Move role types to a separate package (#55665)

* Move role types to a separate package

* Make role type singular and remove _ from directory name

pkg/models/roletype/role_type.go

@@ -0,0 +1,69 @@
+package roletype
+
+import (
+	"fmt"
+	"strings"
+)
+
+// swagger:enum RoleType
+type RoleType string
+
+const (
+	RoleViewer RoleType = "Viewer"
+	RoleEditor RoleType = "Editor"
+	RoleAdmin  RoleType = "Admin"
+)
+
+func (r RoleType) IsValid() bool {
+	return r == RoleViewer || r == RoleAdmin || r == RoleEditor
+}
+
+func (r RoleType) Includes(other RoleType) bool {
+	if r == RoleAdmin {
+		return true
+	}
+
+	if r == RoleEditor {
+		return other != RoleAdmin
+	}
+
+	return r == other
+}
+
+func (r RoleType) Children() []RoleType {
+	switch r {
+	case RoleAdmin:
+		return []RoleType{RoleEditor, RoleViewer}
+	case RoleEditor:
+		return []RoleType{RoleViewer}
+	default:
+		return nil
+	}
+}
+
+func (r RoleType) Parents() []RoleType {
+	switch r {
+	case RoleEditor:
+		return []RoleType{RoleAdmin}
+	case RoleViewer:
+		return []RoleType{RoleEditor, RoleAdmin}
+	default:
+		return nil
+	}
+}
+
+func (r *RoleType) UnmarshalText(data []byte) error {
+	// make sure "viewer" and "Viewer" are both correct
+	str := strings.Title(string(data))
+
+	*r = RoleType(str)
+	if !r.IsValid() {
+		if (*r) != "" {
+			return fmt.Errorf("invalid role value: %s", *r)
+		}
+
+		*r = RoleViewer
+	}
+
+	return nil
+}