"""
utils.converter: Custom URL converters to match patterns in @app.route()
"""

from werkzeug.routing import BaseConverter
from app.models.forum import Forum
import re

class ForumConverter(BaseConverter):

    def to_python(self, url):
        f = Forum.query.filter_by(url=url).first()
        if f is None:
            raise Exception(f"ForumConverter: no forum with url {value}")
        return f

    def to_url(self, forum):
        return forum.url

class TopicSlugConverter(BaseConverter):

    def to_python(self, url):
        """Convert an URL pattern to a Python object, or raise an exception."""
        m = re.fullmatch(r'(\d+)(?:-[\w-]*)?', url)
        if m is None:
            raise Exception(f"TopicSlugConverter: conversation failed")

        return int(m[1], 10)

    def to_url(self, topic_id):
        return str(topic_id)

# Export only the converter classes
__all__ = "ForumConverter TopicSlugConverter".split()