save: add -a option to save all attachments

Allow saving all message parts that have the content disposition
"attachment" header to a folder.

Suggested-by: Ondřej Synáček <ondrej@synacek.org>
Signed-off-by: Robin Jarry <robin@jarry.cc>
Acked-by: Koni Marti <koni.marti@gmail.com>
Tested-by: Moritz Poldrack <moritz@poldrack.dev>

commands/msgview/save.go

@@ -13,6 +13,7 @@ import (
 	"github.com/mitchellh/go-homedir"
 
 	"git.sr.ht/~rjarry/aerc/commands"
+	"git.sr.ht/~rjarry/aerc/lib"
 	"git.sr.ht/~rjarry/aerc/logging"
 	"git.sr.ht/~rjarry/aerc/models"
 	"git.sr.ht/~rjarry/aerc/widgets"
@@ -33,31 +34,36 @@ func (Save) Complete(aerc *widgets.Aerc, args []string) []string {
 	return commands.CompletePath(path)
 }
 
+type saveParams struct {
+	force         bool
+	createDirs    bool
+	trailingSlash bool
+	attachments   bool
+}
+
 func (Save) Execute(aerc *widgets.Aerc, args []string) error {
-	opts, optind, err := getopt.Getopts(args, "fp")
+	opts, optind, err := getopt.Getopts(args, "fpa")
 	if err != nil {
 		return err
 	}
 
-	var (
-		force         bool
-		createDirs    bool
-		trailingSlash bool
-	)
+	var params saveParams
 
 	for _, opt := range opts {
 		switch opt.Option {
 		case 'f':
-			force = true
+			params.force = true
 		case 'p':
-			createDirs = true
+			params.createDirs = true
+		case 'a':
+			params.attachments = true
 		}
 	}
 
 	defaultPath := aerc.Config().General.DefaultSavePath
 	// we either need a path or a defaultPath
 	if defaultPath == "" && len(args) == optind {
-		return errors.New("Usage: :save [-fp] <path>")
+		return errors.New("Usage: :save [-fpa] <path>")
 	}
 
 	// as a convenience we join with spaces, so that the user doesn't need to
@@ -68,10 +74,10 @@ func (Save) Execute(aerc *widgets.Aerc, args []string) error {
 	// it gets stripped by Clean.
 	// we auto generate a name if a directory was given
 	if len(path) > 0 {
-		trailingSlash = path[len(path)-1] == '/'
+		params.trailingSlash = path[len(path)-1] == '/'
 	} else if len(defaultPath) > 0 && len(path) == 0 {
 		// empty path, so we might have a default that ends in a trailingSlash
-		trailingSlash = defaultPath[len(defaultPath)-1] == '/'
+		params.trailingSlash = defaultPath[len(defaultPath)-1] == '/'
 	}
 
 	// Absolute paths are taken as is so that the user can override the default
@@ -89,27 +95,53 @@ func (Save) Execute(aerc *widgets.Aerc, args []string) error {
 	if !ok {
 		return fmt.Errorf("SelectedTab is not a MessageViewer")
 	}
-	pi := mv.SelectedMessagePart()
 
-	if trailingSlash || isDirExists(path) {
+	store := mv.Store()
+
+	if params.attachments {
+		parts := mv.AttachmentParts()
+		if len(parts) == 0 {
+			return fmt.Errorf("This message has no attachments")
+		}
+		params.trailingSlash = true
+		for _, pi := range parts {
+			if err := savePart(pi, path, store, aerc, &params); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+
+	pi := mv.SelectedMessagePart()
+	return savePart(pi, path, store, aerc, &params)
+}
+
+func savePart(
+	pi *widgets.PartInfo,
+	path string,
+	store *lib.MessageStore,
+	aerc *widgets.Aerc,
+	params *saveParams,
+) error {
+
+	if params.trailingSlash || isDirExists(path) {
 		filename := generateFilename(pi.Part)
 		path = filepath.Join(path, filename)
 	}
 
 	dir := filepath.Dir(path)
-	if createDirs && dir != "" {
+	if params.createDirs && dir != "" {
 		err := os.MkdirAll(dir, 0755)
 		if err != nil {
 			return err
 		}
 	}
 
-	if pathExists(path) && !force {
+	if pathExists(path) && !params.force {
 		return fmt.Errorf("%q already exists and -f not given", path)
 	}
 
 	ch := make(chan error, 1)
-	store := mv.Store()
 	store.FetchBodyPart(pi.Msg.Uid, pi.Index, func(reader io.Reader) {
 		f, err := os.Create(path)
 		if err != nil {