// Package validator use for valiate struct
package validator

import (
	"context"
	"reflect"
	"strings"

	"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"
	en_translations "github.com/go-playground/validator/v10/translations/en"
	zh_translations "github.com/go-playground/validator/v10/translations/zh"
	"github.com/samber/lo"

	"git.ifooth.com/common/pkg/i18n"
)

var (
	validate     *validator.Validate
	uni          *ut.UniversalTranslator
	defaultTrans ut.Translator
	zhTrans      ut.Translator
)

// ValidationError 校验错误
type ValidationError struct {
	ctx    context.Context
	rawErr error
}

// Validator 实现了 Validate 接口自定义调用
type Validator interface {
	Validate() error
}

func (e *ValidationError) getTranslator() ut.Translator {
	acceptLang, ok := i18n.GetLang(e.ctx)
	if ok && acceptLang == "zh" {
		return zhTrans
	}
	return defaultTrans
}

// Error error iface
func (e *ValidationError) Error() string {
	if _, ok := e.rawErr.(*validator.InvalidValidationError); ok {
		return e.rawErr.Error()
	}

	errs := e.rawErr.(validator.ValidationErrors)
	// 只返回单个错误
	for _, ve := range errs {
		return ve.Translate(e.getTranslator())
	}

	return e.rawErr.Error()
}

// Struct 通过 validate tag 校验结构体, Validate 校验需要传入指针类型
func Struct(ctx context.Context, s any) error {
	err := validate.StructCtx(ctx, s)
	if err != nil {
		return &ValidationError{ctx: ctx, rawErr: err}
	}

	// 实现了 Validate 接口自定义调用
	if v, ok := s.(Validator); ok {
		return v.Validate()
	}

	return nil
}

// tagNameFunc 优先从 json tag 获取名称
func tagNameFunc(fld reflect.StructField) string {
	name := strings.SplitN(fld.Tag.Get("json"), ",", 2)[0]
	if name == "-" {
		return ""
	}
	return name
}

func init() {
	validate = validator.New(validator.WithRequiredStructEnabled())
	validate.RegisterTagNameFunc(tagNameFunc)

	// 默认使用英文
	en := en.New()
	zh := zh.New()
	uni = ut.New(en, en, zh)
	defaultTrans, _ = uni.GetTranslator("en")
	lo.Must0(en_translations.RegisterDefaultTranslations(validate, defaultTrans))

	zhTrans, _ = uni.GetTranslator("zh")
	lo.Must0(zh_translations.RegisterDefaultTranslations(validate, zhTrans))
}