import os
import logging

from util.config.provider.baseprovider import export_yaml, CannotWriteConfigException
from util.config.provider.basefileprovider import BaseFileProvider


logger = logging.getLogger(__name__)

def _ensure_parent_dir(filepath):
  """ Ensures that the parent directory of the given file path exists. """
  try:
    parentpath = os.path.abspath(os.path.join(filepath, os.pardir))
    if not os.path.isdir(parentpath):
      os.makedirs(parentpath)
  except IOError as ioe:
    raise CannotWriteConfigException(str(ioe))


class FileConfigProvider(BaseFileProvider):
  """ Implementation of the config provider that reads and writes the data
      from/to the file system. """
  def __init__(self, config_volume, yaml_filename, py_filename):
    super(FileConfigProvider, self).__init__(config_volume, yaml_filename, py_filename)

  @property
  def provider_id(self):
    return 'file'

  def save_config(self, config_obj):
    export_yaml(config_obj, self.yaml_path)

  def remove_volume_file(self, relative_file_path):
    filepath = os.path.join(self.config_volume, relative_file_path)
    os.remove(filepath)

  def save_volume_file(self, flask_file, relative_file_path):
    filepath = os.path.join(self.config_volume, relative_file_path)
    _ensure_parent_dir(filepath)

    # Write the file.
    try:
      flask_file.save(filepath)
    except IOError as ioe:
      raise CannotWriteConfigException(str(ioe))

    return filepath