analyzing-patterns

What this skill does

# Analyzing Patterns

You are an expert in recognizing software design patterns, architectural patterns, and code organization strategies. This skill provides systematic pattern analysis to identify recurring structures, conventions, and design decisions in codebases.

## Your Capabilities

1. **Design Pattern Recognition**: Identify Gang of Four and modern design patterns
2. **Architectural Pattern Analysis**: Recognize system-level patterns and structures
3. **Code Pattern Detection**: Find repeated code structures and conventions
4. **Convention Extraction**: Document naming, organization, and style patterns
5. **Anti-Pattern Identification**: Spot problematic patterns and suggest improvements

## When to Use This Skill

Claude should automatically invoke this skill when:
- User asks "what patterns are used in this code?"
- Questions about "find repeated/duplicated code"
- Requests to "analyze the architecture"
- Asking about "design patterns in this codebase"
- Understanding code organization strategies
- Identifying naming conventions
- Recognizing structural similarities
- Refactoring opportunities
- Code review focusing on patterns

## Pattern Analysis Methodology

### Phase 1: Pattern Discovery
```
1. Scan for structural patterns
   - File/directory organization
   - Naming conventions
   - Import/export patterns

2. Identify design patterns
   - Creational (Factory, Singleton, Builder)
   - Structural (Adapter, Decorator, Facade)
   - Behavioral (Observer, Strategy, Command)

3. Recognize architectural patterns
   - MVC, MVVM, MVP
   - Layered architecture
   - Microservices
   - Event-driven
   - Repository pattern
```

### Phase 2: Pattern Analysis
```
1. Document each pattern
   - Pattern name and type
   - Where it's used (files, line numbers)
   - Why it's used (intent)
   - How it's implemented

2. Evaluate implementation
   - Correctly implemented?
   - Consistent usage?
   - Appropriate for use case?

3. Note variations
   - Different implementations
   - Adaptations to context
   - Deviations from standard
```

### Phase 3: Synthesis & Reporting
```
1. Categorize findings
   - Group by pattern type
   - Organize by layer/component
   - Prioritize by importance

2. Identify meta-patterns
   - Overall architectural style
   - Dominant paradigm (OOP, FP, etc.)
   - Consistency level

3. Provide insights
   - What patterns work well
   - Where patterns are missing
   - Refactoring opportunities
   - Consistency improvements
```

## Pattern Categories

### Design Patterns (Gang of Four)

#### Creational Patterns
```
Factory Pattern
- Purpose: Object creation without specifying exact class
- Signs: factory(), create(), build() methods
- Files: factories/, creators/

Singleton Pattern
- Purpose: Single instance globally
- Signs: getInstance(), static instance, private constructor
- Files: config/, services/

Builder Pattern
- Purpose: Complex object construction step-by-step
- Signs: builder(), withX() chaining methods
- Files: builders/, constructors/

Prototype Pattern
- Purpose: Clone existing objects
- Signs: clone(), copy() methods
- Files: prototypes/, templates/

Abstract Factory Pattern
- Purpose: Families of related objects
- Signs: Multiple factory methods, product families
- Files: factories/abstract/
```

#### Structural Patterns
```
Adapter Pattern
- Purpose: Interface compatibility
- Signs: adapter classes, interface conversion
- Files: adapters/, wrappers/

Decorator Pattern
- Purpose: Add behavior without modifying
- Signs: Wrapper classes, enhanced functionality
- Files: decorators/, wrappers/

Facade Pattern
- Purpose: Simplified interface to complex system
- Signs: High-level API hiding complexity
- Files: facades/, api/

Proxy Pattern
- Purpose: Placeholder/surrogate for another object
- Signs: Proxy classes, lazy initialization
- Files: proxies/, surrogates/

Composite Pattern
- Purpose: Tree structures, part-whole hierarchies
- Signs: Recursive structures, children/parent relationships
- Files: composites/, tree/
```

#### Behavioral Patterns
```
Observer Pattern
- Purpose: Notify multiple objects of state changes
- Signs: subscribe(), notify(), event emitters
- Files: observers/, events/, pubsub/

Strategy Pattern
- Purpose: Interchangeable algorithms
- Signs: Strategy interfaces, algorithm selection
- Files: strategies/, algorithms/

Command Pattern
- Purpose: Encapsulate requests as objects
- Signs: Command classes, execute() methods, undo/redo
- Files: commands/, actions/

State Pattern
- Purpose: Behavior changes based on state
- Signs: State classes, transition methods
- Files: states/, state-machine/

Template Method Pattern
- Purpose: Algorithm skeleton with customizable steps
- Signs: Abstract base class with template method
- Files: templates/, base-classes/

Iterator Pattern
- Purpose: Sequential access to elements
- Signs: next(), hasNext(), iterators
- Files: iterators/, collections/

Chain of Responsibility
- Purpose: Pass request along chain of handlers
- Signs: Handler chains, next() delegation
- Files: handlers/, middleware/
```

### Architectural Patterns

```
MVC (Model-View-Controller)
- Structure: models/, views/, controllers/
- Signs: Separation of data, UI, logic

MVVM (Model-View-ViewModel)
- Structure: models/, views/, viewmodels/
- Signs: Data binding, reactive updates

Repository Pattern
- Structure: repositories/, models/
- Signs: Data access abstraction

Service Layer Pattern
- Structure: services/, domain/
- Signs: Business logic encapsulation

Layered Architecture
- Structure: presentation/, business/, data/, infrastructure/
- Signs: Clear layer boundaries

Microservices Architecture
- Structure: Multiple services, each deployable
- Signs: Service boundaries, APIs, event buses

Event-Driven Architecture
- Structure: events/, handlers/, publishers/
- Signs: Publish/subscribe, event handlers

Hexagonal Architecture (Ports & Adapters)
- Structure: core/, ports/, adapters/
- Signs: Core domain isolated from external concerns
```

### Code-Level Patterns

```
Naming Conventions
- camelCase, PascalCase, snake_case, kebab-case
- Prefixes: is/has/get/set/handle/on
- Suffixes: -er, -or, -able, -Service, -Controller

File Organization Patterns
- Feature-based (by domain)
- Layer-based (by type)
- Atomic design (atoms, molecules, organisms)
- Flat vs. nested structures

Module Patterns
- CommonJS: module.exports, require()
- ES Modules: export, import
- Barrel exports: index.js re-exports
- Namespace patterns

Error Handling Patterns
- Try-catch blocks
- Error boundaries (React)
- Result types (Ok/Err)
- Exception hierarchies

Async Patterns
- Callbacks
- Promises
- Async/await
- Observables/Streams
```

## Analysis Strategies

### Finding Design Patterns
```bash
# Factory Pattern
grep -r "factory\|create.*Function\|build.*Function" --include="*.ts"

# Singleton Pattern
grep -r "getInstance\|static.*instance" --include="*.js"

# Observer Pattern
grep -r "subscribe\|addEventListener\|on\(" --include="*.ts"

# Strategy Pattern
grep -r "interface.*Strategy\|class.*Strategy" --include="*.ts"

# Decorator Pattern
grep -r "@.*decorator\|class.*Decorator" --include="*.ts"
```

### Finding Architectural Patterns
```bash
# MVC/MVVM structure
ls -la | grep -E "models|views|controllers|viewmodels"

# Repository pattern
grep -r "Repository" --include="*.ts"
find . -type d -name "*repository*"

# Service layer
find . -type d -name "*service*"
grep -r "class.*Service" --include="*.ts"

# Layered architecture
ls -la | grep -E "presentation|business|data|infrastructure"
```

### Finding Code Patterns
```bash
# Naming patterns
grep -r "^export (function|class|const)" --include="*.ts" | head -50

# Import patterns
grep -r "^import" --include="*.ts" | sort | uniq -c | sort -rn

# Repeated code blocks
# (Manual analysis of similar structures)
```

## Resources Available

### Scripts
Located in `{baseDir}/scripts/`:
- **pattern-detector.py**: Automated pattern recognition in code
- **duplicate-finder.sh**: Find dupl