from notification_service import send_notification


class BankAccount:
    def __init__(self, owner, balance=0):
        if not owner.strip():
            raise ValueError("Owner is required")
        if balance < 0:
            raise ValueError("Initial balance cannot be negative")
        self.owner = owner
        self.balance = balance

    def deposit(self, amount):
        if amount <= 0:
            raise ValueError("Deposit must be positive")
        self.balance += amount
        return self.balance

    def withdraw(self, amount):
        if amount <= 0:
            raise ValueError("Withdrawal must be positive")
        if amount > self.balance:
            raise ValueError("Insufficient funds")
        self.balance -= amount
        return self.balance

    def transfer(self, recipient, amount):
        if recipient is self:
            raise ValueError("Cannot transfer to the same account")
        if amount <= 0:
            raise ValueError("Transfer must be positive")
        if amount > self.balance:
            raise ValueError("Insufficient funds")
        self.balance -= amount
        recipient.balance += amount
        send_notification(recipient.owner, f"Received {amount} from {self.owner}")
        return self.balance