# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [1.1.0] - 2025-12-14

### Added - Security Enhancements 🔒

#### Security Headers Middleware
- **New File**: `app/middleware/security.py` - OWASP-compliant security headers
- Implements all critical security headers:
  - `X-Content-Type-Options: nosniff` - Prevents MIME sniffing
  - `X-Frame-Options: DENY` - Prevents clickjacking
  - `X-XSS-Protection: 1; mode=block` - XSS protection
  - `Content-Security-Policy` - Controls resource loading (Scalar CDN whitelisted)
  - `Referrer-Policy: strict-origin-when-cross-origin` - Controls referrer info
  - `Permissions-Policy` - Disables geolocation, microphone, camera
  - `Strict-Transport-Security` - Forces HTTPS (production only)

#### Health Endpoint Security
- Added environment-aware detail levels:
  - **Production**: Minimal info (status + timestamp only)
  - **Development**: Detailed diagnostics (uptime, version, data loader status)
- Optional Basic Authentication support:
  - Configurable via `HEALTH_CHECK_AUTH_ENABLED`
  - Credentials: `HEALTH_CHECK_USERNAME`, `HEALTH_CHECK_PASSWORD`
- New settings in `app/settings.py`:
  - `health_check_detailed` - Control detail level
  - `health_check_auth_enabled` - Enable authentication
  - `health_check_username` - Auth username
  - `health_check_password` - Auth password (set via env var)

#### Header Exposure Control
- **Removed**: Automatic `X-Powered-By` header from `app/middleware/metrics.py`
- **Added**: Configurable `expose_server_header` setting (default: False)
- Security-first approach: No technology stack disclosure by default

### Added - Performance Optimizations ⚡

#### Redis-Based Caching Service
- **New File**: `app/services/cache_service.py` - Enhanced caching layer
- Features:
  - Automatic cache key generation from query parameters
  - Configurable TTL (default: 30 minutes for queries)
  - Redis backend with fallback to no-cache
  - Cache invalidation by pattern
  - Connection timeout and error handling
- Integrated into `ProvinceService`:
  - Caches query results before returning
  - Smart cache key generation includes all filter parameters
  - Transparent operation (falls back gracefully if Redis unavailable)

### Added - Testing Infrastructure 🧪

#### New Test Files
- `tests/test_services/test_base_service.py` - Base service utility tests (18 tests)
  - Field filtering tests (3 tests)
  - Sorting tests (5 tests)
  - Pagination validation tests (10 tests)
- `tests/test_middleware/test_security.py` - Security middleware tests (11 tests)
  - All security headers validation
  - Server header exposure control
  - Error response header validation

#### Existing Test Files (Discovered)
- `tests/test_data_loader.py` - DataLoader singleton tests (14 tests)
- `tests/test_services/test_province_service.py` - Province service tests (18 tests)
- `tests/test_api/test_provinces_endpoint.py` - Province endpoint integration tests (19 tests)

**Total Test Coverage**: 80+ tests across all layers

### Added - CI/CD Pipeline 🚀

#### GitHub Actions Workflow
- **New File**: `.github/workflows/ci.yml` - Comprehensive CI/CD pipeline
- **Jobs**:
  1. **Test** (Matrix: Python 3.8, 3.9, 3.10, 3.11)
     - Runs pytest with coverage
     - Uploads coverage to Codecov
     - Caches pip dependencies
  2. **Lint** (Code quality checks)
     - Black formatting validation
     - isort import sorting
     - flake8 linting
     - mypy type checking
  3. **Security** (Vulnerability scanning)
     - Bandit security scan
     - Safety dependency check
  4. **Build** (Docker image)
     - Builds and pushes to Docker Hub (main/develop only)
     - Trivy vulnerability scan
     - Multi-layer caching

### Added - Development Tools 🛠️

#### Pre-Commit Hooks
- **New File**: `.pre-commit-config.yaml` - Automated code quality
- **Hooks**:
  - Black (formatting)
  - isort (import sorting)
  - flake8 (linting)
  - Bandit (security)
  - mypy (type checking)
  - Standard hooks (trailing whitespace, EOF, YAML/JSON validation)
  - Prettier (JSON/YAML formatting)
  - Markdownlint (Markdown linting)

### Added - Documentation 📚

#### Configuration Files
- **New File**: `.env.production.recommended` - Production config template
  - All settings with security-first defaults
  - Comprehensive checklist for production deployment
  - Best practices for each configuration option

### Changed

#### Settings
- **Modified**: `app/settings.py` - Added security settings section
  - `expose_server_header: bool = False`
  - `health_check_detailed: bool = True`
  - `health_check_auth_enabled: bool = False`
  - `health_check_username: str = "admin"`
  - `health_check_password: str = ""`

#### Main Application
- **Modified**: `app/main.py` - Integrated security middleware
  - Added `SecurityHeadersMiddleware` (first in chain for all responses)
  - Enhanced `/health` endpoint with authentication and detail control
  - Import statement for security middleware

#### Metrics Middleware
- **Modified**: `app/middleware/metrics.py` - Removed header exposure
  - Removed automatic `X-Powered-By: Turkiye-API` header
  - Added comment explaining security-based removal
  - Header now controlled by SecurityHeadersMiddleware

#### Province Service
- **Modified**: `app/services/province_service.py` - Added caching
  - Imports `cache_service`
  - Cache check at method start
  - Cache storage before return
  - Smart cache key generation from all parameters

### Security Fixes

- ✅ **CRITICAL**: Added OWASP-compliant security headers
- ✅ **CRITICAL**: Secured health endpoint (minimal info + auth option)
- ✅ **CRITICAL**: Removed technology stack exposure (X-Powered-By)
- ✅ **HIGH**: Added Content Security Policy
- ✅ **HIGH**: Added Strict Transport Security (production)
- ✅ **MEDIUM**: Added Permissions Policy (disabled unused features)

### Performance Improvements

- ✅ **HIGH**: Redis-based query caching (30min TTL)
- ✅ **MEDIUM**: Automatic cache key generation
- ✅ **MEDIUM**: Graceful fallback when cache unavailable
- ✅ **LOW**: Reduced repeated data processing overhead

### Testing Improvements

- ✅ **CRITICAL**: Added 29+ new tests (BaseService, SecurityMiddleware)
- ✅ **HIGH**: Discovered existing tests (60+ tests already present)
- ✅ **MEDIUM**: Test coverage now spans all architectural layers
- ✅ **MEDIUM**: CI/CD runs tests on Python 3.8-3.11

### Developer Experience

- ✅ **HIGH**: Full CI/CD pipeline with 4 parallel jobs
- ✅ **HIGH**: Pre-commit hooks for automatic code quality
- ✅ **MEDIUM**: Comprehensive production configuration template
- ✅ **MEDIUM**: Security and dependency scanning in CI
- ✅ **LOW**: Docker vulnerability scanning with Trivy

## Implementation Summary

### Files Created (9 new files)
1. `app/middleware/security.py` - Security headers middleware
2. `app/services/cache_service.py` - Enhanced caching service
3. `tests/test_services/test_base_service.py` - BaseService tests
4. `tests/test_middleware/__init__.py` - Middleware test package
5. `tests/test_middleware/test_security.py` - Security middleware tests
6. `.github/workflows/ci.yml` - CI/CD pipeline
7. `.pre-commit-config.yaml` - Pre-commit hooks
8. `.env.production.recommended` - Production config template
9. `CHANGELOG.md` - This file

### Files Modified (4 files)
1. `app/settings.py` - Added security settings
2. `app/main.py` - Integrated security middleware and secured health endpoint
3. `app/middleware/metrics.py` - Removed X-Powered-By header
4. `app/services/province_service.py` - Added caching layer

### Breaking Changes

**None** - All changes are backward compatible

### Migration Guide

#### To Enable New Features:

1. **Security Headers** (Automatic - no action needed)
   - Already enabled in production

2. **Health Endpoint Security**
   ```env
   # .env
   HEALTH_CHECK_DETAILED=false  # Minimal info in production
   HEALTH_CHECK_AUTH_ENABLED=true  # Require authentication
   HEALTH_CHECK_PASSWORD=your-secure-password
   ```

3. **Redis Caching**
   ```env
   # .env
   REDIS_URL=redis://your-redis-host:6379/0
   ```

4. **Pre-Commit Hooks**
   ```bash
   pip install pre-commit
   pre-commit install
   ```

5. **CI/CD** (GitHub only)
   - Add secrets to GitHub repository:
     - `DOCKERHUB_USERNAME`
     - `DOCKERHUB_TOKEN`

### Next Steps

- [ ] Install pytest: `pip install pytest pytest-cov pytest-asyncio`
- [ ] Run tests: `pytest tests/ -v --cov=app`
- [ ] Setup pre-commit: `pre-commit install`
- [ ] Configure Redis for caching (optional but recommended)
- [ ] Update `.env` with production settings
- [ ] Review and enable health endpoint authentication
- [ ] Set up GitHub Actions secrets for Docker deployment

---

## Previous Versions

### [1.0.0] - Initial Release
- FastAPI-based REST API
- Multi-language support (EN/TR)
- Rate limiting
- Prometheus metrics
- Docker deployment
- Interactive Scalar documentation

---

**For more details**, see individual commit messages or the comprehensive analysis report in `.serena/memories/`.
