feat: add support for formatting jsonnet with substation cli (#250)

cmd/substation/fmt.go

@@ -0,0 +1,107 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/google/go-jsonnet/formatter"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(fmtCmd)
+	fmtCmd.PersistentFlags().BoolP("write", "w", false, "write result to (source) file instead of stdout")
+	fmtCmd.PersistentFlags().BoolP("recursive", "R", false, "recursively format all files")
+}
+
+var fmtCmd = &cobra.Command{
+	Use:   "fmt [path]",
+	Short: "format configs",
+	Long: `'substation fmt' formats Jsonnet files.
+It prints the formatted output to stdout by default.
+Use the --write flag to update the files in-place.
+
+The command can format a single file or a directory.
+Use the --recursive flag to format all files in a directory and its subdirectories.
+
+Supported file extensions: .jsonnet, .libsonnet`,
+	Example: `  substation fmt config.jsonnet
+  substation fmt -w config.jsonnet
+  substation fmt -R /path/to/configs
+  substation fmt -w -R /path/to/configs`,
+	Args: cobra.MaximumNArgs(1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		// Default to current directory if no path is provided
+		path := "."
+		if len(args) > 0 {
+			path = args[0]
+		}
+
+		write, err := cmd.Flags().GetBool("write")
+		if err != nil {
+			return err
+		}
+
+		recursive, err := cmd.Flags().GetBool("recursive")
+		if err != nil {
+			return err
+		}
+
+		return formatPath(path, write, recursive)
+	},
+}
+
+func formatPath(path string, write, recursive bool) error {
+	fi, err := os.Stat(path)
+	if err != nil {
+		return err
+	}
+
+	if !fi.IsDir() {
+		return formatFile(path, write)
+	}
+
+	return filepath.Walk(path, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if info.IsDir() {
+			if !recursive && path != "." {
+				return filepath.SkipDir
+			}
+			return nil
+		}
+
+		ext := filepath.Ext(path)
+		if ext != ".jsonnet" && ext != ".libsonnet" {
+			return nil
+		}
+		return formatFile(path, write)
+	})
+}
+
+func formatFile(path string, write bool) error {
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return err
+	}
+
+	formatted, err := formatter.Format(path, string(content), formatter.DefaultOptions())
+	if err != nil {
+		return err
+	}
+
+	if write {
+		err = os.WriteFile(path, []byte(formatted), 0o644)
+		if err != nil {
+			return err
+		}
+		fmt.Println(path)
+	} else {
+		fmt.Println(formatted)
+	}
+
+	return nil
+}