class SessionBackendComparison:
    """Comprehensive comparison of Django session backends"""
    
    @staticmethod
    def backend_matrix():
        """Detailed comparison of all session backends"""
        
        backends = {
            'database': {
                'engine': 'django.contrib.sessions.backends.db',
                'storage': 'Database table (django_session)',
                'persistence': 'Permanent until expired/deleted',
                'performance': 'Medium (database I/O)',
                'scalability': 'Good (with proper DB scaling)',
                'complexity': 'Low',
                'memory_usage': 'Low server memory',
                'fault_tolerance': 'High (database reliability)',
                'setup_complexity': 'Minimal (just run migrations)',
                'maintenance': 'Requires periodic cleanup',
                'best_for': 'Most web applications',
                'avoid_when': 'Extremely high traffic without DB optimization'
            },
            'cache': {
                'engine': 'django.contrib.sessions.backends.cache',
                'storage': 'Cache system (Redis, Memcached, etc.)',
                'persistence': 'Temporary (cache eviction)',
                'performance': 'Very High (memory access)',
                'scalability': 'Excellent (cache scaling)',
                'complexity': 'Medium',
                'memory_usage': 'High cache memory',
                'fault_tolerance': 'Medium (cache failures)',
                'setup_complexity': 'Medium (cache configuration)',
                'maintenance': 'Automatic expiration',
                'best_for': 'High-performance applications',
                'avoid_when': 'Need guaranteed persistence'
            },
            'cached_db': {
                'engine': 'django.contrib.sessions.backends.cached_db',
                'storage': 'Cache + Database fallback',
                'persistence': 'Permanent (database backup)',
                'performance': 'High (cache) + reliability (DB)',
                'scalability': 'Very Good',
                'complexity': 'High',
                'memory_usage': 'Medium (cache + DB)',
                'fault_tolerance': 'Very High (dual storage)',
                'setup_complexity': 'High (cache + DB setup)',
                'maintenance': 'Cache + DB maintenance',
                'best_for': 'High-traffic production apps',
                'avoid_when': 'Simple applications or limited resources'
            },
            'file': {
                'engine': 'django.contrib.sessions.backends.file',
                'storage': 'File system',
                'persistence': 'Permanent until deleted',
                'performance': 'Medium (file I/O)',
                'scalability': 'Poor (single server)',
                'complexity': 'Low',
                'memory_usage': 'Very Low',
                'fault_tolerance': 'Medium (file system reliability)',
                'setup_complexity': 'Low (directory creation)',
                'maintenance': 'Manual file cleanup',
                'best_for': 'Development, simple deployments',
                'avoid_when': 'Multi-server deployments'
            },
            'signed_cookies': {
                'engine': 'django.contrib.sessions.backends.signed_cookies',
                'storage': 'Client browser (signed cookies)',
                'persistence': 'Browser-dependent',
                'performance': 'Excellent (no server storage)',
                'scalability': 'Perfect (stateless)',
                'complexity': 'Medium',
                'memory_usage': 'None (server-side)',
                'fault_tolerance': 'High (no server dependency)',
                'setup_complexity': 'Low (just configuration)',
                'maintenance': 'None',
                'best_for': 'Stateless applications, microservices',
                'avoid_when': 'Large session data or high security needs'
            }
        }
        
        return backends
    
    @staticmethod
    def selection_criteria():
        """Criteria for selecting session backend"""
        
        criteria = {
            'traffic_volume': {
                'low': 'Database or File backend',
                'medium': 'Database or Cache backend',
                'high': 'Cache or Cached DB backend',
                'very_high': 'Cache backend with proper scaling'
            },
            'data_persistence_needs': {
                'critical': 'Database or Cached DB backend',
                'important': 'Database backend',
                'moderate': 'Cache or Cached DB backend',
                'not_important': 'Cache or Signed Cookies backend'
            },
            'infrastructure_complexity': {
                'simple': 'Database or File backend',
                'moderate': 'Cache backend',
                'complex': 'Cached DB backend',
                'minimal': 'Signed Cookies backend'
            },
            'security_requirements': {
                'high': 'Database or Cached DB backend',
                'medium': 'Cache or Database backend',
                'low': 'Any backend with proper configuration',
                'stateless': 'Signed Cookies with encryption'
            }
        }
        
        return criteria

# Database backend configuration
DATABASE_SESSION_CONFIG = {
    # Basic configuration
    'SESSION_ENGINE': 'django.contrib.sessions.backends.db',
    
    # Session table configuration
    'SESSION_SERIALIZER': 'django.contrib.sessions.serializers.JSONSerializer',
    
    # Cookie settings
    'SESSION_COOKIE_AGE': 1209600,  # 2 weeks
    'SESSION_EXPIRE_AT_BROWSER_CLOSE': False,
    'SESSION_SAVE_EVERY_REQUEST': False,
    
    # Database optimization
    'DATABASE_ROUTERS': ['myapp.routers.SessionRouter'],  # Optional: separate DB
}

# Custom session model (optional)
from django.contrib.sessions.models import AbstractBaseSession

class CustomSession(AbstractBaseSession):
    """Extended session model with additional fields"""
    
    user_id = models.IntegerField(null=True, blank=True, db_index=True)
    ip_address = models.GenericIPAddressField(null=True, blank=True)
    user_agent = models.TextField(blank=True)
    created_at = models.DateTimeField(auto_now_add=True)
    last_activity = models.DateTimeField(auto_now=True)
    
    class Meta:
        db_table = 'custom_sessions'
        indexes = [
            models.Index(fields=['user_id', 'expire_date']),
            models.Index(fields=['ip_address', 'expire_date']),
            models.Index(fields=['last_activity']),
        ]
    
    @classmethod
    def get_session_store_class(cls):
        return SessionStore

# Custom session store for extended model
from django.contrib.sessions.backends.db import SessionStore as DBStore

class SessionStore(DBStore):
    """Custom session store with additional functionality"""
    
    @classmethod
    def get_model_class(cls):
        return CustomSession
    
    def create_model_instance(self, data):
        """Create session instance with additional data"""
        
        obj = super().create_model_instance(data)
        
        # Add custom fields if available in session data
        if hasattr(self, '_request'):
            obj.user_id = getattr(self._request.user, 'id', None)
            obj.ip_address = self._request.META.get('REMOTE_ADDR')
            obj.user_agent = self._request.META.get('HTTP_USER_AGENT', '')
        
        return obj

# Database session optimization
class DatabaseSessionOptimization:
    """Optimization techniques for database sessions"""
    
    @staticmethod
    def database_indexes():
        """Recommended database indexes for session table"""
        
        indexes = {
            'expire_date': 'CREATE INDEX idx_session_expire ON django_session(expire_date);',
            'session_key': 'CREATE UNIQUE INDEX idx_session_key ON django_session(session_key);',
            'composite': 'CREATE INDEX idx_session_expire_key ON django_session(expire_date, session_key);'
        }
        
        return indexes
    
    @staticmethod
    def cleanup_strategies():
        """Session cleanup strategies for database backend"""
        
        strategies = {
            'django_command': {
                'command': 'python manage.py clearsessions',
                'description': 'Built-in Django cleanup command',
                'frequency': 'Daily via cron job',
                'cron_example': '0 2 * * * /path/to/venv/bin/python /path/to/project/manage.py clearsessions'
            },
            'custom_cleanup': {
                'description': 'Custom cleanup with additional logic',
                'implementation': """
                from django.core.management.base import BaseCommand
                from django.contrib.sessions.models import Session
                from django.utils import timezone
                from datetime import timedelta
                
                class Command(BaseCommand):
                    def handle(self, *args, **options):
                        # Clean expired sessions
                        expired_count = Session.objects.filter(
                            expire_date__lt=timezone.now()
                        ).delete()[0]
                        
                        # Clean old sessions (30+ days)
                        old_threshold = timezone.now() - timedelta(days=30)
                        old_count = Session.objects.filter(
                            expire_date__lt=old_threshold
                        ).delete()[0]
                        
                        self.stdout.write(
                            f'Cleaned {expired_count} expired and {old_count} old sessions'
                        )
                """
            },
            'database_maintenance': {
                'description': 'Database-level maintenance',
                'postgresql': 'VACUUM ANALYZE django_session;',
                'mysql': 'OPTIMIZE TABLE django_session;',
                'sqlite': 'VACUUM;'
            }
        }
        
        return strategies
    
    @staticmethod
    def performance_monitoring():
        """Monitor database session performance"""
        
        monitoring_queries = {
            'session_count': 'SELECT COUNT(*) FROM django_session;',
            'expired_sessions': """
                SELECT COUNT(*) FROM django_session 
                WHERE expire_date < NOW();
            """,
            'large_sessions': """
                SELECT session_key, LENGTH(session_data) as size 
                FROM django_session 
                ORDER BY size DESC 
                LIMIT 10;
            """,
            'session_age_distribution': """
                SELECT 
                    CASE 
                        WHEN expire_date < NOW() THEN 'Expired'
                        WHEN expire_date < NOW() + INTERVAL 1 DAY THEN '< 1 day'
                        WHEN expire_date < NOW() + INTERVAL 7 DAY THEN '< 1 week'
                        ELSE '> 1 week'
                    END as age_group,
                    COUNT(*) as count
                FROM django_session 
                GROUP BY age_group;
            """
        }
        
        return monitoring_queries

# Cache backend configuration
CACHE_SESSION_CONFIG = {
    # Session engine
    'SESSION_ENGINE': 'django.contrib.sessions.backends.cache',
    'SESSION_CACHE_ALIAS': 'default',
    
    # Cache configuration
    'CACHES': {
        'default': {
            'BACKEND': 'django.core.cache.backends.redis.RedisCache',
            'LOCATION': 'redis://127.0.0.1:6379/1',
            'OPTIONS': {
                'CLIENT_CLASS': 'django_redis.client.DefaultClient',
                'CONNECTION_POOL_KWARGS': {
                    'max_connections': 50,
                    'retry_on_timeout': True,
                },
                'SERIALIZER': 'django_redis.serializers.json.JSONSerializer',
                'COMPRESSOR': 'django_redis.compressors.zlib.ZlibCompressor',
            },
            'KEY_PREFIX': 'session',
            'TIMEOUT': 1209600,  # 2 weeks
        }
    }
}

# Redis-specific configuration
REDIS_SESSION_CONFIG = {
    'CACHES': {
        'default': {
            'BACKEND': 'django.core.cache.backends.redis.RedisCache',
            'LOCATION': [
                'redis://127.0.0.1:6379/1',
                'redis://127.0.0.1:6380/1',  # Redis cluster
            ],
            'OPTIONS': {
                'CLIENT_CLASS': 'django_redis.client.ShardClient',
                'CONNECTION_POOL_KWARGS': {
                    'max_connections': 100,
                    'retry_on_timeout': True,
                    'health_check_interval': 30,
                },
                'SERIALIZER': 'django_redis.serializers.json.JSONSerializer',
                'COMPRESSOR': 'django_redis.compressors.zlib.ZlibCompressor',
                'IGNORE_EXCEPTIONS': True,  # Graceful degradation
            }
        }
    }
}

# Memcached configuration
MEMCACHED_SESSION_CONFIG = {
    'CACHES': {
        'default': {
            'BACKEND': 'django.core.cache.backends.memcached.PyMemcacheCache',
            'LOCATION': [
                '127.0.0.1:11211',
                '127.0.0.1:11212',  # Multiple servers
            ],
            'OPTIONS': {
                'MAX_ENTRIES': 1000000,
                'CULL_FREQUENCY': 3,
            }
        }
    }
}

# Cache session optimization
class CacheSessionOptimization:
    """Optimization techniques for cache-based sessions"""
    
    @staticmethod
    def cache_key_strategies():
        """Strategies for cache key management"""
        
        strategies = {
            'key_prefixing': {
                'purpose': 'Namespace separation',
                'implementation': 'KEY_PREFIX in cache configuration',
                'example': 'session:abc123def456'
            },
            'key_versioning': {
                'purpose': 'Cache invalidation',
                'implementation': 'VERSION parameter in cache operations',
                'example': 'session:v2:abc123def456'
            },
            'key_sharding': {
                'purpose': 'Distribute load across cache nodes',
                'implementation': 'Consistent hashing in cache client',
                'example': 'Use ShardClient for Redis'
            }
        }
        
        return strategies
    
    @staticmethod
    def cache_performance_tuning():
        """Performance tuning for cache sessions"""
        
        tuning_options = {
            'connection_pooling': {
                'redis': 'CONNECTION_POOL_KWARGS with max_connections',
                'memcached': 'Built-in connection pooling',
                'benefit': 'Reduced connection overhead'
            },
            'serialization': {
                'json': 'Fast, human-readable, limited types',
                'pickle': 'Full Python object support, security risk',
                'msgpack': 'Fast binary serialization',
                'recommendation': 'JSON for sessions'
            },
            'compression': {
                'zlib': 'Good compression ratio, moderate CPU',
                'lz4': 'Fast compression, lower ratio',
                'none': 'No compression overhead',
                'recommendation': 'zlib for large sessions'
            },
            'timeout_settings': {
                'socket_timeout': 'Network operation timeout',
                'connect_timeout': 'Connection establishment timeout',
                'retry_on_timeout': 'Automatic retry on timeout',
                'recommendation': 'Enable retries with reasonable timeouts'
            }
        }
        
        return tuning_options
    
    @staticmethod
    def cache_monitoring():
        """Monitor cache session performance"""
        
        monitoring_metrics = {
            'redis_metrics': [
                'INFO memory',
                'INFO stats',
                'INFO keyspace',
                'SLOWLOG GET 10'
            ],
            'memcached_metrics': [
                'stats',
                'stats items',
                'stats slabs'
            ],
            'django_cache_metrics': [
                'cache.get() hit rate',
                'cache.set() success rate',
                'Average response time',
                'Connection pool usage'
            ]
        }
        
        return monitoring_metrics

# Cache session fallback handling
class CacheSessionFallback:
    """Handle cache failures gracefully"""
    
    @staticmethod
    def fallback_middleware():
        """Middleware to handle cache session failures"""
        
        class CacheSessionFallbackMiddleware:
            """Fallback to database sessions on cache failure"""
            
            def __init__(self, get_response):
                self.get_response = get_response
            
            def __call__(self, request):
                try:
                    response = self.get_response(request)
                    return response
                except Exception as e:
                    # Log cache failure
                    logger.error(f"Cache session failure: {e}")
                    
                    # Switch to database sessions temporarily
                    self.switch_to_database_sessions(request)
                    
                    response = self.get_response(request)
                    return response
            
            def switch_to_database_sessions(self, request):
                """Temporarily switch to database sessions"""
                
                from django.contrib.sessions.backends.db import SessionStore
                
                # Replace session store
                request.session = SessionStore(request.session.session_key)
        
        return CacheSessionFallbackMiddleware
    
    @staticmethod
    def health_check_system():
        """Health check system for cache backend"""
        
        class CacheHealthChecker:
            """Monitor cache health and switch backends if needed"""
            
            def __init__(self):
                self.failure_count = 0
                self.max_failures = 3
                self.check_interval = 60  # seconds
                self.last_check = 0
            
            def is_cache_healthy(self):
                """Check if cache is responding"""
                
                from django.core.cache import cache
                import time
                
                current_time = time.time()
                
                if current_time - self.last_check < self.check_interval:
                    return self.failure_count < self.max_failures
                
                try:
                    # Simple cache test
                    test_key = f'health_check_{current_time}'
                    cache.set(test_key, 'ok', 10)
                    result = cache.get(test_key)
                    
                    if result == 'ok':
                        self.failure_count = 0
                        self.last_check = current_time
                        return True
                    else:
                        self.failure_count += 1
                
                except Exception:
                    self.failure_count += 1
                
                self.last_check = current_time
                return self.failure_count < self.max_failures
        
        return CacheHealthChecker

# Cached database backend configuration
CACHED_DB_SESSION_CONFIG = {
    # Session engine
    'SESSION_ENGINE': 'django.contrib.sessions.backends.cached_db',
    'SESSION_CACHE_ALIAS': 'default',
    
    # Cache configuration (same as cache backend)
    'CACHES': {
        'default': {
            'BACKEND': 'django.core.cache.backends.redis.RedisCache',
            'LOCATION': 'redis://127.0.0.1:6379/1',
            'OPTIONS': {
                'CLIENT_CLASS': 'django_redis.client.DefaultClient',
                'CONNECTION_POOL_KWARGS': {
                    'max_connections': 50,
                },
                'SERIALIZER': 'django_redis.serializers.json.JSONSerializer',
            },
            'TIMEOUT': 1209600,
        }
    },
    
    # Database configuration (for fallback)
    'DATABASES': {
        'default': {
            'ENGINE': 'django.db.backends.postgresql',
            'NAME': 'myproject',
            'USER': 'myuser',
            'PASSWORD': 'mypassword',
            'HOST': '127.0.0.1',
            'PORT': '5432',
            'OPTIONS': {
                'MAX_CONNS': 20,
            }
        }
    }
}

# Custom cached database session store
from django.contrib.sessions.backends.cached_db import SessionStore as CachedDBStore

class OptimizedCachedDBStore(CachedDBStore):
    """Optimized cached database session store"""
    
    def __init__(self, session_key=None):
        super().__init__(session_key)
        self.cache_timeout = 3600  # 1 hour cache timeout
        self.cache_key_prefix = 'session_v2'
    
    def load(self):
        """Load session with optimized cache strategy"""
        
        # Try cache first
        try:
            data = self._cache.get(self.cache_key, version=self.cache_key_version)
            if data is not None:
                return data
        except Exception:
            # Cache failure, continue to database
            pass
        
        # Fallback to database
        data = super().load()
        
        # Store in cache for future requests
        try:
            self._cache.set(
                self.cache_key,
                data,
                self.cache_timeout,
                version=self.cache_key_version
            )
        except Exception:
            # Cache write failure, continue with database data
            pass
        
        return data
    
    def save(self, must_create=False):
        """Save session with cache invalidation"""
        
        # Save to database first
        super().save(must_create)
        
        # Update cache
        try:
            self._cache.set(
                self.cache_key,
                self._get_session(no_load=True),
                self.cache_timeout,
                version=self.cache_key_version
            )
        except Exception:
            # Cache write failure, database save was successful
            pass
    
    def delete(self, session_key=None):
        """Delete session from both cache and database"""
        
        # Delete from cache
        try:
            self._cache.delete(self.cache_key, version=self.cache_key_version)
        except Exception:
            pass
        
        # Delete from database
        super().delete(session_key)

# Cached database optimization strategies
class CachedDBOptimization:
    """Optimization strategies for cached database sessions"""
    
    @staticmethod
    def cache_warming_strategy():
        """Strategies for warming the session cache"""
        
        strategies = {
            'lazy_loading': {
                'description': 'Load sessions into cache on first access',
                'pros': ['Simple implementation', 'No unnecessary cache usage'],
                'cons': ['First request slower', 'Cache misses on new sessions']
            },
            'proactive_warming': {
                'description': 'Pre-load frequently accessed sessions',
                'implementation': """
                from django.core.management.base import BaseCommand
                from django.contrib.sessions.models import Session
                from django.core.cache import cache
                
                class Command(BaseCommand):
                    def handle(self, *args, **options):
                        # Get active sessions from last 24 hours
                        recent_sessions = Session.objects.filter(
                            expire_date__gte=timezone.now(),
                            # Add criteria for active sessions
                        )
                        
                        for session in recent_sessions:
                            cache_key = f'session_v2:{session.session_key}'
                            cache.set(cache_key, session.get_decoded(), 3600)
                """,
                'pros': ['Faster response times', 'Reduced database load'],
                'cons': ['More complex', 'Potential cache memory usage']
            },
            'selective_caching': {
                'description': 'Cache only sessions meeting certain criteria',
                'criteria': [
                    'Authenticated users only',
                    'Sessions with significant data',
                    'Frequently accessed sessions',
                    'Premium user sessions'
                ]
            }
        }
        
        return strategies
    
    @staticmethod
    def consistency_management():
        """Manage consistency between cache and database"""
        
        consistency_approaches = {
            'write_through': {
                'description': 'Write to both cache and database simultaneously',
                'pros': ['Strong consistency', 'Cache always up-to-date'],
                'cons': ['Slower writes', 'Both systems must be available']
            },
            'write_behind': {
                'description': 'Write to cache immediately, database asynchronously',
                'pros': ['Fast writes', 'Better user experience'],
                'cons': ['Potential data loss', 'Eventual consistency only']
            },
            'cache_aside': {
                'description': 'Application manages cache and database separately',
                'pros': ['Flexible', 'Handles failures gracefully'],
                'cons': ['More complex application logic', 'Potential inconsistency']
            }
        }
        
        return consistency_approaches
    
    @staticmethod
    def monitoring_and_alerting():
        """Monitor cached database session performance"""
        
        monitoring_points = {
            'cache_hit_ratio': {
                'metric': 'Percentage of session reads served from cache',
                'target': '> 80%',
                'alert_threshold': '< 70%'
            },
            'cache_write_success': {
                'metric': 'Percentage of successful cache writes',
                'target': '> 95%',
                'alert_threshold': '< 90%'
            },
            'database_fallback_rate': {
                'metric': 'Percentage of requests falling back to database',
                'target': '< 20%',
                'alert_threshold': '> 30%'
            },
            'response_time_distribution': {
                'metric': 'P50, P95, P99 response times',
                'target': 'P95 < 100ms',
                'alert_threshold': 'P95 > 200ms'
            }
        }
        
        return monitoring_points

# File backend configuration
FILE_SESSION_CONFIG = {
    # Session engine
    'SESSION_ENGINE': 'django.contrib.sessions.backends.file',
    
    # File storage path
    'SESSION_FILE_PATH': '/var/lib/django/sessions',  # Custom path
    # 'SESSION_FILE_PATH': None,  # Use system temp directory
    
    # File permissions
    'FILE_UPLOAD_PERMISSIONS': 0o644,
    'FILE_UPLOAD_DIRECTORY_PERMISSIONS': 0o755,
}

# File session optimization
class FileSessionOptimization:
    """Optimization techniques for file-based sessions"""
    
    @staticmethod
    def directory_structure():
        """Optimize directory structure for file sessions"""
        
        structure_options = {
            'flat_structure': {
                'path': '/var/lib/django/sessions/',
                'pattern': 'sessionid_abc123def456',
                'pros': ['Simple', 'Easy to implement'],
                'cons': ['Poor performance with many files', 'Directory listing slow'],
                'suitable_for': '< 1000 concurrent sessions'
            },
            'hashed_subdirectories': {
                'path': '/var/lib/django/sessions/ab/cd/',
                'pattern': 'ab/cd/sessionid_abcdef123456',
                'implementation': """
                import os
                import hashlib
                
                def get_session_file_path(session_key):
                    hash_obj = hashlib.md5(session_key.encode())
                    hash_hex = hash_obj.hexdigest()
                    
                    # Create 2-level directory structure
                    dir1 = hash_hex[:2]
                    dir2 = hash_hex[2:4]
                    
                    base_path = '/var/lib/django/sessions'
                    dir_path = os.path.join(base_path, dir1, dir2)
                    
                    # Ensure directory exists
                    os.makedirs(dir_path, exist_ok=True)
                    
                    return os.path.join(dir_path, f'session_{session_key}')
                """,
                'pros': ['Better performance', 'Scalable', 'Even distribution'],
                'cons': ['More complex', 'Directory traversal overhead'],
                'suitable_for': '1000+ concurrent sessions'
            },
            'time_based_structure': {
                'path': '/var/lib/django/sessions/2024/01/15/',
                'pattern': 'YYYY/MM/DD/sessionid_abc123',
                'pros': ['Easy cleanup by date', 'Natural archiving'],
                'cons': ['Uneven distribution', 'Hot spots on current date'],
                'suitable_for': 'Applications with clear usage patterns'
            }
        }
        
        return structure_options
    
    @staticmethod
    def file_system_optimization():
        """File system optimization for session storage"""
        
        optimizations = {
            'file_system_choice': {
                'ext4': 'Good general purpose, supports large directories',
                'xfs': 'Excellent for large files and directories',
                'btrfs': 'Advanced features, snapshots, compression',
                'zfs': 'Enterprise features, integrity checking'
            },
            'mount_options': {
                'noatime': 'Disable access time updates for better performance',
                'relatime': 'Update access time only when modified',
                'data=writeback': 'Faster writes (ext4)',
                'barrier=0': 'Disable write barriers (if UPS protected)'
            },
            'directory_settings': {
                'max_files_per_directory': '10000-50000 (filesystem dependent)',
                'directory_permissions': '0755 (readable, executable)',
                'file_permissions': '0644 (readable by owner and group)'
            }
        }
        
        return optimizations
    
    @staticmethod
    def cleanup_strategies():
        """File session cleanup strategies"""
        
        cleanup_methods = {
            'cron_based_cleanup': {
                'description': 'Regular cleanup via cron job',
                'implementation': """
                #!/bin/bash
                # Cleanup script for file sessions
                
                SESSION_DIR="/var/lib/django/sessions"
                DAYS_OLD=7
                
                # Find and delete old session files
                find "$SESSION_DIR" -name "session_*" -type f -mtime +$DAYS_OLD -delete
                
                # Clean up empty directories
                find "$SESSION_DIR" -type d -empty -delete
                """,
                'cron_entry': '0 2 * * * /path/to/cleanup_sessions.sh'
            },
            'django_management_command': {
                'description': 'Custom Django management command',
                'implementation': """
                from django.core.management.base import BaseCommand
                from django.conf import settings
                import os
                import time
                
                class Command(BaseCommand):
                    def handle(self, *args, **options):
                        session_dir = getattr(settings, 'SESSION_FILE_PATH', '/tmp')
                        max_age = 7 * 24 * 3600  # 7 days in seconds
                        current_time = time.time()
                        
                        cleaned_count = 0
                        
                        for root, dirs, files in os.walk(session_dir):
                            for file in files:
                                if file.startswith('session_'):
                                    file_path = os.path.join(root, file)
                                    
                                    if os.path.getmtime(file_path) < current_time - max_age:
                                        os.remove(file_path)
                                        cleaned_count += 1
                        
                        self.stdout.write(f'Cleaned {cleaned_count} old session files')
                """
            },
            'application_level_cleanup': {
                'description': 'Cleanup during application runtime',
                'implementation': """
                import os
                import time
                from django.conf import settings
                
                class SessionFileCleanup:
                    def __init__(self):
                        self.last_cleanup = 0
                        self.cleanup_interval = 3600  # 1 hour
                    
                    def maybe_cleanup(self):
                        current_time = time.time()
                        
                        if current_time - self.last_cleanup > self.cleanup_interval:
                            self.cleanup_old_files()
                            self.last_cleanup = current_time
                    
                    def cleanup_old_files(self):
                        session_dir = getattr(settings, 'SESSION_FILE_PATH', '/tmp')
                        max_age = 24 * 3600  # 1 day
                        current_time = time.time()
                        
                        try:
                            for file in os.listdir(session_dir):
                                if file.startswith('session_'):
                                    file_path = os.path.join(session_dir, file)
                                    
                                    if os.path.getmtime(file_path) < current_time - max_age:
                                        os.remove(file_path)
                        except OSError:
                            pass  # Handle permission errors gracefully
                """
            }
        }
        
        return cleanup_methods

# Custom file session store
from django.contrib.sessions.backends.file import SessionStore as FileStore
import os
import hashlib

class OptimizedFileStore(FileStore):
    """Optimized file session store with directory sharding"""
    
    def _get_session_file_path(self):
        """Get file path with directory sharding"""
        
        if self.session_key is None:
            self._session_key = self._get_new_session_key()
        
        # Create hash-based directory structure
        hash_obj = hashlib.md5(self.session_key.encode())
        hash_hex = hash_obj.hexdigest()
        
        dir1 = hash_hex[:2]
        dir2 = hash_hex[2:4]
        
        session_dir = os.path.join(self.storage_path, dir1, dir2)
        
        # Ensure directory exists
        os.makedirs(session_dir, mode=0o755, exist_ok=True)
        
        return os.path.join(session_dir, self.session_key)
    
    def load(self):
        """Load session with error handling"""
        
        try:
            return super().load()
        except (IOError, OSError, EOFError):
            # File corrupted or missing, create new session
            self._session_key = None
            return {}
    
    def save(self, must_create=False):
        """Save session with atomic write"""
        
        session_file_path = self._get_session_file_path()
        temp_file_path = session_file_path + '.tmp'
        
        try:
            # Write to temporary file first
            with open(temp_file_path, 'wb') as f:
                f.write(self.encode(self._get_session(no_load=True)).encode())
            
            # Atomic move to final location
            os.rename(temp_file_path, session_file_path)
            
        except (IOError, OSError):
            # Clean up temporary file on error
            try:
                os.remove(temp_file_path)
            except OSError:
                pass
            raise

# Signed cookies backend configuration
SIGNED_COOKIES_SESSION_CONFIG = {
    # Session engine
    'SESSION_ENGINE': 'django.contrib.sessions.backends.signed_cookies',
    
    # Security settings
    'SECRET_KEY': 'your-secret-key-here',  # Must be secure and consistent
    'SESSION_SERIALIZER': 'django.contrib.sessions.serializers.JSONSerializer',
    
    # Cookie settings
    'SESSION_COOKIE_HTTPONLY': True,
    'SESSION_COOKIE_SECURE': True,  # HTTPS only
    'SESSION_COOKIE_SAMESITE': 'Strict',
    'SESSION_COOKIE_AGE': 3600,  # Shorter expiry for security
    
    # Size limitations
    'SESSION_COOKIE_MAX_SIZE': 3000,  # Leave room for other cookie attributes
}

# Signed cookies optimization
class SignedCookiesOptimization:
    """Optimization techniques for signed cookie sessions"""
    
    @staticmethod
    def data_minimization():
        """Strategies for minimizing session data size"""
        
        strategies = {
            'store_references': {
                'description': 'Store IDs instead of full objects',
                'example': {
                    'bad': {'user': {'id': 1, 'name': 'John', 'email': 'john@example.com'}},
                    'good': {'user_id': 1}
                }
            },
            'compress_data': {
                'description': 'Compress session data before signing',
                'implementation': """
                import zlib
                import base64
                import json
                
                def compress_session_data(data):
                    json_data = json.dumps(data)
                    compressed = zlib.compress(json_data.encode())
                    return base64.b64encode(compressed).decode()
                
                def decompress_session_data(compressed_data):
                    compressed = base64.b64decode(compressed_data.encode())
                    json_data = zlib.decompress(compressed).decode()
                    return json.loads(json_data)
                """
            },
            'selective_storage': {
                'description': 'Store only essential data in cookies',
                'criteria': [
                    'Authentication status',
                    'User preferences (minimal)',
                    'Shopping cart (item count only)',
                    'Language/locale settings'
                ]
            },
            'data_expiration': {
                'description': 'Use shorter expiration for sensitive data',
                'implementation': """
                def set_tiered_session_data(response, data):
                    # Critical data - short expiry
                    critical_data = {k: v for k, v in data.items() 
                                   if k in ['user_id', 'is_authenticated']}
                    response.set_signed_cookie('session_critical', 
                                             json.dumps(critical_data), 
                                             max_age=1800)  # 30 minutes
                    
                    # Preferences - longer expiry
                    pref_data = {k: v for k, v in data.items() 
                               if k in ['theme', 'language']}
                    response.set_signed_cookie('session_prefs', 
                                             json.dumps(pref_data), 
                                             max_age=86400)  # 1 day
                """
            }
        }
        
        return strategies
    
    @staticmethod
    def security_enhancements():
        """Security enhancements for signed cookie sessions"""
        
        enhancements = {
            'key_rotation': {
                'description': 'Rotate signing keys periodically',
                'implementation': """
                # settings.py
                SECRET_KEY_FALLBACKS = [
                    'old-secret-key-1',
                    'old-secret-key-2',
                ]
                
                # Custom session store with key rotation
                from django.contrib.sessions.backends.signed_cookies import SessionStore
                from django.core.signing import BadSignature
                
                class RotatingKeySessionStore(SessionStore):
                    def load(self):
                        try:
                            return super().load()
                        except BadSignature:
                            # Try fallback keys
                            for old_key in settings.SECRET_KEY_FALLBACKS:
                                try:
                                    return self._load_with_key(old_key)
                                except BadSignature:
                                    continue
                            return {}
                """
            },
            'encryption_layer': {
                'description': 'Add encryption on top of signing',
                'implementation': """
                from cryptography.fernet import Fernet
                import base64
                
                class EncryptedSignedCookieStore(SessionStore):
                    def __init__(self, session_key=None):
                        super().__init__(session_key)
                        self.cipher = Fernet(self._get_encryption_key())
                    
                    def _get_encryption_key(self):
                        # Derive encryption key from SECRET_KEY
                        import hashlib
                        key_material = settings.SECRET_KEY.encode()
                        key = hashlib.sha256(key_material).digest()
                        return base64.urlsafe_b64encode(key)
                    
                    def encode(self, session_dict):
                        # First serialize and sign
                        signed_data = super().encode(session_dict)
                        
                        # Then encrypt
                        encrypted_data = self.cipher.encrypt(signed_data.encode())
                        return base64.b64encode(encrypted_data).decode()
                    
                    def decode(self, session_data):
                        # First decrypt
                        encrypted_data = base64.b64decode(session_data.encode())
                        signed_data = self.cipher.decrypt(encrypted_data).decode()
                        
                        # Then verify signature and deserialize
                        return super().decode(signed_data)
                """
            },
            'integrity_checking': {
                'description': 'Additional integrity checks',
                'implementation': """
                import hashlib
                import hmac
                
                class IntegrityCheckedSessionStore(SessionStore):
                    def encode(self, session_dict):
                        # Add timestamp and checksum
                        session_dict['_timestamp'] = time.time()
                        session_dict['_checksum'] = self._calculate_checksum(session_dict)
                        
                        return super().encode(session_dict)
                    
                    def decode(self, session_data):
                        session_dict = super().decode(session_data)
                        
                        # Verify timestamp (prevent replay attacks)
                        timestamp = session_dict.get('_timestamp', 0)
                        if time.time() - timestamp > 3600:  # 1 hour max age
                            return {}
                        
                        # Verify checksum
                        stored_checksum = session_dict.pop('_checksum', None)
                        calculated_checksum = self._calculate_checksum(session_dict)
                        
                        if not hmac.compare_digest(stored_checksum or '', calculated_checksum):
                            return {}
                        
                        return session_dict
                    
                    def _calculate_checksum(self, session_dict):
                        # Calculate HMAC of session data
                        data = json.dumps(session_dict, sort_keys=True)
                        return hmac.new(
                            settings.SECRET_KEY.encode(),
                            data.encode(),
                            hashlib.sha256
                        ).hexdigest()
                """
            }
        }
        
        return enhancements
    
    @staticmethod
    def fallback_strategies():
        """Fallback strategies for signed cookie limitations"""
        
        strategies = {
            'hybrid_approach': {
                'description': 'Use signed cookies with server-side fallback',
                'implementation': """
                class HybridSessionStore:
                    def __init__(self, session_key=None):
                        self.cookie_store = SignedCookieStore(session_key)
                        self.db_store = DatabaseStore(session_key)
                        self.size_limit = 3000
                    
                    def load(self):
                        # Try cookie first
                        data = self.cookie_store.load()
                        
                        # Check if data was truncated (fallback marker)
                        if data.get('_fallback_to_db'):
                            return self.db_store.load()
                        
                        return data
                    
                    def save(self, must_create=False):
                        data = self._get_session(no_load=True)
                        
                        # Try to fit in cookie
                        if len(json.dumps(data)) < self.size_limit:
                            self.cookie_store.save(must_create)
                        else:
                            # Fallback to database
                            self.db_store.save(must_create)
                            
                            # Set marker in cookie
                            self.cookie_store._session_cache = {'_fallback_to_db': True}
                            self.cookie_store.save(must_create)
                """
            },
            'progressive_degradation': {
                'description': 'Gracefully handle cookie size limits',
                'implementation': """
                def save_with_degradation(self, must_create=False):
                    data = self._get_session(no_load=True)
                    
                    # Priority order for session data
                    priority_keys = [
                        'user_id', 'is_authenticated',  # Critical
                        'csrf_token', 'language',       # Important
                        'theme', 'preferences',         # Nice to have
                        'cart_items', 'form_data'       # Optional
                    ]
                    
                    # Try to fit data by priority
                    for max_priority in range(len(priority_keys)):
                        filtered_data = {
                            k: v for k, v in data.items()
                            if k in priority_keys[:max_priority + 1]
                        }
                        
                        if len(json.dumps(filtered_data)) < self.size_limit:
                            self._session_cache = filtered_data
                            super().save(must_create)
                            return
                    
                    # If even critical data doesn't fit, store minimal info
                    minimal_data = {'user_id': data.get('user_id')}
                    self._session_cache = minimal_data
                    super().save(must_create)
                """
            }
        }
        
        return strategies