Updated with reviews and TODOs.

src/main/java/com/employee_wise/assignment/constants/EmailConstants.java

@@ -2,6 +2,8 @@
 
 import com.employee_wise.assignment.entity.Employee;
 
+// TODO this can be done via something called Server side templating engine
+//
 public class EmailConstants {
 
 	public static String getAdditionMessage(String manName, Employee emp) {

src/main/java/com/employee_wise/assignment/constants/EndPoint.java

@@ -1,5 +1,6 @@
 package com.employee_wise.assignment.constants;
 
+// TODO this entire class is useless
 public class EndPoint {
 
 	public static final String EMPLOYEE = "/employee";

src/main/java/com/employee_wise/assignment/constants/ErrorCodeEnum.java

@@ -14,8 +14,8 @@ public enum ErrorCodeEnum {
 	MAIL_NOT_SENT("10008","Failed Request, Mail could not be sent to the Reciepent");
 
 
-	private String errorCode;
-	private String errorMessage;
+	private final String errorCode;
+	private final String errorMessage;
 
 	private ErrorCodeEnum(String errorCode, String errorMessage) {
 		this.errorCode=errorCode;

src/main/java/com/employee_wise/assignment/controller/Controller.java

@@ -37,14 +37,14 @@ public class Controller {
 	public ResponseEntity<PostEmployeeResponse> addEmployee(@RequestBody Employee emp){
 
 		 PostEmployeeResponse savedEmp = this.empSerImp.addEmployee(emp);
-		 return new ResponseEntity<PostEmployeeResponse>(savedEmp,HttpStatus.CREATED); 
+		 return new ResponseEntity<>(savedEmp,HttpStatus.CREATED);
 	}
 
 	@GetMapping(EndPoint.GET_EMPLOYEE_BY_ID+ "/{id}")
 	public ResponseEntity<Employee> getEmployeeById(@PathVariable("id") String id){
 
 		 Employee returnedEmp = this.empSerImp.getEmployeeById(id);
-		 return new ResponseEntity<Employee>(returnedEmp,HttpStatus.FOUND); 
+		 return new ResponseEntity<>(returnedEmp,HttpStatus.FOUND);
 	}
 
 	@GetMapping(EndPoint.GET_ALL_EMPLOYEE)
@@ -55,13 +55,13 @@ public ResponseEntity<List<Employee>> getAllEmployee(
 			){
 
 		 List<Employee> returnedEmp = this.empSerImp.getAllEmployee(pageNumber, pageSize, sortBy);
-		 return new ResponseEntity<List<Employee>>(returnedEmp,HttpStatus.FOUND); 
+		 return new ResponseEntity<>(returnedEmp,HttpStatus.FOUND);
 	}
 
 	@PutMapping(EndPoint.UPDATE_EMPLOYEE_BY_ID + "/{id}")
 	public ResponseEntity<PostEmployeeResponse> updateEmployeeById(@PathVariable("id") String id, @RequestBody Employee emp){
 		PostEmployeeResponse updatedEmp = this.empSerImp.updateEmployeeById(id, emp);
-		return new ResponseEntity<PostEmployeeResponse>(updatedEmp,HttpStatus.OK);
+		return new ResponseEntity<>(updatedEmp,HttpStatus.OK);
 	}
 
 	@DeleteMapping(EndPoint.DELETE_EMPLOYEE_BY_ID+"/{id}")
@@ -75,21 +75,21 @@ public ResponseEntity<Employee> deleteEmployeeById(@PathVariable String id){
 	@GetMapping(EndPoint.GET_MANAGER_BY_NTH_LEVEL+ "/{id}" + "/{n}")
 	public ResponseEntity<PostEmployeeResponse> getNthManager(@PathVariable("id") String id, @PathVariable("n") Integer n){
 		PostEmployeeResponse Emp = this.empSerImp.getNthManager(id, n);
-		return new ResponseEntity<PostEmployeeResponse>(Emp,HttpStatus.OK);
+		return new ResponseEntity<>(Emp,HttpStatus.OK);
 	}
 
 	@PostMapping(EndPoint.SEND_SIMPLE_MAIL)
     public ResponseEntity<EmailResponse> sendMail(@RequestBody EmailDetails details)
     {
         EmailResponse status = emailService.sendSimpleMail(details);
-        return new ResponseEntity<EmailResponse>(status,HttpStatus.OK);
+        return new ResponseEntity<>(status,HttpStatus.OK);
     }
 
     @PostMapping(EndPoint.SEND_MAIL_WITH_ATTACHMENT)
     public ResponseEntity<EmailResponse> sendMailWithAttachment(@RequestBody EmailDetails details)
     {
         EmailResponse status = emailService.sendMailWithAttachment(details);
-        return new ResponseEntity<EmailResponse>(status,HttpStatus.OK);
+        return new ResponseEntity<>(status,HttpStatus.OK);
     }
 
 }

src/main/java/com/employee_wise/assignment/entity/EmailDetails.java

@@ -1,16 +1,8 @@
 package com.employee_wise.assignment.entity;
 
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
-
-@Data
-@AllArgsConstructor
-@NoArgsConstructor
-public class EmailDetails {
-
-    private String recipient;
-    private String msgBody;
-    private String subject;
-    private String attachment;
-}
+public record EmailDetails (
+        String recipient,
+        String msgBody,
+        String subject,
+        String attachment
+) implements NonNullCopier<EmailDetails>{}

src/main/java/com/employee_wise/assignment/entity/Employee.java

@@ -12,14 +12,14 @@
 import lombok.NoArgsConstructor;
 import lombok.Setter;
 
-
+// TODO migrate this to Record too - Java 17 Records
 @Data
 @NoArgsConstructor
 @AllArgsConstructor
 @Getter
 @Setter
 @Document
-public class Employee {
+public class Employee implements  NonNullCopier<Employee> {
 
 	@Id
 	@Indexed(unique = true)

src/main/java/com/employee_wise/assignment/entity/NonNullCopier.java

@@ -0,0 +1,21 @@
+package com.employee_wise.assignment.entity;
+
+import java.lang.reflect.Field;
+import java.util.Arrays;
+
+public interface NonNullCopier<T> {
+
+    default void autoCopy(T src){
+        if ( getClass() != src.getClass() ) return;
+        Field[] fields = getClass().getDeclaredFields();
+        Arrays.stream(fields).forEach( f -> {
+            try {
+                Object val = f.get(src) ;
+                if ( val != null ){
+                    f.set(this, val);
+                }
+            } catch (IllegalAccessException ignored) {
+            }
+        });
+    }
+}

src/main/java/com/employee_wise/assignment/exceptions/EmployeeException.java

@@ -6,6 +6,7 @@
 import lombok.Getter;
 import lombok.Setter;
 
+// TODO migrate to record
 @Getter
 @Setter
 @AllArgsConstructor

src/main/java/com/employee_wise/assignment/pojo/EmployeeError.java

@@ -5,6 +5,8 @@
 import lombok.Data;
 import lombok.NoArgsConstructor;
 
+// TODO migrate to record
+
 @Data
 @Builder
 @AllArgsConstructor

src/main/java/com/employee_wise/assignment/repository/EmployeeRepo.java

@@ -7,6 +7,10 @@
 
 import com.employee_wise.assignment.entity.Employee;
 
+// TODO are we using MongoDB? If not, why we are using MongoRepo?
+// import org.springframework.data.jpa.repository.JpaRepository;
+// import org.springframework.stereotype.Repository;
+// https://hevodata.com/learn/spring-boot-mysql/
 @Repository
 public interface EmployeeRepo extends MongoRepository<Employee , UUID>{
 

src/main/java/com/employee_wise/assignment/response/EmailResponse.java

@@ -8,6 +8,8 @@
 import lombok.NoArgsConstructor;
 import lombok.Setter;
 
+// TODO migrate to Java 17 Record
+// Also probably not needed
 @Data
 @Getter
 @Setter

src/main/java/com/employee_wise/assignment/response/PostEmployeeResponse.java

@@ -8,6 +8,8 @@
 import lombok.NoArgsConstructor;
 import lombok.Setter;
 
+// TODO migrate to Java 17 Record
+// Not required,
 @Data
 @Getter
 @Setter

src/main/java/com/employee_wise/assignment/service/EmployeeService.java

@@ -10,10 +10,13 @@
 @Service
 public interface EmployeeService {
 
-	public PostEmployeeResponse addEmployee(Employee emp);
-	public List<Employee> getAllEmployee(Integer pageNumber, Integer pageSize, String sortBy);
-	public Employee getEmployeeById(String Id);
-	public PostEmployeeResponse updateEmployeeById(String id,Employee emp);
-	public Employee deleteEmployeeById(String id);
-	public PostEmployeeResponse getNthManager(String id, Integer n);
+	// TODO, refactor to return the new created employee id
+	PostEmployeeResponse addEmployee(Employee emp);
+	List<Employee> getAllEmployee(Integer pageNumber, Integer pageSize, String sortBy);
+	Employee getEmployeeById(String Id);
+	PostEmployeeResponse updateEmployeeById(String id,Employee emp);
+	Employee deleteEmployeeById(String id);
+
+	// TODO refactor to return the Employee, not this
+	PostEmployeeResponse getNthManager(String id, Integer n);
 }

src/main/java/com/employee_wise/assignment/serviceImpl/EmailServiceImpl.java

@@ -34,12 +34,12 @@ public EmailResponse sendSimpleMail(EmailDetails details)
             SimpleMailMessage mailMessage = new SimpleMailMessage();
 
             mailMessage.setFrom(sender);
-            mailMessage.setTo(details.getRecipient());
-            mailMessage.setText(details.getMsgBody());
-            mailMessage.setSubject(details.getSubject());
+            mailMessage.setTo(details.recipient());
+            mailMessage.setText(details.msgBody());
+            mailMessage.setSubject(details.subject());
 
             javaMailSender.send(mailMessage);
-            return new EmailResponse(details.getRecipient().toString(),"Email is Successfully sent to Recipent.");
+            return new EmailResponse(details.recipient(),"Email is Successfully sent to Recipent.");
         }
         catch (Exception e) {
         	throw new EmployeeException(HttpStatus.INTERNAL_SERVER_ERROR,
@@ -56,16 +56,16 @@ public EmailResponse sendMailWithAttachment(EmailDetails details)
         try {
             mimeMessageHelper = new MimeMessageHelper(mimeMessage, true);
             mimeMessageHelper.setFrom(sender);
-            mimeMessageHelper.setTo(details.getRecipient());
-            mimeMessageHelper.setText(details.getMsgBody());
-            mimeMessageHelper.setSubject(details.getSubject());
+            mimeMessageHelper.setTo(details.recipient());
+            mimeMessageHelper.setText(details.msgBody());
+            mimeMessageHelper.setSubject(details.subject());
 
-            FileSystemResource file = new FileSystemResource(new File(details.getAttachment()));
+            FileSystemResource file = new FileSystemResource(new File(details.attachment()));
 
             mimeMessageHelper.addAttachment(file.getFilename(), file);
 
             javaMailSender.send(mimeMessage);
-            return new EmailResponse(details.getRecipient().toString(),"Email with provided Attachment is Successfully sent to Recipent.");
+            return new EmailResponse(details.recipient(),"Email with provided Attachment is Successfully sent to Recipent.");
         }
         catch (MessagingException e) {
         	throw new EmployeeException(HttpStatus.INTERNAL_SERVER_ERROR,

src/main/java/com/employee_wise/assignment/serviceImpl/EmployeeServiceImpl.java

@@ -42,7 +42,7 @@ public class EmployeeServiceImpl implements EmployeeService{
 	@Override
 	public PostEmployeeResponse addEmployee(Employee emp) {
 		Employee saveEmp = this.repo.save(emp);
-		if(saveEmp == null) {
+		if(saveEmp == null) { // TODO refactor, this code is no go , will not get triggered - read the doc
 			throw new EmployeeException(HttpStatus.INTERNAL_SERVER_ERROR,
 					ErrorCodeEnum.EMPLOYEE_NOT_ADDED.getErrorCode(),
 					ErrorCodeEnum.EMPLOYEE_NOT_ADDED.getErrorMessage());
@@ -109,37 +109,24 @@ public Employee deleteEmployeeById(String id) {
 	@Override
 	public PostEmployeeResponse updateEmployeeById(String id, Employee emp) {
 		UUID uuid = UUID.fromString(id);
-		List<Employee> empl = this.repo.findById(uuid).stream().collect(Collectors.toList());
-		Employee employee = empl.get(0);
-		if(employee == null) {
+		// TODO this is not how you do it
+		Optional<Employee> opt = this.repo.findById(uuid);
+		if(opt.isEmpty()) {
 			throw new EmployeeException(HttpStatus.INTERNAL_SERVER_ERROR,
 					ErrorCodeEnum.EMPLOYEE_NOT_FOUND.getErrorCode(),
 					ErrorCodeEnum.EMPLOYEE_NOT_FOUND.getErrorMessage());
 		}
-		else {
-			if(emp.getEmployeeName() != null) {
-				employee.setEmployeeName(emp.getEmployeeName());
-			}
-			if(emp.getEmail() != null) {
-				employee.setEmail(emp.getEmail());
-			}
-			if(emp.getPhoneNumber() != null) {
-				employee.setPhoneNumber(emp.getPhoneNumber());
-			}
-			if(emp.getReportsTo() != null) {
-				employee.setReportsTo(emp.getReportsTo());
-			}
-			if(emp.getProfileImage() != null) {
-				employee.setProfileImage(emp.getProfileImage());
-			}
-		}
+		Employee employee = opt.get();
+		// TODO this is another lotta code, no need, can do much better
+		employee.autoCopy(emp);
 
 		Employee saveEmp = this.repo.save(employee);
-		if(saveEmp == null) {
+		if(saveEmp == null) { // TODO this never happens
 			throw new EmployeeException(HttpStatus.INTERNAL_SERVER_ERROR,
 					ErrorCodeEnum.EMPLOYEE_NOT_UPDATED.getErrorCode(),
 					ErrorCodeEnum.EMPLOYEE_NOT_UPDATED.getErrorMessage());
 		}
+		// This never happens
 		Employee mEmpl = getEmployeeById(saveEmp.getReportsTo().toString());
 		if(mEmpl == null) {
 			throw new EmployeeException(HttpStatus.INTERNAL_SERVER_ERROR,
@@ -150,7 +137,7 @@ public PostEmployeeResponse updateEmployeeById(String id, Employee emp) {
 		emailServ.sendSimpleMail(email);
 		return new PostEmployeeResponse(saveEmp.getId().toString(), "Employee is Updated");
 	}
-	
+
 	@Override
 	public PostEmployeeResponse getNthManager(String id, Integer n) {
 	    UUID uuid = UUID.fromString(id);
@@ -181,13 +168,15 @@ public PostEmployeeResponse getNthManager(String id, Integer n) {
 	    }
 	}
 
+	// TODO this is a bad impl, create a write through cache here
+	// TODO Cache out the entire org in memory and return as fast as you can
 	private Employee findNthManager(Employee employee, int n) {
 	    UUID managerId = employee.getReportsTo();
 
 	    while (managerId != null && n > BASE_LEVEL) {
 	        Optional<Employee> optionalManager = this.repo.findById(managerId).stream().findFirst();
 
-	        if (!optionalManager.isPresent()) {
+	        if (optionalManager.isEmpty()) {
 	        	throw new EmployeeException(HttpStatus.INTERNAL_SERVER_ERROR,
 		                ErrorCodeEnum.MANAGER_NOT_FOUND.getErrorCode(),
 		                ErrorCodeEnum.MANAGER_NOT_FOUND.getErrorMessage());