package cd

import (
	"errors"
	"fmt"
	"os"
	"syscall"

	"gosh/internal/paths"
)

func fmtError(dir string, err error) string {
	switch {
	case errors.Is(err, os.ErrNotExist):
		return fmt.Sprintf("directory \"%s\" does not exist", dir)
	case errors.Is(err, os.ErrPermission):
		return fmt.Sprintf("Permission denied: \"%s\"", dir)
	case errors.Is(err, syscall.ENOTDIR):
		return fmt.Sprintf("\"%s\" is not a directory", dir)
	}
	return err.Error()
}

func Exec(args []string) error {
	dir := ""
	if len(args) > 0 {
		dir = args[0]
	}

	dir = paths.Expand(dir)
	if err := os.Chdir(dir); err != nil {
		return errors.New("cd: " + fmtError(dir, err))
	}
	return nil
}