from app.extensions import db
from datetime import datetime


class Budget(db.Model):
    __tablename__ = 'budgets'

    id = db.Column(db.Integer, primary_key=True)
    category_id = db.Column(db.Integer, db.ForeignKey('categories.id'), nullable=False)
    month = db.Column(db.String(7), nullable=False, index=True)  # YYYY-MM
    limit_amount = db.Column(db.Numeric(15, 2), nullable=False)
    rollover_enabled = db.Column(db.Boolean, default=False)
    rollover_amount = db.Column(db.Numeric(15, 2), default=0.00)
    created_at = db.Column(db.DateTime, default=datetime.utcnow)

    category = db.relationship('Category')

    __table_args__ = (
        db.UniqueConstraint('category_id', 'month', name='uq_budget_category_month'),
    )

    def __repr__(self):
        return f'<Budget {self.month} cat={self.category_id} limit={self.limit_amount}>'