daily strike

Here is an example of a Spring Boot program that gives a “daily strike” to a user if they log in daily:

@RestController
@RequestMapping("/api/login")
public class LoginController {
    private Map<String, LocalDate> userLastLoginMap = new HashMap<>();

    @PostMapping
    public ResponseEntity<String> login(@RequestBody User user) {
        LocalDate today = LocalDate.now();
        LocalDate lastLoginDate = userLastLoginMap.getOrDefault(user.getUsername(), today.minusDays(1));

        if (today.isEqual(lastLoginDate.plusDays(1))) {
            userLastLoginMap.put(user.getUsername(), today);
            return new ResponseEntity<>("Welcome! You have earned a daily strike!", HttpStatus.OK);
        } else {
            userLastLoginMap.put(user.getUsername(), today);
            return new ResponseEntity<>("Welcome!", HttpStatus.OK);
        }
    }
}

This program uses a RestController and @RequestMapping annotation to map the /api/login endpoint to the login method. The login method takes in a User object as a request body, which should have a username property.

The login method uses a Map to store the last login date for each user. When a user logs in, the program checks the stored last login date for that user and compares it to the current date. If the difference between the stored date and the current date is exactly one day, then the user earns a “daily strike” and the response is “Welcome! You have earned a daily strike!”. If the difference is not exactly one day, then the user does not earn a daily strike and the response is simply “Welcome!”

Note that this example is only a rough guide and additional security feature like encrypting password, validating payload and request,etc. needs to be done in real time scenario.

what more features can be added

There are many additional features that can be added to this Spring Boot program to improve its functionality and security:

1. Authentication and Authorization: Currently, the program doesn’t perform any authentication to verify that the user attempting to log in is actually who they claim to be. Adding authentication would involve verifying a user’s credentials (such as a username and password) before allowing them to access the system. Authorization would then be used to restrict access to certain resources or functionality based on the user’s role or permissions.
2. Password Encryption: Passwords should be encrypted and securely stored in the database. In this example, we don’t have a DB or any other storage for user’s data, and it’s storing data in memory which is not advisable for real time scenario.
3. Input validation: The program should validate user input to ensure that it is in the expected format and to prevent attacks such as SQL injection and cross-site scripting (XSS).
4. Session Management: The program should handle session management to keep track of logged-in users and to ensure that users are only able to access resources that they are authorized to access.
5. Rate Limiting: To prevent brute-force attacks, rate-limiting can be implemented to limit the number of login attempts that a user can make within a certain time period.
6. Security Configuration: Spring Boot provides various security properties for the fine-grained security configuration, like csrf protection, request security, etc which could be utilized to increase the security of the application.
7. Logging: The program should log important events such as successful logins and failed login attempts for monitoring and auditing purposes.
8. Notifications: A feature can be added to notify users of their daily strike status, maybe through an email or a push notification.

This is by no means an exhaustive list, and depending on the specific requirements of your application, there may be other features that need to be added as well. But, implementing above points can improve security and user experience.

award user with some coins if user logins some consecutive days

Here’s an example of how you could modify the previous Spring Boot program to award a user with coins if they log in on consecutive days:

@RestController
@RequestMapping("/api/login")
public class LoginController {
    private Map<String, LocalDate> userLastLoginMap = new HashMap<>();
    private Map<String, Integer> userCoinsMap = new HashMap<>();

    @PostMapping
    public ResponseEntity<String> login(@RequestBody User user) {
        LocalDate today = LocalDate.now();
        LocalDate lastLoginDate = userLastLoginMap.getOrDefault(user.getUsername(), today.minusDays(1));

        if (today.isEqual(lastLoginDate.plusDays(1))) {
            userLastLoginMap.put(user.getUsername(), today);
            int consecutiveDays = userCoinsMap.getOrDefault(user.getUsername(), 0) + 1;
            userCoinsMap.put(user.getUsername(), consecutiveDays);
            return new ResponseEntity<>("Welcome! You have earned a daily strike and " + consecutiveDays + " coins!", HttpStatus.OK);
        } else {
            userLastLoginMap.put(user.getUsername(), today);
            userCoinsMap.put(user.getUsername(), 0);
            return new ResponseEntity<>("Welcome!", HttpStatus.OK);
        }
    }
}

In this example, two maps are used to store user’s last login date and consecutive days logged in respectively. When a user logs in, the program checks the stored last login date for that user and compares it to the current date, like before. If the difference between the stored date and the current date is exactly one day, then the user earns a “daily strike” as well as a coin.

Coins for user will be incremented if the user logs in consecutive days otherwise resetting it to zero.

Note that this is just a simple example and in real-time, you might want to consider persisting user data, validating payload, handling security and so on.

what should be the user entity

The User entity is a representation of a user in your application and will typically include properties such as a unique identifier (e.g. an ID or username), password, and any other relevant information about the user.

Here’s an example of what a User entity might look like:

public class User {

    private String username;
    private String password;
    private String email;
    private String fullname;
    private LocalDateTime lastLogin;
    private boolean enabled;
    private List<Role> roles;
    // Getters and Setters

    // Hashcode, equals and toString
}

In this example, the User entity has properties for a username, password, email, full name, last login time, enabled state, and roles. The username property is used as a unique identifier for the user, while the password property is used to store the user’s hashed and salted password. The email property is used to store the user’s email, and the fullname property is used to store user’s full name.

lastLogin property is used to store the timestamp of the last login. enabled property could be used to enable or disable a user account in case of any suspicious activity or other security concerns. roles property could be used for managing user roles and roles-based authorization.

Note that, this is a simple example, you might want to add or remove some properties based on the requirement of your application. You might also want to consider implementing UserDetails interface from Spring Security, which provides additional security and user management functionality.

what should be in service layer

The service layer is an intermediate layer between the controller and the data access layer (such as a repository) in a Spring Boot application. Its main purpose is to handle business logic and interact with the data access layer to perform CRUD operations on the data.

Here’s an example of what a UserService class might look like:

@Service
public class UserService {

    @Autowired
    private UserRepository userRepository;

    public User findByUsername(String username) {
        return userRepository.findByUsername(username);
    }

    public User save(User user) {
        return userRepository.save(user);
    }

    public void delete(String username) {
        userRepository.deleteByUsername(username);
    }

    public List<User> findAll() {
        return userRepository.findAll();
    }

    public boolean authenticate(String username, String password) {
        User user = userRepository.findByUsername(username);
        // check if the password matches the hash and salt stored in the DB
        // and update the last login time.
    }
}

In this example, the UserService class has methods for finding a user by their username, saving a user, deleting a user, finding all users, and authenticating a user. The findByUsername and findAll methods are used to retrieve user data from the data access layer (UserRepository), while the save and delete methods are used to update and delete user data, respectively. The authenticate method takes in user’s username and password as an argument, it then looks for the user from the repository and verifies the password.

The @Service annotation is used to indicate that this class is a service bean managed by Spring. It also injects UserRepository to interact with database or any other storage.

Please note that, this is a simple example for showcasing the concept, you should implement the security feature like password encryption, salting, rate limiting, exception handling etc, and consider persisting the user data in a database or other storage system in a real-time scenario.

how properties file looks like

In Spring Boot, you can use a properties file to externalize configuration such as database connection settings, application-specific settings, and other environment-specific settings. A properties file is a simple text file that stores key-value pairs, with each key-value pair on a new line.

Here is an example of a properties file that contains some basic configuration settings for a Spring Boot application:

# Database connection settings
spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=myuser
spring.datasource.password=mypassword

# Application settings
app.name=My App
app.version=1.0

# Server settings
server.port=8080

# Security settings
security.basic.enabled=false
security.user.name=user
security.user.password=password

In this example, there are four sections :

• First section is for the database connection settings. It contains the URL of the database, the username and password to connect to the database.
• Second section is for the application-specific settings. It contains the name of the application and the version number.
• Third section is for the server settings. It contains the port number on which the application will run.
• Fourth section is for the security settings. It contains settings to enable or disable basic security, and also the user name and password for basic authentication.

Each key-value pair is separated by an equals sign (=). Comments can be added to the properties file by starting a line with a # character.

Properties file can be placed in the src/main/resources directory of your project. By default, Spring Boot looks for a file named application.properties or application.yml in this directory, but you can also specify a different file name or location using the spring.config.name and spring.config.location properties.

It is important to keep in mind that in a production environment, the sensitive information such as password, secret key should not be hardcoded in properties file and instead should be passed through environment variable or some other secure way.

In order to persist the user data in a database, you’ll need to create a data access layer (DAL) using a technology such as JDBC, Hibernate, or JPA. I will show you an example of how to create the DAL using Spring Data JPA and an in-memory H2 database.

First, you’ll need to add the necessary dependencies to your pom.xml file or build.gradle:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <scope>runtime</scope>
</dependency>

You will also need to create a data.sql file in the src/main/resources directory and insert some sample data for testing.

Copy codeINSERT INTO users (username, password, email, fullname, last_login) VALUES
    ('user1', '$2a$10$M0R5G5S5k5y5V5e5J5F5I5q5O5vFjDdg8OsLZ/U2QfH6yE5O5l5e6', 'user1@example.com', 'User 1', now()),
    ('user2', '$2a$10$T0T5T5P5o5w5e5r5S5e5c5r5e5t5S5a5l5t5F5i5n5g5W5o5r5d5', 'user2@example.com', 'User 2', now());

Next, you’ll need to create a UserRepository interface that extends JpaRepository and define methods to perform CRUD operations on the User entity.

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    User findByUsername(String username);
    void deleteByUsername(String username);
}

The JpaRepository interface provides several methods for performing CRUD operations on the data, such as findOne, save, delete, etc. In addition, you can also define custom methods like findByUsername and deleteByUsername that use the naming conventions to automatically generate the query based on the method name.

Finally, you’ll need to update your application.properties or application.yml file to configure the H2 database and Spring Data JPA.

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.username=sa
spring.datasource.password=
spring.datasource.driver-class-name=org.h2.Driver

spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=create-drop

This should be enough to get you started with using a database in your Spring Boot application.