feat: add helper to auto-generate cli docs (#40)

docs/docs.go

@@ -0,0 +1,99 @@
+package docs
+
+import (
+	"bytes"
+	"embed"
+	"html/template"
+	"sort"
+	"strings"
+
+	"github.com/urfave/cli/v2"
+)
+
+type PluginArg struct {
+	Name        string
+	EnvVars     []string
+	Description string
+	Default     string
+}
+
+type CliTemplate struct {
+	Name        string
+	Version     string
+	Description string
+	Usage       string
+	UsageText   string
+	GlobalArgs  []*PluginArg
+}
+
+//go:embed templates
+var templateFs embed.FS
+
+// ToMarkdown creates a markdown string for the `*App`
+// The function errors if either parsing or writing of the string fails.
+func ToMarkdown(app *cli.App) (string, error) {
+	var w bytes.Buffer
+
+	tpls, err := template.New("cli").ParseFS(templateFs, "**/*.tmpl")
+	if err != nil {
+		return "", err
+	}
+
+	if err := tpls.ExecuteTemplate(&w, "markdown.md.tmpl", GetTemplateData(app)); err != nil {
+		return "", err
+	}
+
+	return w.String(), nil
+}
+
+func GetTemplateData(app *cli.App) *CliTemplate {
+	return &CliTemplate{
+		Name:        app.Name,
+		Version:     app.Version,
+		Description: prepareMultilineString(app.Description),
+		Usage:       prepareMultilineString(app.Usage),
+		UsageText:   prepareMultilineString(app.UsageText),
+		GlobalArgs:  prepareArgsWithValues(app.VisibleFlags()),
+	}
+}
+
+func prepareMultilineString(s string) string {
+	return strings.TrimRight(
+		strings.TrimSpace(
+			strings.ReplaceAll(s, "\n", " "),
+		),
+		".\r\n\t",
+	)
+}
+
+func prepareArgsWithValues(flags []cli.Flag) []*PluginArg {
+	return parseFlags(flags)
+}
+
+func parseFlags(flags []cli.Flag) []*PluginArg {
+	args := make([]*PluginArg, 0)
+
+	for _, f := range flags {
+		flag, ok := f.(cli.DocGenerationFlag)
+		if !ok {
+			continue
+		}
+
+		modArg := &PluginArg{}
+
+		name := flag.GetEnvVars()[0]
+		name = strings.TrimPrefix(name, "PLUGIN_")
+		modArg.Name = strings.ToLower(strings.TrimSpace(name))
+
+		modArg.Description = flag.GetUsage()
+		modArg.Default = flag.GetDefaultText()
+
+		args = append(args, modArg)
+	}
+
+	sort.SliceStable(args, func(i, j int) bool {
+		return args[i].Name < args[j].Name
+	})
+
+	return args
+}

docs/docs_test.go

@@ -0,0 +1,67 @@
+package docs
+
+import (
+	"bytes"
+	"os"
+	"testing"
+
+	"github.com/urfave/cli/v2"
+)
+
+func testApp() *cli.App {
+	app := &cli.App{
+		Name:        "test",
+		Description: "test description",
+		Flags: []cli.Flag{
+			&cli.StringFlag{
+				Name:    "dummy-flag",
+				Usage:   "dummy flag desc",
+				EnvVars: []string{"PLUGIN_DUMMY_FLAG"},
+				Value:   "test",
+			},
+			&cli.StringFlag{
+				Name:    "simpe-flag",
+				EnvVars: []string{"PLUGIN_X_SIMPLE_FLAG"},
+			},
+			&cli.StringFlag{
+				Name:    "other.flag",
+				Usage:   "other flag with desc",
+				EnvVars: []string{"PLUGIN_Z_OTHER_FLAG"},
+			},
+		},
+	}
+
+	return app
+}
+
+func testFileContent(t *testing.T, file string) string {
+	t.Helper()
+
+	data, err := os.ReadFile(file)
+	if err != nil {
+		t.Error(err)
+	}
+
+	data = bytes.ReplaceAll(data, []byte("\r\n"), []byte("\n"))
+
+	return string(data)
+}
+
+func TestToMarkdownFull(t *testing.T) {
+	tests := []struct {
+		name string
+		app  *cli.App
+		want string
+	}{
+		{"normal branch", testApp(), "testdata/expected-doc-full.md"},
+	}
+
+	for _, tt := range tests {
+		want := testFileContent(t, tt.want)
+		t.Run(tt.name, func(t *testing.T) {
+			if got, _ := ToMarkdown(tt.app); got != want {
+				t.Errorf("got = %v, want %v", got, want)
+			}
+		})
+	}
+}

docs/templates/markdown.md.tmpl

@@ -0,0 +1,15 @@
+{{ with .Name }}# {{ . }}{{ end }}
+{{- with .Description }}
+
+{{ . }}
+{{- end }}
+{{- if .GlobalArgs }}
+
+## Parameters
+{{ range $v := .GlobalArgs }}
+**_{{ $v.Name }}_**{{ with $v.Default }} (defaut: {{ . }}){{ end }}{{ if $v.Description }}{{ "\\" }}{{ end }}
+{{- with $v.Description }}
+ {{ . }}
+{{- end }}
+{{ end -}}
+{{ end -}}

docs/testdata/expected-doc-full.md

@@ -0,0 +1,13 @@
+# test
+
+test description
+
+## Parameters
+
+**_dummy_flag_** (defaut: "test")\
+ dummy flag desc
+
+**_x_simple_flag_**
+
+**_z_other_flag_**\
+ other flag with desc