refactor: setup to Maven REST API with CI/CD and tooling

.githooks/pre-commit

@@ -0,0 +1,13 @@
+#!/bin/sh
+echo '====================================================='
+echo 'Running pre-commit checks (Spotless, Checkstyle)...'
+echo '====================================================='
+if ! mvn spotless:check checkstyle:check; then
+    echo '====================================================='
+    echo '❌ PRE-COMMIT FAILED: Code quality checks did not pass.'
+    echo 'Please fix the errors above or run "mvn spotless:apply" to format.'
+    echo '====================================================='
+    exit 1
+fi
+echo '✅ All checks passed! Proceeding with commit.'
+exit 0

.github/workflows/deploy.yml

@@ -0,0 +1,82 @@
+name: Manual Deployment
+
+on:
+  workflow_dispatch: # Allows manual triggering from GitHub UI
+
+jobs:
+  # Job 1: Tooling System & Testing
+  validate-and-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - name: Set up JDK 17
+        uses: actions/setup-java@v6
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+          cache: maven
+      - name: Validate & Test (Format, Lint, Test)
+        run: mvn spotless:check checkstyle:check test
+
+  # Job 2: Build the Deployment Artifact
+  build-artifact:
+    needs: validate-and-test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - name: Set up JDK 17
+        uses: actions/setup-java@v6
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+          cache: maven
+      - name: Build Fat JAR
+        run: mvn clean package -DskipTests
+      - name: Upload Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: deployment-jar
+          path: target/basic-web-server-1.0-SNAPSHOT.jar
+
+  # Job 3: Actual Deployment to Target Server
+  deploy:
+    needs: build-artifact
+    runs-on: ubuntu-latest
+    steps:
+      - name: Download Artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: deployment-jar
+
+      - name: Copy Artifact to VM via SCP
+        uses: appleboy/scp-action@v1
+        with:
+          host: ${{ secrets.SERVER_HOST }}
+          username: ${{ secrets.SERVER_USER }}
+          key: ${{ secrets.SERVER_SSH_KEY }}
+          port: ${{ secrets.SERVER_PORT || '22' }}
+          source: "basic-web-server-1.0-SNAPSHOT.jar"
+          target: "/opt/basic-web-server/"
+
+      - name: Restart Service via SSH
+        uses: appleboy/ssh-action@v1
+        with:
+          host: ${{ secrets.SERVER_HOST }}
+          username: ${{ secrets.SERVER_USER }}
+          key: ${{ secrets.SERVER_SSH_KEY }}
+          port: ${{ secrets.SERVER_PORT || '22' }}
+          script: |
+            echo "Deployment starting on remote VM..."
+            cd /opt/basic-web-server
+
+            # If you are using a systemd service (recommended professional approach):
+            # sudo systemctl restart basic-web-server
+
+            # Or if you are using a raw shell script to restart:
+            echo "Stopping old server instance..."
+            pkill -f 'basic-web-server-1.0-SNAPSHOT.jar' || true
+
+            echo "Starting new server instance in background..."
+            nohup java -jar basic-web-server-1.0-SNAPSHOT.jar > server.log 2>&1 &
+
+            echo "Deployment completed successfully!"

.github/workflows/pr-check.yml

@@ -0,0 +1,26 @@
+name: PR Check
+
+on:
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  validate-and-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - name: Set up JDK 17
+        uses: actions/setup-java@v6
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+          cache: maven
+
+      - name: Formatter Check (Spotless)
+        run: mvn spotless:check
+
+      - name: Linter Check (Checkstyle)
+        run: mvn checkstyle:check
+
+      - name: Type Check & Test (Compile + JUnit)
+        run: mvn clean test

.gitignore

@@ -1,2 +1,46 @@
-bin/
-.vscode/
+# Compiled class file
+*.class
+
+# Log file
+*.log
+
+# BlueJ files
+*.ctxt
+
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.nar
+*.ear
+*.zip
+*.tar.gz
+*.rar
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+
+# Maven
+target/
+pom.xml.tag
+pom.xml.releaseBackup
+pom.xml.versionsBackup
+pom.xml.next
+release.properties
+dependency-reduced-pom.xml
+buildNumber.properties
+.mvn/timing.properties
+# https://github.com/takari/maven-wrapper#usage-without-binary-jar
+.mvn/wrapper/maven-wrapper.jar
+
+# IDEs
+.idea/
+*.iml
+*.iws
+.classpath
+.project
+.settings/
+.vscode/
+bin/

README.md

@@ -1,23 +1,22 @@
-# Basic Java Web Server Project
+# Basic Java Web Server REST API
 
 <img src="docs/img/java-img.jpg" width="100%">
 
-This is a basic web server project built with **native Java**, utilizing only the Java standard library without any external frameworks. It demonstrates fundamental concepts such as routing, handling different HTTP methods, and processing URL parameters and query strings. The goal of this project is to serve as a reference for anyone interested in understanding how a web service can be implemented using just Java.
+This is a basic web server project originally built with native Java, now refactored into a **professional RESTful JSON API**. It demonstrates fundamental backend concepts such as handling HTTP methods, thread pools for concurrency, routing, and processing JSON payloads. The goal of this project is to serve as an educational reference for building a modern web service in Java from scratch.
 
 ## Features
 
-- **Basic Routing**: Set up routes for different endpoints.
-- **Route with Parameters**: Handle dynamic routes with URL parameters.
-- **Query Parameters**: Extract and process query strings from the URL.
-- **HTTP Methods**: Support for common HTTP methods: `GET`, `POST`, `PATCH`, `DELETE`.
+- **REST API (JSON)**: Fully responds and consumes `application/json` using Google's Gson library.
+- **Concurrency**: Built-in `ThreadPoolExecutor` for handling multiple HTTP requests simultaneously.
+- **Maven Architecture**: Standardized project structure and dependency management.
+- **Dev Tooling**: Code automatically formatted via **Spotless** (Google Java Format) and linted via **Checkstyle**.
+- **CI/CD Ready**: Includes GitHub Actions for PR checks (Format/Lint/Test) and multi-stage manual deployment pipelines using SCP/SSH.
 
 ## Getting Started
 
 ### Prerequisites
 
-Ensure you have **Java Development Kit (JDK)** installed on your machine.
-
-- [Download JDK](https://www.oracle.com/java/technologies/downloads/) (or the version you prefer)
+Ensure you have **Java Development Kit (JDK) 17+** and **Apache Maven** installed on your machine.
 
 ### Installation
 
@@ -32,64 +31,145 @@ Ensure you have **Java Development Kit (JDK)** installed on your machine.
 
 ### Running the Server
 
-1. Compile Java program first:
-    ```bash
-    javac -d bin src/Main.java src/controller/*.java src/model/*.java src/utils/*.java
-    ```
-2. Run compiled program
-    ```bash
-    java -cp bin Main
-    ```
+Using Maven, you can compile and start the server immediately:
+```bash
+mvn clean compile exec:java -Dexec.mainClass="com.server.Main"
+```
+The server will be running at `http://localhost:8000`
 
-The server will be running at http://localhost:8000
+### Building the Executable JAR
+If you want to build a deployment-ready Fat JAR:
+```bash
+mvn clean package -DskipTests
+java -jar target/basic-web-server-1.0-SNAPSHOT.jar
+```
 
+## Tooling & Testing
 
-## Endpoints
-Here are the key endpoints that you can interact with:
+Run the automated tests:
+```bash
+mvn test
+```
 
+Format the codebase and check for linting errors:
+```bash
+mvn spotless:apply checkstyle:check
 ```
-GET / : Returns a simple welcome message and provide simple form to handle request input
-GET /users : Fetch all users
-GET /users/:id : Fetch a data by their ID
-POST /users : Add a new user
-PATCH /users/:id : Update user information
-DELETE /users/:id : Delete a user by their ID
-GET /search?name=&job= : Retrieves data based on user input from a search form, filtering results by name and job
+
+### Pre-commit Hooks
+This project strictly enforces code quality using Git pre-commit hooks (Spotless and Checkstyle).
+After cloning the repository, you **must** configure Git to use the local hooks directory:
+```bash
+git config core.hooksPath .githooks
 ```
+Every time you commit, it will automatically verify formatting and linting. If it fails, the commit will be aborted.
 
-## Query Parameters
-Example: /search?name=John&job=data+analyst
-Query parameters can be extracted and used in request processing.
+## Endpoints
+Here are the key REST endpoints you can interact with. All endpoints strictly consume and return `application/json`.
+
+### 1. API Health Check
+- **`GET /`**
+  - **Response (200 OK):**
+    ```json
+    {
+      "status": "UP",
+      "message": "Welcome to Basic Web Server API",
+      "totalUsers": 8
+    }
+    ```
 
-## HTTP Methods
-The service supports the following HTTP methods:
+### 2. Fetch All Users
+- **`GET /users`**
+  - **Response (200 OK):**
+    ```json
+    [
+      { "name": "Alex", "job": "Data Analyst" },
+      { "name": "Budi", "job": "Frontend Web Developer" }
+    ]
+    ```
 
-```
-GET: Retrieve data.
-POST: Submit new data.
-PATCH: Update partial existing data.
-DELETE: Remove data.
-```
+### 3. Fetch User by ID
+- **`GET /users/:id`** *(e.g. `/users/1`)*
+  - **Response (200 OK):**
+    ```json
+    {
+      "name": "Alex",
+      "job": "Data Analyst"
+    }
+    ```
+
+### 4. Create New User
+- **`POST /users`**
+  - **Request Body:**
+    ```json
+    {
+      "name": "John Doe",
+      "job": "Backend Engineer"
+    }
+    ```
+  - **Response (201 Created):**
+    ```json
+    {
+      "status": "success",
+      "message": "User added successfully"
+    }
+    ```
+
+### 5. Update User Information
+- **`PATCH /users/:id`** *(e.g. `/users/1`)*
+  - **Request Body:**
+    ```json
+    {
+      "job": "Senior Data Analyst"
+    }
+    ```
+  - **Response (200 OK):**
+    ```json
+    {
+      "status": "success",
+      "message": "Data updated successfully"
+    }
+    ```
+
+### 6. Delete a User
+- **`DELETE /users/:id`** *(e.g. `/users/1`)*
+  - **Response (200 OK):**
+    ```json
+    {
+      "status": "success",
+      "message": "Data deleted successfully"
+    }
+    ```
+
+### 7. Search Users
+- **`GET /search?name=&job=`** *(e.g. `/search?job=Data Analyst`)*
+  - **Response (200 OK):**
+    ```json
+    [
+      { "name": "Alex", "job": "Data Analyst" },
+      { "name": "Dono", "job": "Data Analyst" }
+    ]
+    ```
 
 ## Code Structure
-The project is simple and has the following structure:
+The project uses the standard Maven structure:
 
 ```bash
 /root
-├───bin  # compiled Java file
-│   ├─── /controller
-│   ├─── /model
-│   └─── /utils
-├───lib
+├───.github/workflows   # CI/CD Pipelines
+├───pom.xml             # Build config and dependencies
 └───src
-    ├─── /controller    # A handler for any request
-    ├─── /model         # A temporary data user blueprint
-    ├─── /utils         # Some helper function
-    └─── Main.java      # Main server logic
+    ├───main/java/com/server
+    │   ├─── /controller    # HTTP route handlers
+    │   ├─── /model         # Data structures and tracking
+    │   ├─── /utils         # Parsers and HTTP helpers
+    │   └─── Main.java      # Server initialization and Thread Pool
+    └───test/java/com/server
+        └─── /model         # JUnit 5 test cases
 ```
 
 ## License
 This project is licensed under the MIT License.
 
 ## Acknowledgments
-This project is intended to help others learn the basics of building a web service with Java native ☕.
+This project is intended to help others learn the basics of building a robust REST API with Java ☕.