from datetime import datetime, timezone
from app.extensions import db
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(50), nullable=False)
    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))
    transaction_id = db.Column(db.String(50))

    @classmethod
    def get_all_repayments(cls, loan_id=None, customer_id=None, product_id=None,
                          start_date=None, end_date=None, page=1, limit=20):
        """
        Get all repayments with optional filtering

        Args:
            loan_id (str, optional): Filter by loan ID
            customer_id (str, optional): Filter by customer 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 Repayment objects, total count)
        """
        query = cls.query

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

        if customer_id:
            query = query.filter(cls.customer_id == customer_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 created_at descending (newest first)
        query = query.order_by(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

    def to_dict(self):
        """
        Convert the Repayment object to a dictionary format for JSON serialization.
        """
        return {
            'loan_id': self.loan_id,
            'customer_id': self.customer_id,
            'product_id': self.product_id,
            'transaction_id': self.transaction_id,
            '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'<Repayment {self.id}>'