Add :detach command

Add a command for removing attachments from a composed message. Syntax
is :detach [path], with path being an optional argument specifying the
path of one existing attachment. If no path is specified, the first
attachment is removed.

commands/compose/detach.go

@@ -0,0 +1,55 @@
+package compose
+
+import (
+	"fmt"
+	"time"
+
+	"git.sr.ht/~sircmpwn/aerc/widgets"
+	"github.com/gdamore/tcell"
+)
+
+type Detach struct{}
+
+func init() {
+	register(Detach{})
+}
+
+func (_ Detach) Aliases() []string {
+	return []string{"detach"}
+}
+
+func (_ Detach) Complete(aerc *widgets.Aerc, args []string) []string {
+	composer, _ := aerc.SelectedTab().(*widgets.Composer)
+
+	return composer.GetAttachments()
+}
+
+func (_ Detach) Execute(aerc *widgets.Aerc, args []string) error {
+	var path string
+	composer, _ := aerc.SelectedTab().(*widgets.Composer)
+
+	if len(args) > 2 {
+		return fmt.Errorf("Usage: :detach [path]")
+	}
+
+	if len(args) == 2 {
+		path = args[1]
+	} else {
+		// if no attachment is specified, delete the first in the list
+		atts := composer.GetAttachments()
+		if len(atts) > 0 {
+			path = atts[0]
+		} else {
+			return fmt.Errorf("No attachments to delete")
+		}
+	}
+
+	if err := composer.DeleteAttachment(path); err != nil {
+		return err
+	}
+
+	aerc.PushStatus(fmt.Sprintf("Detached %s", path), 10*time.Second).
+		Color(tcell.ColorDefault, tcell.ColorGreen)
+
+	return nil
+}