Tic Tac Toe Plugin

A professional WordPress plugin implementing a single-player Tic Tac Toe game with three difficulty levels, developed as a technical assessment.

Author

Rivka Fus

Overview

This plugin provides a complete Tic Tac Toe game implementation for WordPress, featuring an intelligent AI opponent with three difficulty levels, player statistics tracking, and a clean REST API interface.

Features Implemented

Part 1: Plugin and Game Creation

• ✅ Standard WordPress plugin structure with separate installer
• ✅ PHP-based game logic with full session management
• ✅ Single-player mode against computer AI
• ✅ Three distinct difficulty levels:
  • Easy: Random move selection - perfect for beginners
  • Medium: Tactical AI that tries to win and blocks player moves
  • Hard: Minimax algorithm implementation - optimal play (never loses)

Part 2: Database Management

• ✅ Uses WordPress native wp_postmeta table (no custom tables)
• ✅ Custom post types for game sessions and player data
• ✅ Complete CRUD operations using WordPress functions
• ✅ Player statistics tracking:
  • Total points (10 per win)
  • Games played, won, lost, and tied
  • Win rate calculation

Part 3: REST API

• ✅ POST /wp-json/tic-tac-toe/v1/session - Initialize new game
• ✅ POST /wp-json/tic-tac-toe/v1/move - Play move and get updated board
• ✅ GET /wp-json/tic-tac-toe/v1/session/{id} - Retrieve session state
• ✅ Full input validation and sanitization
• ✅ Proper error handling with WP_Error

Additional Features

Beyond the core requirements, the plugin includes:

• Admin Dashboard: View comprehensive player statistics
• Shortcode Support: Easy integration with [tic_tac_toe]
• Dynamic Settings: Players can change name and difficulty without page refresh
• Responsive Design: Works seamlessly on mobile, tablet, and desktop
• Security First: All inputs validated, outputs escaped, SQL queries prepared

Installation

Method 1: Manual Installation

1. Download the plugin files
2. Upload the tic-tac-toe-plugin folder to /wp-content/plugins/
3. Activate the plugin through the WordPress admin panel
4. The plugin will automatically set up required data structures

Method 2: WordPress Admin

1. Go to Plugins → Add New
2. Click "Upload Plugin"
3. Choose the plugin ZIP file
4. Click "Install Now" then "Activate"

Usage

Frontend - Shortcode

Add the game to any page or post using the shortcode:

[tic_tac_toe]

With custom parameters:

[tic_tac_toe player_name="John" difficulty="hard"]

Parameters:

• player_name - Default player name (default: "Player")
• difficulty - Default difficulty level: easy, medium, or hard (default: "medium")

Admin Dashboard

1. Navigate to Tic Tac Toe → Players in WordPress admin
2. View comprehensive statistics for all players:
   • Total points
   • Games played, won, lost, tied
   • Win rate percentage

REST API

Initialize Game Session

curl -X POST https://yoursite.com/wp-json/tic-tac-toe/v1/session \
  -H "Content-Type: application/json" \
  -d '{
    "mode": "single",
    "player_name": "John",
    "difficulty": "hard"
  }'

Response:

{
  "session_id": "550e8400-e29b-41d4-a716-446655440000",
  "message": "Session created successfully"
}

Play Move

curl -X POST https://yoursite.com/wp-json/tic-tac-toe/v1/move \
  -H "Content-Type: application/json" \
  -d '{
    "session_id": "550e8400-e29b-41d4-a716-446655440000",
    "x": 0,
    "y": 0
  }'

Response:

{
  "board": [
    {"x": 0, "y": 0, "value": "X"},
    {"x": 1, "y": 0, "value": "O"},
    {"x": 2, "y": 0, "value": ""},
    ...
  ],
  "winner": ""
}

🏗️ Technical Architecture

File Structure

tic-tac-toe-plugin/
├── assets/
│   ├── css/
│   │   ├── admin.css          # Admin dashboard styles
│   │   └── frontend.css       # Frontend game styles
│   └── js/
│       ├── admin.js           # Admin JavaScript
│       └── frontend.js        # Frontend game logic
├── includes/
│   ├── class-admin.php        # Admin interface management
│   ├── class-api.php          # REST API endpoints
│   ├── class-database.php     # Database operations
│   ├── class-frontend.php     # Frontend shortcode
│   └── class-game-logic.php   # Game logic and AI
├── installer.php              # Separate installer
├── tic-tac-toe-plugin.php     # Main plugin file
└── README.md                  # This file

Design Decisions

Why Custom Post Types?

• Assignment requires using wp_postmeta
• Leverages WordPress built-in systems
• No custom database tables needed
• Easy backup and migration
• Follows WordPress best practices

Why Minimax for Hard Mode?

• Guarantees optimal play (never loses)
• Classic game theory algorithm
• Demonstrates advanced programming skills
• Instant performance on 3×3 board

Why Separate Classes?

• Separation of Concerns: Each class has a single responsibility
• Maintainability: Easy to update and extend
• Testability: Individual components can be tested
• WordPress Standards: Follows recommended plugin architecture

Security Features

• ✅ Direct Access Prevention: All files check ABSPATH
• ✅ SQL Injection Protection: All queries use $wpdb->prepare()
• ✅ XSS Prevention: All output escaped with esc_html(), esc_attr()
• ✅ Input Sanitization: All inputs cleaned with sanitize_text_field()
• ✅ REST API Validation: Complete validation callbacks on all endpoints
• ✅ Nonce Verification: AJAX requests include nonce tokens

Algorithm Highlights

Minimax Implementation

The Hard difficulty uses the classic Minimax algorithm:

1. Recursively explores all possible game outcomes
2. Assigns scores to terminal states:
   • Computer win: +10 (minus depth for faster wins)
   • Human win: -10 (plus depth to delay losses)
   • Tie: 0
3. Maximizes computer score, minimizes human score
4. Returns optimal move based on complete game tree analysis

Performance: On a 3×3 board, the algorithm evaluates at most 362,880 states but due to pruning and early game termination, responses are instant (<1ms).

Testing

Tested with:

• ✅ WordPress 6.0+
• ✅ PHP 7.2+
• ✅ WP_DEBUG mode enabled (no errors)
• ✅ Multiple browsers (Chrome, Firefox, Safari, Edge)
• ✅ Mobile devices (responsive design) Database Schema

Custom Post Types

tic_tac_toe_session

Stores game session data in wp_postmeta:

• tic_tac_toe_session - Serialized session data (board, players, status)
• tic_tac_toe_session_id - UUID for quick lookups

tic_tac_toe_player

Stores player statistics in wp_postmeta:

• tic_tac_toe_player_name - Player name
• tic_tac_toe_player_points - Total points earned
• tic_tac_toe_player_games_played - Total games
• tic_tac_toe_player_games_won - Wins
• tic_tac_toe_player_games_lost - Losses
• tic_tac_toe_player_games_tied - Ties

Future Enhancement Ideas

While the current implementation meets all requirements, potential enhancements include:

• Per-difficulty statistics tracking
• Multiplayer mode (two human players)
• Game history and replay functionality
• Integration with WordPress user accounts
• Difficulty-based scoring (Easy: 5pts, Medium: 10pts, Hard: 20pts)
• Leaderboard system
• Tournament mode
• Internationalization (i18n) support

Development Notes

Time Spent: Approximately 6-8 hours

• Initial setup and architecture: 1 hour
• Core game logic and AI: 2-3 hours
• Database integration: 1 hour
• REST API implementation: 1 hour
• Frontend/Admin interfaces: 1-2 hours
• Testing and refinement: 1 hour

WordPress Standards Compliance:

• Follows WordPress Coding Standards
• Uses WordPress functions exclusively
• No direct SQL queries (except with $wpdb->prepare())
• Proper hook usage throughout

Contact

For questions or clarifications:

• Developer: Rivka Fus
• Email: r45771@gmail.com
• Phone: 0583264771

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Note: This plugin was developed as part of a technical assessment for a WordPress Developer position. It demonstrates proficiency in WordPress development, PHP programming, algorithm implementation, and adherence to coding standards.