formatError.go

package gpc

import (
	"reflect"
	"regexp"
	"strings"
	"sync"

	ut "github.com/go-playground/universal-translator"
	"github.com/go-playground/validator/v10"
)

type FormatError struct {
	Errors []FormatErrorMetadata `json:"errors"`
}

type FormatErrorMetadata struct {
	Msg   string `json:"msg"`
	Param string `json:"param"`
	Tag   string `json:"tag"`
}

func formatError(err error, trans ut.Translator, customMessage interface{}) (*FormatError, error) {
	var (
		mutex           *sync.RWMutex = new(sync.RWMutex)
		errResponsePool *sync.Pool    = new(sync.Pool)
	)

	errResponsePool.New = func() interface{} {
		return new(FormatError)
	}
	errResponse := errResponsePool.Get().(*FormatError)

	for i, e := range err.(validator.ValidationErrors) {
		errResult := new(FormatErrorMetadata)
		errResult.Param = e.StructField()

		if _, ok := reflect.TypeOf(customMessage).Field(i).Tag.Lookup("gpc"); !ok {
			errResult.Msg = e.Translate(trans)
		} else {
			strucField, _ := reflect.TypeOf(customMessage).FieldByName(e.StructField())
			structTags := strucField.Tag.Get("gpc")

			regexTag := regexp.MustCompile(`=+[\w].*`)
			regexVal := regexp.MustCompile(`[\w]+=`)
			tags := strings.Split(structTags, ",")

			for j, v := range tags {
				replacedTag := regexTag.ReplaceAllString(tags[j], "")
				if replacedTag == e.ActualTag() {
					errResult.Msg = regexVal.ReplaceAllString(v, "")
				}
			}
		}

		mutex.RLock()
		defer mutex.RUnlock()

		errResult.Tag = e.ActualTag()
		errResponse.Errors = append(errResponse.Errors, *errResult)
	}

	errResponsePool.Put(errResponse)
	return errResponse, nil
}