Add Java orders service

Author: cghyzel

services/orders-java/Dockerfile

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+FROM maven:3.9-eclipse-temurin-17 AS build
+WORKDIR /app
+COPY . .
+RUN mvn test
+RUN mvn clean package -DskipTests
+
+FROM eclipse-temurin:17-jdk
+WORKDIR /app
+COPY --from=build /app/target/*.jar app.jar
+ENTRYPOINT ["java", "-jar", "app.jar"]

services/orders-java/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
+         http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>org.springframework.boot</groupId>
+    <artifactId>spring-boot-starter-parent</artifactId>
+    <version>3.1.4</version>
+    <relativePath/>
+  </parent>
+
+  <groupId>com.example</groupId>
+  <artifactId>orders-java</artifactId>
+  <version>1.0.0</version>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-web</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.json</groupId>
+      <artifactId>json</artifactId>
+      <version>20231013</version>
+    </dependency>
+    <dependency>
+      <groupId>org.springdoc</groupId>
+      <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
+      <version>2.1.0</version>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>5.10.0</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-maven-plugin</artifactId>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>3.0.0-M9</version>
+      </plugin>
+    </plugins>
+  </build>
+</project>

services/orders-java/src/main/java/com/example/orders/OrdersApplication.java

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+package com.example.orders;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class OrdersApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(OrdersApplication.class, args);
+    }
+}

services/orders-java/src/main/java/com/example/orders/controller/OrderController.java

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+package com.example.orders.controller;
+
+import org.springframework.beans.factory.annotation.Value;
+import com.example.orders.model.OrderRequest;
+import org.json.JSONObject;
+import org.springframework.http.*;
+import org.springframework.web.bind.annotation.*;
+import org.springframework.web.client.RestTemplate;
+
+@RestController
+@RequestMapping("/orders")
+public class OrderController {
+
+    private final RestTemplate restTemplate = new RestTemplate();
+
+    @Value("${AUTH_SERVICE_URL:http://auth-python:8000}")
+    private String authServiceUrl;
+
+    @Value("${BILLING_SERVICE_URL:http://billing-csharp:80}")
+    private String billingServiceUrl;
+
+    @PostMapping
+    public ResponseEntity<String> placeOrder(@RequestBody OrderRequest request,
+                                             @RequestHeader("Authorization") String authHeader) {
+        if (authHeader == null || !authHeader.startsWith("Bearer ")) {
+            return ResponseEntity.status(HttpStatus.UNAUTHORIZED).body("Missing token");
+        }
+
+        String token = authHeader.substring(7);
+        String username = validateToken(token);
+        if (username == null) {
+            return ResponseEntity.status(HttpStatus.UNAUTHORIZED).body("Invalid session");
+        }
+
+        boolean billed = charge(username, request.productId, request.quantity);
+        if (!billed) {
+            return ResponseEntity.status(HttpStatus.PAYMENT_REQUIRED).body("Billing failed");
+        }
+
+        return ResponseEntity.ok("Order placed successfully by " + username);
+    }
+
+    protected String validateToken(String token) {
+        String authUrl = authServiceUrl + "/auth/validate?token=" + token;
+        try {
+            ResponseEntity<String> authResponse = restTemplate.getForEntity(authUrl, String.class);
+            if (!authResponse.getStatusCode().is2xxSuccessful()) return null;
+
+            String body = authResponse.getBody();
+            return body.contains("username") ? body.split(":")[1].replaceAll("[\"{} ]", "") : null;
+        } catch (Exception e) {
+            return null;
+        }
+    }
+
+    protected boolean charge(String username, String productId, int quantity) {
+        HttpHeaders headers = new HttpHeaders();
+        headers.setContentType(MediaType.APPLICATION_JSON);
+        headers.set("X-Service-Secret", System.getenv("BILLING_SECRET"));
+
+        JSONObject payload = new JSONObject();
+        payload.put("username", username);
+        payload.put("productId", productId);
+        payload.put("quantity", quantity);
+
+        HttpEntity<String> entity = new HttpEntity<>(payload.toString(), headers);
+        try {
+            ResponseEntity<String> billingResponse = restTemplate.postForEntity(
+                billingServiceUrl + "/billing/charge", entity, String.class);
+            return billingResponse.getStatusCode().is2xxSuccessful();
+        } catch (Exception e) {
+            return false;
+        }
+    }
+}

services/orders-java/src/main/java/com/example/orders/model/OrderRequest.java

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+package com.example.orders.model;
+
+public class OrderRequest {
+    public String productId;
+    public int quantity;
+}

services/orders-java/src/test/java/com/example/orders/OrdersApplicationTests.java

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+package com.example.orders;
+
+import com.example.orders.controller.OrderController;
+import com.example.orders.model.OrderRequest;
+import org.junit.jupiter.api.Test;
+import org.springframework.http.ResponseEntity;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class OrderControllerTests {
+
+    static class MockedOrderController extends OrderController {
+        private final boolean validToken;
+        private final boolean billingSuccess;
+        private final String mockUser;
+
+        public MockedOrderController(boolean validToken, boolean billingSuccess, String mockUser) {
+            this.validToken = validToken;
+            this.billingSuccess = billingSuccess;
+            this.mockUser = mockUser;
+        }
+
+        @Override
+        protected String validateToken(String token) {
+            return validToken ? mockUser : null;
+        }
+
+        @Override
+        protected boolean charge(String username, String productId, int quantity) {
+            return billingSuccess;
+        }
+    }
+
+    @Test
+    void testOrderSuccess() {
+        MockedOrderController controller = new MockedOrderController(true, true, "alice");
+
+        OrderRequest req = new OrderRequest();
+        req.productId = "widget-123";
+        req.quantity = 2;
+
+        ResponseEntity<String> response = controller.placeOrder(req, "Bearer faketoken");
+
+        assertEquals(200, response.getStatusCodeValue());
+        assertTrue(response.getBody().contains("alice"));
+    }
+
+    @Test
+    void testInvalidToken() {
+        MockedOrderController controller = new MockedOrderController(false, true, "alice");
+
+        OrderRequest req = new OrderRequest();
+        req.productId = "widget-123";
+        req.quantity = 2;
+
+        ResponseEntity<String> response = controller.placeOrder(req, "Bearer faketoken");
+
+        assertEquals(401, response.getStatusCodeValue());
+    }
+
+    @Test
+    void testBillingFailure() {
+        MockedOrderController controller = new MockedOrderController(true, false, "alice");
+
+        OrderRequest req = new OrderRequest();
+        req.productId = "widget-123";
+        req.quantity = 2;
+
+        ResponseEntity<String> response = controller.placeOrder(req, "Bearer faketoken");
+
+        assertEquals(402, response.getStatusCodeValue());
+    }
+
+    @Test
+    void testMissingAuthHeader() {
+        MockedOrderController controller = new MockedOrderController(true, true, "alice");
+
+        OrderRequest req = new OrderRequest();
+        req.productId = "widget-123";
+        req.quantity = 2;
+
+        ResponseEntity<String> response = controller.placeOrder(req, null);
+
+        assertEquals(401, response.getStatusCodeValue());
+    }
+}