"""
Audit logging system for tracking critical operations across all services
"""

import uuid
from datetime import datetime, timezone
from typing import Optional, Dict, Any
from enum import Enum
import structlog
from sqlalchemy import Column, String, DateTime, Text, Index
from sqlalchemy.dialects.postgresql import UUID, JSON

logger = structlog.get_logger()


class AuditSeverity(str, Enum):
    """Severity levels for audit events"""
    LOW = "low"
    MEDIUM = "medium"
    HIGH = "high"
    CRITICAL = "critical"


class AuditAction(str, Enum):
    """Common audit action types"""
    CREATE = "create"
    READ = "read"
    UPDATE = "update"
    DELETE = "delete"
    APPROVE = "approve"
    REJECT = "reject"
    CANCEL = "cancel"
    EXPORT = "export"
    IMPORT = "import"
    INVITE = "invite"
    REMOVE = "remove"
    UPGRADE = "upgrade"
    DOWNGRADE = "downgrade"
    DEACTIVATE = "deactivate"
    ACTIVATE = "activate"


def create_audit_log_model(Base):
    """
    Factory function to create AuditLog model for any service
    Each service has its own audit_logs table in their database

    Usage in service models/__init__.py:
        from shared.database.base import Base
        from shared.security import create_audit_log_model

        AuditLog = create_audit_log_model(Base)

    Args:
        Base: SQLAlchemy declarative base for the service

    Returns:
        AuditLog model class bound to the service's Base
    """

    class AuditLog(Base):
        """
        Audit log model for tracking critical operations
        Each service has its own audit_logs table for data locality
        """
        __tablename__ = "audit_logs"

        # Primary identification
        id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)

        # Tenant and user context
        tenant_id = Column(UUID(as_uuid=True), nullable=False, index=True)
        user_id = Column(UUID(as_uuid=True), nullable=False, index=True)

        # Action details
        action = Column(String(100), nullable=False, index=True)  # create, update, delete, etc.
        resource_type = Column(String(100), nullable=False, index=True)  # supplier, recipe, order, etc.
        resource_id = Column(String(255), nullable=True, index=True)

        # Severity and categorization
        severity = Column(
            String(20),
            nullable=False,
            default="medium",
            index=True
        )  # low, medium, high, critical

        # Service identification
        service_name = Column(String(100), nullable=False, index=True)

        # Details
        description = Column(Text, nullable=True)

        # Audit trail data
        changes = Column(JSON, nullable=True)  # Before/after values for updates
        audit_metadata = Column(JSON, nullable=True)  # Additional context

        # Request context
        ip_address = Column(String(45), nullable=True)  # IPv4 or IPv6
        user_agent = Column(Text, nullable=True)
        endpoint = Column(String(255), nullable=True)
        method = Column(String(10), nullable=True)  # GET, POST, PUT, DELETE

        # Timestamps
        created_at = Column(
            DateTime(timezone=True),
            nullable=False,
            default=lambda: datetime.now(timezone.utc),
            index=True
        )

        # Composite indexes for common query patterns
        __table_args__ = (
            Index('idx_audit_tenant_created', 'tenant_id', 'created_at'),
            Index('idx_audit_user_created', 'user_id', 'created_at'),
            Index('idx_audit_resource_type_action', 'resource_type', 'action'),
            Index('idx_audit_severity_created', 'severity', 'created_at'),
            Index('idx_audit_service_created', 'service_name', 'created_at'),
        )

        def __repr__(self):
            return (
                f"<AuditLog(id={self.id}, tenant={self.tenant_id}, "
                f"action={self.action}, resource={self.resource_type}, "
                f"severity={self.severity})>"
            )

        def to_dict(self):
            """Convert audit log to dictionary"""
            return {
                "id": str(self.id),
                "tenant_id": str(self.tenant_id),
                "user_id": str(self.user_id),
                "action": self.action,
                "resource_type": self.resource_type,
                "resource_id": self.resource_id,
                "severity": self.severity,
                "service_name": self.service_name,
                "description": self.description,
                "changes": self.changes,
                "metadata": self.audit_metadata,
                "ip_address": self.ip_address,
                "user_agent": self.user_agent,
                "endpoint": self.endpoint,
                "method": self.method,
                "created_at": self.created_at.isoformat() if self.created_at else None,
            }

    return AuditLog


class AuditLogger:
    """Service for logging audit events"""

    def __init__(self, service_name: str, audit_log_model):
        """
        Initialize AuditLogger with service-specific AuditLog model

        Args:
            service_name: Name of the service (e.g., "production-service")
            audit_log_model: The service-specific AuditLog model class created via create_audit_log_model()
        """
        if not audit_log_model:
            raise ValueError(f"audit_log_model is required for AuditLogger in {service_name}")

        self.service_name = service_name
        self.audit_log_model = audit_log_model
        self.logger = logger.bind(service=service_name)

    async def log_event(
        self,
        db_session,
        tenant_id: str,
        user_id: str,
        action: str,
        resource_type: str,
        resource_id: Optional[str] = None,
        severity: str = "medium",
        description: Optional[str] = None,
        changes: Optional[Dict[str, Any]] = None,
        audit_metadata: Optional[Dict[str, Any]] = None,
        endpoint: Optional[str] = None,
        method: Optional[str] = None,
        ip_address: Optional[str] = None,
        user_agent: Optional[str] = None,
    ):
        """
        Log an audit event

        Args:
            db_session: Database session
            tenant_id: Tenant ID
            user_id: User ID who performed the action
            action: Action performed (create, update, delete, etc.)
            resource_type: Type of resource (user, sale, recipe, etc.)
            resource_id: ID of the resource affected
            severity: Severity level (low, medium, high, critical)
            description: Human-readable description
            changes: Dictionary of before/after values for updates
            audit_metadata: Additional context
            endpoint: API endpoint
            method: HTTP method
            ip_address: Client IP address
            user_agent: Client user agent
        """
        try:
            audit_log = self.audit_log_model(
                tenant_id=uuid.UUID(tenant_id) if isinstance(tenant_id, str) else tenant_id,
                user_id=uuid.UUID(user_id) if isinstance(user_id, str) else user_id,
                action=action,
                resource_type=resource_type,
                resource_id=resource_id,
                severity=severity,
                service_name=self.service_name,
                description=description,
                changes=changes,
                audit_metadata=audit_metadata,
                endpoint=endpoint,
                method=method,
                ip_address=ip_address,
                user_agent=user_agent,
            )

            db_session.add(audit_log)
            await db_session.commit()

            self.logger.info(
                "audit_event_logged",
                tenant_id=str(tenant_id),
                user_id=str(user_id),
                action=action,
                resource_type=resource_type,
                resource_id=resource_id,
                severity=severity,
            )

        except Exception as e:
            self.logger.error(
                "audit_log_failed",
                error=str(e),
                tenant_id=str(tenant_id),
                user_id=str(user_id),
                action=action,
            )
            # Don't raise - audit logging should not block operations

    async def log_deletion(
        self,
        db_session,
        tenant_id: str,
        user_id: str,
        resource_type: str,
        resource_id: str,
        resource_data: Optional[Dict[str, Any]] = None,
        **kwargs
    ):
        """Convenience method for logging deletions"""
        return await self.log_event(
            db_session=db_session,
            tenant_id=tenant_id,
            user_id=user_id,
            action=AuditAction.DELETE.value,
            resource_type=resource_type,
            resource_id=resource_id,
            severity=AuditSeverity.HIGH.value,
            description=f"Deleted {resource_type} {resource_id}",
            audit_metadata={"deleted_data": resource_data} if resource_data else None,
            **kwargs
        )

    async def log_role_change(
        self,
        db_session,
        tenant_id: str,
        user_id: str,
        target_user_id: str,
        old_role: str,
        new_role: str,
        **kwargs
    ):
        """Convenience method for logging role changes"""
        return await self.log_event(
            db_session=db_session,
            tenant_id=tenant_id,
            user_id=user_id,
            action=AuditAction.UPDATE.value,
            resource_type="user_role",
            resource_id=target_user_id,
            severity=AuditSeverity.HIGH.value,
            description=f"Changed user role from {old_role} to {new_role}",
            changes={
                "before": {"role": old_role},
                "after": {"role": new_role}
            },
            **kwargs
        )

    async def log_subscription_change(
        self,
        db_session,
        tenant_id: str,
        user_id: str,
        action: str,
        old_plan: Optional[str] = None,
        new_plan: Optional[str] = None,
        **kwargs
    ):
        """Convenience method for logging subscription changes"""
        return await self.log_event(
            db_session=db_session,
            tenant_id=tenant_id,
            user_id=user_id,
            action=action,
            resource_type="subscription",
            resource_id=tenant_id,
            severity=AuditSeverity.CRITICAL.value,
            description=f"Subscription {action}: {old_plan} -> {new_plan}" if old_plan else f"Subscription {action}: {new_plan}",
            changes={
                "before": {"plan": old_plan} if old_plan else None,
                "after": {"plan": new_plan} if new_plan else None
            },
            **kwargs
        )


def create_audit_logger(service_name: str, audit_log_model) -> AuditLogger:
    """
    Factory function to create audit logger for a service

    Args:
        service_name: Name of the service (e.g., "production-service")
        audit_log_model: The service-specific AuditLog model class (REQUIRED - created via create_audit_log_model)

    Returns:
        Configured AuditLogger instance

    Example:
        from app.models import AuditLog
        from shared.security import create_audit_logger

        audit_logger = create_audit_logger("production-service", AuditLog)
    """
    return AuditLogger(service_name, audit_log_model)