Generate flag types (again?)

Closes #1381

internal/genflags/cmd/genflags/main.go

@@ -0,0 +1,161 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	_ "embed"
+	"log"
+	"os"
+	"os/exec"
+	"os/signal"
+	"path/filepath"
+	"strings"
+	"syscall"
+	"text/template"
+
+	"github.com/urfave/cli/v2"
+	"github.com/urfave/cli/v2/internal/genflags"
+	"gopkg.in/yaml.v2"
+)
+
+const (
+	defaultPackageName = "cli"
+)
+
+func sh(ctx context.Context, exe string, args ...string) (string, error) {
+	cmd := exec.CommandContext(ctx, exe, args...)
+	cmd.Stderr = os.Stderr
+	outBytes, err := cmd.Output()
+	return string(outBytes), err
+}
+
+func main() {
+	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer stop()
+
+	top := "../../"
+	if v, err := sh(ctx, "git", "rev-parse", "--show-toplevel"); err == nil {
+		top = strings.TrimSpace(v)
+	}
+
+	app := &cli.App{
+		Flags: []cli.Flag{
+			&cli.PathFlag{
+				Name:    "flag-spec-yaml",
+				Aliases: []string{"f"},
+				Value:   filepath.Join(top, "flag-spec.yaml"),
+			},
+			&cli.PathFlag{
+				Name:    "generated-output",
+				Aliases: []string{"o"},
+				Value:   filepath.Join(top, "zz_generated.flags.go"),
+			},
+			&cli.PathFlag{
+				Name:    "generated-test-output",
+				Aliases: []string{"t"},
+				Value:   filepath.Join(top, "zz_generated.flags_test.go"),
+			},
+			&cli.StringFlag{
+				Name:    "generated-package-name",
+				Aliases: []string{"p"},
+				Value:   defaultPackageName,
+			},
+			&cli.StringFlag{
+				Name:    "generated-test-package-name",
+				Aliases: []string{"T"},
+				Value:   defaultPackageName + "_test",
+			},
+			&cli.StringFlag{
+				Name:    "urfave-cli-namespace",
+				Aliases: []string{"n"},
+				Value:   "",
+			},
+			&cli.StringFlag{
+				Name:    "urfave-cli-test-namespace",
+				Aliases: []string{"N"},
+				Value:   "cli.",
+			},
+		},
+		Action: runGenFlags,
+	}
+
+	if err := app.RunContext(ctx, os.Args); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func runGenFlags(cCtx *cli.Context) error {
+	specBytes, err := os.ReadFile(cCtx.Path("flag-spec-yaml"))
+	if err != nil {
+		return err
+	}
+
+	spec := &genflags.Spec{}
+	if err := yaml.Unmarshal(specBytes, spec); err != nil {
+		return err
+	}
+
+	if cCtx.IsSet("generated-package-name") {
+		spec.PackageName = strings.TrimSpace(cCtx.String("generated-package-name"))
+	}
+
+	if strings.TrimSpace(spec.PackageName) == "" {
+		spec.PackageName = defaultPackageName
+	}
+
+	if cCtx.IsSet("generated-test-package-name") {
+		spec.TestPackageName = strings.TrimSpace(cCtx.String("generated-test-package-name"))
+	}
+
+	if strings.TrimSpace(spec.TestPackageName) == "" {
+		spec.TestPackageName = defaultPackageName + "_test"
+	}
+
+	if cCtx.IsSet("urfave-cli-namespace") {
+		spec.UrfaveCLINamespace = strings.TrimSpace(cCtx.String("urfave-cli-namespace"))
+	}
+
+	if cCtx.IsSet("urfave-cli-test-namespace") {
+		spec.UrfaveCLITestNamespace = strings.TrimSpace(cCtx.String("urfave-cli-test-namespace"))
+	} else {
+		spec.UrfaveCLITestNamespace = "cli."
+	}
+
+	genTmpl, err := template.New("gen").Parse(genflags.TemplateString)
+	if err != nil {
+		return err
+	}
+
+	genTestTmpl, err := template.New("gen_test").Parse(genflags.TestTemplateString)
+	if err != nil {
+		return err
+	}
+
+	genBuf := &bytes.Buffer{}
+	if err := genTmpl.Execute(genBuf, spec); err != nil {
+		return err
+	}
+
+	genTestBuf := &bytes.Buffer{}
+	if err := genTestTmpl.Execute(genTestBuf, spec); err != nil {
+		return err
+	}
+
+	if err := os.WriteFile(cCtx.Path("generated-output"), genBuf.Bytes(), 0644); err != nil {
+		return err
+	}
+
+	if err := os.WriteFile(cCtx.Path("generated-test-output"), genTestBuf.Bytes(), 0644); err != nil {
+		return err
+	}
+
+	if _, err := sh(cCtx.Context, "goimports", "-w", cCtx.Path("generated-output")); err != nil {
+		return err
+	}
+
+	if _, err := sh(cCtx.Context, "goimports", "-w", cCtx.Path("generated-test-output")); err != nil {
+		return err
+	}
+
+	return nil
+}