feat(config): add config init subcommand with --new flag

cmd/config_cmd.go

@@ -2,8 +2,11 @@ package cmd
 
 import (
 	"fmt"
+	"os"
+	"path/filepath"
 	"strings"
 
+	"github.com/BurntSushi/toml"
 	"github.com/spf13/cobra"
 )
 
@@ -64,8 +67,50 @@ var configPathCmd = &cobra.Command{
 	},
 }
 
+func writeConfigFile(cfg Config) error {
+	p, err := configPath()
+	if err != nil {
+		return fmt.Errorf("cannot determine config path: %w", err)
+	}
+	if err := os.MkdirAll(filepath.Dir(p), 0o750); err != nil {
+		return fmt.Errorf("cannot create config directory: %w", err)
+	}
+	f, err := os.Create(p)
+	if err != nil {
+		return fmt.Errorf("cannot write config: %w", err)
+	}
+	defer f.Close()
+	enc := toml.NewEncoder(f)
+	return enc.Encode(cfg)
+}
+
+var configInitCmd = &cobra.Command{
+	Use:          "init",
+	Short:        "Generate default config file",
+	Args:         cobra.NoArgs,
+	SilenceUsage: true,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		p, err := configPath()
+		if err != nil {
+			return fmt.Errorf("cannot determine config path: %w", err)
+		}
+		newFlag, _ := cmd.Flags().GetBool("new")
+		if !newFlag {
+			if _, err := os.Stat(p); err == nil {
+				return withHint(
+					fmt.Errorf("config file already exists"),
+					"use 'pda config edit' or 'pda config init --new'",
+				)
+			}
+		}
+		return writeConfigFile(defaultConfig())
+	},
+}
+
 func init() {
+	configInitCmd.Flags().Bool("new", false, "overwrite existing config file")
 	configCmd.AddCommand(configGetCmd)
+	configCmd.AddCommand(configInitCmd)
 	configCmd.AddCommand(configListCmd)
 	configCmd.AddCommand(configPathCmd)
 	rootCmd.AddCommand(configCmd)