caro/docs/codebase-summary.md

Codebase Summary

Directory Structure

caro/
├── .github/
│   └── workflows/
│       └── build.yml                    CI: build + test (Java 25 + Node 22)
├── server/                              Standalone Netty server (Java 25, Maven)
│   ├── src/main/java/com/miti99/caro/
│   │   ├── common/
│   │   │   ├── channel/                 Netty utilities (ChannelUtils)
│   │   │   ├── entity/                  Data models (Board, Room, GameMove, Msg, ClientSide)
│   │   │   ├── enums/                   ServerEventCode, ClientEventCode, PieceType, etc.
│   │   │   ├── exception/               LandlordException
│   │   │   ├── features/                Feature flags
│   │   │   ├── handler/                 Protocol codec (DefaultDecoder)
│   │   │   ├── helper/                  GomokuHelper, MapHelper
│   │   │   ├── print/                   SimplePrinter
│   │   │   ├── robot/                   AI engine (GomokuAI)
│   │   │   ├── transfer/                Binary serialization (ByteKit, ByteLink, TransferProtocolUtils)
│   │   │   └── utils/                   JsonUtils (gson), ListUtils, OptionsUtils, StreamUtils
│   │   └── server/
│   │       ├── event/                   ServerEventListener_* handlers
│   │       ├── handler/                 Netty pipeline (Protobuf/WS codecs)
│   │       ├── proxy/                   ProtobufProxy, WebsocketProxy
│   │       ├── timer/                   RoomClearTask
│   │       ├── SimpleServer.java        Server entry point
│   │       └── ServerContains.java      Global state container
│   ├── src/main/resources/
│   │   └── proto/                       .proto files + generate.sh (future proto-over-WS)
│   ├── src/test/java/com/miti99/caro/common/
│   │   ├── helper/tests/GomokuHelperTest.java    29 JUnit 5 tests
│   │   └── robot/tests/GomokuAITest.java          8 JUnit 5 tests
│   ├── Dockerfile                       Multi-stage (maven:3.9-eclipse-temurin-25, eclipse-temurin:25-jre-alpine)
│   └── pom.xml                          Standalone (no parent), maven-shade-plugin 3.6.0
├── client/                              Phaser 3 + Vite client
│   ├── src/
│   │   ├── main.js                      Phaser boot
│   │   ├── config/
│   │   │   ├── game-config.js           Phaser configuration
│   │   │   └── protocol-constants.js    Event code enums
│   │   ├── scenes/
│   │   │   ├── boot-scene.js            Initialize, connect to server
│   │   │   ├── menu-scene.js            Menus (overlay DOM)
│   │   │   └── game-scene.js            Main gameplay scene
│   │   ├── services/
│   │   │   ├── event-bus.js             Pub/sub event dispatcher
│   │   │   ├── connection-service.js    WebSocket client
│   │   │   └── game-state-service.js    Client-side state
│   │   ├── objects/
│   │   │   ├── board.js                 Game board renderer
│   │   │   └── stone.js                 Individual stone sprite
│   │   └── ui/
│   │       ├── menu-ui.js               Menu components
│   │       └── game-ui.js               Game HUD & notifications
│   ├── Dockerfile                       Nginx-based static server
│   ├── index.html
│   ├── vite.config.js
│   └── package.json                     caro-client 0.0.1-beta
├── docs/                                (this directory)
│   ├── project-overview-pdr.md
│   ├── system-architecture.md
│   ├── codebase-summary.md
│   ├── code-standards.md
│   └── deployment-guide.md
├── plans/                               Implementation plans
├── docker-compose.yml                   services: server, client
├── README.md
├── LICENSE
└── .gitignore

---

Key Java Packages

com.miti99.caro.common (Shared code)

Entities:

• Board.java — 15x15 game board, move validation, win/draw detection (BOARD_SIZE=15, WIN_CONDITION=5)
• Room.java — Game session state (id, type, status, players, board, moveHistory)
• GameMove.java — Single move (row, col, piece, playerId, timestamp)
• Msg.java — WebSocket JSON envelope (record: code, data, info)
• ServerTransferData.java / ClientTransferData.java — Protobuf-generated wire types
• ClientSide.java — Player connection state (nickname, status, role)

Enums:

• ServerEventCode — client→server action codes
• ClientEventCode — server→client response codes
• PieceType — EMPTY, BLACK, WHITE
• GameResult — IN_PROGRESS, BLACK_WIN, WHITE_WIN, DRAW
• RoomType, RoomStatus, ClientRole, ClientStatus

Game Logic:

• GomokuHelper.java — Win detection (4 directions), board rendering
• GomokuAI.java — AI move selection (Easy/Medium/Hard)

Utilities:

• JsonUtils.java — gson wrapper (toJson, fromJson)
• ListUtils, OptionsUtils, StreamUtils
• MapHelper.java — Fluent map builder (uses gson)

Protocol:

• ByteKit, ByteLink — Byte buffer operations
• TransferProtocolUtils.java — Protocol framing (#...$ delimiters, gson JSON body)
• DefaultDecoder.java — Protobuf message decoder

---

com.miti99.caro.server (Server code)

Entry Point:

• SimpleServer.java — Bootstrap (-p {port}, default 1024)
  • Starts TCP proxy on port and WebSocket proxy on port+1
• ServerContains.java — Singleton global state (rooms, client sides, channel map)

Event Handlers (ServerEventListener_*):

• CODE_CLIENT_NICKNAME_SET, CODE_ROOM_CREATE, CODE_ROOM_CREATE_PVE, CODE_GET_ROOMS
• CODE_ROOM_JOIN, CODE_GAME_STARTING, CODE_GAME_READY, CODE_GAME_MOVE
• CODE_GAME_WATCH / CODE_GAME_WATCH_EXIT, CODE_CLIENT_OFFLINE

Network Handlers:

• ProtobufTransferHandler — TCP/Protobuf codec
• WebsocketTransferHandler — WebSocket JSON codec (uses JsonUtils.fromJson(text, Msg.class))
• SecondProtobufCodec — Second-pass protobuf decoder

Message Proxies:

• ProtobufProxy — TCP server bootstrap
• WebsocketProxy — WebSocket server bootstrap (no static file handler; non-WS HTTP → default Netty 400/403)

Background Tasks:

• RoomClearTask — Periodic cleanup

---

Client (JavaScript/Phaser 3)

Boot:

• main.js — Create Phaser game instance, start boot scene

Config:

• game-config.js — Phaser config (800x800, Scale.FIT, scenes: [BootScene, MenuScene, GameScene])
• protocol-constants.js — Export event code enums matching server

Scenes:

• BootScene — Create services, connect WebSocket, load assets, transition to menu
• MenuScene — Nickname input, lobby, room list, difficulty selector
• GameScene — Board + stones, click handling, move history, turn indicator, game over

Services:

• EventBus — Pub/sub decoupling scenes and services
• ConnectionService — WebSocket client with heartbeat + auto-reconnect
• GameStateService — Client-side state container

Game Objects:

• Board — 15x15 wood-textured grid
• Stone — Gradient stone sprite with drop animation

UI:

• MenuUI — Nickname form, room list, settings
• GameUI — HUD, move history, game over modal, toasts

---

Build Configuration

Maven (Java)

File: server/pom.xml (standalone, no parent)

Coordinates: com.miti99.caro:caro-server:0.0.1-beta

Key Plugins:

• maven-compiler-plugin 3.13.0 — Java 25 source/target (<release>25</release>), -parameters
• maven-surefire-plugin 3.5.2 — JUnit 5 runner
• maven-shade-plugin 3.6.0 — Fat jar with ManifestResourceTransformer, ServicesResourceTransformer, AppendingTransformer (for META-INF/io.netty.versions.properties)

Dependencies:

• io.netty:netty-all:4.1.115.Final — async networking
• com.google.protobuf:protobuf-java:3.25.5 — binary serialization
• com.google.code.gson:gson:2.11.0 — JSON (supports records)
• org.junit.jupiter:junit-jupiter:5.11.3 — testing (test scope)

Build Command:

mvn -f server/pom.xml clean package
# Produces: server/target/caro-server-0.0.1-beta.jar (shaded fat jar)

Vite (JavaScript)

File: client/package.json

Package: caro-client 0.0.1-beta

Scripts:

• npm run dev — Dev server (port 5173, hot reload)
• npm run build — Production build to dist/
• npm run preview — Preview production build

Dependencies:

• phaser ^3.87.0 — Game engine
• vite ^6.3.1 — Bundler (dev-only)

Output: client/dist/ (index.html + bundled JS, ~1.5 MB / 346 KB gzipped)

---

Testing

Test Framework: JUnit 5 (org.junit.jupiter.api)

Test Files:

1. server/src/test/java/com/miti99/caro/common/helper/tests/GomokuHelperTest.java — 29 tests (win detection, edges, draw, game flow)
2. server/src/test/java/com/miti99/caro/common/robot/tests/GomokuAITest.java — 8 tests (Easy/Medium/Hard AI)

Run Tests:

mvn -f server/pom.xml clean test

Coverage: ~100% for game logic (Board, GomokuHelper, GomokuAI)

---

Dependencies Summary

Scope	Dependencies
server runtime	Netty 4.1.115, Protobuf 3.25.5, gson 2.11.0
server test	JUnit Jupiter 5.11.3
client runtime	Phaser 3.87
client build	Vite 6.3

---

Important Files by Feature

Game Logic

• server/src/main/java/com/miti99/caro/common/entity/Board.java
• server/src/main/java/com/miti99/caro/common/helper/GomokuHelper.java
• server/src/main/java/com/miti99/caro/common/robot/GomokuAI.java

Networking

• server/src/main/java/com/miti99/caro/server/handler/WebsocketTransferHandler.java
• server/src/main/java/com/miti99/caro/server/handler/ProtobufTransferHandler.java
• server/src/main/java/com/miti99/caro/common/channel/ChannelUtils.java
• client/src/services/connection-service.js

Game Flow

• server/src/main/java/com/miti99/caro/server/event/ServerEventListener_CODE_GAME_MOVE.java
• server/src/main/java/com/miti99/caro/server/event/ServerEventListener_CODE_GAME_STARTING.java
• client/src/scenes/game-scene.js

UI

• client/src/objects/board.js
• client/src/ui/game-ui.js
• client/src/ui/menu-ui.js

---

Code Quality

Metrics:

• Lines of Code: ~5,000 Java, ~1,500 JavaScript
• Test Coverage: Game logic ~100%, server flow ~80%, client varies
• File Size: Most Java files < 200 lines, JavaScript < 300 lines

Java 25 features in use:

• record for immutable DTOs (Msg)
• Switch expressions (GomokuHelper.getWinnerMessage, GomokuAI.getNextMove)
• var for obvious local types

---

Build Artifacts

Artifact	Location	Purpose
Server jar	server/target/caro-server-0.0.1-beta.jar	Shaded executable fat jar
Client dist	client/dist/	Static files for web UI

---

Continuous Integration

GitHub Actions:

build.yml

• Trigger: push/PR on master (ignores .md and .gitignore)
• Jobs:
  • build-server — Setup Java 25 (Temurin), mvn -f server/pom.xml -B clean verify
  • build-client — Setup Node 22, npm ci, npm run build

Deployment is handled via Docker Compose from this repo; there is no hosted deployment pipeline.

---

Version & Release

Current Version: 0.0.1-beta (both caro-server and caro-client)

Versioning: Semantic versioning (MAJOR.MINOR.PATCH) with -beta suffix during pre-1.0.