chore: add clear-work-dir flag (#57)

It will completely clear the specified working directory.

cmd/zigbee/firmware/build.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io/fs"
 	"log"
 	"os"
 	"path/filepath"
@@ -24,6 +25,9 @@ func buildCmd() *cli.Command {
 			&cli.BoolFlag{
 				Name: "only-generate",
 			},
+			&cli.BoolFlag{
+				Name: "clear-work-dir",
+			},
 		},
 		Action: buildFirmware,
 	}
@@ -53,6 +57,12 @@ func buildFirmware(ctx *cli.Context) error {
 		return fmt.Errorf("new generator: %w", err)
 	}
 
+	if ctx.Bool("clear-work-dir") {
+		if err := clearWorkDir(workDir); err != nil {
+			return err
+		}
+	}
+
 	if err := generator.Generate(workDir, cfg); err != nil {
 		return fmt.Errorf("generate base: %w", err)
 	}
@@ -123,3 +133,28 @@ func runBuild(ctx context.Context, device *config.Device, workDir string) error
 
 	return nil
 }
+
+func clearWorkDir(workDir string) error {
+	return filepath.WalkDir(workDir, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			var pathErr *os.PathError
+			if !errors.As(err, &pathErr) {
+				return err
+			}
+
+			if errors.Is(pathErr, os.ErrNotExist) {
+				return nil
+			}
+
+			return err
+		}
+
+		if path == workDir {
+			return nil
+		}
+
+		log.Printf("deleting %s\n", path)
+
+		return os.RemoveAll(path)
+	})
+}