from datetime import datetime, timezone, timedelta
from os.path import devnull
from sqlalchemy.exc import IntegrityError
from app.extensions import db
from sqlalchemy.orm import relationship

class LoanCharge(db.Model):
    __tablename__ = 'loan_charges'

    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    loan_id = db.Column(db.Integer, nullable=False)
    transaction_id = db.Column(db.String(50), nullable=True)
    code = db.Column(db.String(50), nullable=False)
    amount = db.Column(db.Float, default=0.0)
    percent = db.Column(db.Float, default=0.0)
    description = db.Column(db.Text, nullable=True)
    due = db.Column(db.Integer, nullable=False)
    due_date = db.Column(db.DateTime, 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))

    loan = relationship(
        "Loan",
        primaryjoin="LoanCharge.loan_id == Loan.id",
        foreign_keys=[loan_id],
        back_populates="loan_charges",
    )

    def __repr__(self):
        return f"<LoanCharge {self.id} - Loan {self.loan_id} - {self.code}>"

    def to_dict(self):
        """
        Convert the Loan charge object to a dictionary format for JSON serialization.
        """
        return {
            'id': self.id,
            'loanId': self.loan_id,
            'transactionId': self.transaction_id,
            'code': self.code,
            'amount': self.amount,
            'percent': self.percent,
            'description': self.description,
            'due': self.due
        }
    #get last penal
    @classmethod
    def get_last_penal_no(cls, loan_id):
        """
        Returns the last penal number created for a loan.
        Example:
            PENAL1 -> returns 1
            PENAL3 -> returns 3
        If none exists, returns 0.
        """
        last_penal = (
            cls.query
            .filter(cls.loan_id == loan_id)
            .filter(cls.code.like("PENAL%"))
            .order_by(cls.id.desc())
            .first()
        )

        if not last_penal:
            return 0

        try:
            return int(last_penal.code.replace("PENAL", ""))
        except ValueError:
            return 0
    @classmethod
    def get_penal_charges_by_loan_id(cls, loan_id):
        """
        Returns all penal charges for a specific loan.
        """
        return cls.query.filter(
            cls.loan_id == loan_id,
            cls.code.like("PENAL%")
        ).all()
    
    
    @classmethod
    def get_loan_charge_by_debt_id(cls, debt_id):
        return cls.query.filter_by(loan_id=debt_id)
    
    #create penal charge
    @classmethod
    def create_penal_charges_for_loan(cls, loan_id, transaction_id, percent, penal_no, schedule_number, penal_amount=0.0):
        """
        Create a penal charge for a given loan and schedule.
        """

        if loan_id is None:
            raise ValueError("loan_id cannot be None")

        code = f"PENAL{penal_no:02d}-SCHEDULE{schedule_number:02d}"

        # Check if this penal charge already exists
        existing = cls.query.filter_by(
            loan_id=loan_id,
            code=code
        ).first()

        if existing:
            return existing

        now = datetime.now(timezone.utc)

        penal_charge = cls(
            loan_id=loan_id,
            transaction_id=transaction_id,
            code=code,
            amount=penal_amount,
            percent=percent,
            description=f"Penal Charge {penal_no} for loan {loan_id} schedule {schedule_number}",
            due=True,
            due_date=now
        )

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

        return penal_charge