[WIP] Add self-contained enhancement features for wrapify (zero dependencies)

[Copilot]

Wrapify Enhancement Implementation Plan

This PR implements comprehensive enhancement features for wrapify using ONLY Go's standard library - zero external dependencies.

Implementation Checklist:

Phase 1: Foundation & Cleanup

• Remove external dependency on github.com/sivaosorg/unify4g
• Create new directory structure for enhancement features
• Implement standard library replacements for removed utilities
• Ensure backward compatibility with existing API

Phase 2: Core Infrastructure

• Enhanced wrapper with plugin architecture
• Configuration management system (config/)
• Structured logging system (logging/)
• Metrics collection foundation (metrics/)

Phase 3: Performance Features

• Built-in caching system with TTL (cache/)
• Response compression (gzip/deflate) (compression/)
• Response streaming & pagination (streaming/, pagination/)

Phase 4: Security & Validation

• Rate limiting engine (ratelimit/)
• Security headers & CORS (security/, cors/)
• Input validation framework (validation/)

Phase 5: Advanced Features

• Response transformation engine (transform/)
• Content negotiation (negotiation/)
• Health check system (health/)

Phase 6: Developer Experience

• Testing & mocking framework (testing/)
• HTTP middleware adapters (middleware/)
• Request/Response interceptors (interceptors/)

Technical Requirements:

• ✅ Zero external dependencies (only Go standard library)
• ✅ Backward compatibility maintained
• ✅ Sub-microsecond overhead for basic operations
• ✅ Thread-safe operations
• ✅ 95%+ test coverage target

Current Status: Analysis complete, starting Phase 1 implementation.

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Self-Contained Enhancement Features for Wrapify

Overview

Implement comprehensive enhancement features for wrapify using ONLY Go's standard library - zero external dependencies. Build everything from scratch to create a clean, lightweight, production-ready API response wrapping library that developers can trust without dependency concerns.

Core Philosophy

• Zero External Dependencies: Use only Go standard library (net/http, encoding/json, sync, time, etc.)
• Self-Contained: All functionality implemented from scratch
• Lightweight: Minimal memory footprint and fast performance
• Clean Code: Maintainable, well-documented, and testable

Enhancement Features to Implement

1. Built-in Caching System (Standard Library Only)

// Using sync.Map and time for TTL
type Cache struct {
    store sync.Map
    ttl   time.Duration
}

• In-Memory Cache: Using sync.Map for thread-safe operations
• TTL Support: Custom TTL implementation with time.Timer
• LRU Eviction: Custom LRU implementation using doubly-linked list
• Cache Statistics: Hit/miss ratios, memory usage tracking
• Pattern-based Invalidation: Regex-based cache key invalidation

2. Response Compression (Standard Library Only)

// Using compress/gzip, compress/flate
type Compressor interface {
    Compress(data []byte) ([]byte, error)
    Decompress(data []byte) ([]byte, error)
}

• Gzip Compression: Using compress/gzip
• Deflate Compression: Using compress/flate
• Auto-detection: Content-type based compression selection
• Compression Levels: Configurable compression levels
• Size Thresholds: Only compress responses above certain size

3. Rate Limiting Engine (Standard Library Only)

// Using sync, time, and custom algorithms
type RateLimiter struct {
    requests map[string]*TokenBucket
    mutex    sync.RWMutex
}

• Token Bucket Algorithm: Custom implementation using time.Ticker
• Sliding Window: Time-based sliding window using sync.Map
• Fixed Window: Simple counter-based rate limiting
• Per-IP Limiting: IP-based rate limiting with cleanup goroutines
• Custom Key Functions: Rate limit by user ID, API key, etc.

4. Security Headers & CORS (Standard Library Only)

type SecurityConfig struct {
    HSTS            bool
    CSP             string
    XFrameOptions   string
    CORSOrigins     []string
}

• Security Headers: HSTS, CSP, X-Frame-Options, X-Content-Type-Options
• CORS Handling: Full CORS implementation with preflight support
• Content Security Policy: Configurable CSP header generation
• Referrer Policy: Custom referrer policy implementation
• XSS Protection: Built-in XSS protection headers

5. Input Validation Framework (Standard Library Only)

type Validator struct {
    rules map[string][]ValidationRule
}

type ValidationRule func(interface{}) error

• Built-in Validators: Email, URL, phone, credit card, etc.
• Custom Validators: Plugin system for custom validation rules
• Nested Validation: Support for validating nested structs
• Error Aggregation: Collect and format all validation errors
• Regex Validators: Pattern-based validation using regexp

6. Response Transformation Engine (Standard Library Only)

type Transformer interface {
    Transform(data interface{}) (interface{}, error)
}

• Field Filtering: Include/exclude specific fields from responses
• Data Masking: Mask sensitive data (emails, phones, etc.)
• Format Conversion: JSON, XML, CSV output using standard encoders
• Field Renaming: Map internal field names to external ones
• Conditional Fields: Show/hide fields based on user permissions

7. Metrics & Monitoring System (Standard Library Only)

type MetricsCollector struct {
    counters map[string]*Counter
    gauges   map[string]*Gauge
    histograms map[string]*Histogram
}

• Performance Metrics: Response times, request counts, error rates
• Custom Metrics: User-defined counters, gauges, histograms
• Memory Metrics: Runtime memory statistics using runtime
• Export Formats: Prometheus format, JSON format
• Real-time Dashboard: Simple HTML dashboard using html/template

8. Structured Logging System (Standard Library Only)

type Logger struct {
    level  LogLevel
    output io.Writer
    format LogFormat
}

• Log Levels: DEBUG, INFO, WARN, ERROR, FATAL
• Structured Logging: JSON and key-value pair formats
• Request Correlation: Automatic request ID generation and tracking
• Performance Logging: Automatic request/response timing
• Rotation Support: Size and time-based log rotation

9. Configuration Management (Standard Library Only)

type Config struct {
    Cache      CacheConfig      `json:"cache"`
    RateLimit  RateLimitConfig  `json:"rateLimit"`
    Security   SecurityConfig   `json:"security"`
}

• JSON Configuration: Using encoding/json
• Environment Variables: Using os.Getenv with fallbacks
• YAML Support: Custom YAML parser (no external deps)
• Hot Reloading: File watcher using fsnotify alternative
• Validation: Configuration validation on startup

10. Response Streaming & Pagination (Standard Library Only)

type StreamWriter struct {
    writer io.Writer
    encoder *json.Encoder
}

• Streaming Responses: Large dataset streaming using io.Writer
• Cursor Pagination: Efficient pagination for large datasets
• Offset Pagination: Traditional offset/limit pagination
• Stream Compression: Compressed streaming responses
• Chunked Encoding: HTTP chunked transfer encoding

11. Health Check System (Standard Library Only)

type HealthChecker struct {
    checks map[string]HealthCheck
}

type HealthCheck func() error

• Health Endpoints: /health, /ready, /live
• Custom Health Checks: Database, external service checks
• Graceful Degradation: Partial health status reporting
• Dependency Monitoring: Monitor critical dependencies
• Circuit Breaker: Basic circuit breaker pattern

12. Testing & Mocking Framework (Standard Library Only)

type MockResponse struct {
    StatusCode int
    Headers    map[string]string
    Body       interface{}
}

• Mock Generators: Generate mock responses for testing
• Request Recorders: Record and replay HTTP requests
• Assertion Helpers: Custom assertion functions for tests
• Benchmark Utilities: Performance testing helpers
• Coverage Tools: Code coverage analysis helpers

13. HTTP Middleware Adapters (Standard Library Only)

type MiddlewareAdapter func(http.Handler) http.Handler

func ToGinMiddleware(wrapper *Wrapper) gin.HandlerFunc
func ToEchoMiddleware(wrapper *Wrapper) echo.MiddlewareFunc

• Standard HTTP: Native net/http middleware
• Framework Adapters: Adapters for popular frameworks (interface only)
• Chain Management: Middleware chaining and ordering
• Conditional Middleware: Apply middleware based on conditions
• Error Recovery: Panic recovery middleware

14. Content Negotiation (Standard Library Only)

type ContentNegotiator struct {
    supportedTypes map[string]Encoder
}

• Accept Header Parsing: Parse and respect Accept headers
• Multiple Formats: JSON, XML, CSV, Plain Text, HTML
• Quality Values: Support for q-values in Accept headers
• Default Formats: Fallback content types
• Custom Encoders: Plugin system for custom formats

15. Request/Response Interceptors (Standard Library Only)

type Interceptor interface {
    BeforeRequest(req *http.Request) error
    AfterResponse(resp *Response) error
}

• Request Interceptors: Modify requests before processing
• Response Interceptors: Modify responses before sending
• Chain Processing: Multiple interceptor support
• Conditional Execution: Run interceptors based on conditions
• Error Handling: Proper error propagation

Directory Structure

wrapify/
├── cache/              # Caching system
├── compression/        # Response compression
├── config/            # Configuration management
├── cors/              # CORS handling
├── examples/          # Example applications
├── health/            # Health check system
├── interceptors/      # Request/Response interceptors
├── logging/           # Structured logging
├── metrics/           # Metrics collection
├── middleware/        # HTTP middleware adapters
├── negotiation/       # Content negotiation
├── pagination/        # Pagination helpers
├── ratelimit/         # Rate limiting
├── security/          # Security features
├── streaming/         # Response streaming
├── testing/           # Testing utilities
├── transform/         # Response transformation
├── validation/        # Input validation
└── wrapper/           # Enhanced core wrapper

Technical Requirements

Performance Goals

• Sub-microsecond overhead for basic operations
• Zero allocations in hot paths where possible
• Memory efficient with proper pooling using sync.Pool
• Concurrent safe all operations thread-safe

Quality Standards

• 100% Standard Library: No external dependencies
• 95%+ Test Coverage: Comprehensive testing
• Benchmarks: Performance benchmarks for all features
• Race Testing: go test -race clean
• Memory Profiling: No memory leaks

Compatibility

• Go 1.19+: Minimum supported version
• Backward Compatible: Existing API unchanged
• Zero Breaking Changes: Additive enhancements only
• Cross Platform: Windows, Linux, macOS support

Implementation Phases

Phase 1: Core Infrastructure

1. Enhanced wrapper with plugin architecture
2. Configuration management system
3. Logging and metrics foundation

Phase 2: Performance Features

1. Caching system with TTL
2. Response compression
3. Streaming responses

Phase 3: Security & Validation

1. Rate limiting engine
2. Security headers and CORS
3. Input validation framework

Phase 4: Advanced Features

1. Response transformation
2. Content negotiation
3. Health check system

Phase 5: Developer Experience

1. Testing and mocking framework
2. Comprehensive examples
3. Documentation and guides

This implementation will create a powerful, self-contained API response wrapping library that requires zero external dependencies while providing enterprise-grade features.

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