from pathlib import Path
import shutil
import logging

def rm(path: Path):
    """Delete whatever is specified by `path`"""
    if path.is_dir():
        shutil.rmtree(str(path))
    else:
        path.unlink()

class InplaceBackup:
    """Utility class for moving a file out of the way by appending a '~'"""

    log = logging.getLogger('%s.inplace-backup' % __name__)

    def __init__(self, path: Path):
        self.path = path
        self.backup()

    def backup(self):
        """Move 'path' to 'path~'"""
        if not self.path.exists():
            raise FileNotFoundError("Can't backup path which doesn't exist")

        self.backup_path = Path(str(self.path) + '~')
        if self.backup_path.exists():
            self.log.warning("Overwriting existing backup '{}'".format(self.backup_path))
            rm(self.backup_path)

        shutil.move(str(self.path), str(self.backup_path))

    def restore(self):
        """Move 'path~' to 'path'"""
        try:
            getattr(self, 'backup_path')
        except AttributeError as err:
            raise RuntimeError("Can't restore file before backing it up") from err

        if not self.backup_path.exists():
            raise FileNotFoundError("Can't restore backup which doesn't exist")

        if self.path.exists():
            self.log.warning("Overwriting '{0}' with backup file".format(self.path))
            rm(self.path)

        shutil.move(str(self.backup_path), str(self.path))

    def remove(self):
        """Remove 'path~'"""
        rm(self.backup_path)