from app import db
from app.models.post import Post
from app.models.comment import Comment
from config import V5Config

class Thread(Post):
    """ Some thread, such as a topic, program, tutorial """

    # Foreign Post object ID
    __tablename__ = 'thread'
    id = db.Column(db.Integer, db.ForeignKey('post.id'), primary_key=True)

    # Identify threads as a type of posts using the table name, and add a
    # column to further discriminate types of threads
    thread_type = db.Column(db.String(20))
    __mapper_args__ = {
        'polymorphic_identity': __tablename__,
        'polymorphic_on': thread_type
    }

    # Properties
    title = db.Column(db.Unicode(V5Config.THREAD_NAME_MAXLEN))
    # Also a relation [comments] populated from the Comment class.

    # Relations
    top_comment_id = db.Column(db.Integer, db.ForeignKey('comment.id'))
    top_comment    = db.relationship('Comment', foreign_keys=top_comment_id)

    def __init__(self, author, text, title):
        """ Create a Thread """
        Post.__init__(author, text)
        self.title = title

    def __repr__(self):
        return f'<Thread #{self.id}'