from datetime import datetime, timezone
from app.api.enums.loan_status import LoanStatus
from app.extensions import db
from app.models.customer import Customer
from app.models.loan import Loan
from sqlalchemy.exc import IntegrityError


class Repayment(db.Model):
    __tablename__ = 'repayments'

    id = db.Column(
        db.Integer,
        primary_key=True,
        autoincrement=True,
    )
    loan_id = db.Column(db.String(50), nullable=False)
    customer_id = db.Column(db.String(50), nullable=False)
    product_id = db.Column(db.String(20), 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))

    @classmethod
    def create_repayment(cls, customer_id, loan_id, product_id):

        # Check customer exists
        if not Customer.is_valid_customer(customer_id):
            raise ValueError("Invalid customer")

        # Check loan exists
        loan = Loan.get_customer_loan(loan_id = loan_id, customer_id = customer_id)
        
        # Check that the loan is active
        if loan.status != LoanStatus.ACTIVE:
            raise ValueError(f"Repayment cannot be processed. Loan status: ({loan.status})")
        

        repayment = cls(
            customer_id=customer_id,
            loan_id=loan_id,
            product_id=product_id,
        )

        try:
            db.session.add(repayment)
        except IntegrityError as err:
            raise ValueError(f"Database integrity error: {err}")

        return repayment

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