"""Object-Oriented Programming: Twitter example

=== CSC148 Winter 2021 ===
Department of Mathematical and Computational Sciences,
University of Toronto Mississauga

=== Module description ===
This module contains two sample classes Tweet and Person that we developed
as a way to introduce the major concepts of object-oriented programming.

"""
from __future__ import annotations  # Reference: 1.4 Type Annotations

from datetime import date  # Python library for working with dates (and times)
from typing import List    # Python library for expressing complex types


class Tweet:
    """A tweet, like in Twitter.

    === Attributes ===
    content: the contents of the tweet.
    userid: the id of the user who wrote the tweet.
    created_at: the date the tweet was written.
    likes: the number of likes this tweet has received.

    === Representation Invariants ===
    - len(self.content) <= 280
        Question for next class: how do we enforce this invariant?
    """
    # Attribute types
    content: str
    userid: str
    created_at: date
    likes: int

    def __init__(self, who: str, when: date, what: str) -> None:
        """Initialize a new Tweet.

        >>> t = Tweet('Rukhsana', date(2017, 9, 16), 'Hey!')
        >>> t.userid
        'Rukhsana'
        >>> t.created_at
        datetime.date(2017, 9, 16)
        >>> t.content
        'Hey!'
        >>> t.likes
        0
        """
        self.userid = who
        self.content = what
        self.created_at = when
        self.likes = 0

    def like(self, n: int) -> None:
        """Record the fact that this tweet received <n> likes.

        These likes are in addition to the ones <self> already has.

        >>> t = Tweet('Rukhsana', date(2017, 9, 16), 'Hey!')
        >>> t.like(3)
        >>> t.likes
        3
        """
        self.likes += n

    def edit(self, new_content: str) -> None:
        """Replace the contents of this tweet with the new message.

        >>> t = Tweet('Rukhsana', date(2017, 9, 16), 'Hey!')
        >>> t.edit('Rukhsana is cool')
        >>> t.content
        'Rukhsana is cool'
        """
        # Note: this is the incorrect version from the worksheet.
        # Notice how both PyCharm and python_ta pick up on this error.
        old_user = self.userid
        old_date = self.created_at
        self = Tweet(old_user, old_date, new_content)


class User:
    """A Twitter user.

    === Attributes ===
    userid: the userid of this Twitter user.
    bio: the bio of this Twitter user.
    tweets: a list of the tweets that this user has made.
    follows: a list of users that this user follows
    """
    userid: str
    bio: str
    tweets: List[Tweet]
    follows: List[User]

    def __init__(self, id_: str, bio: str) -> None:
        """Initialize this User.

        >>> david = User('David', 'is cool')
        >>> david.tweets
        []
        """
        # Remember to initialize attributes...
        self.userid = id_
        self.bio = bio
        self.tweets = []
        self.follows = []  # Don't forget about this!

    def tweet(self, message: str) -> None:
        """Record that this User made a tweet with the given content.

        Use date.today() to get the current date for the newly created tweet.
        """
        new_tweet = Tweet(self.userid, date.today(), message)
        self.tweets.append(new_tweet)

    def follow_user(self, other_user: User) -> None:
        """Record that this user follows the other user.

        Just one of many possible implementations. Other possibilities include:
            - storing userid (a string) rather than the User
            - using an additional attribute to store num_followed
            - using an additional list to store followers as well
        """
        self.follows.append(other_user)


if __name__ == '__main__':
    import python_ta
    python_ta.check_all(config={
        'extra-imports': ['datetime']
    })