__author__ = "geduldig"
__date__ = "February 7, 2013"
__license__ = "MIT"


import os


class TwitterOAuth:

    """Optional class for retrieving Twitter credentials stored in a text file.

    :param consumer_key: Twitter application consumer key
    :param consumer_secret: Twitter application consumer secret
    :param access_token_key: Twitter application access token key
    :param access_token_secret: Twitter application access token secret
    """

    def __init__(
            self,
            consumer_key,
            consumer_secret,
            access_token_key,
            access_token_secret):
        self.consumer_key = consumer_key
        self.consumer_secret = consumer_secret
        self.access_token_key = access_token_key
        self.access_token_secret = access_token_secret

    @classmethod
    def read_file(cls, file_name=None):
        """Read OAuth credentials from a text file.  File format:

                consumer_key=YOUR_CONSUMER_KEY

                consumer_secret=YOUR_CONSUMER_SECRET

                access_token_key=YOUR_ACCESS_TOKEN

                access_token_secret=YOUR_ACCESS_TOKEN_SECRET

        :param file_name: File containing credentials or None (default) reads credentials
                          from TwitterAPI/credentials.txt
        """
        if file_name is None:
            path = os.path.dirname(__file__)
            file_name = os.path.join(path, 'credentials.txt')

        with open(file_name) as f:
            oauth = {}
            for line in f:
                if '=' in line:
                    tokens = line.strip().split('=', 1)
                    if len(tokens) != 2 or not tokens[1]:
                        raise Exception(cls.usage(file_name))
                    oauth[tokens[0].strip()] = tokens[1].strip()
            return TwitterOAuth(
                oauth['consumer_key'],
                oauth['consumer_secret'],
                oauth['access_token_key'],
                oauth['access_token_secret'])

    @classmethod
    def usage(cls, file_name):
        return (f'Credentials file: {file_name}\n'
                 'Expected format:\n'
                 'consumer_key=YOUR_CONSUMER_KEY\n'
                 'consumer_secret=YOUR_CONSUMER_SECRET\n'
                 'access_token_key=YOUR_ACCESS_TOKEN\n'
                 'access_token_secret=YOUR_ACCESS_TOKEN_SECRET\n')