##############################################################################
# Copyright (c) 2015 Orange
# guyrodrigue.koffi@orange.com / koffirodrigue@gmail.com
# All rights reserved. This program and the accompanying materials
# are made available under the terms of the Apache License, Version 2.0
# which accompanies this distribution, and is available at
# http://www.apache.org/licenses/LICENSE-2.0
##############################################################################


from ConfigParser import SafeConfigParser, NoOptionError


def prepare_put_request(edit_request, key, new_value, old_value):
    """
    This function serves to prepare the elements in the update request.
    We try to avoid replace the exact values in the db
    edit_request should be a dict in which we add an entry (key) after
    comparing values
    """
    if not (new_value is None):
        if len(new_value) > 0:
            if new_value != old_value:
                edit_request[key] = new_value

    return edit_request


class ParseError(Exception):
    """
    Custom exception class for config file
    """

    def __init__(self, message):
        self.msg = message

    def __str__(self):
        return 'error parsing config file : %s' % self.msg


class APIConfig:
    """
    The purpose of this class is to load values correctly from the config file.
    Each key is declared as an attribute in __init__() and linked in parse()
    """

    def __init__(self):
        self._default_config_location = "config.ini"
        self.mongo_url = None
        self.api_port = None
        self.api_debug_on = None
        self._parser = None

    def _get_parameter(self, section, param):
        try:
            return self._parser.get(section, param)
        except NoOptionError:
            raise ParseError("[%s.%s] parameter not found" % (section, param))

    def _get_int_parameter(self, section, param):
        try:
            return int(self._get_parameter(section, param))
        except ValueError:
            raise ParseError("[%s.%s] not an int" % (section, param))

    def _get_bool_parameter(self, section, param):
        result = self._get_parameter(section, param)
        if str(result).lower() == 'true':
            return True
        if str(result).lower() == 'false':
            return False

        raise ParseError(
            "[%s.%s : %s] not a boolean" % (section, param, result))

    @staticmethod
    def parse(config_location=None):
        obj = APIConfig()

        if config_location is None:
            config_location = obj._default_config_location

        obj._parser = SafeConfigParser()
        obj._parser.read(config_location)
        if not obj._parser:
            raise ParseError("%s not found" % config_location)

        # Linking attributes to keys from file with their sections
        obj.mongo_url = obj._get_parameter("mongo", "url")
        obj.api_port = obj._get_int_parameter("api", "port")
        obj.api_debug_on = obj._get_bool_parameter("api", "debug")
        return obj

    def __str__(self):
        return "mongo_url = %s \n" \
               "api_port = %s \n" \
               "api_debug_on = %s \n" % (self.mongo_url,
                                         self.api_port,
                                         self.api_debug_on)