Initial commit: The Ultimate Antigravity Skills Collection (58 Skills)

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+# Services and Repositories - Business Logic Layer
+
+Complete guide to organizing business logic with services and data access with repositories.
+
+## Table of Contents
+
+- [Service Layer Overview](#service-layer-overview)
+- [Dependency Injection Pattern](#dependency-injection-pattern)
+- [Singleton Pattern](#singleton-pattern)
+- [Repository Pattern](#repository-pattern)
+- [Service Design Principles](#service-design-principles)
+- [Caching Strategies](#caching-strategies)
+- [Testing Services](#testing-services)
+
+---
+
+## Service Layer Overview
+
+### Purpose of Services
+
+**Services contain business logic** - the 'what' and 'why' of your application:
+
+```
+Controller asks: "Should I do this?"
+Service answers: "Yes/No, here's why, and here's what happens"
+Repository executes: "Here's the data you requested"
+```
+
+**Services are responsible for:**
+- ✅ Business rules enforcement
+- ✅ Orchestrating multiple repositories
+- ✅ Transaction management
+- ✅ Complex calculations
+- ✅ External service integration
+- ✅ Business validations
+
+**Services should NOT:**
+- ❌ Know about HTTP (Request/Response)
+- ❌ Direct Prisma access (use repositories)
+- ❌ Handle route-specific logic
+- ❌ Format HTTP responses
+
+---
+
+## Dependency Injection Pattern
+
+### Why Dependency Injection?
+
+**Benefits:**
+- Easy to test (inject mocks)
+- Clear dependencies
+- Flexible configuration
+- Promotes loose coupling
+
+### Excellent Example: NotificationService
+
+**File:** `/blog-api/src/services/NotificationService.ts`
+
+```typescript
+// Define dependencies interface for clarity
+export interface NotificationServiceDependencies {
+    prisma: PrismaClient;
+    batchingService: BatchingService;
+    emailComposer: EmailComposer;
+}
+
+// Service with dependency injection
+export class NotificationService {
+    private prisma: PrismaClient;
+    private batchingService: BatchingService;
+    private emailComposer: EmailComposer;
+    private preferencesCache: Map<string, { preferences: UserPreference; timestamp: number }> = new Map();
+    private CACHE_TTL = (notificationConfig.preferenceCacheTTLMinutes || 5) * 60 * 1000;
+
+    // Dependencies injected via constructor
+    constructor(dependencies: NotificationServiceDependencies) {
+        this.prisma = dependencies.prisma;
+        this.batchingService = dependencies.batchingService;
+        this.emailComposer = dependencies.emailComposer;
+    }
+
+    /**
+     * Create a notification and route it appropriately
+     */
+    async createNotification(params: CreateNotificationParams) {
+        const { recipientID, type, title, message, link, context = {}, channel = 'both', priority = NotificationPriority.NORMAL } = params;
+
+        try {
+            // Get template and render content
+            const template = getNotificationTemplate(type);
+            const rendered = renderNotificationContent(template, context);
+
+            // Create in-app notification record
+            const notificationId = await createNotificationRecord({
+                instanceId: parseInt(context.instanceId || '0', 10),
+                template: type,
+                recipientUserId: recipientID,
+                channel: channel === 'email' ? 'email' : 'inApp',
+                contextData: context,
+                title: finalTitle,
+                message: finalMessage,
+                link: finalLink,
+            });
+
+            // Route notification based on channel
+            if (channel === 'email' || channel === 'both') {
+                await this.routeNotification({
+                    notificationId,
+                    userId: recipientID,
+                    type,
+                    priority,
+                    title: finalTitle,
+                    message: finalMessage,
+                    link: finalLink,
+                    context,
+                });
+            }
+
+            return notification;
+        } catch (error) {
+            ErrorLogger.log(error, {
+                context: {
+                    '[NotificationService] createNotification': {
+                        type: params.type,
+                        recipientID: params.recipientID,
+                    },
+                },
+            });
+            throw error;
+        }
+    }
+
+    /**
+     * Route notification based on user preferences
+     */
+    private async routeNotification(params: { notificationId: number; userId: string; type: string; priority: NotificationPriority; title: string; message: string; link?: string; context?: Record<string, any> }) {
+        // Get user preferences with caching
+        const preferences = await this.getUserPreferences(params.userId);
+
+        // Check if we should batch or send immediately
+        if (this.shouldBatchEmail(preferences, params.type, params.priority)) {
+            await this.batchingService.queueNotificationForBatch({
+                notificationId: params.notificationId,
+                userId: params.userId,
+                userPreference: preferences,
+                priority: params.priority,
+            });
+        } else {
+            // Send immediately via EmailComposer
+            await this.sendImmediateEmail({
+                userId: params.userId,
+                title: params.title,
+                message: params.message,
+                link: params.link,
+                context: params.context,
+                type: params.type,
+            });
+        }
+    }
+
+    /**
+     * Determine if email should be batched
+     */
+    shouldBatchEmail(preferences: UserPreference, notificationType: string, priority: NotificationPriority): boolean {
+        // HIGH priority always immediate
+        if (priority === NotificationPriority.HIGH) {
+            return false;
+        }
+
+        // Check batch mode
+        const batchMode = preferences.emailBatchMode || BatchMode.IMMEDIATE;
+        return batchMode !== BatchMode.IMMEDIATE;
+    }
+
+    /**
+     * Get user preferences with caching
+     */
+    async getUserPreferences(userId: string): Promise<UserPreference> {
+        // Check cache first
+        const cached = this.preferencesCache.get(userId);
+        if (cached && Date.now() - cached.timestamp < this.CACHE_TTL) {
+            return cached.preferences;
+        }
+
+        const preference = await this.prisma.userPreference.findUnique({
+            where: { userID: userId },
+        });
+
+        const finalPreferences = preference || DEFAULT_PREFERENCES;
+
+        // Update cache
+        this.preferencesCache.set(userId, {
+            preferences: finalPreferences,
+            timestamp: Date.now(),
+        });
+
+        return finalPreferences;
+    }
+}
+```
+
+**Usage in Controller:**
+
+```typescript
+// Instantiate with dependencies
+const notificationService = new NotificationService({
+    prisma: PrismaService.main,
+    batchingService: new BatchingService(PrismaService.main),
+    emailComposer: new EmailComposer(),
+});
+
+// Use in controller
+const notification = await notificationService.createNotification({
+    recipientID: 'user-123',
+    type: 'AFRLWorkflowNotification',
+    context: { workflowName: 'AFRL Monthly Report' },
+});
+```
+
+**Key Takeaways:**
+- Dependencies passed via constructor
+- Clear interface defines required dependencies
+- Easy to test (inject mocks)
+- Encapsulated caching logic
+- Business rules isolated from HTTP
+
+---
+
+## Singleton Pattern
+
+### When to Use Singletons
+
+**Use for:**
+- Services with expensive initialization
+- Services with shared state (caching)
+- Services accessed from many places
+- Permission services
+- Configuration services
+
+### Example: PermissionService (Singleton)
+
+**File:** `/blog-api/src/services/permissionService.ts`
+
+```typescript
+import { PrismaClient } from '@prisma/client';
+
+class PermissionService {
+    private static instance: PermissionService;
+    private prisma: PrismaClient;
+    private permissionCache: Map<string, { canAccess: boolean; timestamp: number }> = new Map();
+    private CACHE_TTL = 5 * 60 * 1000; // 5 minutes
+
+    // Private constructor prevents direct instantiation
+    private constructor() {
+        this.prisma = PrismaService.main;
+    }
+
+    // Get singleton instance
+    public static getInstance(): PermissionService {
+        if (!PermissionService.instance) {
+            PermissionService.instance = new PermissionService();
+        }
+        return PermissionService.instance;
+    }
+
+    /**
+     * Check if user can complete a workflow step
+     */
+    async canCompleteStep(userId: string, stepInstanceId: number): Promise<boolean> {
+        const cacheKey = `${userId}:${stepInstanceId}`;
+
+        // Check cache
+        const cached = this.permissionCache.get(cacheKey);
+        if (cached && Date.now() - cached.timestamp < this.CACHE_TTL) {
+            return cached.canAccess;
+        }
+
+        try {
+            const post = await this.prisma.post.findUnique({
+                where: { id: postId },
+                include: {
+                    author: true,
+                    comments: {
+                        include: {
+                            user: true,
+                        },
+                    },
+                },
+            });
+
+            if (!post) {
+                return false;
+            }
+
+            // Check if user has permission
+            const canEdit = post.authorId === userId ||
+                await this.isUserAdmin(userId);
+
+            // Cache result
+            this.permissionCache.set(cacheKey, {
+                canAccess: isAssigned,
+                timestamp: Date.now(),
+            });
+
+            return isAssigned;
+        } catch (error) {
+            console.error('[PermissionService] Error checking step permission:', error);
+            return false;
+        }
+    }
+
+    /**
+     * Clear cache for user
+     */
+    clearUserCache(userId: string): void {
+        for (const [key] of this.permissionCache) {
+            if (key.startsWith(`${userId}:`)) {
+                this.permissionCache.delete(key);
+            }
+        }
+    }
+
+    /**
+     * Clear all cache
+     */
+    clearCache(): void {
+        this.permissionCache.clear();
+    }
+}
+
+// Export singleton instance
+export const permissionService = PermissionService.getInstance();
+```
+
+**Usage:**
+
+```typescript
+import { permissionService } from '../services/permissionService';
+
+// Use anywhere in the codebase
+const canComplete = await permissionService.canCompleteStep(userId, stepId);
+
+if (!canComplete) {
+    throw new ForbiddenError('You do not have permission to complete this step');
+}
+```
+
+---
+
+## Repository Pattern
+
+### Purpose of Repositories
+
+**Repositories abstract data access** - the 'how' of data operations:
+
+```
+Service: "Get me all active users sorted by name"
+Repository: "Here's the Prisma query that does that"
+```
+
+**Repositories are responsible for:**
+- ✅ All Prisma operations
+- ✅ Query construction
+- ✅ Query optimization (select, include)
+- ✅ Database error handling
+- ✅ Caching database results
+
+**Repositories should NOT:**
+- ❌ Contain business logic
+- ❌ Know about HTTP
+- ❌ Make decisions (that's service layer)
+
+### Repository Template
+
+```typescript
+// repositories/UserRepository.ts
+import { PrismaService } from '@project-lifecycle-portal/database';
+import type { User, Prisma } from '@project-lifecycle-portal/database';
+
+export class UserRepository {
+    /**
+     * Find user by ID with optimized query
+     */
+    async findById(userId: string): Promise<User | null> {
+        try {
+            return await PrismaService.main.user.findUnique({
+                where: { userID: userId },
+                select: {
+                    userID: true,
+                    email: true,
+                    name: true,
+                    isActive: true,
+                    roles: true,
+                    createdAt: true,
+                    updatedAt: true,
+                },
+            });
+        } catch (error) {
+            console.error('[UserRepository] Error finding user by ID:', error);
+            throw new Error(`Failed to find user: ${userId}`);
+        }
+    }
+
+    /**
+     * Find all active users
+     */
+    async findActive(options?: { orderBy?: Prisma.UserOrderByWithRelationInput }): Promise<User[]> {
+        try {
+            return await PrismaService.main.user.findMany({
+                where: { isActive: true },
+                orderBy: options?.orderBy || { name: 'asc' },
+                select: {
+                    userID: true,
+                    email: true,
+                    name: true,
+                    roles: true,
+                },
+            });
+        } catch (error) {
+            console.error('[UserRepository] Error finding active users:', error);
+            throw new Error('Failed to find active users');
+        }
+    }
+
+    /**
+     * Find user by email
+     */
+    async findByEmail(email: string): Promise<User | null> {
+        try {
+            return await PrismaService.main.user.findUnique({
+                where: { email },
+            });
+        } catch (error) {
+            console.error('[UserRepository] Error finding user by email:', error);
+            throw new Error(`Failed to find user with email: ${email}`);
+        }
+    }
+
+    /**
+     * Create new user
+     */
+    async create(data: Prisma.UserCreateInput): Promise<User> {
+        try {
+            return await PrismaService.main.user.create({ data });
+        } catch (error) {
+            console.error('[UserRepository] Error creating user:', error);
+            throw new Error('Failed to create user');
+        }
+    }
+
+    /**
+     * Update user
+     */
+    async update(userId: string, data: Prisma.UserUpdateInput): Promise<User> {
+        try {
+            return await PrismaService.main.user.update({
+                where: { userID: userId },
+                data,
+            });
+        } catch (error) {
+            console.error('[UserRepository] Error updating user:', error);
+            throw new Error(`Failed to update user: ${userId}`);
+        }
+    }
+
+    /**
+     * Delete user (soft delete by setting isActive = false)
+     */
+    async delete(userId: string): Promise<User> {
+        try {
+            return await PrismaService.main.user.update({
+                where: { userID: userId },
+                data: { isActive: false },
+            });
+        } catch (error) {
+            console.error('[UserRepository] Error deleting user:', error);
+            throw new Error(`Failed to delete user: ${userId}`);
+        }
+    }
+
+    /**
+     * Check if email exists
+     */
+    async emailExists(email: string): Promise<boolean> {
+        try {
+            const count = await PrismaService.main.user.count({
+                where: { email },
+            });
+            return count > 0;
+        } catch (error) {
+            console.error('[UserRepository] Error checking email exists:', error);
+            throw new Error('Failed to check if email exists');
+        }
+    }
+}
+
+// Export singleton instance
+export const userRepository = new UserRepository();
+```
+
+**Using Repository in Service:**
+
+```typescript
+// services/userService.ts
+import { userRepository } from '../repositories/UserRepository';
+import { ConflictError, NotFoundError } from '../utils/errors';
+
+export class UserService {
+    /**
+     * Create new user with business rules
+     */
+    async createUser(data: { email: string; name: string; roles: string[] }): Promise<User> {
+        // Business rule: Check if email already exists
+        const emailExists = await userRepository.emailExists(data.email);
+        if (emailExists) {
+            throw new ConflictError('Email already exists');
+        }
+
+        // Business rule: Validate roles
+        const validRoles = ['admin', 'operations', 'user'];
+        const invalidRoles = data.roles.filter((role) => !validRoles.includes(role));
+        if (invalidRoles.length > 0) {
+            throw new ValidationError(`Invalid roles: ${invalidRoles.join(', ')}`);
+        }
+
+        // Create user via repository
+        return await userRepository.create({
+            email: data.email,
+            name: data.name,
+            roles: data.roles,
+            isActive: true,
+        });
+    }
+
+    /**
+     * Get user by ID
+     */
+    async getUser(userId: string): Promise<User> {
+        const user = await userRepository.findById(userId);
+
+        if (!user) {
+            throw new NotFoundError(`User not found: ${userId}`);
+        }
+
+        return user;
+    }
+}
+```
+
+---
+
+## Service Design Principles
+
+### 1. Single Responsibility
+
+Each service should have ONE clear purpose:
+
+```typescript
+// ✅ GOOD - Single responsibility
+class UserService {
+    async createUser() {}
+    async updateUser() {}
+    async deleteUser() {}
+}
+
+class EmailService {
+    async sendEmail() {}
+    async sendBulkEmails() {}
+}
+
+// ❌ BAD - Too many responsibilities
+class UserService {
+    async createUser() {}
+    async sendWelcomeEmail() {}  // Should be EmailService
+    async logUserActivity() {}   // Should be AuditService
+    async processPayment() {}    // Should be PaymentService
+}
+```
+
+### 2. Clear Method Names
+
+Method names should describe WHAT they do:
+
+```typescript
+// ✅ GOOD - Clear intent
+async createNotification()
+async getUserPreferences()
+async shouldBatchEmail()
+async routeNotification()
+
+// ❌ BAD - Vague or misleading
+async process()
+async handle()
+async doIt()
+async execute()
+```
+
+### 3. Return Types
+
+Always use explicit return types:
+
+```typescript
+// ✅ GOOD - Explicit types
+async createUser(data: CreateUserDTO): Promise<User> {}
+async findUsers(): Promise<User[]> {}
+async deleteUser(id: string): Promise<void> {}
+
+// ❌ BAD - Implicit any
+async createUser(data) {}  // No types!
+```
+
+### 4. Error Handling
+
+Services should throw meaningful errors:
+
+```typescript
+// ✅ GOOD - Meaningful errors
+if (!user) {
+    throw new NotFoundError(`User not found: ${userId}`);
+}
+
+if (emailExists) {
+    throw new ConflictError('Email already exists');
+}
+
+// ❌ BAD - Generic errors
+if (!user) {
+    throw new Error('Error');  // What error?
+}
+```
+
+### 5. Avoid God Services
+
+Don't create services that do everything:
+
+```typescript
+// ❌ BAD - God service
+class WorkflowService {
+    async startWorkflow() {}
+    async completeStep() {}
+    async assignRoles() {}
+    async sendNotifications() {}  // Should be NotificationService
+    async validatePermissions() {}  // Should be PermissionService
+    async logAuditTrail() {}  // Should be AuditService
+    // ... 50 more methods
+}
+
+// ✅ GOOD - Focused services
+class WorkflowService {
+    constructor(
+        private notificationService: NotificationService,
+        private permissionService: PermissionService,
+        private auditService: AuditService
+    ) {}
+
+    async startWorkflow() {
+        // Orchestrate other services
+        await this.permissionService.checkPermission();
+        await this.workflowRepository.create();
+        await this.notificationService.notify();
+        await this.auditService.log();
+    }
+}
+```
+
+---
+
+## Caching Strategies
+
+### 1. In-Memory Caching
+
+```typescript
+class UserService {
+    private cache: Map<string, { user: User; timestamp: number }> = new Map();
+    private CACHE_TTL = 5 * 60 * 1000; // 5 minutes
+
+    async getUser(userId: string): Promise<User> {
+        // Check cache
+        const cached = this.cache.get(userId);
+        if (cached && Date.now() - cached.timestamp < this.CACHE_TTL) {
+            return cached.user;
+        }
+
+        // Fetch from database
+        const user = await userRepository.findById(userId);
+
+        // Update cache
+        if (user) {
+            this.cache.set(userId, { user, timestamp: Date.now() });
+        }
+
+        return user;
+    }
+
+    clearUserCache(userId: string): void {
+        this.cache.delete(userId);
+    }
+}
+```
+
+### 2. Cache Invalidation
+
+```typescript
+class UserService {
+    async updateUser(userId: string, data: UpdateUserDTO): Promise<User> {
+        // Update in database
+        const user = await userRepository.update(userId, data);
+
+        // Invalidate cache
+        this.clearUserCache(userId);
+
+        return user;
+    }
+}
+```
+
+---
+
+## Testing Services
+
+### Unit Tests
+
+```typescript
+// tests/userService.test.ts
+import { UserService } from '../services/userService';
+import { userRepository } from '../repositories/UserRepository';
+import { ConflictError } from '../utils/errors';
+
+// Mock repository
+jest.mock('../repositories/UserRepository');
+
+describe('UserService', () => {
+    let userService: UserService;
+
+    beforeEach(() => {
+        userService = new UserService();
+        jest.clearAllMocks();
+    });
+
+    describe('createUser', () => {
+        it('should create user when email does not exist', async () => {
+            // Arrange
+            const userData = {
+                email: 'test@example.com',
+                name: 'Test User',
+                roles: ['user'],
+            };
+
+            (userRepository.emailExists as jest.Mock).mockResolvedValue(false);
+            (userRepository.create as jest.Mock).mockResolvedValue({
+                userID: '123',
+                ...userData,
+            });
+
+            // Act
+            const user = await userService.createUser(userData);
+
+            // Assert
+            expect(user).toBeDefined();
+            expect(user.email).toBe(userData.email);
+            expect(userRepository.emailExists).toHaveBeenCalledWith(userData.email);
+            expect(userRepository.create).toHaveBeenCalled();
+        });
+
+        it('should throw ConflictError when email exists', async () => {
+            // Arrange
+            const userData = {
+                email: 'existing@example.com',
+                name: 'Test User',
+                roles: ['user'],
+            };
+
+            (userRepository.emailExists as jest.Mock).mockResolvedValue(true);
+
+            // Act & Assert
+            await expect(userService.createUser(userData)).rejects.toThrow(ConflictError);
+            expect(userRepository.create).not.toHaveBeenCalled();
+        });
+    });
+});
+```
+
+---
+
+**Related Files:**
+- [SKILL.md](SKILL.md) - Main guide
+- [routing-and-controllers.md](routing-and-controllers.md) - Controllers that use services
+- [database-patterns.md](database-patterns.md) - Prisma and repository patterns
+- [complete-examples.md](complete-examples.md) - Full service/repository examples