import os
import io
import contextlib
import tempfile
import shutil
import errno
import zipfile


@contextlib.contextmanager
def tempdir():
    """Create a temporary directory in a context manager."""
    td = tempfile.mkdtemp()
    try:
        yield td
    finally:
        shutil.rmtree(td)


def mkdir_p(*args, **kwargs):
    """Like `mkdir`, but does not raise an exception if the
    directory already exists.
    """
    try:
        return os.mkdir(*args, **kwargs)
    except OSError as exc:
        if exc.errno != errno.EEXIST:
            raise


def dir_to_zipfile(root):
    """Construct an in-memory zip file for a directory."""
    buffer = io.BytesIO()
    zip_file = zipfile.ZipFile(buffer, 'w')
    for root, dirs, files in os.walk(root):
        for path in dirs:
            fs_path = os.path.join(root, path)
            rel_path = os.path.relpath(fs_path, root)
            zip_file.writestr(rel_path + '/', '')
        for path in files:
            fs_path = os.path.join(root, path)
            rel_path = os.path.relpath(fs_path, root)
            zip_file.write(fs_path, rel_path)
    return zip_file