Backend Complete: Interface Refactoring & Service Container Enhancements

Repository Interface Optimization:
- Created IBaseRepository.ts and IPaginatedRepository.ts
- Refactored all 7 repository interfaces to extend base interfaces
- Eliminated ~200 lines of redundant code (70% reduction)
- Improved type safety and maintainability

 Dependency Injection Improvements:
- Added EmailService and GameTokenService to DIContainer
- Updated CreateUserCommandHandler constructor for DI
- Updated RequestPasswordResetCommandHandler constructor for DI
- Enhanced testability and service consistency

 Environment Configuration:
- Created comprehensive .env.example with 40+ variables
- Organized into 12 logical sections (Database, Security, Email, etc.)
- Added security guidelines and best practices
- Documented all backend environment requirements

 Documentation:
- Added comprehensive codebase review
- Created refactoring summary report
- Added frontend implementation guide

Impact: Improved code quality, reduced maintenance overhead, enhanced developer experience

SerpentRace_Backend/tests/Application/Services/ChatConfiguration.test.ts

@@ -0,0 +1,159 @@
+import { WebSocketService } from '../../../src/Application/Services/WebSocketService';
+import { Server as HttpServer } from 'http';
+import { EventEmitter } from 'events';
+
+describe('Chat Configuration', () => {
+    let mockHttpServer: HttpServer;
+
+    beforeAll(() => {
+        // Create a more complete HTTP server mock that extends EventEmitter
+        const httpServerMock = new EventEmitter();
+        
+        // Add necessary methods that Socket.IO expects
+        Object.assign(httpServerMock, {
+            on: jest.fn(),
+            listen: jest.fn(),
+            close: jest.fn(),
+            listeners: jest.fn().mockReturnValue([]),
+            removeListener: jest.fn(),
+            removeAllListeners: jest.fn(),
+            setMaxListeners: jest.fn(),
+            getMaxListeners: jest.fn().mockReturnValue(0),
+            listenerCount: jest.fn().mockReturnValue(0),
+            prependListener: jest.fn(),
+            prependOnceListener: jest.fn(),
+            off: jest.fn(),
+            once: jest.fn(),
+            emit: jest.fn(),
+            // HTTP server specific
+            timeout: 0,
+            keepAliveTimeout: 5000,
+            maxHeadersCount: null,
+            headersTimeout: 60000,
+            requestTimeout: 0
+        });
+
+        mockHttpServer = httpServerMock as unknown as HttpServer;
+    });
+
+    afterEach(() => {
+        // Clean up environment variables
+        delete process.env.CHAT_MAX_MESSAGES_PER_USER;
+        delete process.env.CHAT_MESSAGE_CLEANUP_WEEKS;
+        delete process.env.CHAT_INACTIVITY_TIMEOUT_MINUTES;
+    });
+
+    describe('Environment Variable Configuration', () => {
+        it('should use default chat configuration values', () => {
+            const service = new WebSocketService(mockHttpServer);
+
+            expect(service['maxMessagesPerUser']).toBe(100);
+            expect(service['messageCleanupWeeks']).toBe(4);
+            expect(service['chatTimeout']).toBe(30);
+        });
+
+        it('should use environment variable for CHAT_MAX_MESSAGES_PER_USER', () => {
+            process.env.CHAT_MAX_MESSAGES_PER_USER = '50';
+
+            const service = new WebSocketService(mockHttpServer);
+
+            expect(service['maxMessagesPerUser']).toBe(50);
+        });
+
+        it('should use environment variable for CHAT_MESSAGE_CLEANUP_WEEKS', () => {
+            // Arrange
+            process.env.CHAT_MESSAGE_CLEANUP_WEEKS = '8';
+
+            // Act
+            const service = new WebSocketService(mockHttpServer);
+
+            // Assert
+            expect(service['messageCleanupWeeks']).toBe(8);
+        });
+
+        it('should use environment variable for CHAT_INACTIVITY_TIMEOUT_MINUTES', () => {
+            // Arrange
+            process.env.CHAT_INACTIVITY_TIMEOUT_MINUTES = '60';
+
+            // Act
+            const service = new WebSocketService(mockHttpServer);
+
+            // Assert
+            expect(service['chatTimeout']).toBe(60);
+        });
+
+        it('should handle invalid numeric environment variables gracefully', () => {
+            // Arrange
+            process.env.CHAT_MAX_MESSAGES_PER_USER = 'invalid';
+            process.env.CHAT_MESSAGE_CLEANUP_WEEKS = 'also-invalid';
+            process.env.CHAT_INACTIVITY_TIMEOUT_MINUTES = 'not-a-number';
+
+            // Act
+            const service = new WebSocketService(mockHttpServer);
+
+            // Assert - parseInt of invalid strings returns NaN
+            expect(service['maxMessagesPerUser']).toBe(NaN);
+            expect(service['messageCleanupWeeks']).toBe(NaN);
+            expect(service['chatTimeout']).toBe(NaN);
+        });
+    });
+
+    describe('Rate Limiting Logic', () => {
+        it('should initialize with empty user message counts', () => {
+            // Act
+            const service = new WebSocketService(mockHttpServer);
+
+            // Assert
+            expect(service['userMessageCounts']).toBeDefined();
+            expect(service['userMessageCounts'].size).toBe(0);
+        });
+
+        it('should allow messages within rate limit', () => {
+            // Arrange
+            process.env.CHAT_MAX_MESSAGES_PER_USER = '5';
+            const service = new WebSocketService(mockHttpServer);
+            const userId = 'test-user';
+
+            // Act & Assert - should allow first 5 messages
+            for (let i = 0; i < 5; i++) {
+                expect(service['checkMessageRateLimit'](userId)).toBe(true);
+            }
+        });
+
+        it('should block messages when rate limit exceeded', () => {
+            // Arrange
+            process.env.CHAT_MAX_MESSAGES_PER_USER = '3';
+            const service = new WebSocketService(mockHttpServer);
+            const userId = 'test-user';
+
+            // Act - send 3 messages (should be allowed)
+            for (let i = 0; i < 3; i++) {
+                expect(service['checkMessageRateLimit'](userId)).toBe(true);
+            }
+
+            // Assert - 4th message should be blocked
+            expect(service['checkMessageRateLimit'](userId)).toBe(false);
+        });
+
+        it('should reset rate limit after time window', (done) => {
+            // Arrange
+            process.env.CHAT_MAX_MESSAGES_PER_USER = '2';
+            const service = new WebSocketService(mockHttpServer);
+            const userId = 'test-user';
+
+            // Act - exhaust rate limit
+            expect(service['checkMessageRateLimit'](userId)).toBe(true);
+            expect(service['checkMessageRateLimit'](userId)).toBe(true);
+            expect(service['checkMessageRateLimit'](userId)).toBe(false); // Should be blocked
+
+            // Mock time passage by manipulating the internal state
+            const userStats = service['userMessageCounts'].get(userId)!;
+            userStats.lastReset = Date.now() - (60 * 1000 + 1); // More than 1 minute ago
+            service['userMessageCounts'].set(userId, userStats);
+
+            // Assert - should be allowed again after reset
+            expect(service['checkMessageRateLimit'](userId)).toBe(true);
+            done();
+        });
+    });
+});