first commit

app/models/loan.py

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+from datetime import datetime, timezone
+from app.extensions import db
+from app.models.customer import Customer
+from app.models.account import Account
+from sqlalchemy.exc import IntegrityError
+
+
+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)
+    account_id = db.Column(db.String(50), nullable=False)
+    offer_id = db.Column(db.String(20), nullable=False)
+    principal_amount = db.Column(db.Float, nullable=False)
+    status = db.Column(db.String(20), default='pending')
+    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_loan(cls, customer_id, account_id, offer_id, principal_amount, status='pending'):
+
+        # Check if customer exists
+        is_valid = Customer.is_valid_customer(customer_id)
+        if not is_valid:
+            raise ValueError("Customer does not exist")
+        
+        # # Check for active loans
+        # has_active_loans = cls.has_active_loans(customer_id)
+        # if has_active_loans:
+        #     raise ValueError("Customer has active loans")
+
+
+        # Create and save the loan
+        loan = cls(
+            customer_id=customer_id,
+            account_id=account_id,
+            offer_id=offer_id,
+            principal_amount=principal_amount,
+            status=status
+        )
+
+        try:
+            db.session.add(loan)
+            db.session.commit()
+        except IntegrityError as err:
+            db.session.rollback()
+            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.
+        """
+        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 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
+        
+        db.session.commit()
+    
+    def __repr__(self):
+        return f'<Loan {self.id}>'