commands: add OptionsProvider and OptionCompleter

Improve command completion by supporting option flags and option
arguments completion. Option completion is activated when the command
implements the OptionsProvider interface. Implementing the
OptionCompleter allows the completion of individual option arguments.

The completion interfaces harmonizes the completion behavior in aerc,
makes the completion code clearer and simplifies the completion
functionality.

With this patch, the Complete method on commands will only have to deal
with the actual completion, i.e. paths, folders, etc and not worry about
options. To remove all options and its mandatory arguments from args,
use commands.Operands().

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 9 insertions, 4 deletions

diff --git a/main.go b/main.go
index 99557d2b..9dd166fe 100644
--- a/main.go
+++ b/main.go
@@ -88,13 +88,18 @@ func execCommand(
 	return nil
 }
 
-func getCompletions(aerc *widgets.Aerc, cmd string) []string {
+func getCompletions(aerc *widgets.Aerc, cmd string) ([]string, string) {
 	var completions []string
+	var prefix string
 	for _, set := range getCommands(aerc.SelectedTabContent()) {
-		completions = append(completions, set.GetCompletions(aerc, cmd)...)
+		options, s := set.GetCompletions(aerc, cmd)
+		if s != "" {
+			prefix = s
+		}
+		completions = append(completions, options...)
 	}
 	sort.Strings(completions)
-	return completions
+	return completions, prefix
 }
 
 // set at build time
@@ -198,7 +203,7 @@ func main() {
 		msg *models.MessageInfo,
 	) error {
 		return execCommand(aerc, ui, cmd, acct, msg)
-	}, func(cmd string) []string {
+	}, func(cmd string) ([]string, string) {
 		return getCompletions(aerc, cmd)
 	}, &commands.CmdHistory, deferLoop)