vkhazin / shared-bank-account

Shared Bank Account

RDBMS Schema

Overview

Account

• AccountId: uuid, PK
• Owner: uuid FK to Organization
• Account Status: Active or Inactive
• ...

User

• UserId: uuid, PK
• ...

Account User

• AccountUserId: uuid, PK
• AccountId: uuid, FK to account, composite Unique Index
• UserId: uuid, FK to users, composite Unique Index
• UserType: Administrator or Standard
• Status: Active or Inactive

Transaction

• TransactionId: uuid, PK
• AccountId: uuid, FK to account
• UserId: uuid, FK to user
• TransactionType: Deposit or Withdraw
• Amount: money
• Balance: money
• Timestamp: date-time

Comments: Append-only table

Withdraw Limit

• WithdrawLimitId: uuid, PK
• AccountId: uuid, FK to account, composite Unique Index
• UserId: uuid, FK to users, composite Unique Index
• LimitType: daily, weekly, or monthly
• Amount: money
• Timestamp: date-time

Comments: Records are append-only to preserve the history. The timestamp used to locate the most recent record for limit validation purposes.

Organization

• OrganizationId: uuid, PK
• ...

Organization Users

• OrganizationUserId: uuid, PK
• OrganizationId: uuid, FK
• UserId: uuid, FK
• ...

Account Audit Trail

• AccountAuditTrailId: uuid, PK
• AccountId: uuid
• ActorUserId: uuid
• Timestamp: date-time
• OldValues: json
• NewValues: json

Comments: Append-only table

Account User Audit Trail

• AccountUserAuditTrailId: uuid, PK
• AccountId: uuid, non-unique index
• UserId: uuid, non-unique index
• ActorUserId: uuid, non-unique index
• Timestamp: date-time, non-unique index desc
• OldValues: json
• NewValues: json

Comments: Append-only table

User Audit Trail

• UserAuditTrailId: uuid, PK
• UserId: uuid, non-unique index
• ActorUserId: uuid, non-unique index
• Timestamp: date-time, non-unique index desc
• OldValues: json
• NewValues: json

Comments: Append-only table

Classes

Bank Account

Methods

• open(admin_user_id: str, account: dict) -> dict

  * User id will be added to account user as admin
  

• get(account_id: str, admin_user_id: str) -> dict

  * User id must be 'active' on the account user list with type == Administrator
  

• update(account_id: str, admin_user_id: str, account_details: dict) -> dict

  * User id must be 'active' on the account user list with type == Administrator
  

• close(account_id: str, admin_user_id: str)

  * User id must be 'active' on the account user list with type == Administrator
  

• deposit_funds(account_id: str, user_id: str, amount: float)

    * User must be 'active' on the list of account users for the account
  

• withdraw_funds(account_id: str, user_id, amount: float) -> dict

    * User must not exceed limit as defined in the withdraw limits
    * Withdraw limit is compared to the total of all transactions 
      for the given user for the day, week, or month
    * Withdraw amount should not exceed the latest balance available for the account
  

• view_available_balance(account_id: str, user_id: str) -> dict

    * Available balance is a delta between withdraw limits
    * And total sum of withdraw transaction for the given user and account 
      for the day, week, or month
  

• view_transaction_history(**kwargs) -> list of dict

  account_id
  user_id: filter transactions by user_id
  start_date: to filter the history, today is the default
  end_date: to filter the history, 2999-12-31 is the default
  transaction_type: to filter the history
  offset: int = 0
  limit: int = 100, max limit is enforced to avoid large result set 
  

• view_transaction_history_as_admin:

  account_id
  admin_user_id: validate user is an account Administrator 
  user_ids: list of str to filter transactions, 
            when list is empty - retrieve all,
            transactions by other admins will be filtered out
  start_date: to filter the history, today is the default
  end_date: to filter the history, 2999-12-31 is the default
  transaction_type: to filter the history
  offset: int = 0
  limit: int = 100, max limit is enforced to avoid large result set 
  

• get_withdraw_limits(**kwargs) -> list of dict

  account_id: str
  admin_user_id: str
  user_id: str = None
  include_inactive: Boolean = False
  offset: int = 0
  limit: int = 100, max limit is enforced to avoid large result set 
  

• place_withdraw_limit(**kwargs)

  account_id
  admin_user_id:   validate the user is on the list of account users 
                  and is active with type == Administrator
  user_id:  validate the user is on the list of account users 
            and is active and with type != Administrator
  limit_type: daily, weekly, or monthly
  amount: verify the value is positive
  

• add_user(account_id: str, admin_user_id: str, user: dict) -> dict

  * Cannot add user to an account where user is not on the list of 
    organization users for the account owner organization
  

• get_users(account_id: str, admin_user_id: str, offset: int = 0, limit: int = 100) -> list of dict
• remove_user(account_id: str, admin_user_id: str, user_id: str)
• update_user(account_id: str, admin_user_id: str, user: dict)

Authorizer

Internal-use class to move validation rules from the Bank Account class

• validate_user_is_admin(account_id: str, user_id: str) -> Boolean
• validate_withdraw_limit(account_id: str, user_id: str, amount: float) -> Boolean

Repository

Internal-use class to move data repository related code away from other classes

• execute(sql_statement: str)
• execute_query(sql_statement: str) -> list

Users

• Subcommittee is treated as a user
• No requirements provided for user management

Organization

• Family is treated as an organization
• No requirements provided for organization management