"""Knowledge Base model.

Non-asset plugin model. The `knowledgebase` table lives in the core Alembic
chain (bundled-plugin schema is folded into core, ADR-004); this class just
maps it and is registered via the plugin's get_models hook. The appid FK
references the core applications table by name, which resolves at mapper config
time without importing the core model.
"""

from datetime import datetime, timezone

from shopdb.api import db, BaseModel


def _utcnow():
    # naive UTC to match the other DB DateTime columns (stored without tzinfo)
    return datetime.now(timezone.utc).replace(tzinfo=None)


class KnowledgeBase(BaseModel):
    """Knowledge Base article linking to external resources."""
    __tablename__ = 'knowledgebase'

    linkid = db.Column(db.Integer, primary_key=True)
    appid = db.Column(db.Integer, db.ForeignKey('applications.appid'))
    shortdescription = db.Column(db.String(500), nullable=False)
    linkurl = db.Column(db.String(2000))
    keywords = db.Column(db.String(500))
    clicks = db.Column(db.Integer, default=0)
    lastupdated = db.Column(db.DateTime, default=_utcnow, onupdate=_utcnow)

    # Relationship to the core Application model (resolved by class name).
    application = db.relationship('Application', backref=db.backref('knowledgebase_articles', lazy='dynamic'))

    def __repr__(self):
        return f"<KnowledgeBase {self.linkid}: {self.shortdescription[:50] if self.shortdescription else 'No desc'}>"

    def increment_clicks(self):
        """Increment click counter."""
        self.clicks = (self.clicks or 0) + 1