Kiril petrov interview

src/main/java/com/devexperts/ApplicationRunner.java

@@ -1,7 +1,7 @@
 package com.devexperts;
 
 import com.devexperts.service.AccountService;
-import com.devexperts.service.AccountServiceImpl;
+import com.devexperts.service.impl.AccountServiceImpl;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.context.annotation.Bean;
@@ -12,8 +12,4 @@ public static void main(String[] args) {
             SpringApplication.run(ApplicationRunner.class, args);
     }
 
-    @Bean
-    AccountService accountService() {
-        return new AccountServiceImpl();
-    }
 }

src/main/java/com/devexperts/account/Account.java

@@ -32,4 +32,5 @@ public Double getBalance() {
     public void setBalance(Double balance) {
         this.balance = balance;
     }
+
 }

src/main/java/com/devexperts/dto/ErrorDto.java

@@ -0,0 +1,44 @@
+package com.devexperts.dto;
+
+import org.springframework.http.HttpStatus;
+
+import java.time.LocalDateTime;
+
+public class ErrorDto {
+
+    private String message;
+
+    private HttpStatus status;
+
+    private LocalDateTime time;
+
+    public ErrorDto(String message, HttpStatus status, LocalDateTime time) {
+        this.message = message;
+        this.status = status;
+        this.time = time;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    public HttpStatus getStatus() {
+        return status;
+    }
+
+    public void setStatus(HttpStatus status) {
+        this.status = status;
+    }
+
+    public LocalDateTime getTime() {
+        return time;
+    }
+
+    public void setTime(LocalDateTime time) {
+        this.time = time;
+    }
+}

src/main/java/com/devexperts/dto/TransferMoneyDto.java

@@ -0,0 +1,42 @@
+package com.devexperts.dto;
+
+import javax.validation.constraints.NotNull;
+
+public class TransferMoneyDto {
+
+    @NotNull
+    private Long sourceId;
+    @NotNull
+    private Long targetId;
+    private double amount;
+
+    public TransferMoneyDto(Long sourceId, Long targetId, double amount) {
+        this.sourceId = sourceId;
+        this.targetId = targetId;
+        this.amount = amount;
+    }
+
+    public Long getSourceId() {
+        return sourceId;
+    }
+
+    public void setSourceId(Long sourceId) {
+        this.sourceId = sourceId;
+    }
+
+    public Long getTargetId() {
+        return targetId;
+    }
+
+    public void setTargetId(Long targetId) {
+        this.targetId = targetId;
+    }
+
+    public double getAmount() {
+        return amount;
+    }
+
+    public void setAmount(double amount) {
+        this.amount = amount;
+    }
+}

src/main/java/com/devexperts/exception/BadRequestException.java

@@ -0,0 +1,8 @@
+package com.devexperts.exception;
+
+public class BadRequestException extends RuntimeException {
+
+    public BadRequestException(String msg) {
+        super(msg);
+    }
+}

src/main/java/com/devexperts/exception/InsufficentFundsException.java

@@ -0,0 +1,8 @@
+package com.devexperts.exception;
+
+public class InsufficentFundsException extends RuntimeException {
+
+    public InsufficentFundsException(String msg) {
+        super(msg);
+    }
+}

src/main/java/com/devexperts/exception/NotFoundException.java

@@ -0,0 +1,9 @@
+package com.devexperts.exception;
+
+public class NotFoundException extends RuntimeException {
+
+    public NotFoundException(String msg) {
+        super(msg);
+    }
+
+}

src/main/java/com/devexperts/handler/GlobalExceptionHandler.java

@@ -0,0 +1,57 @@
+package com.devexperts.handler;
+
+import com.devexperts.dto.ErrorDto;
+import com.devexperts.exception.BadRequestException;
+import com.devexperts.exception.InsufficentFundsException;
+import com.devexperts.exception.NotFoundException;
+import org.springframework.context.support.DefaultMessageSourceResolvable;
+import org.springframework.http.HttpStatus;
+import org.springframework.validation.FieldError;
+import org.springframework.web.bind.MethodArgumentNotValidException;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+
+import java.time.LocalDateTime;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+@RestControllerAdvice
+public class GlobalExceptionHandler {
+
+    @ExceptionHandler(BadRequestException.class)
+    @ResponseStatus(HttpStatus.BAD_REQUEST)
+    public ErrorDto handleBadRequests(BadRequestException exception) {
+        return convertExceptionToErrorDto(HttpStatus.BAD_REQUEST, exception.getMessage());
+    }
+
+    @ExceptionHandler(NotFoundException.class)
+    @ResponseStatus(HttpStatus.NOT_FOUND)
+    public ErrorDto handleBadRequests(NotFoundException exception) {
+        return convertExceptionToErrorDto(HttpStatus.NOT_FOUND, exception.getMessage());
+    }
+
+    @ExceptionHandler(InsufficentFundsException.class)
+    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
+    public ErrorDto handleBadRequests(InsufficentFundsException exception) {
+        return convertExceptionToErrorDto(HttpStatus.INTERNAL_SERVER_ERROR, exception.getMessage());
+    }
+
+    @ExceptionHandler(MethodArgumentNotValidException.class)
+    @ResponseStatus(HttpStatus.BAD_REQUEST)
+    public ErrorDto handleMethodArgumentNotValidException(MethodArgumentNotValidException exception) {
+        final Map<String, String> errorMessages = exception.getBindingResult().getFieldErrors().stream()
+                .collect(Collectors.toMap(FieldError::getField, DefaultMessageSourceResolvable::getDefaultMessage));
+        return convertExceptionToErrorDto(HttpStatus.BAD_REQUEST, errorMessages.toString());
+    }
+
+    @ExceptionHandler(NumberFormatException.class)
+    @ResponseStatus(HttpStatus.BAD_REQUEST)
+    public ErrorDto handleMethodArgumentNotValidException(NumberFormatException exception) {
+        return convertExceptionToErrorDto(HttpStatus.BAD_REQUEST, exception.getMessage());
+    }
+
+    private static ErrorDto convertExceptionToErrorDto(final HttpStatus status, final String message) {
+        return new ErrorDto(message, status, LocalDateTime.now());
+    }
+}

src/main/java/com/devexperts/rest/AbstractAccountController.java

@@ -1,7 +1,8 @@
 package com.devexperts.rest;
 
+import com.devexperts.dto.TransferMoneyDto;
 import org.springframework.http.ResponseEntity;
 
 public abstract class AbstractAccountController {
-    abstract ResponseEntity<Void> transfer(long sourceId, long targetId, double amount);
+    abstract ResponseEntity<Void> transfer(TransferMoneyDto transferMoneyDto);
 }

src/main/java/com/devexperts/rest/AccountController.java

@@ -1,14 +1,32 @@
 package com.devexperts.rest;
 
+import com.devexperts.dto.TransferMoneyDto;
+import com.devexperts.service.AccountService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.PutMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
+import javax.validation.Valid;
+
 @RestController
 @RequestMapping("/api")
 public class AccountController extends AbstractAccountController {
 
-    public ResponseEntity<Void> transfer(long sourceId, long targetId, double amount) {
-        return null;
+    private final AccountService service;
+
+    @Autowired
+    public AccountController(AccountService service) {
+        this.service = service;
     }
+
+    @PostMapping("operations/transfer")
+    public ResponseEntity<Void> transfer(@Valid TransferMoneyDto transferMoneyDto) {
+        service.transfer(transferMoneyDto);
+        return new ResponseEntity<>(HttpStatus.OK);
+    }
+
 }

src/main/java/com/devexperts/service/AccountService.java

@@ -1,6 +1,7 @@
 package com.devexperts.service;
 
 import com.devexperts.account.Account;
+import com.devexperts.dto.TransferMoneyDto;
 
 public interface AccountService {
 
@@ -29,9 +30,7 @@ public interface AccountService {
     /**
      * Transfers given amount of money from source account to target account
      *
-     * @param source account to transfer money from
-     * @param target account to transfer money to
-     * @param amount dollar amount to transfer
+     * @param dto the ids of both accounts and the amount to be transferred
      * */
-    void transfer(Account source, Account target, double amount);
+    void transfer(TransferMoneyDto dto);
 }

src/main/java/com/devexperts/service/impl/AccountServiceImpl.java

@@ -0,0 +1,63 @@
+package com.devexperts.service.impl;
+
+import com.devexperts.account.Account;
+import com.devexperts.account.AccountKey;
+import com.devexperts.dto.TransferMoneyDto;
+import com.devexperts.exception.BadRequestException;
+import com.devexperts.exception.NotFoundException;
+import com.devexperts.service.AccountService;
+import org.springframework.stereotype.Service;
+import org.springframework.web.client.HttpClientErrorException;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+@Service
+public class AccountServiceImpl implements AccountService {
+
+    private final Map<AccountKey, Account> accounts = new HashMap<>();
+
+    @Override
+    public void clear() {
+        accounts.clear();
+    }
+
+    @Override
+    public void createAccount(Account account) {
+        accounts.put(account.getAccountKey(), account);
+    }
+
+    @Override
+    public Account getAccount(long id) {
+        return accounts.get(AccountKey.valueOf(id));
+    }
+
+    @Override
+    public synchronized void transfer(TransferMoneyDto dto) {
+        Account source = accounts.get(AccountKey.valueOf(dto.getSourceId()));
+        Account target = accounts.get(AccountKey.valueOf(dto.getTargetId()));
+        transfer(source, target, dto.getAmount());
+    }
+
+    public void transfer(Account source, Account target, double amount) {
+        if(source == null) {
+            throw new NotFoundException("The source account doesnt exist");
+        }
+        if(target == null) {
+            throw new NotFoundException("The target account doesnt exist");
+        }
+        if(source.equals(target)) {
+            throw new BadRequestException("Its pointless to transfer money between the same account");
+        }
+        if(amount < 0) {
+            throw new BadRequestException("The amount can't be a negative value");
+        }
+        if(source.getBalance() < amount) {
+            throw new BadRequestException("The source account doesnt have sufficient amount");
+        }
+        source.setBalance(source.getBalance() - amount);
+        target.setBalance(target.getBalance() + amount);
+    }
+}

src/main/resources/sql/data/accounts.sql

@@ -0,0 +1 @@
+CREATE TABLE IF NOT EXISTS accounts (ID int, FIRST_NAME varchar(255), LAST_NAME varchar(255), BALANCE DECIMAL);

src/main/resources/sql/data/select.sql

@@ -0,0 +1 @@
+SELECT * FROM accounts AS ACC INNER JOIN transfers AS TR on ACC.ID = TR.SOURCE_ID WHERE TRANSFER_TIME >= '2019-01-01'  GROUP BY ACC.ID HAVING SUM(TR.AMOUNT) > 1000

src/main/resources/sql/data/transfers.sql

@@ -0,0 +1 @@
+CREATE TABLE IF NOT EXISTS transfers (ID int, SOURCE_ID int, TARGET_ID int, AMOUNT DECIMAL, TRANSFER_TIME TIMESTAMP);