from datetime import datetime, timezone, timedelta
from app.api.enums.loan_status import LoanStatus
from app.extensions import db
from sqlalchemy.orm import relationship
from sqlalchemy.sql import func
import logging
logger = logging.getLogger(__name__)



class TransactionOffer(db.Model):
    __tablename__ = 'transaction_offers'

    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    customer_id = db.Column(db.String(50), nullable=False)
    transaction_id = db.Column(db.String(50), nullable=False)
    original_transaction = db.Column(db.String(50), nullable=True)
    offer_id = db.Column(db.String(20), nullable=False)
    product_id = db.Column(db.String(20), nullable=True)
    min_amount = db.Column(db.Float, nullable=False)
    max_amount = db.Column(db.Float, nullable=False)
    eligible_amount = db.Column(db.Float, nullable=True)
    tenor = db.Column(db.Integer, nullable=True)  # tenor in months, typically

    created_at = db.Column(db.DateTime(timezone=True), server_default=func.now())
    updated_at = db.Column(db.DateTime(timezone=True), server_default=func.now(), onupdate=func.now())
    # customer = relationship(
    #     "Customer",
    #     primaryjoin="Customer.id == TransactionOffer.customer_id",
    #     foreign_keys=[customer_id],
    #     back_populates="transaction_offers",
    # )

    @classmethod
    def is_valid_transaction_offer(cls, transaction_offer, customer_id, product_id):
        transaction_offer = cls.query.filter_by(
            id = transaction_offer,
            customer_id = customer_id,
            # product_id = product_id
            # transaction_id = transaction_id,
            ).first()


        if not transaction_offer:
            return False
        return transaction_offer

    @classmethod
    def create_transaction_offer(cls, customer_id, transaction_id, original_transaction, offer_id, min_amount, max_amount, eligible_amount=None, product_id=None, tenor=None):
        """
        Class method to create and save a TransactionOffer.
        """
        transaction_offer = cls(
            customer_id=customer_id,
            transaction_id=transaction_id,
            original_transaction=original_transaction,
            offer_id=offer_id,
            min_amount=min_amount,
            max_amount=max_amount,
            eligible_amount=eligible_amount,
            product_id=product_id,
            tenor=tenor,
            created_at=datetime.now(timezone.utc),
            updated_at=datetime.now(timezone.utc)
        )

        db.session.add(transaction_offer)
        db.session.flush()

        return transaction_offer
    
    @classmethod
    def get_lifetime_loan_count(cls, customer_id):
        """
        Returns the total number of loans ever created for a customer.
        """
        return cls.query.filter_by(customer_id=customer_id).count()


    @classmethod
    def get_latest_transaction_offer(cls, customer_id):
        """
        Returns the most recent transaction offer for the given customer based on creation time.
        """
        return cls.query.filter_by(customer_id=customer_id) \
            .order_by(cls.created_at.desc()) \
            .first()
    
    @classmethod
    def get_transaction_offer(cls, transaction_offer_id):
        """
        Returns a transaction offer by its ID.
        """
        return cls.query.get(transaction_offer_id)


    

    def to_dict(self):
        return {
            'id': self.id,
            'customerId': self.customer_id,
            'transactionId': self.transaction_id,
            'offerId': self.offer_id,
            'productId': self.product_id,
            'minAmount': self.min_amount,
            'maxAmount': self.max_amount,
            'eligibleAmount': self.eligible_amount,
            'tenor': self.tenor,
            'createdAt': self.created_at.isoformat() if self.created_at else None,
            'updatedAt': self.updated_at.isoformat() if self.updated_at else None,
        }

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