Added an error catching decorator and finished account deposit

README.md

@@ -1,14 +1,20 @@
-# ksi
+# nu (ν)
 
 ## Sources
 
 ### Signal catching
+
 - [Catch SIGTERM](https://dnmtechs.com/graceful-sigterm-signal-handling-in-python-3-best-practices-and-implementation/)
-- [Get ENUM name from value](https://stackoverflow.com/a/38716384)
 - [Windows termination signals](https://stackoverflow.com/a/35792192)
+- ~~[Get ENUM name from value](https://stackoverflow.com/a/38716384)~~  
+  Unused because of required compatibility with lower version python (3.9)
 
 ### Networking
+
 - [Dynamically finding host IP address](https://stackoverflow.com/a/28950776)
+- [IP Regex](https://ihateregex.io/expr/ip/)
 
 ### Database
+
 - [SqlAlchemy session generator](https://stackoverflow.com/a/71053353)
+- [Error handling decorator](https://chatgpt.com/share/67a46109-d38c-8005-ac36-677e6511ddcd)

src/bank_node/bank_node.py

@@ -51,6 +51,7 @@ class BankNode():
             signal.signal(signal.SIGBREAK, self.gracefully_exit)
 
     def start(self):
+        try:
             for port in range(self.config.scan_port_start, self.config.scan_port_end + 1):
                 self.logger.debug("Trying port %d", port)
                 try:
@@ -60,9 +61,18 @@ class BankNode():
                 except socket.error as e:
                     if e.errno == 98:  # Address is in use
                         self.logger.info("Port %d in use, trying next port", port)
+                    else:
+                        raise
+
 
             self.logger.error("All ports are in use")
             self.exit_with_error()
+        except socket.error as e:
+            if e.errno == 99: # Cannot assign to requested address
+                self.logger.critical("Cannot use the IP address %s", self.config.ip)
+            else:
+                self.logger.critical("Unknown error: %s", e)
+            self.exit_with_error()
 
     def __start_server(self, port: int):
         with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as socket_server:

src/bank_protocol/command_handler.py

@@ -39,6 +39,9 @@ class CommandHandler:
         command = self.registered_commands[request.command_code]
         try:
             response = command(request, self.config)
+            if response is not None:
                 return f"{request.command_code} {response}"
+            else:
+                return request.command_code
         except DatabaseError as e:
             return f"ER {e.message}"

src/bank_protocol/commands/account_deposit_command.py

@@ -1,14 +1,19 @@
 from core import Request, BankNodeConfig
 from bank_protocol.exceptions import InvalidRequest
+from services.account_service import deposit_into_account
+from utils.constants import MONEY_AMOUNT_MAXIMUM
 
 
 def account_deposit(request: Request, config: BankNodeConfig):
+    try:
         split_body = request.body.split("/")
         split_ip = split_body[1].split(" ")
 
         account = split_body[0]
         ip = split_ip[0]
         amount = split_ip[1]
+    except IndexError as e:
+        raise InvalidRequest("Invalid request format") from e
 
     if not account.isdigit():
         raise InvalidRequest("Account must be a number")
@@ -18,5 +23,15 @@ def account_deposit(request: Request, config: BankNodeConfig):
     if account_parsed < 10_000 or account_parsed > 99_999:
         raise InvalidRequest("Account number out of range")
 
+    if not amount.isdigit():
+        raise InvalidRequest("Deposit amount must be a number")
+
+    amount_parsed = int(amount)
+
+    if amount_parsed > MONEY_AMOUNT_MAXIMUM:
+        raise InvalidRequest("Cannot deposit this much")
+
+    deposit_into_account(account_parsed, amount_parsed)
+
 
 __all__ = ["account_deposit"]

src/bank_protocol/commands/bank_code_command.py

@@ -1,12 +1,10 @@
-from typing import Dict
-
-from core import Request, Response
+from core import Request, Response, BankNodeConfig
 from bank_protocol.exceptions import InvalidRequest
 
-def bank_code(request: Request, config: Dict) -> Response:
+def bank_code(request: Request, config: BankNodeConfig) -> Response:
     if request.body is not None:
         raise InvalidRequest("Incorrect usage")
 
-    return config["ip"]
+    return config.ip
 
 __all__ = ["bank_code"]

src/bank_protocol/commands/bank_number_of_clients_command.py

@@ -1,7 +1,12 @@
-from core.request import Request
+from core import Request, Response
+from bank_protocol.exceptions import InvalidRequest
+from services.account_service import get_account_count
 
-def bank_number_of_clients(request: Request):
-    pass
+def bank_number_of_clients(request: Request, _) -> Response:
+    if request.body is not None:
+        raise InvalidRequest("Incorrect usage")
 
+    number_of_clients = get_account_count()
+    return number_of_clients
 
 __all__ = ["bank_number_of_clients"]

src/bank_protocol/commands/bank_total_amount_command.py

@@ -1,7 +1,13 @@
-from core.request import Request
+from core import Request, Response
+from bank_protocol.exceptions import InvalidRequest
+from services.account_service import get_total_balance
 
-def bank_total_amount(request: Request):
-    pass
+def bank_total_amount(request: Request, _):
+    if request.body is not None:
+        raise InvalidRequest("Incorrect usage")
+
+    total_balace = get_total_balance()
+    return total_balace
 
 
 __all__ = ["bank_total_amount"]

src/core/config.py

@@ -48,8 +48,7 @@ class BankNodeConfig:
 
         # IP validation
         if not re.match(IP_REGEX, ip):
-            self.logger.error("Invalid IP in configuration")
-            raise ConfigError("Invalid IP in configuration")
+            raise ConfigError(f"Invalid IP {ip} in configuration")
 
         self.used_port: int
         self.ip = ip

src/database/database_manager.py

@@ -4,9 +4,9 @@ from contextlib import contextmanager
 
 from sqlalchemy.orm import sessionmaker, Session
 from sqlalchemy import create_engine, text
-from sqlalchemy.exc import DatabaseError
+from sqlalchemy.exc import DatabaseError as SqlAlchemyDatabaseError
 
-from database.exceptions import DatabaseConnectionError
+from database.exceptions import DatabaseError
 from models.base_model import Base
 
 
@@ -45,9 +45,9 @@ class DatabaseManager():
                 connection.execute(text("select 1"))
             self.logger.debug("Database connection successful")
             return True
-        except DatabaseError as e:
+        except SqlAlchemyDatabaseError as e:
             self.logger.critical("Database connection failed: %s", e)
-            raise DatabaseConnectionError("Database connection failed") from e
+            raise DatabaseError("Database connection failed", DatabaseError.CONNECTION_ERROR) from e
 
         return False
 

src/database/exception_catcher_decorator.py

@@ -0,0 +1,13 @@
+from functools import wraps
+from sqlalchemy.exc import DatabaseError as SqlAlchemyDatabaseError
+from database.exceptions import DatabaseError
+
+
+def handle_database_errors(func):
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        try:
+            return func(*args, **kwargs)
+        except SqlAlchemyDatabaseError as e:
+            raise DatabaseError(str(e), -1) from e
+    return wrapper

src/database/exceptions.py

@@ -1,52 +1,24 @@
 class DatabaseError(Exception):
-    def __init__(self, message: str):
+    # Inspired by OSError which also uses errno's
+    # It's a better approach than using a class for each error
+    UNKNOWN_ERROR = -1
+
+    CONNECTION_ERROR = 1
+    EMPTY_CONFIG = 2
+    DUPLICATE_ENTRY = 3
+    NONEXISTENT_ACCOUNT = 4
+    OUT_OF_ACCOUNT_SPACE = 5
+    INSUFFICIENT_BALANCE = 6
+    INVALID_OPERATION = 7
+
+    def __init__(self, message: str, errno: int, **kwargs):
+
         super().__init__(message)
         self.message = message
+        self.errno = errno
+
+        for key, value in kwargs.items():
+            setattr(self, key, value)
 
 
-class DatabaseConnectionError(DatabaseError):
-    def __init__(self, message: str):
-        super().__init__(message)
-        self.message = message
-
-
-class EmptyDatabaseConfigError(Exception):
-    def __init__(self, message: str, config_name: str):
-        super().__init__(message)
-
-        self.message = message
-        self.config_name = config_name
-
-
-class DuplicateEntryError(DatabaseError):
-    def __init__(self, duplicate_entry_name: str, message: str):
-        super().__init__(message)
-        self.duplicate_entry_name = duplicate_entry_name
-        self.message = message
-
-
-class NonexistentAccountError(DatabaseError):
-    def __init__(self, message: str):
-        super().__init__(message)
-        self.message = message
-
-
-class OutOfAccountSpaceError(DatabaseError):
-    def __init__(self, message: str):
-        super().__init__(message)
-        self.message = message
-
-
-class InsufficientBalance(DatabaseError):
-    def __init__(self, message: str):
-        super().__init__(message)
-        self.message = message
-
-
-class InvalidOperation(DatabaseError):
-    def __init__(self, message: str):
-        super().__init__(message)
-        self.message = message
-
-
-__all__ = ["DatabaseError", "DatabaseConnectionError", "DuplicateEntryError", "InsufficientBalance", "OutOfAccountSpaceError", "NonexistentAccountError", "EmptyDatabaseConfigError", "InvalidOperation"]
+__all__ = ["DatabaseError"]

src/services/account_service.py

@@ -2,21 +2,24 @@ from sqlalchemy import func
 
 from models import Account
 from database import DatabaseManager
-from database.exceptions import OutOfAccountSpaceError, NonexistentAccountError, InsufficientBalance, InvalidOperation
+from database.exceptions import DatabaseError
+from database.exception_catcher_decorator import handle_database_errors
 from utils.constants import MIN_ACCOUNT_NUMBER, MAX_ACCOUNT_NUMBER
 
 
+@handle_database_errors
 def get_next_id() -> int:
     with DatabaseManager.get_session() as session:
         current_max_id = session.query(func.max(Account.account_number)).scalar()
         current_max_id = current_max_id + 1 if current_max_id is not None else MIN_ACCOUNT_NUMBER
 
         if current_max_id > MAX_ACCOUNT_NUMBER:
-            raise OutOfAccountSpaceError("Too many users already exist, cannot open new account")
+            raise DatabaseError("Too many users already exist, cannot open new account", DatabaseError.OUT_OF_ACCOUNT_SPACE)
 
         return current_max_id
 
 
+@handle_database_errors
 def create_account() -> int:
     new_id = get_next_id()
 
@@ -27,47 +30,68 @@ def create_account() -> int:
     return new_id
 
 
+@handle_database_errors
 def get_account_balance(account_number: int) -> int:
     with DatabaseManager.get_session() as session:
         account: Account = session.query(Account).where(Account.account_number == account_number).one_or_none()
         if account is None:
-            raise NonexistentAccountError(f"Account with number {account_number} doesn't exist")
+            raise DatabaseError(f"Account with number {account_number} doesn't exist", DatabaseError.NONEXISTENT_ACCOUNT)
 
         return account.balance
 
 
+@handle_database_errors
 def withdraw_from_account(account_number: int, amount: int):
-    modify_balance(account_number, amount, True)
-
-
-def deposit_into_account(account_number: int, amount: int):
     modify_balance(account_number, amount, False)
 
 
-def modify_balance(account_number: int, amount: int, subtract: bool):
+@handle_database_errors
+def deposit_into_account(account_number: int, amount: int):
+    modify_balance(account_number, amount, True)
+
+
+@handle_database_errors
+def modify_balance(account_number: int, amount: int, add: bool):
     with DatabaseManager.get_session() as session:
         account: Account = session.query(Account).where(Account.account_number == account_number).one_or_none()
         if account is None:
-            raise NonexistentAccountError(f"Account with number {account_number} doesn't exist")
+            raise DatabaseError(f"Account with number {account_number} doesn't exist", DatabaseError.NONEXISTENT_ACCOUNT)
 
-        if subtract:
+        if add:
             account.balance += amount
         else:
             if account.balance - amount < 0:
-                raise InsufficientBalance("Not enough funds on account to withdraw this much")
+                raise DatabaseError("Not enough funds on account to withdraw this much", DatabaseError.INSUFFICIENT_BALANCE)
             account.balance -= amount
 
         session.commit()
 
 
+@handle_database_errors
 def delete_account(account_number: int):
     with DatabaseManager.get_session() as session:
         account: Account = session.query(Account).where(Account.account_number == account_number).one_or_none()
         if account is None:
-            raise NonexistentAccountError(f"Account with number {account_number} doesn't exist")
+            raise DatabaseError(f"Account with number {account_number} doesn't exist", DatabaseError.NONEXISTENT_ACCOUNT)
 
         if account.balance > 0:
-            raise InvalidOperation("Cannot delete an account with leftover funds")
+            raise DatabaseError("Cannot delete an account with leftover funds", DatabaseError.INVALID_OPERATION)
 
         session.delete(account)
         session.commit()
+
+
+@handle_database_errors
+def get_total_balance() -> int:
+    with DatabaseManager.get_session() as session:
+        total_sum = session.query(func.sum(Account.balance)).scalar()
+
+        return total_sum if total_sum is not None else 0
+
+
+@handle_database_errors
+def get_account_count() -> int:
+    with DatabaseManager.get_session() as session:
+        total_sum = session.query(func.count(Account.account_number)).scalar()
+
+        return total_sum if total_sum is not None else 0

src/utils/constants.py

@@ -1,8 +1,9 @@
 import re
+import sys
 
-IP_REGEX = r"^[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}$"
-ACCOUNT_NUMBER_REGEX = r"[0-9]{9}"
-MONEY_AMOUNT_MAXIMUM = (2 ^ 63) - 1
+IP_REGEX = r"^(\b25[0-5]|\b2[0-4][0-9]|\b[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$"
+ACCOUNT_NUMBER_REGEX = r"^(1[0-9]{8})|([2-9][0-9]{8})$"
+MONEY_AMOUNT_MAXIMUM = 2**63 - 1
 
 MIN_ACCOUNT_NUMBER = 10_000
 MAX_ACCOUNT_NUMBER = 99_999