package validator

import (
	"encoding/json"
	"errors"
	"fmt"
	"sync"

	"github.com/gin-gonic/gin/binding"
	"github.com/go-playground/locales/zh"
	uTrans "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"
)

const (
	local = "zh"
)

func NewValidator() binding.StructValidator {
	return &customValidator{}
}

type customValidator struct {
	once       sync.Once
	validate   *validator.Validate
	translator uTrans.Translator
}

func (c *customValidator) ValidateStruct(obj interface{}) error {
	c.lazyinit()
	if err := c.validate.Struct(obj); err != nil {
		return c.translate(err)
	}

	return nil
}

func (c *customValidator) Engine() any {
	c.lazyinit()
	return c.validate
}

func (c *customValidator) lazyinit() {
	c.once.Do(func() {
		c.validate = validator.New()
		c.validate.SetTagName("binding")

		if err := c.setTrans(); err != nil {
			fmt.Printf("setTrans fail %s", err.Error())
		}

		if err := c.registerValidation(); err != nil {
			fmt.Printf("registervalidation fail:%s", err.Error())
		}
	})
}

// 暂时写死英文翻译中文,todo 根据IP或者根据请求头语言决定翻译
func (c *customValidator) setTrans() error {
	zh := zh.New()
	uni := uTrans.New(zh, zh)

	trans, exist := uni.GetTranslator(local)
	if !exist {
		return fmt.Errorf("uni.GetTranslator %s fail", local)
	}

	c.translator = trans

	switch local {
	case "en":
		if err := enTranslations.RegisterDefaultTranslations(c.validate, c.translator); err != nil {
			return fmt.Errorf("enTranslations fail:%s", err.Error())
		}
	case "zh":
		if err := zhTranslations.RegisterDefaultTranslations(c.validate, c.translator); err != nil {
			return fmt.Errorf("zhTranslations fail:%s", err.Error())
		}
	default:
		if err := zhTranslations.RegisterDefaultTranslations(c.validate, c.translator); err != nil {
			return fmt.Errorf("zhTranslations fail:%s", err.Error())
		}
	}

	return nil
}

func (c *customValidator) registerValidation() error {
	if err := c.validate.RegisterValidation("tableName", tableName); err != nil {
		return err
	}

	return nil
}

func (c *customValidator) translate(err error) error {
	if errs, ok := err.(validator.ValidationErrors); ok {
		tErrMap := errs.Translate(c.translator)
		if tErrMap != nil {
			if errMsg, errTmp := json.Marshal(tErrMap); errTmp == nil {
				return errors.New(string(errMsg))
			} else {
				return fmt.Errorf("validator translate json marshal fail:%s", errTmp)
			}
		}

		// todo 根据定制tag,输出定制的msg
		// todo 翻译后的错误消息按另外的规则输出(当前json)
	}

	return err
}