pkg/imagefilter/formatter: add shell output

This should implement the initial idea of a
copy'n'paste ready list of possibilities.

pkg/imagefilter/formatter.go

@@ -11,9 +11,10 @@ import (
 type OutputFormat string
 
 const (
-	OutputFormatDefault OutputFormat = ""
-	OutputFormatText    OutputFormat = "text"
-	OutputFormatJSON    OutputFormat = "json"
+	OutputFormatDefault   OutputFormat = ""
+	OutputFormatText      OutputFormat = "text"
+	OutputFormatJSON      OutputFormat = "json"
+	OutputFormatTextShell OutputFormat = "shell"
 )
 
 // ResultFormatter will format the given result list to the given io.Writer
@@ -28,6 +29,8 @@ func NewResultsFormatter(format OutputFormat) (ResultsFormatter, error) {
 		return &textResultsFormatter{}, nil
 	case OutputFormatJSON:
 		return &jsonResultsFormatter{}, nil
+	case OutputFormatTextShell:
+		return &shellResultsFormatter{}, nil
 	default:
 		return nil, fmt.Errorf("unsupported formatter %q", format)
 	}
@@ -54,6 +57,26 @@ func (*textResultsFormatter) Output(w io.Writer, all []Result) error {
 	return nil
 }
 
+type shellResultsFormatter struct{}
+
+func (*shellResultsFormatter) Output(w io.Writer, all []Result) error {
+	var errs []error
+
+	for _, res := range all {
+		if _, err := fmt.Fprintf(w, "%s --distro %s --arch %s\n",
+			res.ImgType.Name(),
+			res.Distro.Name(),
+			res.Arch.Name()); err != nil {
+			errs = append(errs, err)
+		}
+	}
+	if len(errs) > 0 {
+		return errors.Join(errs...)
+	}
+
+	return nil
+}
+
 type jsonResultsFormatter struct{}
 
 type distroResultJSON struct {

pkg/imagefilter/formatter_test.go

@@ -65,6 +65,11 @@ func TestResultsFormatter(t *testing.T) {
 			},
 			`[{"distro":{"name":"test-distro-1"},"arch":{"name":"test_arch3"},"image_type":{"name":"qcow2"}},{"distro":{"name":"test-distro-1"},"arch":{"name":"test_arch"},"image_type":{"name":"test_type"}}]` + "\n",
 		},
+		{
+			"shell",
+			[]string{"test-distro-1:qcow2:test_arch3"},
+			"qcow2 --distro test-distro-1 --arch test_arch3\n",
+		},
 	} {
 		res := make([]imagefilter.Result, len(tc.fakeResults))
 		for i, resultSpec := range tc.fakeResults {