from datetime import datetime, timezone, timedelta
from itertools import product
from app.extensions import db
from app.models.customer import Customer
from app.models.account import Account
from sqlalchemy.exc import IntegrityError
from sqlalchemy.orm import relationship
from dateutil.relativedelta import relativedelta 
from datetime import timedelta
import logging
from sqlalchemy import and_, or_, not_
from sqlalchemy.sql import func

logger = logging.getLogger(__name__)


class Loan(db.Model):
    __tablename__ = 'loans'

    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=True)
    original_transaction = db.Column(db.String(50), nullable=True)
    account_id = db.Column(db.String(50), nullable=False)
    offer_id = db.Column(db.String(20), nullable=False)
    product_id = db.Column(db.String(20), nullable=True)
    collection_type = db.Column(db.String(20), nullable=True) 
    current_loan_amount = db.Column(db.Float, nullable=True)  
    initial_loan_amount = db.Column(db.Float, nullable=False) 
    default_penalty_fee = db.Column(db.Float, default=0)  
    continuous_fee = db.Column(db.Float, default=0)
    upfront_fee = db.Column(db.Float, nullable=True, default=0.0)
    repayment_amount = db.Column(db.Float, nullable=True, default=0.0)
    installment_amount = db.Column(db.Float, nullable=True, default=0.0)
    status = db.Column(db.String(20), default='pending')
    tenor = db.Column(db.Integer, nullable=True)
    due_date = db.Column(db.DateTime, nullable=True) 
    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())
    eligible_amount = db.Column(db.Float, nullable=True, default=0.0)
    disburse_date = db.Column(db.DateTime, nullable=True)
    disburse_verify = db.Column(db.DateTime, nullable=True)
    reference = db.Column(db.String(50), nullable=True)
    disburse_result = db.Column(db.String(10), nullable=True)
    disburse_description = db.Column(db.String(100), nullable=True)
    verify_result = db.Column(db.String(10), nullable=True)
    verify_description = db.Column(db.String(100), nullable=True)

    customer = relationship(
        "Customer",
        primaryjoin="Customer.id == Loan.customer_id",
        foreign_keys=[customer_id],
        back_populates="loans",
    )

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

    loan_repayment_schedules = relationship(
        "LoanRepaymentSchedule",
        primaryjoin="LoanRepaymentSchedule.loan_id == Loan.id",
        foreign_keys="LoanRepaymentSchedule.loan_id",
        back_populates="loan",
    )


    @classmethod
    def create_loan(
        cls,
        customer_id,
        account_id,
        offer_id,
        product_id,
        initial_loan_amount,
        collection_type,
        transaction_id,
        original_transaction,
        upfront_fee,
        repayment_amount,
        installment_amount,
        tenor,
        eligible_amount,
        reference,
        status = "pending",
    ):
        # Check if customer exists
        customer = Customer.is_valid_customer(customer_id)
        if not customer:
            raise ValueError("Customer does not exist")

        now = datetime.now(timezone.utc)
        due_date = now + timedelta(days=tenor)

        # Create and save the loan
        loan = cls(
            customer_id = customer_id,
            account_id = account_id,
            offer_id = offer_id,
            product_id = product_id,
            collection_type = collection_type,
            transaction_id = transaction_id,
            original_transaction = original_transaction,
            initial_loan_amount = initial_loan_amount,
            current_loan_amount = initial_loan_amount,
            upfront_fee = upfront_fee,
            repayment_amount = repayment_amount,
            installment_amount = installment_amount,
            due_date=due_date,
            tenor = tenor,
            status = status,
            eligible_amount =eligible_amount,
            reference = reference,
            created_at=datetime.now(timezone.utc),
            updated_at=datetime.now(timezone.utc)
        )
        
        try:
            db.session.add(loan)
        except IntegrityError as err:
            raise ValueError(f"Database integrity error: {err}")
        return loan

    @classmethod
    def has_active_loans(cls, customer_id):
        active_loans = cls.query.filter_by(
            customer_id=customer_id,
            status='active'
        ).count()

        if active_loans > 0:
            return False
        return True
    

    @classmethod
    def get_customer_loan(cls, loan_id, customer_id):
        """
        Get customer's active loans by loan_id.
        """
        loan = cls.query.filter_by(id = loan_id, customer_id = customer_id).first()
        if not loan:
            raise ValueError(f"Loan with ID {loan_id} does not exist or does not belong to customer {customer_id}.")        
        return loan

    @classmethod
    def get_customer_original_loan(cls, customer_id, original_transaction):
        """
        Get customer's original loan  offer.
        """
        original_loan = cls.query.filter(and_( cls.customer_id ==customer_id, cls.original_transaction==original_transaction, cls.transaction_id==original_transaction )).first()
        if not original_loan:
            return None

        logger.info(f" get_customer_original_loan ==>>>>  {original_loan}")
        return original_loan

    @classmethod
    def get_customer_last_loan(cls, customer_id):
        """
        Get customer's active loans.
        """
        logger.info(f"get_customer_last_loan [customer_id] ==>>>>  {customer_id}")
        # loan = cls.query.filter_by( cls.customer_id == customer_id).first()
        loan = cls.query.filter(and_( cls.customer_id ==customer_id, cls.status=='active')).first()

        if not loan:
            return None
            # loan = {
            #     "original_transaction":"",
            #     "eligible_amount": 0,
            #     "loan_amount": 0,
            #     "customer_id": customer_id,
            #     "transaction_id": "",
            #     "resultDescription": "No Active Loan"
            # }
        logger.info(f" get_customer_last_loan ==>>>>  {loan}")
        return loan

    @classmethod
    def get_active_loans_by_original_transaction(cls, original_transaction_id):
        """
        Get all active loans with the same original_transaction ID.
        """

        active_loans = cls.query.filter_by(
        original_transaction=original_transaction_id,
        # status='active'
        ).all()

        return active_loans


    @classmethod
    def update_status(cls, loan_id, status):
        """
        Update the status of the loan with the given loan_id.
        """
        # Retrieve loan 
        loan = cls.query.get(loan_id)
        
        if not loan:
            raise ValueError(f"Loan with ID {loan_id} does not exist.")
        
        if loan.status == status:
            return
        
        # Update loan status and the updated_at timestamp
        loan.status = status


    @classmethod
    def get_daily_loan_count(cls, customer_id, product_id):
        """
        Returns the count of loans created today for a customer.
        """

        start_of_day = datetime.now(timezone.utc).replace(hour=0, minute=0, second=0, microsecond=0)
        end_of_day = start_of_day + timedelta(days=1)

        return cls.query.filter_by(
            customer_id=customer_id,
            product_id=product_id,      
            ).filter(
            cls.created_at >= start_of_day,
            cls.created_at < end_of_day
        ).count()


    def to_dict(self):
        """
        Convert the Loan object to a dictionary format for JSON serialization.
        """
        return {
            'debtId': self.id,
            'transactionId': self.transaction_id,
            'loanRef': self.reference,
            'productId': self.product_id,
            'initialLoanAmount': self.initial_loan_amount,
            'currentLoanAmount': self.current_loan_amount,
            'defaultPenaltyFee': self.default_penalty_fee,
            'continuousFee': self.continuous_fee,
            'collectionType': self.collection_type,
            'upfrontFee': self.upfront_fee,
            'repaymentAmount': self.repayment_amount,
            'installmentAmount': self.installment_amount,
            'status': self.status,
            'tenor': self.tenor,
            'dueDate': self.due_date.isoformat() if self.due_date else None,
            'loanDate': self.created_at.isoformat() if self.created_at else None,
        }
    
    def __repr__(self):
        return f'<Loan {self.id}>'