[Added] Basis for Backend

backend/.devcontainer/Dockerfile

@@ -1,15 +0,0 @@
-# Use an official OpenJDK as a parent image
-FROM openjdk:17-jdk-slim
-
-# Set the working directory
-WORKDIR /app
-
-# Install Maven
-RUN apt-get update && apt-get install -y \
-    maven=3.3.9-4 \
-    && apt-get clean \
-    && rm -rf /var/lib/apt/lists/*
-
-RUN mvn clean package
-
-CMD ["tail","-f","/dev/null"]

backend/.devcontainer/devcontainer.json

@@ -2,13 +2,19 @@
   "name": "Quiz Backend",
   
   "build": {
-    "context": ".",
-    "dockerfile": "Dockerfile",
+    "context": "..",
+    "dockerfile": "../Dockerfile",
     "args": {
-      "WORKDIR": "/app"
-    }
+      "WORKDIR": "/app",
+      // "UID": "${localEnv:USER_UID}",
+      // "GID": "${localEnv:USER_GID}"
     },
-  "runArgs": ["--name=quiz-backend-dev-cont"],
+    "target": "development"
+  },
+  "runArgs": [
+    "--name=quiz-backend-dev-cont",
+    "--net=host" // Allows it to be opened on the host network
+  ],
   "workspaceFolder": "/app",
   "mounts": [
     "source=.,target=/app,type=bind"
@@ -17,6 +23,8 @@
     "vscode": {
       "settings": {},
       "extensions": [
+        "vscjava.vscode-java-pack",
+        "Oracle.oracle-java"
       ]
     }
   }

backend/Dockerfile

@@ -0,0 +1,26 @@
+FROM openjdk:17-jdk-slim AS base
+WORKDIR /app
+RUN apt-get update && apt install -y \
+    maven \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/*
+
+#---Development
+FROM base AS development
+# Switching user so it doesn't use root
+# If root adds files, it takes ownership, making them unremovable on the host except by using sudo
+# node tranfers ownership to the host user
+ENV UID=1000
+ENV GID=1000
+ENV USER=dev
+RUN groupadd -g ${GID} ${USER} \
+    && useradd -m -u ${UID} -g ${USER} ${USER}
+USER ${USER}
+EXPOSE 8080
+CMD ["tail","-f","/dev/null"]
+
+#---Building
+
+
+
+#---Production

backend/pom.xml

@@ -55,6 +55,17 @@
 			<artifactId>spring-boot-starter-test</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+    		<groupId>com.github.ben-manes.caffeine</groupId>
+    		<artifactId>caffeine</artifactId>
+    		<version>3.1.8</version>
+		</dependency>
+		<dependency>
+    		<groupId>org.projectlombok</groupId>
+    		<artifactId>lombok</artifactId>
+    		<version>1.18.34</version>
+    		<scope>provided</scope>
+		</dependency>
 	</dependencies>
 
 	<build>

backend/src/main/java/com/ninjaws/quiz/Config/AppConfig.java

@@ -0,0 +1,14 @@
+package com.ninjaws.quiz.Config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.client.RestTemplate;
+
+@Configuration
+public class AppConfig {
+
+    @Bean
+    public RestTemplate restTemplate() {
+        return new RestTemplate();
+    }
+}

backend/src/main/java/com/ninjaws/quiz/Controllers/QuizController.java

@@ -0,0 +1,37 @@
+package com.ninjaws.quiz.Controllers;
+
+import java.util.Optional;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.ninjaws.quiz.Models.Session;
+import com.ninjaws.quiz.Services.QuizService;
+
+@RestController
+@RequestMapping("/quiz")
+public class QuizController {
+
+    @Autowired
+    private QuizService quizService;
+
+    @GetMapping("/questions")
+    public String startSession() {
+        // String sessionId = generateSessionId();
+        String sessionId = quizService.createSession();
+        return sessionId;
+    }
+
+    @GetMapping("/questions/{sessionId}")
+    public Optional<Session> checkStatus(@PathVariable String sessionId) {
+        return quizService.checkSession(sessionId);
+    }
+
+    // @PostMapping("/checkanswers")
+    // public Result checkAnswers(@RequestBody String answers) {
+    //     return new Result();
+    // }
+}

backend/src/main/java/com/ninjaws/quiz/Exception/GlobalExceptionHandler.java

@@ -0,0 +1,20 @@
+package com.ninjaws.quiz.Exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+
+/**
+ * Determines behaviour when certain types of Exceptions are encountered
+ */
+@ControllerAdvice
+public class GlobalExceptionHandler {
+
+    @ExceptionHandler(IllegalArgumentException.class)
+    public ResponseEntity<String> handleIllegalArgumentException(IllegalArgumentException e) {
+        return ResponseEntity
+                .status(HttpStatus.BAD_REQUEST)
+                .body(e.getMessage());
+    }
+}

backend/src/main/java/com/ninjaws/quiz/Models/ApiResponse.java

@@ -0,0 +1,21 @@
+package com.ninjaws.quiz.Models;
+
+import java.util.List;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import lombok.Getter;
+import lombok.Setter;
+
+
+/**
+ * The response sent by the external API
+ */
+@Getter
+@Setter
+public class ApiResponse {
+    @JsonProperty("response_code")
+    private int responseCode;
+    @JsonProperty("results")
+    private List<Question> results;
+}

backend/src/main/java/com/ninjaws/quiz/Models/Question.java

@@ -0,0 +1,59 @@
+package com.ninjaws.quiz.Models;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import lombok.Getter;
+
+/**
+ * Holds the question, answers, and correct answer
+ * TODO: Should not send correct answer to the user
+ */
+// @Setter()
+@Getter()
+public class Question {
+    private String type;
+    private String difficulty;
+    private String category;
+    private String question;
+    
+    // @JsonIgnore
+    private String correctAnswer;
+    
+    // @JsonIgnore
+    private List<String> incorrectAnswers;
+
+    @JsonProperty("answers")
+    public List<String> getAnswers() {
+        List<String> possibleAnswers = new ArrayList<>(incorrectAnswers);
+        possibleAnswers.add(correctAnswer);
+        Collections.shuffle(possibleAnswers);
+        return possibleAnswers;
+    }
+
+    @JsonProperty("correct_answer")
+    public void setCorrectAnswer(String correctAnswer) {
+        this.correctAnswer = correctAnswer;
+    }
+
+    @JsonProperty("incorrect_answers")
+    public void setIncorrectAnswer(List<String> incorrectAnswers) {
+        this.incorrectAnswers = incorrectAnswers;
+    }
+
+    @JsonProperty("correct_answer")
+    @JsonIgnore
+    public String getCorrectAnswer() {
+        return correctAnswer;
+    }
+
+    @JsonProperty("incorrect_answers")
+    @JsonIgnore
+    public List<String> getIncorrectAnswers() {
+        return incorrectAnswers;
+    }
+}

backend/src/main/java/com/ninjaws/quiz/Models/Request.java

@@ -0,0 +1,14 @@
+package com.ninjaws.quiz.Models;
+
+import lombok.Getter;
+
+@Getter
+public class Request {
+    private final String sessionId;
+    private final String requestUrl;
+
+    public Request(String sessionId, String requestUrl) {
+        this.sessionId = sessionId;
+        this.requestUrl = requestUrl;
+    }
+}

backend/src/main/java/com/ninjaws/quiz/Models/Session.java

@@ -0,0 +1,18 @@
+package com.ninjaws.quiz.Models;
+
+import java.util.List;
+import java.util.UUID;
+
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+public class Session {
+    private final String id;
+    private List<Question> questions;
+
+    public Session() {
+        this.id = UUID.randomUUID().toString();
+    }
+}

backend/src/main/java/com/ninjaws/quiz/QuizApplication.java

@@ -2,8 +2,10 @@ package com.ninjaws.quiz;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.scheduling.annotation.EnableScheduling;
 
 @SpringBootApplication
+@EnableScheduling
 public class QuizApplication {
 
 	public static void main(String[] args) {

backend/src/main/java/com/ninjaws/quiz/Services/ApiService.java

@@ -0,0 +1,23 @@
+package com.ninjaws.quiz.Services;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Service;
+import org.springframework.web.client.RestTemplate;
+
+@Service
+public class ApiService {
+
+    private final RestTemplate restTemplate;
+
+    @Autowired
+    public ApiService(RestTemplate restTemplate) {
+        this.restTemplate = restTemplate;
+    }
+
+    public String requestQuestions(String url) {
+        ResponseEntity<String> response = restTemplate.getForEntity(url, String.class);
+        String jsonData = response.getBody();
+        return jsonData;
+    }
+}

backend/src/main/java/com/ninjaws/quiz/Services/QuizService.java

@@ -0,0 +1,126 @@
+package com.ninjaws.quiz.Services;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.LinkedBlockingQueue;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Service;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.ninjaws.quiz.Models.ApiResponse;
+import com.ninjaws.quiz.Models.Question;
+import com.ninjaws.quiz.Models.Request;
+import com.ninjaws.quiz.Models.Session;
+
+
+@Service
+public class QuizService {
+
+    @Autowired
+    private ApiService apiService;
+    @Autowired
+    private ObjectMapper objectMapper;
+
+    /**
+     * Stores all active sessions
+     * Gets added to when a user requests data
+     * Gets removed from when a user requests their score (by sending their answers)
+     * TODO: Replace with something that automatically removes items after a certain amount of time (Caffein?)
+     */
+    private final Map<String,Session> sessions = new ConcurrentHashMap<>();
+
+    /**
+     * Stores all user requests for data
+     * Executes them in order, one every 5 seconds (the limit of the external API)
+     * Removes them from the Queue when the request was succesful
+     */
+    private final BlockingQueue<Request> requests = new LinkedBlockingQueue<>();
+
+    /**
+     * Actions:
+     * - Creates a session with sessionId
+     * - Adds session to the cache
+     * - Creates request and adds it to the queue
+     * @return The sessionId
+     */
+    public String createSession() {
+        Session session = new Session();
+        sessions.put(session.getId(), session); // TODO: Either remove id from session, or maybe Caffein does allow them together
+        try {
+            requests.put(new Request(session.getId(), "https://opentdb.com/api.php?amount=10"));
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        }
+
+        return session.getId();
+    }
+
+    /**
+     * @param sessionId
+     * Actions:
+     * - Looks up the session in the cache
+     * - Checks if the data from the request is stored
+     * @return The data if it's available, otherwise a statuscode (?)
+     */
+    public Optional<Session> checkSession(String sessionId) throws IllegalArgumentException {
+        Session session = sessions.get(sessionId);
+
+        if(session == null) {
+            throw new IllegalArgumentException("Invalid session ID: " + sessionId);
+        }
+
+        if (session.getQuestions() == null) {
+            return Optional.empty();
+        }
+        System.out.print(session.getQuestions().get(0).getIncorrectAnswers().get(0));
+        return Optional.of(session);
+    }
+
+    /**
+     * Every 5 seconds:
+     * - Take the top request from the queue (removes it)
+     * - Perform the request
+     * - Wait for the data
+     * - Find the matching session from the cache
+     * - Add the data to the session in the cache
+     */
+    @Scheduled(fixedDelay = 5000)
+    protected void processQueue() {
+        Request request = requests.poll();
+        if (request != null) {
+            String json = apiService.requestQuestions(request.getRequestUrl());
+            try {
+                List<Question> questions = extractQuestions(json);
+                Session session = sessions.get(request.getSessionId());
+                session.setQuestions(questions);
+                sessions.put(request.getSessionId(), session);                
+            } catch (IOException e) {
+                //TODO: Log this
+            }
+        }
+    }
+
+    private List<Question> extractQuestions(String json) throws IOException {
+        return objectMapper.readValue(json, ApiResponse.class).getResults();
+    }
+
+    /**
+     * Receives: sessionId and answers
+     * Actions: 
+     * - retrieves session from cache
+     * - Deletes session from cache
+     * - Matches answers answers to correctAnswers
+     * - Calculates score
+     * Returns: calculated score
+     *  */
+    public void calculateScore() {
+        
+    }
+    
+}

backend/src/main/resources/application.properties

@@ -1 +1,2 @@
 spring.application.name=quiz
+server.port=9090

backend/src/main/resources/static/index.html

@@ -0,0 +1 @@
+<h1>Quiz backend</h1>

docker-compose.yml

@@ -4,5 +4,7 @@ services:
       context: ./frontend
       dockerfile: Dockerfile
       target: production
+    image: quiz-frontend-prod
+    container_name: quiz-frontend-prod-cont
     ports:
       - "4200:80"