app/utils/logger.py

import logging
import sys
import json
import time
import uuid
import traceback
from datetime import datetime
from pathlib import Path
from logging.handlers import RotatingFileHandler, TimedRotatingFileHandler
from typing import Optional, Dict, Any, Union
from contextvars import ContextVar
from functools import wraps
from ..core.config import settings

# Create logs directory if it doesn't exist
logs_dir = Path("logs")
logs_dir.mkdir(exist_ok=True)

# Correlation ID context
correlation_id: ContextVar[str] = ContextVar('correlation_id', default='')

class StructuredFormatter(logging.Formatter):
    """Custom formatter that outputs logs in JSON format"""
    
    def __init__(self):
        super().__init__()
        self.default_fields = {
            'hostname': settings.PROJECT_NAME,
            'version': settings.VERSION
        }

    def format(self, record: logging.LogRecord) -> str:
        message = {
            'timestamp': datetime.utcfromtimestamp(record.created).isoformat(),
            'level': record.levelname,
            'logger': record.name,
            'message': record.getMessage(),
            'correlation_id': correlation_id.get(),
            **self.default_fields
        }

        if hasattr(record, 'duration'):
            message['duration'] = f"{record.duration:.3f}s"

        if hasattr(record, 'request_id'):
            message['request_id'] = record.request_id

        if record.exc_info:
            message['exception'] = {
                'type': record.exc_info[0].__name__,
                'message': str(record.exc_info[1]),
                'stacktrace': traceback.format_exception(*record.exc_info)
            }

        # Add any extra fields
        if hasattr(record, 'extra_fields'):
            message.update(record.extra_fields)

        return json.dumps(message)

class CustomLogger(logging.Logger):
    """Enhanced logger with additional functionality"""
    
    def __init__(self, name: str):
        super().__init__(name)
        self.metrics: Dict[str, Dict[str, Union[int, float]]] = {
            'requests': {'count': 0, 'total_duration': 0},
            'errors': {'count': 0},
            'database': {'operations': 0, 'failures': 0}
        }

    def log_with_context(self, level: int, msg: str, extra_fields: Optional[Dict[str, Any]] = None, **kwargs):
        """Log message with additional context"""
        if extra_fields:
            kwargs['extra'] = {'extra_fields': extra_fields}
        self.log(level, msg, **kwargs)

    def start_operation(self, operation_name: str) -> float:
        """Start timing an operation"""
        return time.time()

    def end_operation(self, start_time: float, operation_name: str, success: bool = True):
        """End timing an operation and log its duration"""
        duration = time.time() - start_time
        self.info(
            f"Operation completed: {operation_name}",
            extra={'extra_fields': {
                'operation': operation_name,
                'duration': duration,
                'success': success
            }}
        )
        return duration

class HealthCheckFilter(logging.Filter):
    """Filter to add health check information to log records"""
    def filter(self, record):
        record.health_check = getattr(record, 'health_check', False)
        return True

def setup_logger(name: str) -> CustomLogger:
    """Set up enhanced logger with multiple handlers and formatters"""
    # Use custom logger class
    logging.setLoggerClass(CustomLogger)
    logger = logging.getLogger(name)
    logger.setLevel(logging.INFO)

    # Structured JSON formatter for file logs
    json_formatter = StructuredFormatter()

    # Console handler with standard formatting
    console_handler = logging.StreamHandler(sys.stdout)
    console_handler.setFormatter(logging.Formatter(
        "%(asctime)s - %(name)s - %(levelname)s - %(message)s"
    ))
    logger.addHandler(console_handler)

    # File handler with JSON formatting and daily rotation
    daily_handler = TimedRotatingFileHandler(
        logs_dir / f"{name}.log",
        when="midnight",
        interval=1,
        backupCount=30,  # Keep a month of logs
        encoding="utf-8"
    )
    daily_handler.setFormatter(json_formatter)
    logger.addHandler(daily_handler)

    # Error file handler for error-level logs
    error_handler = RotatingFileHandler(
        logs_dir / f"{name}_error.log",
        maxBytes=10485760,  # 10MB
        backupCount=10
    )
    error_handler.setLevel(logging.ERROR)
    error_handler.setFormatter(json_formatter)
    logger.addHandler(error_handler)

    # Add health check filter
    logger.addFilter(HealthCheckFilter())

    # Separate file handler for health check logs
    health_handler = TimedRotatingFileHandler(
        logs_dir / f"{name}_health_checks.log",
        when='midnight',
        interval=1,
        backupCount=30
    )
    health_handler.setLevel(logging.INFO)
    health_format = logging.Formatter(
        '%(asctime)s - %(levelname)s - %(message)s - Health: %(health_check)s'
    )
    health_handler.setFormatter(health_format)
    health_handler.addFilter(lambda record: getattr(record, 'health_check', False))
    logger.addHandler(health_handler)

    return logger

# Create main application logger
logger = setup_logger("admin_dashboard")

def with_correlation_id():
    """Decorator to add correlation ID to context"""
    def decorator(func):
        @wraps(func)
        async def wrapper(*args, **kwargs):
            correlation = str(uuid.uuid4())
            token = correlation_id.set(correlation)
            try:
                return await func(*args, **kwargs)
            finally:
                correlation_id.reset(token)
        return wrapper
    return decorator

def log_api_request(method: str, path: str, status_code: int, duration: float):
    """Log API request details with enhanced context"""
    logger.info(
        "API Request",
        extra={'extra_fields': {
            'method': method,
            'path': path,
            'status_code': status_code,
            'duration': duration,
            'timestamp': datetime.utcnow().isoformat()
        }}
    )
    # Update metrics
    logger.metrics['requests']['count'] += 1
    logger.metrics['requests']['total_duration'] += duration

def log_error(error: Exception, context: Optional[Dict] = None):
    """Log error with enhanced context and tracking"""
    logger.error(
        f"Error occurred: {str(error)}",
        exc_info=True,
        extra={'extra_fields': {
            'error_type': type(error).__name__,
            'context': context or {},
            'timestamp': datetime.utcnow().isoformat()
        }}
    )
    logger.metrics['errors']['count'] += 1

def log_database_operation(operation: str, collection: str, success: bool, duration: Optional[float] = None):
    """Log database operations with performance metrics"""
    logger.info(
        "Database Operation",
        extra={'extra_fields': {
            'operation_type': operation,
            'collection': collection,
            'success': success,
            'duration': duration,
            'timestamp': datetime.utcnow().isoformat()
        }}
    )
    logger.metrics['database']['operations'] += 1
    if not success:
        logger.metrics['database']['failures'] += 1

def log_health_check(component: str, status: str, details: dict = None):
    """Log health check results"""
    msg = f"Health Check - {component}: {status}"
    if details:
        msg += f" - Details: {details}"
    logger.info(msg, extra={'health_check': True})

def log_maintenance_activity(activity: str, result: str, details: dict = None):
    """Log maintenance activities"""
    msg = f"Maintenance - {activity}: {result}"
    if details:
        msg += f" - Details: {details}"
    logger.info(msg)

def get_metrics() -> Dict[str, Dict[str, Union[int, float]]]:
    """Get current logging metrics"""
    return logger.metrics

def reset_metrics():
    """Reset all logging metrics"""
    logger.metrics = {
        'requests': {'count': 0, 'total_duration': 0},
        'errors': {'count': 0},
        'database': {'operations': 0, 'failures': 0}
    }