refactor: use github.com/jinzhu/copier for MapStruct (#698)

backend/internal/dto/dto_mapper.go

@@ -1,162 +1,27 @@
 package dto
 
 import (
-	"errors"
-	"reflect"
-	"time"
+	"fmt"
 
-	datatype "github.com/pocket-id/pocket-id/backend/internal/model/types"
+	"github.com/jinzhu/copier"
 )
 
 // MapStructList maps a list of source structs to a list of destination structs
-func MapStructList[S any, D any](source []S, destination *[]D) error {
-	*destination = make([]D, 0, len(source))
+func MapStructList[S any, D any](source []S, destination *[]D) (err error) {
+	*destination = make([]D, len(source))
 
-	for _, item := range source {
-		var destItem D
-		if err := MapStruct(item, &destItem); err != nil {
-			return err
+	for i, item := range source {
+		err = MapStruct(item, &((*destination)[i]))
+		if err != nil {
+			return fmt.Errorf("failed to map field %d: %w", i, err)
 		}
-		*destination = append(*destination, destItem)
 	}
 	return nil
 }
 
 // MapStruct maps a source struct to a destination struct
-func MapStruct[S any, D any](source S, destination *D) error {
-	// Ensure destination is a non-nil pointer
-	destValue := reflect.ValueOf(destination)
-	if destValue.Kind() != reflect.Ptr || destValue.IsNil() {
-		return errors.New("destination must be a non-nil pointer to a struct")
-	}
-
-	// Ensure source is a struct
-	sourceValue := reflect.ValueOf(source)
-	if sourceValue.Kind() != reflect.Struct {
-		return errors.New("source must be a struct")
-	}
-
-	return mapStructInternal(sourceValue, destValue.Elem())
-}
-
-func mapStructInternal(sourceVal reflect.Value, destVal reflect.Value) error {
-	for i := 0; i < destVal.NumField(); i++ {
-		destField := destVal.Field(i)
-		destFieldType := destVal.Type().Field(i)
-
-		if destFieldType.Anonymous {
-			if err := mapStructInternal(sourceVal, destField); err != nil {
-				return err
-			}
-			continue
-		}
-
-		sourceField := sourceVal.FieldByName(destFieldType.Name)
-
-		if sourceField.IsValid() && destField.CanSet() {
-			if err := mapField(sourceField, destField); err != nil {
-				return err
-			}
-		}
-	}
-	return nil
-}
-
-//nolint:gocognit
-func mapField(sourceField reflect.Value, destField reflect.Value) error {
-	// Handle pointer to struct in source
-	if sourceField.Kind() == reflect.Ptr && !sourceField.IsNil() {
-		switch {
-		case sourceField.Elem().Kind() == reflect.Struct:
-			switch {
-			case destField.Kind() == reflect.Struct:
-				// Map from pointer to struct -> struct
-				return mapStructInternal(sourceField.Elem(), destField)
-			case destField.Kind() == reflect.Ptr && destField.CanSet():
-				// Map from pointer to struct -> pointer to struct
-				if destField.IsNil() {
-					destField.Set(reflect.New(destField.Type().Elem()))
-				}
-				return mapStructInternal(sourceField.Elem(), destField.Elem())
-			}
-		case destField.Kind() == reflect.Ptr &&
-			destField.CanSet() &&
-			sourceField.Elem().Type().AssignableTo(destField.Type().Elem()):
-			// Handle primitive pointer types (e.g., *string to *string)
-			if destField.IsNil() {
-				destField.Set(reflect.New(destField.Type().Elem()))
-			}
-			destField.Elem().Set(sourceField.Elem())
-			return nil
-		case destField.Kind() != reflect.Ptr &&
-			destField.CanSet() &&
-			sourceField.Elem().Type().AssignableTo(destField.Type()):
-			// Handle *T to T conversion for primitive types
-			destField.Set(sourceField.Elem())
-			return nil
-		}
-	}
-
-	// Handle pointer to struct in destination
-	if destField.Kind() == reflect.Ptr && destField.CanSet() {
-		switch {
-		case sourceField.Kind() == reflect.Struct:
-			// Map from struct -> pointer to struct
-			if destField.IsNil() {
-				destField.Set(reflect.New(destField.Type().Elem()))
-			}
-			return mapStructInternal(sourceField, destField.Elem())
-		case !sourceField.IsZero() && sourceField.Type().AssignableTo(destField.Type().Elem()):
-			// Handle T to *T conversion for primitive types
-			if destField.IsNil() {
-				destField.Set(reflect.New(destField.Type().Elem()))
-			}
-			destField.Elem().Set(sourceField)
-			return nil
-		}
-	}
-
-	switch {
-	case sourceField.Type() == destField.Type():
-		destField.Set(sourceField)
-	case sourceField.Kind() == reflect.Slice && destField.Kind() == reflect.Slice:
-		return mapSlice(sourceField, destField)
-	case sourceField.Kind() == reflect.Struct && destField.Kind() == reflect.Struct:
-		return mapStructInternal(sourceField, destField)
-	default:
-		return mapSpecialTypes(sourceField, destField)
-	}
-	return nil
-}
-
-func mapSlice(sourceField reflect.Value, destField reflect.Value) error {
-	if sourceField.Type().Elem() == destField.Type().Elem() {
-		newSlice := reflect.MakeSlice(destField.Type(), sourceField.Len(), sourceField.Cap())
-		for j := 0; j < sourceField.Len(); j++ {
-			newSlice.Index(j).Set(sourceField.Index(j))
-		}
-		destField.Set(newSlice)
-	} else if sourceField.Type().Elem().Kind() == reflect.Struct && destField.Type().Elem().Kind() == reflect.Struct {
-		newSlice := reflect.MakeSlice(destField.Type(), sourceField.Len(), sourceField.Cap())
-		for j := 0; j < sourceField.Len(); j++ {
-			sourceElem := sourceField.Index(j)
-			destElem := reflect.New(destField.Type().Elem()).Elem()
-			if err := mapStructInternal(sourceElem, destElem); err != nil {
-				return err
-			}
-			newSlice.Index(j).Set(destElem)
-		}
-		destField.Set(newSlice)
-	}
-	return nil
-}
-
-func mapSpecialTypes(sourceField reflect.Value, destField reflect.Value) error {
-	if _, ok := sourceField.Interface().(datatype.DateTime); ok {
-		if sourceField.Type() == reflect.TypeOf(datatype.DateTime{}) && destField.Type() == reflect.TypeOf(time.Time{}) {
-			dateValue := sourceField.Interface().(datatype.DateTime)
-			destField.Set(reflect.ValueOf(dateValue.ToTime()))
-		}
-	}
-	return nil
+func MapStruct(source any, destination any) error {
+	return copier.CopyWithOption(destination, source, copier.Option{
+		DeepCopy: true,
+	})
 }