# -*- coding: utf-8 -*-

from configparser import ConfigParser
from typing import Any, Callable, Dict, List, Optional  # pylint: disable=W0611


class Config:
    """Base configuration object."""

    def get(self, key: str, default: Any = None) -> Any:
        """
        Get the config option as a string

        :param key: config option name
        :param default: default value if no value exists in the config
        :return: option value
        """
        raise NotImplementedError(__name__ + '.get()')

    def get_bool(self, key: str, default: Optional[bool] = None) -> bool:
        """
        Get the config option as a boolean

        :param key: config option name
        :param default: default value if no value exists in the config
        :return: option value
        """
        return bool(self.get(key, default))

    def get_int(self, key: str, default: Optional[int] = None) -> int:
        """
        Get the config option as an integer

        :param key: config option name
        :param default: default value if no value exists in the config
        :return: option value
        """
        return int(self.get(key, default))

    def get_float(self, key: str, default: Optional[float] = None) -> float:
        """
        Get the config option as a float

        :param key: config option name
        :param default: default value if no value exists in the config
        :return: option value
        """
        return float(self.get(key, default))


class FileConfig(Config):
    """Config class that loads configuration options from the locally-cached ZooKeeper config"""
    DEFAULT_FILENAME = '/var/cache/hfs/config.ini'  # type: str
    default_section = 'config-default'  # type: str
    prefixes = []  # type: List[str]

    def __init__(
            self,
            service_prefix: Optional[str] = None,
            filename: Optional[str] = None,
            defaults: Optional[Dict[str, Any]] = None) -> None:
        if filename is None:
            filename = self.DEFAULT_FILENAME
        self.config = ConfigParser(default_section=self.default_section, interpolation=None)
        self.config.read(filename)
        self.prefixes = []
        if service_prefix:
            prefix_parts = service_prefix.split('.')
            while prefix_parts:
                self.prefixes.append('.'.join(prefix_parts) + '.')
                prefix_parts.pop()
        self.prefixes.append('')
        self.defaults = defaults

    def __getattr__(self, key: str) -> Any:
        """
        Get a config key value as a direct attribute of this class.

        :param key: The config key name
        :return: The config key value, if it exists, or None
        """
        return self.get(key)

    def _get(self, getfunc: Callable, key: str, default: Any = None) -> Any:
        if default is None and self.defaults:
            default = self.defaults.get(key)

        for prefix in self.prefixes:
            prefixed_key = prefix + key
            val = getfunc(self.default_section, prefixed_key, fallback=None)
            if val:
                break
        else:
            val = default
        return val

    def get(self, key: str, default: Any = None) -> Any:
        return self._get(self.config.get, key, default)

    def get_bool(self, key: str, default: Optional[bool] = None) -> bool:
        return self._get(self.config.getboolean, key, default)

    def get_int(self, key: str, default: Optional[int] = None) -> int:
        return self._get(self.config.getint, key, default)

    def get_float(self, key: str, default: Optional[float] = None) -> float:
        return self._get(self.config.getfloat, key, default)