Arch Check

Architecture Check Skill

Verify the codebase adheres to architectural principles, layer boundaries, and design patterns.

Instructions

1. Verify Layer Architecture

This project follows a layered architecture:

┌─────────────────────────────────────────┐
│            Controller Layer             │  ← HTTP endpoints
├─────────────────────────────────────────┤
│             Service Layer               │  ← Business logic
├─────────────────────────────────────────┤
│    Provider / Strategy / Mapper Layer   │  ← Data access, transformations
├─────────────────────────────────────────┤
│              Model Layer                │  ← Domain objects (records)
└─────────────────────────────────────────┘

Allowed Dependencies:

• Controller → Service → Provider/Strategy/Mapper → Model
• All layers → Model (models are shared)
• Service → Service (peer services)

Violations to detect:

// BAD: Controller importing Strategy
import ...service.strategy.FetchCurrentConditionsStrategy;

// BAD: Provider importing Controller
import ...controller.SpotsController;

// BAD: Model importing Service
import ...service.AggregatorService;

Use Grep to check imports in each layer:

# Controllers should not import strategies directly
grep -r "import.*strategy" src/main/java/**/controller/

# Providers should not import controllers or services
grep -r "import.*controller\|import.*service[^/]" src/main/java/**/provider/

# Models should not import anything except other models
grep -r "import.*service\|import.*controller\|import.*provider" src/main/java/**/model/

2. Detect Circular Dependencies

Check for circular imports between packages:

Package dependency graph:

controller → service → provider
                    → strategy
                    → mapper
          → model (allowed from all)

Search patterns:

// Check if Service A imports Service B and vice versa
// File: ServiceA.java contains "import ...ServiceB"
// File: ServiceB.java contains "import ...ServiceA"

Common circular dependency patterns:

• Service A calls Service B, Service B calls Service A
• Listener/callback creating cycles
• Utility classes depending on domain classes

3. Package Structure Compliance

Verify expected package structure:

src/main/java/com/github/pwittchen/varun/
├── Application.java           # Main entry point
├── config/                    # Configuration classes
│   └── *Config.java
├── controller/                # REST controllers
│   └── *Controller.java
├── exception/                 # Custom exceptions
│   └── *Exception.java
├── mapper/                    # Data mappers
│   └── *Mapper.java
├── model/                     # Domain models (records)
│   └── *.java
├── provider/                  # Data providers
│   └── *Provider.java
└── service/                   # Business services
    ├── *Service.java
    └── strategy/              # Strategy implementations
        └── *Strategy*.java

Check for:

• Files in wrong packages (e.g., Service in controller package)
• Missing package conventions (e.g., Helper in service package)
• Inconsistent naming (e.g., FooManager instead of FooService)

4. Design Pattern Compliance

Strategy Pattern (CurrentConditions)

// Interface
interface FetchCurrentConditionsStrategy {
    boolean canProcess(int windguruId);
    CurrentConditions fetch();
}

// Check all implementations:
// - Implement the interface
// - Have canProcess() method
// - Are registered/discoverable (via @Component or explicit registration)

Provider Pattern (Data Loading)

// Check providers:
// - Single responsibility (one data source)
// - Return domain models
// - Don't contain business logic

Caching Pattern

// Check cache usage:
// - Caches are in service layer (not controller)
// - Cache keys are consistent
// - Cache invalidation is handled

5. Dependency Injection Compliance

Check for:

// BAD: Direct instantiation of services
private ForecastService service = new ForecastService();

// GOOD: Constructor injection
private final ForecastService service;
public MyService(ForecastService service) {
    this.service = service;
}

// BAD: Field injection (harder to test)
@Autowired
private ForecastService service;

// GOOD: Constructor injection with Lombok
@RequiredArgsConstructor
public class MyService {
    private final ForecastService forecastService;
}

Search for anti-patterns:

grep -r "@Autowired" src/main/java/
grep -r "new.*Service\(\)" src/main/java/

6. Single Responsibility Check

Analyze classes for responsibility violations:

Warning signs:

• Class > 500 lines (potential god class)
• More than 10 public methods
• More than 7 dependencies injected
• Mixed concerns (HTTP + business logic + data access)

Check service classes:

// RED FLAG: Service doing too much
class BigService {
    void handleRequest()      // HTTP concern
    void processData()        // Business logic
    void saveToCache()        // Data concern
    void sendNotification()   // Side effect
    void formatResponse()     // Presentation
}

7. API Design Consistency

Controller conventions:

// Check all controllers follow same patterns:
@RestController
@RequestMapping("/api/v1/...")
public class XxxController {
    // GET for reads
    @GetMapping("/{id}")
    public Mono<Xxx> getById(@PathVariable int id)

    // POST for creates
    @PostMapping
    public Mono<Xxx> create(@RequestBody XxxRequest request)

    // Consistent response types (Mono/Flux)
    // Consistent error handling
}

Check for:

• Mixed response types (some Mono, some blocking)
• Inconsistent URL patterns
• Missing @PathVariable/@RequestParam annotations
• Business logic in controllers

8. Configuration Separation

Check configuration is externalized:

// BAD: Hardcoded values in code
private static final String API_URL = "https://api.example.com";
private static final int TIMEOUT = 5000;

// GOOD: Externalized configuration
@Value("${api.url}")
private String apiUrl;

// or
@ConfigurationProperties(prefix = "api")
public class ApiConfig {
    private String url;
    private int timeout;
}

Search for hardcoded values:

grep -r "http://" src/main/java/
grep -r "https://" src/main/java/
grep -rE "[0-9]{4,}" src/main/java/  # Large numbers (ports, timeouts)

9. Exception Handling Architecture

Check exception flow:

Controller → Service → Provider/Strategy
    ↑           ↑           ↑
    └───────────┴───────────┴── Exceptions bubble up

Controller: Translates to HTTP responses
Service: May wrap in domain exceptions
Provider: Throws low-level exceptions

Verify:

• Custom exceptions extend appropriate base
• Exceptions have meaningful messages
• No swallowed exceptions (empty catch blocks)
• Consistent error response format

10. Test Architecture

Check test structure mirrors main:

src/test/java/
├── controller/     # Controller tests (WebTestClient)
├── service/        # Service unit tests
├── provider/       # Provider tests
├── strategy/       # Strategy tests
└── integration/    # Integration tests

src/e2e/java/       # End-to-end tests (Playwright)

Verify:

• Tests exist for each layer
• Proper mocking (mock dependencies, not internals)
• No test interdependencies

Output Format

## Architecture Health Report

### Summary
| Check | Status | Issues |
|-------|--------|--------|
| Layer Violations | ✓/✗ | X |
| Circular Dependencies | ✓/✗ | X |
| Package Structure | ✓/✗ | X |
| Design Patterns | ✓/✗ | X |
| DI Compliance | ✓/✗ | X |
| Single Responsibility | ✓/✗ | X |
| API Consistency | ✓/✗ | X |

### Layer Violations

#### [Violation Description]
**File**: `path/to/file.java:line`
**Issue**: Controller directly imports Strategy
**Impact**: Bypasses service layer, harder to test
**Fix**: Inject service that uses strategy

### Circular Dependencies

ServiceA ←→ ServiceB (CIRCULAR)

**Fix**: Extract shared logic to new service, or use events

### Package Structure Issues

| File | Current Package | Expected Package |
|------|-----------------|------------------|
| FooHelper.java | service | util or helper |

### Design Pattern Violations

#### Strategy Pattern
- Missing: `XxxStrategy` not implementing interface
- Orphaned: `YyyStrategy` not registered

### Dependency Injection Issues

| File | Line | Issue | Fix |
|------|------|-------|-----|
| Service.java | 15 | Field injection | Use constructor |
| Handler.java | 23 | Direct instantiation | Inject dependency |

### Single Responsibility Concerns

| Class | Lines | Methods | Dependencies | Concern |
|-------|-------|---------|--------------|---------|
| BigService | 650 | 15 | 9 | Consider splitting |

### Hardcoded Values Found

| File | Line | Value | Recommendation |
|------|------|-------|----------------|
| Client.java | 42 | "https://..." | Move to config |

### Architecture Diagram (Current)

┌─────────────┐ ┌─────────────┐ │ Controller │────▶│ Service │ └─────────────┘ └──────┬──────┘ │ ┌────────────┼────────────┐ ▼ ▼ ▼ ┌─────────┐ ┌─────────┐ ┌─────────┐ │Provider │ │Strategy │ │ Mapper │ └─────────┘ └─────────┘ └─────────┘

### Recommendations

1. **Critical**: Fix circular dependency between X and Y
2. **High**: Refactor BigService into smaller services
3. **Medium**: Move hardcoded URLs to configuration
4. **Low**: Rename FooManager to FooService for consistency

Execution Steps

1. Use Glob to list all Java files by package
2. Use Grep to check imports in each layer
3. Read large files to check responsibilities
4. Verify design pattern implementations
5. Check for DI anti-patterns
6. Analyze configuration usage
7. Generate architecture health report

Notes

• This project intentionally has no database layer (in-memory caching)
• Reactive types (Mono/Flux) should be consistent across layers
• Strategy pattern is used for weather station integrations
• Configuration is split between application.yml and code constants
• Some "violations" may be intentional trade-offs - use judgment