refactor: incremental payment flow refactoring — tests, exceptions, REST API, and async events

pom.xml

@@ -67,6 +67,16 @@
 			<artifactId>spring-security-test</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>com.h2database</groupId>
+			<artifactId>h2</artifactId>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.awaitility</groupId>
+			<artifactId>awaitility</artifactId>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 
 	<build>
@@ -80,8 +90,8 @@
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>3.8.0</version>
 				<configuration>
-    					<source>1.8</source>
-    					<target>1.8</target>
+					<source>17</source>
+					<target>17</target>
 				</configuration>
 			</plugin>
 		</plugins>

src/main/java/com/example/bankapp/BankappApplication.java

@@ -2,8 +2,10 @@
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.scheduling.annotation.EnableAsync;
 
 @SpringBootApplication
+@EnableAsync
 public class BankappApplication {
 
 	public static void main(String[] args) {

src/main/java/com/example/bankapp/config/SecurityConfig.java

@@ -4,6 +4,7 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.annotation.Order;
 import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
@@ -25,6 +26,24 @@ public static PasswordEncoder passwordEncoder() {
     }
 
     @Bean
+    @Order(1)
+    public SecurityFilterChain apiSecurityFilterChain(HttpSecurity http) throws Exception {
+        http
+                .securityMatcher("/api/**")
+                .csrf(csrf -> csrf.disable())
+                .authorizeHttpRequests(authz -> authz
+                        .anyRequest().authenticated()
+                )
+                .httpBasic(basic -> {})
+                .headers(headers -> headers
+                        .frameOptions(frameOptions -> frameOptions.sameOrigin())
+                );
+
+        return http.build();
+    }
+
+    @Bean
+    @Order(2)
     public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
         http
                 .csrf(csrf -> csrf.disable())
@@ -57,4 +76,4 @@ public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception
         auth.userDetailsService(accountService).passwordEncoder(passwordEncoder());
 
     }
-}
+}

src/main/java/com/example/bankapp/controller/BankApiController.java

@@ -0,0 +1,67 @@
+package com.example.bankapp.controller;
+
+import com.example.bankapp.dto.*;
+import com.example.bankapp.model.Account;
+import com.example.bankapp.model.Transaction;
+import com.example.bankapp.service.AccountService;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/v1")
+public class BankApiController {
+
+    private final AccountService accountService;
+
+    public BankApiController(AccountService accountService) {
+        this.accountService = accountService;
+    }
+
+    @PostMapping("/deposit")
+    public ResponseEntity<ApiResponse<AccountResponse>> deposit(@RequestBody DepositRequest request) {
+        String username = SecurityContextHolder.getContext().getAuthentication().getName();
+        Account account = accountService.findAccountByUsername(username);
+        accountService.deposit(account, request.getAmount());
+        Account updated = accountService.findAccountByUsername(username);
+        return ResponseEntity.ok(ApiResponse.ok("Deposit successful", AccountResponse.from(updated)));
+    }
+
+    @PostMapping("/withdraw")
+    public ResponseEntity<ApiResponse<AccountResponse>> withdraw(@RequestBody WithdrawRequest request) {
+        String username = SecurityContextHolder.getContext().getAuthentication().getName();
+        Account account = accountService.findAccountByUsername(username);
+        accountService.withdraw(account, request.getAmount());
+        Account updated = accountService.findAccountByUsername(username);
+        return ResponseEntity.ok(ApiResponse.ok("Withdrawal successful", AccountResponse.from(updated)));
+    }
+
+    @PostMapping("/transfer")
+    public ResponseEntity<ApiResponse<AccountResponse>> transfer(@RequestBody TransferRequest request) {
+        String username = SecurityContextHolder.getContext().getAuthentication().getName();
+        Account fromAccount = accountService.findAccountByUsername(username);
+        accountService.transferAmount(fromAccount, request.getToUsername(), request.getAmount());
+        Account updated = accountService.findAccountByUsername(username);
+        return ResponseEntity.ok(ApiResponse.ok("Transfer successful", AccountResponse.from(updated)));
+    }
+
+    @GetMapping("/balance")
+    public ResponseEntity<ApiResponse<AccountResponse>> getBalance() {
+        String username = SecurityContextHolder.getContext().getAuthentication().getName();
+        Account account = accountService.findAccountByUsername(username);
+        return ResponseEntity.ok(ApiResponse.ok("Balance retrieved", AccountResponse.from(account)));
+    }
+
+    @GetMapping("/transactions")
+    public ResponseEntity<ApiResponse<List<TransactionResponse>>> getTransactions() {
+        String username = SecurityContextHolder.getContext().getAuthentication().getName();
+        Account account = accountService.findAccountByUsername(username);
+        List<Transaction> transactions = accountService.getTransactionHistory(account);
+        List<TransactionResponse> response = transactions.stream()
+                .map(TransactionResponse::from)
+                .toList();
+        return ResponseEntity.ok(ApiResponse.ok("Transactions retrieved", response));
+    }
+}

src/main/java/com/example/bankapp/controller/BankController.java

@@ -1,5 +1,6 @@
 package com.example.bankapp.controller;
 
+import com.example.bankapp.exception.BankAppException;
 import com.example.bankapp.model.Account;
 import com.example.bankapp.service.AccountService;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -36,7 +37,7 @@ public String registerAccount(@RequestParam String username, @RequestParam Strin
         try {
             accountService.registerAccount(username, password);
             return "redirect:/login";
-        } catch (RuntimeException e) {
+        } catch (BankAppException e) {
             model.addAttribute("error", e.getMessage());
             return "register";
         }
@@ -48,10 +49,16 @@ public String login() {
     }
 
     @PostMapping("/deposit")
-    public String deposit(@RequestParam BigDecimal amount) {
+    public String deposit(@RequestParam BigDecimal amount, Model model) {
         String username = SecurityContextHolder.getContext().getAuthentication().getName();
         Account account = accountService.findAccountByUsername(username);
-        accountService.deposit(account, amount);
+        try {
+            accountService.deposit(account, amount);
+        } catch (BankAppException e) {
+            model.addAttribute("error", e.getMessage());
+            model.addAttribute("account", account);
+            return "dashboard";
+        }
         return "redirect:/dashboard";
     }
 
@@ -62,7 +69,7 @@ public String withdraw(@RequestParam BigDecimal amount, Model model) {
 
         try {
             accountService.withdraw(account, amount);
-        } catch (RuntimeException e) {
+        } catch (BankAppException e) {
             model.addAttribute("error", e.getMessage());
             model.addAttribute("account", account);
             return "dashboard";
@@ -86,7 +93,7 @@ public String transferAmount(@RequestParam String toUsername, @RequestParam BigD
 
         try {
             accountService.transferAmount(fromAccount, toUsername, amount);
-        } catch (RuntimeException e) {
+        } catch (BankAppException e) {
             model.addAttribute("error", e.getMessage());
             model.addAttribute("account", fromAccount);
             return "dashboard";

src/main/java/com/example/bankapp/dto/AccountResponse.java

@@ -0,0 +1,49 @@
+package com.example.bankapp.dto;
+
+import com.example.bankapp.model.Account;
+
+import java.math.BigDecimal;
+
+public class AccountResponse {
+
+    private Long id;
+    private String username;
+    private BigDecimal balance;
+
+    public AccountResponse() {
+    }
+
+    public AccountResponse(Long id, String username, BigDecimal balance) {
+        this.id = id;
+        this.username = username;
+        this.balance = balance;
+    }
+
+    public static AccountResponse from(Account account) {
+        return new AccountResponse(account.getId(), account.getUsername(), account.getBalance());
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public BigDecimal getBalance() {
+        return balance;
+    }
+
+    public void setBalance(BigDecimal balance) {
+        this.balance = balance;
+    }
+}

src/main/java/com/example/bankapp/dto/ApiResponse.java

@@ -0,0 +1,49 @@
+package com.example.bankapp.dto;
+
+public class ApiResponse<T> {
+
+    private boolean success;
+    private String message;
+    private T data;
+
+    public ApiResponse() {
+    }
+
+    public ApiResponse(boolean success, String message, T data) {
+        this.success = success;
+        this.message = message;
+        this.data = data;
+    }
+
+    public static <T> ApiResponse<T> ok(String message, T data) {
+        return new ApiResponse<>(true, message, data);
+    }
+
+    public static <T> ApiResponse<T> error(String message) {
+        return new ApiResponse<>(false, message, null);
+    }
+
+    public boolean isSuccess() {
+        return success;
+    }
+
+    public void setSuccess(boolean success) {
+        this.success = success;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    public T getData() {
+        return data;
+    }
+
+    public void setData(T data) {
+        this.data = data;
+    }
+}

src/main/java/com/example/bankapp/dto/DepositRequest.java

@@ -0,0 +1,23 @@
+package com.example.bankapp.dto;
+
+import java.math.BigDecimal;
+
+public class DepositRequest {
+
+    private BigDecimal amount;
+
+    public DepositRequest() {
+    }
+
+    public DepositRequest(BigDecimal amount) {
+        this.amount = amount;
+    }
+
+    public BigDecimal getAmount() {
+        return amount;
+    }
+
+    public void setAmount(BigDecimal amount) {
+        this.amount = amount;
+    }
+}

src/main/java/com/example/bankapp/dto/TransactionResponse.java

@@ -0,0 +1,65 @@
+package com.example.bankapp.dto;
+
+import com.example.bankapp.model.Transaction;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+
+public class TransactionResponse {
+
+    private Long id;
+    private BigDecimal amount;
+    private String type;
+    private LocalDateTime timestamp;
+
+    public TransactionResponse() {
+    }
+
+    public TransactionResponse(Long id, BigDecimal amount, String type, LocalDateTime timestamp) {
+        this.id = id;
+        this.amount = amount;
+        this.type = type;
+        this.timestamp = timestamp;
+    }
+
+    public static TransactionResponse from(Transaction transaction) {
+        return new TransactionResponse(
+                transaction.getId(),
+                transaction.getAmount(),
+                transaction.getType(),
+                transaction.getTimestamp()
+        );
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public BigDecimal getAmount() {
+        return amount;
+    }
+
+    public void setAmount(BigDecimal amount) {
+        this.amount = amount;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
+    public LocalDateTime getTimestamp() {
+        return timestamp;
+    }
+
+    public void setTimestamp(LocalDateTime timestamp) {
+        this.timestamp = timestamp;
+    }
+}