from datetime import datetime, timezone
from app.extensions import db
from sqlalchemy.orm import relationship


class Offer(db.Model):
    __tablename__ = 'offers'

    id = db.Column(db.String, primary_key=True)
    product_id = db.Column(db.String, nullable=False)
    min_amount = db.Column(db.Float, nullable=False)
    max_amount = db.Column(db.Float, nullable=False)
    tenor = db.Column(db.Integer, nullable=False)
    schedule = db.Column(db.Integer, nullable=True)
    interest_rate = db.Column(db.Float, default=3.0)
    management_rate = db.Column(db.Float, default=1.0)
    insurance_rate = db.Column(db.Float, default=1.0)
    vat_rate = db.Column(db.Float, default=7.5)
    list_order = db.Column(db.Integer, nullable=True)
    created_at = db.Column(db.DateTime, default=datetime.now(timezone.utc))
    updated_at = db.Column(db.DateTime, default=datetime.now(timezone.utc), onupdate=datetime.now(timezone.utc))

    charges = relationship(
        "Charge",
        back_populates="offer",
        cascade="all, delete-orphan"
    )

    @classmethod
    def get_all_offers(cls, id=None, product_id=None, start_date=None, end_date=None, page=1, limit=20):
        """
        Get all offers with optional filtering

        Args:
            id (str, optional): Filter by offer ID
            product_id (str, optional): Filter by product ID
            start_date (datetime, optional): Filter by start date (created_at)
            end_date (datetime, optional): Filter by end date (created_at)
            page (int, optional): Page number for pagination
            limit (int, optional): Number of items per page

        Returns:
            tuple: (list of Offer objects, total count)
        """
        query = cls.query

        # Apply filters if provided
        if id:
            query = query.filter(cls.id == id)

        if product_id:
            query = query.filter(cls.product_id == product_id)

        if start_date:
            query = query.filter(cls.created_at >= start_date)

        if end_date:
            query = query.filter(cls.created_at <= end_date)

        # Order by list_order ascending (if available) or created_at descending
        query = query.order_by(cls.list_order.asc(), cls.created_at.desc())

        # Get total count before pagination
        total_count = query.count()

        # Apply pagination
        offset = (page - 1) * limit
        query = query.limit(limit).offset(offset)

        return query.all(), total_count

    @classmethod
    def is_valid_offer(cls, offer_id):
        offer = cls.query.filter_by(id=str(offer_id)).first()

        if not offer:
            return False
        return offer

    def to_dict(self):
        """
        Convert the Offer object to a dictionary format for JSON serialization.
        """
        return {
            'id': self.id,
            'product_id': self.product_id,
            'min_amount': self.min_amount,
            'max_amount': self.max_amount,
            'tenor': self.tenor,
            'schedule': self.schedule,
            'interest_rate': self.interest_rate,
            'management_rate': self.management_rate,
            'insurance_rate': self.insurance_rate,
            'vat_rate': self.vat_rate,
            'list_order': self.list_order,
            'created_at': self.created_at.isoformat() if self.created_at else None,
            'updated_at': self.updated_at.isoformat() if self.updated_at else None
        }

    def __repr__(self):
        return f'<Offer {self.id}>'