add ctx, implement exec

d2plugin/exec.go

@@ -41,9 +41,29 @@ type execPlugin struct {
 	opts map[string]string
 }
 
-func (p execPlugin) Flags() []PluginSpecificFlag {
+func (p execPlugin) Flags(ctx context.Context) (_ []PluginSpecificFlag, err error) {
-	// TODO
+	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
-	return nil
+	defer cancel()
+	cmd := exec.CommandContext(ctx, p.path, "flags")
+	defer xdefer.Errorf(&err, "failed to run %v", cmd.Args)
+
+	stdout, err := cmd.Output()
+	if err != nil {
+		ee := &exec.ExitError{}
+		if errors.As(err, &ee) && len(ee.Stderr) > 0 {
+			return nil, fmt.Errorf("%v\nstderr:\n%s", ee, ee.Stderr)
+		}
+		return nil, err
+	}
+
+	var flags []PluginSpecificFlag
+
+	err = json.Unmarshal(stdout, &flags)
+	if err != nil {
+		return nil, fmt.Errorf("failed to unmarshal json: %w", err)
+	}
+
+	return flags, nil
 }
 
 func (p *execPlugin) HydrateOpts(opts []byte) error {

d2plugin/plugin.go

@@ -32,7 +32,7 @@ type Plugin interface {
 	// Info returns the current info information of the plugin.
 	Info(context.Context) (*PluginInfo, error)
 
-	Flags() []PluginSpecificFlag
+	Flags(context.Context) ([]PluginSpecificFlag, error)
 
 	HydrateOpts([]byte) error
 
@@ -123,10 +123,14 @@ func FindPlugin(ctx context.Context, name string) (Plugin, string, error) {
 	return &execPlugin{path: path}, path, nil
 }
 
-func ListPluginFlags() []PluginSpecificFlag {
+func ListPluginFlags(ctx context.Context) ([]PluginSpecificFlag, error) {
 	var out []PluginSpecificFlag
 	for _, p := range plugins {
-		out = append(out, p.Flags()...)
+		flags, err := p.Flags(ctx)
+		if err != nil {
+			return nil, err
 		}
-	return out
+		out = append(out, flags...)
+	}
+	return out, nil
 }

d2plugin/plugin_dagre.go

@@ -21,7 +21,7 @@ type dagrePlugin struct {
 	opts *d2dagrelayout.Opts
 }
 
-func (p dagrePlugin) Flags() []PluginSpecificFlag {
+func (p dagrePlugin) Flags(context.Context) ([]PluginSpecificFlag, error) {
 	return []PluginSpecificFlag{
 		{
 			Name:    "dagre-nodesep",
@@ -37,7 +37,7 @@ func (p dagrePlugin) Flags() []PluginSpecificFlag {
 			Usage:   "number of pixels that separate edges horizontally.",
 			Tag:     "edgesep",
 		},
-	}
+	}, nil
 }
 
 func (p *dagrePlugin) HydrateOpts(opts []byte) error {

d2plugin/plugin_elk.go

@@ -21,7 +21,7 @@ type elkPlugin struct {
 	opts *d2elklayout.ConfigurableOpts
 }
 
-func (p elkPlugin) Flags() []PluginSpecificFlag {
+func (p elkPlugin) Flags(context.Context) ([]PluginSpecificFlag, error) {
 	// ms.Opts.String("", "elk-algorithm", "", d2elklayout.DefaultOpts.Algorithm, "number of pixels that separate nodes horizontally.")
 	//   _, err = ms.Opts.Int64("", "elk-nodeNodeBetweenLayers", "", int64(d2elklayout.DefaultOpts.NodeSpacing), "number of pixels that separate edges horizontally.")
 	//   if err != nil {
@@ -44,7 +44,7 @@ func (p elkPlugin) Flags() []PluginSpecificFlag {
 			Usage:   "number of pixels that separate nodes horizontally.",
 			Tag:     "elk.algorithm",
 		},
-	}
+	}, nil
 }
 
 func (p *elkPlugin) HydrateOpts(opts []byte) error {

main.go

@@ -76,7 +76,7 @@ func run(ctx context.Context, ms *xmain.State) (err error) {
 		return err
 	}
 
-	err = populateLayoutOpts(ms)
+	err = populateLayoutOpts(ctx, ms)
 	if err != nil {
 		return err
 	}
@@ -150,7 +150,7 @@ func run(ctx context.Context, ms *xmain.State) (err error) {
 		return err
 	}
 
-	err = parseLayoutOpts(ms, plugin)
+	err = parseLayoutOpts(ctx, ms, plugin)
 	if err != nil {
 		return err
 	}
@@ -300,8 +300,11 @@ func DiscardSlog(ctx context.Context) context.Context {
 	return ctxlog.With(ctx, slog.Make(sloghuman.Sink(io.Discard)))
 }
 
-func populateLayoutOpts(ms *xmain.State) error {
+func populateLayoutOpts(ctx context.Context, ms *xmain.State) error {
-	pluginFlags := d2plugin.ListPluginFlags()
+	pluginFlags, err := d2plugin.ListPluginFlags(ctx)
+	if err != nil {
+		return err
+	}
 
 	for _, f := range pluginFlags {
 		switch f.Type {
@@ -315,9 +318,13 @@ func populateLayoutOpts(ms *xmain.State) error {
 	return nil
 }
 
-func parseLayoutOpts(ms *xmain.State, plugin d2plugin.Plugin) error {
+func parseLayoutOpts(ctx context.Context, ms *xmain.State, plugin d2plugin.Plugin) error {
 	opts := make(map[string]interface{})
-	for _, f := range plugin.Flags() {
+	flags, err := plugin.Flags(ctx)
+	if err != nil {
+		return err
+	}
+	for _, f := range flags {
 		switch f.Type {
 		case "string":
 			val, _ := ms.Opts.Flags.GetString(f.Name)