# Banking System - Mermaid Class Diagram
```mermaid
classDiagram
class Customer {
-customerId: string
-firstName: string
-lastName: string
-email: string
-phone: string
-dateOfBirth: Date
-address: Address
-creditScore: number
+openAccount(accountType: string): Account
+closeAccount(account: Account): boolean
+applyForLoan(loanAmount: number, loanType: string): LoanApplication
+getAccountBalance(account: Account): number
+transferFunds(fromAccount: Account, toAccount: Account, amount: number): boolean
}
class Account {
-accountNumber: string
-accountType: string
-balance: number
-interestRate: number
-dateOpened: Date
+isActive: boolean {readOnly}
-minimumBalance: number
+deposit(amount: number): boolean
+withdraw(amount: number): boolean
+getBalance(): number
+getTransactionHistory(): Transaction[]
+calculateInterest(): number
+closeAccount(): boolean
}
class Transaction {
-transactionId: string
-transactionType: string
-amount: number
-timestamp: Date
-description: string
-status: string
-fromAccount: Account
-toAccount: Account
+processTransaction(): boolean
+validateTransaction(): boolean
+getTransactionDetails(): string
}
class Loan {
-loanId: string
-loanType: string
-principalAmount: number
-interestRate: number
-termMonths: number
-startDate: Date
-endDate: Date
-monthlyPayment: number
-outstandingBalance: number
-loanStatus: string
+calculateMonthlyPayment(): number
+makePayment(amount: number): boolean
+getRemainingBalance(): number
+refinanceLoan(newInterestRate: number): boolean
}
class Branch {
-branchId: string
-branchName: string
-address: Address
-phoneNumber: string
-manager: Employee
-operatingHours: string
+openBranch(): boolean
+closeBranch(): boolean
+addCustomer(customer: Customer): boolean
+getBranchDetails(): string
}
class Employee {
-employeeId: string
-firstName: string
-lastName: string
-position: string
-department: string
-salary: number
-hireDate: Date
-branch: Branch
+processTransaction(transaction: Transaction): boolean
+approveLoan(loanApplication: LoanApplication): boolean
+openCustomerAccount(customer: Customer, accountType: string): Account
+getEmployeeDetails(): string
}
class Address {
-street: string
-city: string
-state: string
-zipCode: string
-country: string
+validateAddress(): boolean
+getFullAddress(): string
+updateAddress(newAddress: Address): boolean
}
class LoanApplication {
-applicationId: string
-customer: Customer
-loanType: string
-requestedAmount: number
-applicationDate: Date
-applicationStatus: string
-creditScore: number
-income: number
-approvedBy: Employee
-approvalDate: Date
+submitApplication(): boolean
+updateStatus(status: string): boolean
+getApprovalStatus(): string
+calculateLoanTerms(): Loan
}
Customer "1" -- "0..*" Account : owns
Account "1" -- "0..*" Transaction : has
Customer "1" -- "0..*" Loan : has
Customer "1" -- "0..*" LoanApplication : submits
Branch "1" -- "0..*" Customer : serves
Branch "1" -- "0..*" Employee : employs
Employee "1" -- "1" Branch : works at
Customer "1" -- "1" Address : lives at
Branch "1" -- "1" Address : located at
LoanApplication "1" -- "0..1" Employee : approved by
LoanApplication "1" -- "0..1" Loan : results in
```
## System Overview
This banking system includes 8 core entities with comprehensive relationships:
### Core Entities:
- **Customer** - Bank customers with personal information and financial activities
- **Account** - Financial accounts with balance management and transactions
- **Transaction** - Individual financial transactions between accounts
- **Loan** - Loan products with terms and payment management
- **Branch** - Physical bank locations with staff and customers
- **Employee** - Bank staff who process transactions and approve loans
- **Address** - Address information for customers and branches
- **LoanApplication** - Loan request workflow with approval process
### Key Features:
- Comprehensive account management (deposit, withdraw, transfer)
- Transaction history and validation
- Loan application and approval workflow
- Branch and employee management
- Address handling for customers and branches
- Full audit trail with timestamps and status tracking
