Implement :next-part, :prev-part

commands/msgview/next-part.go

@@ -0,0 +1,43 @@
+package msgview
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+
+	"git.sr.ht/~sircmpwn/aerc/widgets"
+)
+
+func init() {
+	register("next-part", NextPrevPart)
+	register("prev-part", NextPrevPart)
+}
+
+func nextPrevPartUsage(cmd string) error {
+	return errors.New(fmt.Sprintf("Usage: %s [n]", cmd))
+}
+
+func NextPrevPart(aerc *widgets.Aerc, args []string) error {
+	if len(args) > 2 {
+		return nextPrevPartUsage(args[0])
+	}
+	var (
+		n   int = 1
+		err error
+	)
+	if len(args) > 1 {
+		n, err = strconv.Atoi(args[1])
+		if err != nil {
+			return nextPrevPartUsage(args[0])
+		}
+	}
+	mv, _ := aerc.SelectedTab().(*widgets.MessageViewer)
+	for ; n > 0; n-- {
+		if args[0] == "prev-part" {
+			mv.PreviousPart()
+		} else {
+			mv.NextPart()
+		}
+	}
+	return nil
+}