feat: add file type filtering for attachment options and file uploads

discord/application_command_option.go

@@ -547,9 +547,18 @@ type ApplicationCommandOptionAttachment struct {
 	Description              string            `json:"description"`
 	DescriptionLocalizations map[Locale]string `json:"description_localizations,omitempty"`
 	Required                 bool              `json:"required,omitempty"`
+	FileTypes                []FileType        `json:"file_types,omitempty"`
 }
 
 func (o ApplicationCommandOptionAttachment) MarshalJSON() ([]byte, error) {
+	if len(o.FileTypes) > MaxFileTypes {
+		return nil, fmt.Errorf("cannot have more than %d file types, got %d", MaxFileTypes, len(o.FileTypes))
+	}
+	for _, fileType := range o.FileTypes {
+		if !fileType.isValid() {
+			return nil, fmt.Errorf("invalid file type %q, must be image, video, audio or a dot-prefixed extension (e.g. \".pdf\")", fileType)
+		}
+	}
 	type applicationCommandOptionAttachment ApplicationCommandOptionAttachment
 	return json.Marshal(struct {
 		Type ApplicationCommandOptionType `json:"type"`

discord/component.go

@@ -1477,6 +1477,8 @@ type FileUploadComponent struct {
 	MaxValues int `json:"max_values,omitempty"`
 	// Required specifies whether the file upload is required. (default: false)
 	Required bool `json:"required"`
+	// FileTypes is the file types to filter for. (default: allows all file types, max: 10)
+	FileTypes []FileType `json:"file_types,omitempty"`
 	// Values is only set when the FileUploadComponent is received from an InteractionTypeModalSubmit
 	Values []snowflake.ID `json:"values,omitempty"`
 }
@@ -1486,6 +1488,14 @@ func (f FileUploadComponent) interactiveComponent() {}
 func (f FileUploadComponent) labelSubComponent()    {}
 
 func (f FileUploadComponent) MarshalJSON() ([]byte, error) {
+	if len(f.FileTypes) > MaxFileTypes {
+		return nil, fmt.Errorf("cannot have more than %d file types, got %d", MaxFileTypes, len(f.FileTypes))
+	}
+	for _, fileType := range f.FileTypes {
+		if !fileType.isValid() {
+			return nil, fmt.Errorf("invalid file type %q, must be image, video, audio or a dot-prefixed extension (e.g. \".pdf\")", fileType)
+		}
+	}
 	type fileUploadComponent FileUploadComponent
 	return json.Marshal(struct {
 		Type ComponentType `json:"type"`
@@ -1538,6 +1548,12 @@ func (f FileUploadComponent) WithRequired(required bool) FileUploadComponent {
 	return f
 }
 
+// WithFileTypes returns a new FileUploadComponent with the provided fileTypes
+func (f FileUploadComponent) WithFileTypes(fileTypes ...FileType) FileUploadComponent {
+	f.FileTypes = fileTypes
+	return f
+}
+
 var (
 	_ Component            = (*RadioGroupComponent)(nil)
 	_ InteractiveComponent = (*RadioGroupComponent)(nil)

discord/file_type.go

@@ -0,0 +1,49 @@
+package discord
+
+import (
+	"fmt"
+	"regexp"
+)
+
+// MaxFileTypes is the maximum number of file types that can be filtered for at once.
+// https://docs.discord.com/developers/reference#file-type-filtering
+const MaxFileTypes = 10
+
+var fileTypeExtensionPattern = regexp.MustCompile(`^\.[\w](?:[\w.-]*[\w])?$`)
+
+// NewFileType creates a new FileType for a custom file extension, e.g. NewFileType(".pdf").
+// The extension must be dot-prefixed and only contain latin letters, digits, dashes or dots.
+// Use the FileTypeImage, FileTypeVideo or FileTypeAudio constants for the preset file groups.
+func NewFileType(extension string) (FileType, error) {
+	if !fileTypeExtensionPattern.MatchString(extension) {
+		return "", fmt.Errorf(`file type extension %q must be dot-prefixed (e.g. ".pdf") and only contain latin letters, digits, dashes or dots`, extension)
+	}
+	return FileType(extension), nil
+}
+
+// FileType represents a type of file to filter for in FileUploadComponents and ApplicationCommandOptionAttachment.
+// It can be a preset group like FileTypeImage, FileTypeVideo or FileTypeAudio, or a custom file extension like ".pdf".
+// File types only match against the file extension, Discord does not validate the actual content of the file.
+// Up to [MaxFileTypes] file types can be specified, each file type is validated when marshaled.
+// https://docs.discord.com/developers/reference#file-type-filtering
+type FileType string
+
+// Preset FileType groups.
+const (
+	FileTypeGroupImage FileType = "image"
+	FileTypeGroupVideo FileType = "video"
+	FileTypeGroupAudio FileType = "audio"
+)
+
+func (t FileType) String() string {
+	return string(t)
+}
+
+func (t FileType) isValid() bool {
+	switch t {
+	case FileTypeGroupImage, FileTypeGroupVideo, FileTypeGroupAudio:
+		return true
+	default:
+		return fileTypeExtensionPattern.MatchString(string(t))
+	}
+}