package validator

import (
	"reflect"
	"strings"
	"sync"

	"github.com/gin-gonic/gin/binding"
	"github.com/go-playground/locales/en"
	ut "github.com/go-playground/universal-translator"
	"gopkg.in/go-playground/validator.v9"
	en_translations "gopkg.in/go-playground/validator.v9/translations/en"
)

var (
	ValidatorUni *ut.UniversalTranslator
)

type defaultValidator struct {
	once     sync.Once
	validate *validator.Validate
}

var v binding.StructValidator = &defaultValidator{}

func init() {
	v.Engine()
}

func (v *defaultValidator) ValidateStruct(obj interface{}) error {

	if kindOfData(obj) == reflect.Struct {

		v.lazyinit()

		if err := v.validate.Struct(obj); err != nil {
			return error(err)
		}
	}

	return nil
}

func (v *defaultValidator) Engine() interface{} {
	v.lazyinit()
	return v.validate
}

func (v *defaultValidator) lazyinit() {
	v.once.Do(func() {
		v.validate = validator.New()

		// 依旧使用bingding tag兼容v8
		v.validate.SetTagName("binding")

		// 错误信息转换
		en := en.New()
		ValidatorUni = ut.New(en, en)
		trans, _ := ValidatorUni.GetTranslator("en")
		en_translations.RegisterDefaultTranslations(v.validate, trans)

		v.validate.RegisterTagNameFunc(func(fld reflect.StructField) string {
			name := strings.SplitN(fld.Tag.Get("comment"), ",", 2)[0]
			if name == "-" {
				return ""
			}
			return name
		})
	})
}

func kindOfData(data interface{}) reflect.Kind {

	value := reflect.ValueOf(data)
	valueType := value.Kind()

	if valueType == reflect.Ptr {
		valueType = value.Elem().Kind()
	}
	return valueType
}