package main

import (
	"fmt"
	"net/http"
	"reflect"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/gin-gonic/gin/binding"
	"github.com/go-playground/locales/en"
	"github.com/go-playground/locales/zh"
	ut "github.com/go-playground/universal-translator"
	"github.com/go-playground/validator/v10"
	enTranslations "github.com/go-playground/validator/v10/translations/en"
	zhTranslations "github.com/go-playground/validator/v10/translations/zh"
)

// 定義一個(gè)全局翻譯器
var trans ut.Translator

type SignUpParam struct {
	Age        uint8  `json:"age" binding:"gte=1,lte=130"`
	Name       string `json:"name" binding:"required"`
	Email      string `json:"email" binding:"required,email"`
	Password   string `json:"password" binding:"required"`
	RePassword string `json:"re_password" binding:"required,eqfield=Password"`
	Date       string `json:"date" binding:"required,datetime=2006-01-02,checkDate"`
}

func InitTrans(locale string) (err error) {
	if v, ok := binding.Validator.Engine().(*validator.Validate); ok {

		// 注冊(cè)獲取 JSON tag 的自定義方法
		v.RegisterTagNameFunc(func(fld reflect.StructField) string {
			name := strings.SplitN(fld.Tag.Get("json"), ",", 2)[0]
			if name == "-" {
				return ""
			}
			return name
		})

		// 注冊(cè)結(jié)構(gòu)體級(jí)別的驗(yàn)證函數(shù)
		v.RegisterStructValidation(SignUpParamStructLevelValidation, SignUpParam{})

		// 注冊(cè)自定義校驗(yàn)方法
		if err := v.RegisterValidation("checkDate", customFunc); err != nil {
			return err
		}

		// 初始化多語(yǔ)言支持
		zhT := zh.New() 
		enT := en.New()
		uni := ut.New(enT, zhT, enT)

                var ok bool
		trans, ok = uni.GetTranslator(locale)
		if !ok {
			return fmt.Errorf("uni.GetTranslator(%s) failed", locale)
		}

		// 注冊(cè)語(yǔ)言翻譯
		switch locale {
		case "en":
			err = enTranslations.RegisterDefaultTranslations(v, trans)
		case "zh":
			err = zhTranslations.RegisterDefaultTranslations(v, trans)
		default:
			err = enTranslations.RegisterDefaultTranslations(v, trans)
		}
		if err != nil {
			return err
		}

		// 注冊(cè)自定義翻譯
		if err := v.RegisterTranslation(
			"checkDate",
			trans,
			registerTranslator("checkDate", "{0}必須晚于當(dāng)前日期"),
			translate,
		); err != nil {
			return err
		}
		return
	}
	return
}

func customFunc(fl validator.FieldLevel) bool {
	date, err := time.Parse("2006-01-02", fl.Field().String())
	if err != nil {
		return false
	}
	return date.After(time.Now())
}

func SignUpParamStructLevelValidation(sl validator.StructLevel) {
	su := sl.Current().Interface().(SignUpParam)
	if su.Password != su.RePassword {
		sl.ReportError(su.RePassword, "re_password", "RePassword", "eqfield", "password")
	}
}

// registerTranslator 為自定義字段添加翻譯功能
func registerTranslator(tag string, msg string) validator.RegisterTranslationsFunc {
	return func(trans ut.Translator) error {
		if err := trans.Add(tag, msg, false); err != nil {
			return err
		}
		return nil
	}
}

// translate 自定義字段的翻譯方法
func translate(trans ut.Translator, fe validator.FieldError) string {
	msg, err := trans.T(fe.Tag(), fe.Field())
	if err != nil {
		panic(fe.(error).Error())
	}
	return msg
}

// removeTopStruct 去除字段名中的結(jié)構(gòu)體名稱(chēng)標(biāo)識(shí)
// refer from:https://github.com/go-playground/validator/issues/633#issuecomment-654382345
func removeTopStruct(fields map[string]string) map[string]string {
	res := map[string]string{}
	for field, err := range fields {
		res[field[strings.Index(field, ".")+1:]] = err
	}
	return res
}

func main() {
	// 初始化翻譯器
	if err := InitTrans("zh"); err != nil {
		fmt.Printf("初始化翻譯器失敗: %v\n", err)
		return
	}

	r := gin.Default()

	r.POST("/signup", func(c *gin.Context) {
		var u SignUpParam
		if err := c.ShouldBind(&u); err != nil {
			errs, ok := err.(validator.ValidationErrors)
			if !ok {
				c.JSON(http.StatusOK, gin.H{"msg": err.Error()})
				return
			}
			c.JSON(http.StatusOK, gin.H{"msg": removeTopStruct(errs.Translate(trans))})
			return
		}

		// 其他的一些業(yè)務(wù)邏輯操作……

		c.JSON(http.StatusOK, gin.H{"msg": "success"})
	})

	err := r.Run(":8080")
	if err != nil {
		fmt.Printf("服務(wù)器運(yùn)行失敗: %v\n", err)
	}
}