import os
import logging

from util.config.provider.baseprovider import (BaseProvider, import_yaml, export_yaml,
                                               CannotWriteConfigException)

logger = logging.getLogger(__name__)

class BaseFileProvider(BaseProvider):
  """ Base implementation of the config provider that reads the data from the file system. """
  def __init__(self, config_volume, yaml_filename, py_filename):
    self.config_volume = config_volume
    self.yaml_filename = yaml_filename
    self.py_filename = py_filename

    self.yaml_path = os.path.join(config_volume, yaml_filename)
    self.py_path = os.path.join(config_volume, py_filename)

  def update_app_config(self, app_config):
    if os.path.exists(self.py_path):
      logger.debug('Applying config file: %s', self.py_path)
      app_config.from_pyfile(self.py_path)

    if os.path.exists(self.yaml_path):
      logger.debug('Applying config file: %s', self.yaml_path)
      import_yaml(app_config, self.yaml_path)

  def get_config(self):
    if not self.config_exists():
      return None

    config_obj = {}
    import_yaml(config_obj, self.yaml_path)
    return config_obj

  def config_exists(self):
    return self.volume_file_exists(self.yaml_filename)

  def volume_exists(self):
    return os.path.exists(self.config_volume)

  def volume_file_exists(self, relative_file_path):
    return os.path.exists(os.path.join(self.config_volume, relative_file_path))

  def get_volume_file(self, relative_file_path, mode='r'):
    return open(os.path.join(self.config_volume, relative_file_path), mode=mode)

  def get_volume_path(self, directory, relative_file_path):
    return os.path.join(directory, relative_file_path)

  def list_volume_directory(self, path):
    dirpath = os.path.join(self.config_volume, path)
    if not os.path.exists(dirpath):
      return None

    if not os.path.isdir(dirpath):
      return None

    return os.listdir(dirpath)

  def get_config_root(self):
    return self.config_volume