feat: Introduce MediaAssetVariant for better asset management

- Added MediaAssetVariant enum with values 'main' and 'preview'.
- Updated media asset service logic to utilize MediaAssetVariant for variant handling.
- Refactored database models and queries to include variant and source_asset_id fields.
- Enhanced validation for asset variants in upload and processing functions.
- Updated Swagger documentation to reflect new variant structure and descriptions.
- Implemented necessary database migrations to support the new variant constraints.

backend/pkg/consts/consts.gen.go

@@ -1343,6 +1343,166 @@ func (x NullMediaAssetTypeStr) Value() (driver.Value, error) {
 	return x.MediaAssetType.String(), nil
 }
 
+const (
+	// MediaAssetVariantMain is a MediaAssetVariant of type main.
+	MediaAssetVariantMain MediaAssetVariant = "main"
+	// MediaAssetVariantPreview is a MediaAssetVariant of type preview.
+	MediaAssetVariantPreview MediaAssetVariant = "preview"
+)
+
+var ErrInvalidMediaAssetVariant = fmt.Errorf("not a valid MediaAssetVariant, try [%s]", strings.Join(_MediaAssetVariantNames, ", "))
+
+var _MediaAssetVariantNames = []string{
+	string(MediaAssetVariantMain),
+	string(MediaAssetVariantPreview),
+}
+
+// MediaAssetVariantNames returns a list of possible string values of MediaAssetVariant.
+func MediaAssetVariantNames() []string {
+	tmp := make([]string, len(_MediaAssetVariantNames))
+	copy(tmp, _MediaAssetVariantNames)
+	return tmp
+}
+
+// MediaAssetVariantValues returns a list of the values for MediaAssetVariant
+func MediaAssetVariantValues() []MediaAssetVariant {
+	return []MediaAssetVariant{
+		MediaAssetVariantMain,
+		MediaAssetVariantPreview,
+	}
+}
+
+// String implements the Stringer interface.
+func (x MediaAssetVariant) String() string {
+	return string(x)
+}
+
+// IsValid provides a quick way to determine if the typed value is
+// part of the allowed enumerated values
+func (x MediaAssetVariant) IsValid() bool {
+	_, err := ParseMediaAssetVariant(string(x))
+	return err == nil
+}
+
+var _MediaAssetVariantValue = map[string]MediaAssetVariant{
+	"main":    MediaAssetVariantMain,
+	"preview": MediaAssetVariantPreview,
+}
+
+// ParseMediaAssetVariant attempts to convert a string to a MediaAssetVariant.
+func ParseMediaAssetVariant(name string) (MediaAssetVariant, error) {
+	if x, ok := _MediaAssetVariantValue[name]; ok {
+		return x, nil
+	}
+	return MediaAssetVariant(""), fmt.Errorf("%s is %w", name, ErrInvalidMediaAssetVariant)
+}
+
+var errMediaAssetVariantNilPtr = errors.New("value pointer is nil") // one per type for package clashes
+
+// Scan implements the Scanner interface.
+func (x *MediaAssetVariant) Scan(value interface{}) (err error) {
+	if value == nil {
+		*x = MediaAssetVariant("")
+		return
+	}
+
+	// A wider range of scannable types.
+	// driver.Value values at the top of the list for expediency
+	switch v := value.(type) {
+	case string:
+		*x, err = ParseMediaAssetVariant(v)
+	case []byte:
+		*x, err = ParseMediaAssetVariant(string(v))
+	case MediaAssetVariant:
+		*x = v
+	case *MediaAssetVariant:
+		if v == nil {
+			return errMediaAssetVariantNilPtr
+		}
+		*x = *v
+	case *string:
+		if v == nil {
+			return errMediaAssetVariantNilPtr
+		}
+		*x, err = ParseMediaAssetVariant(*v)
+	default:
+		return errors.New("invalid type for MediaAssetVariant")
+	}
+
+	return
+}
+
+// Value implements the driver Valuer interface.
+func (x MediaAssetVariant) Value() (driver.Value, error) {
+	return x.String(), nil
+}
+
+// Set implements the Golang flag.Value interface func.
+func (x *MediaAssetVariant) Set(val string) error {
+	v, err := ParseMediaAssetVariant(val)
+	*x = v
+	return err
+}
+
+// Get implements the Golang flag.Getter interface func.
+func (x *MediaAssetVariant) Get() interface{} {
+	return *x
+}
+
+// Type implements the github.com/spf13/pFlag Value interface.
+func (x *MediaAssetVariant) Type() string {
+	return "MediaAssetVariant"
+}
+
+type NullMediaAssetVariant struct {
+	MediaAssetVariant MediaAssetVariant
+	Valid             bool
+}
+
+func NewNullMediaAssetVariant(val interface{}) (x NullMediaAssetVariant) {
+	err := x.Scan(val) // yes, we ignore this error, it will just be an invalid value.
+	_ = err            // make any errcheck linters happy
+	return
+}
+
+// Scan implements the Scanner interface.
+func (x *NullMediaAssetVariant) Scan(value interface{}) (err error) {
+	if value == nil {
+		x.MediaAssetVariant, x.Valid = MediaAssetVariant(""), false
+		return
+	}
+
+	err = x.MediaAssetVariant.Scan(value)
+	x.Valid = (err == nil)
+	return
+}
+
+// Value implements the driver Valuer interface.
+func (x NullMediaAssetVariant) Value() (driver.Value, error) {
+	if !x.Valid {
+		return nil, nil
+	}
+	// driver.Value accepts int64 for int values.
+	return string(x.MediaAssetVariant), nil
+}
+
+type NullMediaAssetVariantStr struct {
+	NullMediaAssetVariant
+}
+
+func NewNullMediaAssetVariantStr(val interface{}) (x NullMediaAssetVariantStr) {
+	x.Scan(val) // yes, we ignore this error, it will just be an invalid value.
+	return
+}
+
+// Value implements the driver Valuer interface.
+func (x NullMediaAssetVariantStr) Value() (driver.Value, error) {
+	if !x.Valid {
+		return nil, nil
+	}
+	return x.MediaAssetVariant.String(), nil
+}
+
 const (
 	// OrderStatusCreated is a OrderStatus of type created.
 	OrderStatusCreated OrderStatus = "created"

backend/pkg/consts/consts.go

@@ -185,6 +185,32 @@ func MediaAssetStatusItems() []requests.KV {
 	return items
 }
 
+// swagger:enum MediaAssetVariant
+// ENUM( main, preview )
+type MediaAssetVariant string
+
+// Description returns the Chinese label for the specific enum value.
+func (t MediaAssetVariant) Description() string {
+	switch t {
+	case MediaAssetVariantMain:
+		return "正片产物"
+	case MediaAssetVariantPreview:
+		return "试看产物"
+	default:
+		return "未知产物"
+	}
+}
+
+// MediaAssetVariantItems returns the KV list for FE dropdowns.
+func MediaAssetVariantItems() []requests.KV {
+	values := MediaAssetVariantValues()
+	items := make([]requests.KV, 0, len(values))
+	for _, v := range values {
+		items = append(items, requests.NewKV(string(v), v.Description()))
+	}
+	return items
+}
+
 // contents
 
 // swagger:enum ContentStatus