Add solution for Challenge 7

Author: go-interview-practice-bot[bot]

challenge-7/submissions/RezaSi/solution-template.go

@@ -0,0 +1,210 @@
+// Package challenge7 contains the solution for Challenge 7: Bank Account with Error Handling.
+package challenge7
+
+import (
+"fmt"
+"strings"
+"sync"
+)
+
+// BankAccount represents a bank account with balance management and minimum balance requirements.
+type BankAccount struct {
+ID string
+Owner string
+Balance float64
+MinBalance float64
+mu sync.Mutex // For thread safety
+}
+
+// Constants for account operations
+const (
+MaxTransactionAmount = 10000.0 // Example limit for deposits/withdrawals
+)
+
+// Custom error types
+
+// AccountError is a general error type for bank account operations.
+type AccountError struct {
+message string
+}
+
+func (e *AccountError) Error() string {
+return e.message
+}
+
+// InsufficientFundsError occurs when a withdrawal or transfer would bring the balance below minimum.
+type InsufficientFundsError struct {
+id string
+owner string
+amtName string
+amount float64
+min float64
+}
+
+func (e *InsufficientFundsError) Error() string {
+return fmt.Sprintf("Acc Id: %s, owner: %s - %s value $%.2f is below minimum $%.2f", e.id, e.owner, e.amtName, e.amount, e.min)
+}
+
+// NegativeAmountError occurs when an amount for deposit, withdrawal, or transfer is negative.
+type NegativeAmountError struct {
+id string
+owner string
+amtName string
+amount float64
+}
+
+func (e *NegativeAmountError) Error() string {
+return fmt.Sprintf("Acc Id: %s, owner: %s - %s value $%.2f is negative", e.id, e.owner, e.amtName, e.amount)
+}
+
+// ExceedsLimitError occurs when a deposit or withdrawal amount exceeds the defined limit.
+type ExceedsLimitError struct {
+id string
+owner string
+amtName string
+amount float64
+}
+
+func (e *ExceedsLimitError) Error() string {
+return fmt.Sprintf("Acc Id: %s, owner: %s - %s value $%.2f exceeds max transaction limit $%.2f",
+e.id, e.owner, e.amtName, e.amount, MaxTransactionAmount)
+}
+
+// NewBankAccount creates a new bank account with the given parameters.
+// It returns an error if any of the parameters are invalid.
+func NewBankAccount(id, owner string, initialBalance, minBalance float64) (*BankAccount, error) {
+if len(strings.TrimSpace(id)) == 0 {
+return nil, &AccountError{"invalid id"}
+}
+if len(strings.TrimSpace(owner)) == 0 {
+return nil, &AccountError{"invalid owner"}
+}
+if initialBalance < 0 {
+return nil, &NegativeAmountError{
+id: id,
+owner: owner,
+amtName: "new account initial balance",
+amount: initialBalance,
+}
+}
+if minBalance < 0 {
+return nil, &NegativeAmountError{
+id: id,
+owner: owner,
+amtName: "new account minimum balance",
+amount: minBalance,
+}
+} // "initial balance less than minimum"
+if initialBalance < minBalance {
+return nil, &InsufficientFundsError{
+id: id,
+owner: owner,
+amtName: "new account initial balance",
+amount: initialBalance,
+min: minBalance,
+}
+}
+
+acc := BankAccount{
+ID: id,
+Owner: owner,
+Balance: initialBalance,
+MinBalance: minBalance,
+}
+return &acc, nil
+}
+
+// Deposit adds the specified amount to the account balance.
+// It returns an error if the amount is invalid or exceeds the transaction limit.
+func (a *BankAccount) Deposit(amount float64) error {
+// lock mutex
+a.mu.Lock()
+defer a.mu.Unlock()
+
+// validate amount
+if amount < 0 {
+return &NegativeAmountError{
+id: a.ID,
+owner: a.Owner,
+amtName: "deposit amount",
+amount: amount,
+}
+}
+if amount > MaxTransactionAmount {
+return &ExceedsLimitError{
+id: a.ID,
+owner: a.Owner,
+amtName: "deposit amount",
+amount: amount,
+}
+}
+
+// increment balance
+a.Balance += amount
+
+return nil
+}
+
+// Withdraw removes the specified amount from the account balance.
+// It returns an error if the amount is invalid, exceeds the transaction limit,
+// or would bring the balance below the minimum required balance.
+func (a *BankAccount) Withdraw(amount float64) error {
+// lock mutex
+a.mu.Lock()
+defer a.mu.Unlock()
+
+// validate amount
+if amount < 0 {
+return &NegativeAmountError{
+id: a.ID,
+owner: a.Owner,
+amtName: "withdrawal amount",
+amount: amount,
+}
+}
+if amount > MaxTransactionAmount {
+return &ExceedsLimitError{
+id: a.ID,
+owner: a.Owner,
+amtName: "withdrawal amount",
+amount: amount,
+}
+}
+if a.Balance-amount < a.MinBalance {
+return &InsufficientFundsError{
+id: a.ID,
+owner: a.Owner,
+amtName: "remaining balance",
+amount: a.Balance - amount,
+min: a.MinBalance,
+}
+}
+
+// decrement balance
+a.Balance -= amount
+
+return nil
+}
+
+// Transfer moves the specified amount from this account to the target account.
+// It returns an error if the amount is invalid, exceeds the transaction limit,
+// or would bring the balance below the minimum required balance.
+func (a *BankAccount) Transfer(amount float64, target *BankAccount) error {
+// capture initial balances
+initSrcBal := a.Balance
+initTgtBal := target.Balance
+
+if err := a.Withdraw(amount); err != nil {
+// revert initial balances
+a.Balance = initSrcBal
+target.Balance = initTgtBal
+return err
+}
+if err := target.Deposit(amount); err != nil {
+// revert initial balances
+a.Balance = initSrcBal
+target.Balance = initTgtBal
+return err
+}
+return nil
+}