add help

d2plugin/plugin.go

@@ -10,6 +10,7 @@ import (
 	"os/exec"
 
 	"oss.terrastruct.com/util-go/xexec"
+	"oss.terrastruct.com/util-go/xmain"
 
 	"oss.terrastruct.com/d2/d2graph"
 )
@@ -28,6 +29,15 @@ type PluginSpecificFlag struct {
 	Tag string
 }
 
+func (f *PluginSpecificFlag) AddToOpts(opts *xmain.Opts) {
+	switch f.Type {
+	case "string":
+		opts.String("", f.Name, "", f.Default.(string), f.Usage)
+	case "int64":
+		opts.Int64("", f.Name, "", f.Default.(int64), f.Usage)
+	}
+}
+
 type Plugin interface {
 	// Info returns the current info information of the plugin.
 	Info(context.Context) (*PluginInfo, error)

d2plugin/plugin_dagre.go

@@ -5,6 +5,7 @@ package d2plugin
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 
 	"oss.terrastruct.com/d2/d2graph"
 	"oss.terrastruct.com/d2/d2layouts/d2dagrelayout"
@@ -53,18 +54,27 @@ func (p *dagrePlugin) HydrateOpts(opts []byte) error {
 	return nil
 }
 
-func (p dagrePlugin) Info(context.Context) (*PluginInfo, error) {
+func (p dagrePlugin) Info(ctx context.Context) (*PluginInfo, error) {
+	opts := xmain.NewOpts(nil, nil, nil)
+	flags, err := p.Flags(ctx)
+	if err != nil {
+		return nil, err
+	}
+	for _, f := range flags {
+		f.AddToOpts(opts)
+	}
+
 	return &PluginInfo{
 		Name:      "dagre",
 		ShortHelp: "The directed graph layout library Dagre",
-		LongHelp: `dagre is a directed graph layout library for JavaScript.
+		LongHelp: fmt.Sprintf(`dagre is a directed graph layout library for JavaScript.
 See https://github.com/dagrejs/dagre
-The implementation of this plugin is at: https://github.com/terrastruct/d2/tree/master/d2plugin/d2dagrelayout
 
-note: dagre is the primary layout algorithm for text to diagram generator Mermaid.js.
-      See https://github.com/mermaid-js/mermaid
-      We have a useful comparison at https://text-to-diagram.com/?example=basic&a=d2&b=mermaid
-`,
+Flags correspond to ones found at https://github.com/dagrejs/dagre/wiki. See dagre's reference for more on each.
+
+Flags:
+%s
+`, opts.Defaults()),
 	}, nil
 }
 

d2plugin/plugin_elk.go

@@ -5,6 +5,7 @@ package d2plugin
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 
 	"oss.terrastruct.com/d2/d2graph"
 	"oss.terrastruct.com/d2/d2layouts/d2elklayout"
@@ -27,35 +28,35 @@ func (p elkPlugin) Flags(context.Context) ([]PluginSpecificFlag, error) {
 			Name:    "elk-algorithm",
 			Type:    "string",
 			Default: d2elklayout.DefaultOpts.Algorithm,
-			Usage:   "layout algorithm. https://www.eclipse.org/elk/reference/options/org-eclipse-elk-algorithm.html",
+			Usage:   "layout algorithm",
 			Tag:     "elk.algorithm",
 		},
 		{
 			Name:    "elk-nodeNodeBetweenLayers",
 			Type:    "int64",
 			Default: int64(d2elklayout.DefaultOpts.NodeSpacing),
-			Usage:   "the spacing to be preserved between any pair of nodes of two adjacent layers. https://www.eclipse.org/elk/reference/options/org-eclipse-elk-layered-spacing-nodeNodeBetweenLayers.html",
+			Usage:   "the spacing to be preserved between any pair of nodes of two adjacent layers",
 			Tag:     "spacing.nodeNodeBetweenLayers",
 		},
 		{
 			Name:    "elk-padding",
 			Type:    "string",
 			Default: d2elklayout.DefaultOpts.Padding,
-			Usage:   "the padding to be left to a parent element’s border when placing child elements. https://www.eclipse.org/elk/reference/options/org-eclipse-elk-padding.html",
+			Usage:   "the padding to be left to a parent element’s border when placing child elements",
 			Tag:     "elk.padding",
 		},
 		{
 			Name:    "elk-edgeNodeBetweenLayers",
 			Type:    "int64",
 			Default: int64(d2elklayout.DefaultOpts.EdgeNodeSpacing),
-			Usage:   "the spacing to be preserved between nodes and edges that are routed next to the node’s layer. https://www.eclipse.org/elk/reference/options/org-eclipse-elk-layered-spacing-edgeNodeBetweenLayers.html",
+			Usage:   "the spacing to be preserved between nodes and edges that are routed next to the node’s layer",
 			Tag:     "spacing.edgeNodeBetweenLayers",
 		},
 		{
 			Name:    "elk-nodeSelfLoop",
 			Type:    "int64",
 			Default: int64(d2elklayout.DefaultOpts.SelfLoopSpacing),
-			Usage:   "spacing to be preserved between a node and its self loops. https://www.eclipse.org/elk/reference/options/org-eclipse-elk-spacing-nodeSelfLoop.html",
+			Usage:   "spacing to be preserved between a node and its self loops",
 			Tag:     "elk.spacing.nodeSelfLoop",
 		},
 	}, nil
@@ -75,13 +76,27 @@ func (p *elkPlugin) HydrateOpts(opts []byte) error {
 	return nil
 }
 
-func (p elkPlugin) Info(context.Context) (*PluginInfo, error) {
+func (p elkPlugin) Info(ctx context.Context) (*PluginInfo, error) {
+	opts := xmain.NewOpts(nil, nil, nil)
+	flags, err := p.Flags(ctx)
+	if err != nil {
+		return nil, err
+	}
+	for _, f := range flags {
+		f.AddToOpts(opts)
+	}
 	return &PluginInfo{
 		Name:      "elk",
 		ShortHelp: "Eclipse Layout Kernel (ELK) with the Layered algorithm.",
-		LongHelp: `ELK is a layout engine offered by Eclipse.
+		LongHelp: fmt.Sprintf(`ELK is a layout engine offered by Eclipse.
 Originally written in Java, it has been ported to Javascript and cross-compiled into D2.
-See https://github.com/kieler/elkjs for more.`,
+See https://github.com/kieler/elkjs for more.
+
+Flags correspond to ones found in https://www.eclipse.org/elk/reference.html. See ELK's reference for more on each.
+
+Flags:
+%s
+`, opts.Defaults()),
 	}, nil
 }
 

main.go

@@ -307,12 +307,9 @@ func populateLayoutOpts(ctx context.Context, ms *xmain.State) error {
 	}
 
 	for _, f := range pluginFlags {
-		switch f.Type {
-		case "string":
-			ms.Opts.String("", f.Name, "", f.Default.(string), f.Usage)
-		case "int64":
-			ms.Opts.Int64("", f.Name, "", f.Default.(int64), f.Usage)
-		}
+		f.AddToOpts(ms.Opts)
+		// Don't pollute the main d2 flagset with these. It'll be a lot
+		ms.Opts.Flags.MarkHidden(f.Name)
 	}
 
 	return nil