from datetime import datetime, timezone
from app.extensions import db
from sqlalchemy.exc import IntegrityError

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)
    code = db.Column(db.String(50), nullable=False)
    amount = db.Column(db.Float, default=0.00)
    percent = db.Column(db.Float)
    description = db.Column(db.String(255))
    due = db.Column(db.Integer)
    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))
    due_date = db.Column(db.DateTime)

    @classmethod
    def get_all_loan_charges(cls, loan_id=None, transaction_id=None, code=None, start_date=None, end_date=None,
                            due_before=None, due_after=None, page=1, limit=20):
        """
        Get all loan charges with optional filtering

        Args:
            loan_id (int, optional): Filter by loan ID
            transaction_id (int, optional): Filter by transaction ID
            code (str, optional): Filter by charge code
            start_date (datetime, optional): Filter by start date (created_at)
            end_date (datetime, optional): Filter by end date (created_at)
            due_before (datetime, optional): Filter charges due before this date
            due_after (datetime, optional): Filter charges due after this date
            page (int, optional): Page number for pagination
            limit (int, optional): Number of items per page

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

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

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

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

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

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

        if due_before:
            query = query.filter(cls.due_date <= due_before)

        if due_after:
            query = query.filter(cls.due_date >= due_after)

        # 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 LoanCharge object to a dictionary format for JSON serialization.
        """
        return {
            'loan_id': self.loan_id,
            'code': self.code,
            'amount': self.amount,
            'percent': self.percent,
            'description': self.description,
            'due': self.due,
            'transaction_id': self.transaction_id,
            'due_date': self.due_date.isoformat() if self.due_date else None,
            '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'<LoanCharge {self.id}>'