feat: Implement Banking System Features and Tests

lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/AuditLog.java

@@ -0,0 +1,47 @@
+package com.codedifferently.lesson17.bank;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Records audit logs for account-related actions. This class maintains a list of log entries for
+ * tracking account additions.
+ */
+public class AuditLog {
+
+  // List to hold log entries
+  private final List<String> logEntries = new ArrayList<>();
+
+  /**
+   * Logs the addition of a new account by recording its account number.
+   *
+   * @param accountNumber The account number of the newly added account.
+   */
+  public void logAccountAddition(String accountNumber) {
+    logEntries.add("Account added: " + accountNumber);
+  }
+
+  /**
+   * Retrieves all log entries recorded in the audit log.
+   *
+   * @return A new list containing all log entries.
+   */
+  public List<String> getLogEntries() {
+    // Return a copy of the log entries to prevent external modification
+    return new ArrayList<>(logEntries);
+  }
+
+  /**
+   * Retrieves the last log entry recorded in the audit log.
+   *
+   * @return The most recent log entry as a String, or null if there are no entries.
+   */
+  public String getLastEntry() {
+    // Check if the log is empty and return null if so
+    if (logEntries.isEmpty()) {
+      return null; // Or throw an exception if preferred
+    }
+    // Return the last log entry
+    return logEntries.get(logEntries.size() - 1);
+  }
+}

lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/BankAtm.java

@@ -1,88 +1,158 @@
 package com.codedifferently.lesson17.bank;
 
 import com.codedifferently.lesson17.bank.exceptions.AccountNotFoundException;
+import java.util.Currency;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.UUID;
 
-/** Represents a bank ATM. */
+/**
+ * Represents a bank ATM that manages customer accounts and transactions. This class handles account
+ * management, deposits, withdrawals, and logging actions.
+ */
 public class BankAtm {
 
+  // Map to store customers by their unique ID
   private final Map<UUID, Customer> customerById = new HashMap<>();
+
+  // Map to store checking accounts by their account number
   private final Map<String, CheckingAccount> accountByNumber = new HashMap<>();
 
+  // Audit log to record account-related actions
+  private final AuditLog auditLog = new AuditLog();
+
   /**
-   * Adds a checking account to the bank.
+   * Adds a checking account to the bank's records.
    *
-   * @param account The account to add.
+   * @param account The CheckingAccount to add.
    */
   public void addAccount(CheckingAccount account) {
+    // Add the account to the account map using its account number
     accountByNumber.put(account.getAccountNumber(), account);
+
+    // Register each owner of the account in the customer map
     account
         .getOwners()
         .forEach(
             owner -> {
               customerById.put(owner.getId(), owner);
             });
+
+    // Log the account addition in the audit log
+    auditLog.logAccountAddition(account.getAccountNumber());
   }
 
   /**
-   * Finds all accounts owned by a customer.
+   * Finds all accounts owned by a specific customer.
    *
-   * @param customerId The ID of the customer.
-   * @return The unique set of accounts owned by the customer.
+   * @param customerId The ID of the customer whose accounts are to be found.
+   * @return A unique set of CheckingAccounts owned by the customer, or an empty set if none are
+   *     found.
    */
   public Set<CheckingAccount> findAccountsByCustomerId(UUID customerId) {
     return customerById.containsKey(customerId)
         ? customerById.get(customerId).getAccounts()
-        : Set.of();
+        : Set.of(); // Return an empty set if the customer does not exist
   }
 
   /**
-   * Deposits funds into an account.
+   * Deposits a specified amount of funds into an account.
    *
-   * @param accountNumber The account number.
-   * @param amount The amount to deposit.
+   * @param accountNumber The account number to deposit into.
+   * @param amount The amount of money to deposit.
    */
   public void depositFunds(String accountNumber, double amount) {
+    // Retrieve the account or throw an exception if not found
     CheckingAccount account = getAccountOrThrow(accountNumber);
-    account.deposit(amount);
+    account.deposit(amount); // Deposit the amount into the account
   }
 
   /**
    * Deposits funds into an account using a check.
    *
-   * @param accountNumber The account number.
-   * @param check The check to deposit.
+   * @param accountNumber The account number to deposit into.
+   * @param check The Check object representing the check to be deposited.
    */
   public void depositFunds(String accountNumber, Check check) {
+    // Retrieve the account or throw an exception if not found
     CheckingAccount account = getAccountOrThrow(accountNumber);
-    check.depositFunds(account);
+    check.depositFunds(account); // Process the check and deposit funds into the account
+  }
+
+  /**
+   * Deposits funds into an account while converting from a specified currency.
+   *
+   * @param accountNumber The account number to deposit into.
+   * @param amount The amount to deposit.
+   * @param currency The currency of the deposit amount.
+   */
+  public void depositFunds(String accountNumber, double amount, Currency currency) {
+    // Retrieve the account or throw an exception if not found
+    CheckingAccount account = getAccountOrThrow(accountNumber);
+
+    // Validate the provided currency
+    if (currency == null || !isValidCurrency(currency)) {
+      throw new IllegalArgumentException("Invalid currency provided");
+    }
+
+    // Convert the amount to the account's currency (assuming USD for this example)
+    Currency accountCurrency =
+        Currency.getInstance("USD"); // Replace with actual account currency if necessary
+    double convertedAmount = CurrencyConverter.convert(amount, currency, accountCurrency);
+
+    account.deposit(convertedAmount); // Deposit the converted amount into the account
+  }
+
+  /**
+   * Checks if the provided currency is valid.
+   *
+   * @param currency The currency to validate.
+   * @return true if the currency is valid; false otherwise.
+   */
+  private boolean isValidCurrency(Currency currency) {
+    // Define valid currencies
+    return currency.getCurrencyCode().equals("USD")
+        || currency.getCurrencyCode().equals("GBP")
+        || currency.getCurrencyCode().equals("CAD")
+        || currency.getCurrencyCode().equals("EUR");
+  }
+
+  /**
+   * Retrieves all entries from the audit log.
+   *
+   * @return A list of log entries recorded in the audit log.
+   */
+  public List<String> getAuditLogEntries() {
+    return auditLog.getLogEntries(); // Return the audit log entries
   }
 
   /**
-   * Withdraws funds from an account.
+   * Withdraws a specified amount of funds from an account.
    *
-   * @param accountNumber
-   * @param amount
+   * @param accountNumber The account number to withdraw from.
+   * @param amount The amount of money to withdraw.
    */
   public void withdrawFunds(String accountNumber, double amount) {
+    // Retrieve the account or throw an exception if not found
     CheckingAccount account = getAccountOrThrow(accountNumber);
-    account.withdraw(amount);
+    account.withdraw(amount); // Withdraw the specified amount from the account
   }
 
   /**
-   * Gets an account by its number or throws an exception if not found.
+   * Retrieves an account by its account number, throwing an exception if not found.
    *
-   * @param accountNumber The account number.
-   * @return The account.
+   * @param accountNumber The account number to search for.
+   * @return The CheckingAccount associated with the given account number.
+   * @throws AccountNotFoundException if the account is not found or is closed.
    */
   private CheckingAccount getAccountOrThrow(String accountNumber) {
     CheckingAccount account = accountByNumber.get(accountNumber);
+    // Check if the account is found and is not closed
     if (account == null || account.isClosed()) {
       throw new AccountNotFoundException("Account not found");
     }
-    return account;
+    return account; // Return the found account
   }
 }

lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/BusinessCheckingAccount.java

@@ -0,0 +1,32 @@
+package com.codedifferently.lesson17.bank;
+
+import java.util.Set;
+
+/**
+ * Represents a business checking account, which is a specialized type of checking account. This
+ * account must have at least one owner designated as a business.
+ */
+public class BusinessCheckingAccount extends CheckingAccount {
+
+  /**
+   * Creates a new BusinessCheckingAccount with the specified account number, owners, and initial
+   * balance.
+   *
+   * @param accountNumber The account number for the business checking account.
+   * @param owners A set of Customer objects representing the owners of the account.
+   * @param initialBalance The initial balance to set for the account.
+   * @throws IllegalArgumentException if no owner is designated as a business.
+   */
+  public BusinessCheckingAccount(
+      String accountNumber, Set<Customer> owners, double initialBalance) {
+    super(
+        accountNumber,
+        owners,
+        initialBalance); // Call the superclass constructor to initialize common fields
+
+    // Ensure that at least one owner is a business customer
+    if (!owners.stream().anyMatch(Customer::isBusiness)) {
+      throw new IllegalArgumentException("At least one owner must be a business");
+    }
+  }
+}

lesson_17/bank/bank_app/src/main/java/com/codedifferently/lesson17/bank/Check.java

@@ -2,67 +2,80 @@
 
 import com.codedifferently.lesson17.bank.exceptions.CheckVoidedException;
 
-/** Represents a check. */
+/**
+ * Represents a check that can be deposited into a checking account. A check has a number, an
+ * amount, and is associated with a checking account.
+ */
 public class Check {
 
+  // The unique identifier for the check
   private final String checkNumber;
+
+  // The amount specified on the check
   private final double amount;
+
+  // The checking account that the check is drawn from
   private final CheckingAccount account;
+
+  // Indicates whether the check has been voided
   private boolean isVoided = false;
 
   /**
-   * Creates a new check.
+   * Creates a new check with the specified check number, amount, and associated account.
    *
    * @param checkNumber The check number.
-   * @param amount The amount of the check.
-   * @param account The account the check is drawn on.
+   * @param amount The amount of the check (must be positive).
+   * @param account The checking account the check is drawn on.
+   * @throws IllegalArgumentException if the amount is negative.
    */
   public Check(String checkNumber, double amount, CheckingAccount account) {
     if (amount < 0) {
-      throw new IllegalArgumentException("Check amount must be positive");
+      throw new IllegalArgumentException(
+          "Check amount must be positive"); // Validate the check amount
     }
     this.checkNumber = checkNumber;
     this.amount = amount;
-    this.account = account;
+    this.account = account; // Assign the associated checking account
   }
 
   /**
    * Gets the voided status of the check.
    *
-   * @return True if the check is voided, and false otherwise.
+   * @return True if the check is voided; false otherwise.
    */
   public boolean getIsVoided() {
-    return isVoided;
+    return isVoided; // Return the voided status
   }
 
-  /** Voids the check. */
+  /** Voids the check, preventing it from being deposited. */
   public void voidCheck() {
-    isVoided = true;
+    isVoided = true; // Set the voided status to true
   }
 
   /**
-   * Deposits the check into an account.
+   * Deposits the check into the specified account.
    *
    * @param toAccount The account to deposit the check into.
+   * @throws CheckVoidedException if the check is voided.
    */
   public void depositFunds(CheckingAccount toAccount) {
     if (isVoided) {
-      throw new CheckVoidedException("Check is voided");
+      throw new CheckVoidedException("Check is voided"); // Check if the check is voided
     }
-    account.withdraw(amount);
-    toAccount.deposit(amount);
-    voidCheck();
+    account.withdraw(amount); // Withdraw the amount from the original account
+    toAccount.deposit(amount); // Deposit the amount into the specified account
+    voidCheck(); // Void the check after successful deposit
   }
 
   @Override
   public int hashCode() {
-    return checkNumber.hashCode();
+    return checkNumber.hashCode(); // Generate hash code based on the check number
   }
 
   @Override
   public boolean equals(Object obj) {
     if (obj instanceof Check other) {
-      return checkNumber.equals(other.checkNumber);
+      return checkNumber.equals(other.checkNumber); // Check equality based on the check number
     }
     return false;
   }
@@ -77,6 +90,6 @@ public String toString() {
         + amount
         + ", account="
         + account.getAccountNumber()
-        + '}';
+        + '}'; // Return a string representation of the check
   }
 }