通知中间件
func ErrorToEmail(sender EmailSender, logger log.Logger) middleware.Middleware {
	helper := log.NewHelper(logger)
	return func(handler middleware.Handler) middleware.Handler {
		return func(ctx context.Context, req interface{}) (interface{}, error) {
			var (
				username string
				body     string
				method   string
				path     string
				ip       string
			)

			// 获取用户信息
			if claims, ok := GetClaims(ctx); ok {
				username = claims.Username
			}
			if username == "" {
				username = "Unknown"
			}

			if tr, ok := transport.FromServerContext(ctx); ok {
				path = tr.Operation()
				if header := tr.RequestHeader(); header != nil {
					method = header.Get(":method")
				}

				if ht, ok := tr.(kratoshttp.Transporter); ok {
					r := ht.Request()
					ip = getClientIP(r)

					// 读取body
					bodyBytes, _ := io.ReadAll(r.Body)
					r.Body = io.NopCloser(bytes.NewBuffer(bodyBytes))
					body = string(bodyBytes)
				}
			}

			start := time.Now()
			reply, err := handler(ctx, req)
			latency := time.Since(start)

			// 如果有错误，发送邮件
			if err != nil && sender != nil {
				subject := fmt.Sprintf("%s %s调用了%s报错了", username, ip, path)
				content := fmt.Sprintf(
					"接收到的请求为%s\n请求方式为%s\n报错信息如下%s\n耗时%s\n",
					body, method, err.Error(), latency.String(),
				)
				if sendErr := sender.SendError(subject, content); sendErr != nil {
					helper.Error("ErrorToEmail Failed, err:", sendErr)
				}
			}

			return reply, err
		}
	}
}