"""Structured logging with correlation IDs and context management."""

import logging
import json
import uuid
import time
from typing import Dict, Any, Optional, Union
from datetime import datetime
from contextvars import ContextVar
from dataclasses import dataclass, asdict
from enum import Enum

# Context variable for correlation ID
correlation_id_context: ContextVar[Optional[str]] = ContextVar('correlation_id', default=None)


class LogLevel(Enum):
    """Log levels."""
    DEBUG = "DEBUG"
    INFO = "INFO"
    WARNING = "WARNING"
    ERROR = "ERROR"
    CRITICAL = "CRITICAL"


@dataclass
class LogContext:
    """Structured log context."""
    correlation_id: str
    operation: Optional[str] = None
    component: Optional[str] = None
    user_id: Optional[str] = None
    session_id: Optional[str] = None
    request_id: Optional[str] = None
    metadata: Optional[Dict[str, Any]] = None

    def to_dict(self) -> Dict[str, Any]:
        """Convert to dictionary."""
        return {k: v for k, v in asdict(self).items() if v is not None}


class StructuredLogger:
    """Structured logger with correlation ID support."""

    def __init__(self, name: str, enable_json_logging: bool = True):
        """
        Initialize structured logger.

        Args:
            name: Logger name
            enable_json_logging: Whether to use JSON format
        """
        self.logger = logging.getLogger(name)
        self.enable_json_logging = enable_json_logging
        self._setup_formatter()

    def _setup_formatter(self) -> None:
        """Setup log formatter."""
        if self.enable_json_logging:
            formatter = JsonFormatter()
        else:
            formatter = ContextFormatter()

        # Apply formatter to all handlers
        for handler in self.logger.handlers:
            handler.setFormatter(formatter)

    def _get_log_data(self, message: str, level: str,
                     context: Optional[LogContext] = None,
                     extra: Optional[Dict[str, Any]] = None,
                     exception: Optional[Exception] = None) -> Dict[str, Any]:
        """
        Prepare log data structure.

        Args:
            message: Log message
            level: Log level
            context: Log context
            extra: Extra data
            exception: Exception if any

        Returns:
            Dict[str, Any]: Structured log data
        """
        # Get correlation ID from context or generate new one
        correlation_id = correlation_id_context.get()
        if not correlation_id and context:
            correlation_id = context.correlation_id
        if not correlation_id:
            correlation_id = str(uuid.uuid4())

        log_data = {
            'timestamp': datetime.utcnow().isoformat() + 'Z',
            'level': level,
            'message': message,
            'correlation_id': correlation_id,
            'logger_name': self.logger.name
        }

        # Add context information
        if context:
            log_data.update(context.to_dict())

        # Add extra data
        if extra:
            log_data['extra'] = extra

        # Add exception information
        if exception:
            log_data['exception'] = {
                'type': type(exception).__name__,
                'message': str(exception),
                'module': getattr(exception, '__module__', None)
            }

            # Add stack trace for debugging
            import traceback
            log_data['exception']['traceback'] = traceback.format_exc()

        return log_data

    def debug(self, message: str, context: Optional[LogContext] = None,
             extra: Optional[Dict[str, Any]] = None) -> None:
        """Log debug message."""
        if self.logger.isEnabledFor(logging.DEBUG):
            log_data = self._get_log_data(message, LogLevel.DEBUG.value, context, extra)
            # Use 'structured_data' to avoid conflicts with LogRecord attributes
            self.logger.info(message, extra={'structured_data': log_data})

    def info(self, message: str, context: Optional[LogContext] = None,
            extra: Optional[Dict[str, Any]] = None) -> None:
        """Log info message."""
        if self.logger.isEnabledFor(logging.INFO):
            log_data = self._get_log_data(message, LogLevel.INFO.value, context, extra)
            # Use 'structured_data' to avoid conflicts with LogRecord attributes
            self.logger.info(message, extra={'structured_data': log_data})

    def warning(self, message: str, context: Optional[LogContext] = None,
               extra: Optional[Dict[str, Any]] = None) -> None:
        """Log warning message."""
        if self.logger.isEnabledFor(logging.WARNING):
            log_data = self._get_log_data(message, LogLevel.WARNING.value, context, extra)
            # Use 'structured_data' to avoid conflicts with LogRecord attributes
            self.logger.warning(message, extra={'structured_data': log_data})

    def error(self, message: str, context: Optional[LogContext] = None,
             extra: Optional[Dict[str, Any]] = None,
             exception: Optional[Exception] = None) -> None:
        """Log error message."""
        if self.logger.isEnabledFor(logging.ERROR):
            log_data = self._get_log_data(message, LogLevel.ERROR.value, context, extra, exception)
            # Use 'structured_data' to avoid conflicts with LogRecord attributes
            self.logger.error(message, extra={'structured_data': log_data})

    def critical(self, message: str, context: Optional[LogContext] = None,
                extra: Optional[Dict[str, Any]] = None,
                exception: Optional[Exception] = None) -> None:
        """Log critical message."""
        if self.logger.isEnabledFor(logging.CRITICAL):
            log_data = self._get_log_data(message, LogLevel.CRITICAL.value, context, extra, exception)
            # Use 'structured_data' to avoid conflicts with LogRecord attributes
            self.logger.critical(message, extra={'structured_data': log_data})

    def log_operation_start(self, operation: str, context: Optional[LogContext] = None,
                          extra: Optional[Dict[str, Any]] = None) -> str:
        """
        Log operation start and return correlation ID.

        Args:
            operation: Operation name
            context: Log context
            extra: Extra data

        Returns:
            str: Correlation ID for the operation
        """
        correlation_id = str(uuid.uuid4())

        if context:
            context.correlation_id = correlation_id
            context.operation = operation
        else:
            context = LogContext(correlation_id=correlation_id, operation=operation)

        # Set correlation ID in context
        correlation_id_context.set(correlation_id)

        self.info(f"Operation started: {operation}", context, extra)
        return correlation_id

    def log_operation_end(self, operation: str, correlation_id: str,
                         success: bool = True, duration: Optional[float] = None,
                         context: Optional[LogContext] = None,
                         extra: Optional[Dict[str, Any]] = None) -> None:
        """
        Log operation end.

        Args:
            operation: Operation name
            correlation_id: Correlation ID
            success: Whether operation succeeded
            duration: Operation duration in seconds
            context: Log context
            extra: Extra data
        """
        if context:
            context.correlation_id = correlation_id
            context.operation = operation
        else:
            context = LogContext(correlation_id=correlation_id, operation=operation)

        # Add performance data
        if extra is None:
            extra = {}
        extra['success'] = success
        if duration is not None:
            extra['duration_seconds'] = duration

        status = "completed successfully" if success else "failed"
        message = f"Operation {status}: {operation}"

        if success:
            self.info(message, context, extra)
        else:
            self.error(message, context, extra)

    def log_performance_metric(self, metric_name: str, value: Union[int, float],
                             unit: str = None, context: Optional[LogContext] = None,
                             extra: Optional[Dict[str, Any]] = None) -> None:
        """
        Log performance metric.

        Args:
            metric_name: Name of the metric
            value: Metric value
            unit: Unit of measurement
            context: Log context
            extra: Extra data
        """
        if extra is None:
            extra = {}

        extra['metric'] = {
            'name': metric_name,
            'value': value,
            'unit': unit,
            'timestamp': time.time()
        }

        message = f"Performance metric: {metric_name}={value}"
        if unit:
            message += f" {unit}"

        self.info(message, context, extra)


class JsonFormatter(logging.Formatter):
    """JSON log formatter."""

    def format(self, record: logging.LogRecord) -> str:
        """Format log record as JSON."""
        try:
            # Get structured data from extra
            log_data = getattr(record, 'structured_data', {})

            # Ensure basic fields are present
            if 'timestamp' not in log_data:
                log_data['timestamp'] = datetime.utcnow().isoformat() + 'Z'
            if 'level' not in log_data:
                log_data['level'] = record.levelname
            if 'message' not in log_data:
                log_data['message'] = record.getMessage()
            if 'logger_name' not in log_data:
                log_data['logger_name'] = record.name

            # Add standard log record fields
            log_data.update({
                'module': record.module,
                'function': record.funcName,
                'line': record.lineno,
                'thread': record.thread,
                'process': record.process
            })

            return json.dumps(log_data, default=str, ensure_ascii=False)

        except Exception as e:
            # Fallback to standard formatting
            return f"JSON formatting error: {e} | Original: {record.getMessage()}"


class ContextFormatter(logging.Formatter):
    """Context-aware log formatter."""

    def __init__(self):
        """Initialize formatter."""
        super().__init__(
            fmt='%(asctime)s - %(name)s - %(levelname)s - [%(correlation_id)s] - %(message)s',
            datefmt='%Y-%m-%d %H:%M:%S'
        )

    def format(self, record: logging.LogRecord) -> str:
        """Format log record with context."""
        try:
            # Get correlation ID from context or record
            correlation_id = correlation_id_context.get()
            if not correlation_id:
                structured_data = getattr(record, 'structured_data', {})
                correlation_id = structured_data.get('correlation_id', 'unknown')

            # Add correlation ID to record
            record.correlation_id = correlation_id

            # Add context information if available
            structured_data = getattr(record, 'structured_data', {})
            if 'operation' in structured_data:
                record.message = f"[{structured_data['operation']}] {record.getMessage()}"

            return super().format(record)

        except Exception as e:
            # Fallback formatting
            return f"Formatting error: {e} | Original: {record.getMessage()}"


def get_structured_logger(name: str, enable_json_logging: bool = True) -> StructuredLogger:
    """
    Get a structured logger instance.

    Args:
        name: Logger name
        enable_json_logging: Whether to use JSON format

    Returns:
        StructuredLogger: Configured structured logger
    """
    return StructuredLogger(name, enable_json_logging)


def set_correlation_id(correlation_id: str) -> None:
    """
    Set correlation ID in context.

    Args:
        correlation_id: Correlation ID to set
    """
    correlation_id_context.set(correlation_id)


def get_correlation_id() -> Optional[str]:
    """
    Get current correlation ID from context.

    Returns:
        Optional[str]: Current correlation ID
    """
    return correlation_id_context.get()


def generate_correlation_id() -> str:
    """
    Generate a new correlation ID.

    Returns:
        str: New correlation ID
    """
    return str(uuid.uuid4())