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"""
Command handling for CQRS pattern implementation.
This module provides command definitions and handlers for write operations,
separating them from read queries for better scalability.
"""
from typing import Any, Dict, Optional, Type, TypeVar, Generic
from abc import ABC, abstractmethod
from dataclasses import dataclass
from datetime import datetime
import uuid
from pydantic import BaseModel, Field
from src.core import get_logger
from src.infrastructure.events.event_bus import EventBus, EventType, Event
logger = get_logger(__name__)
T = TypeVar('T')
class Command(BaseModel):
"""Base class for all commands."""
command_id: str = Field(default_factory=lambda: str(uuid.uuid4()))
timestamp: datetime = Field(default_factory=datetime.utcnow)
user_id: Optional[str] = None
metadata: Dict[str, Any] = Field(default_factory=dict)
class CommandResult(BaseModel):
"""Result of command execution."""
success: bool
command_id: str
data: Optional[Any] = None
error: Optional[str] = None
events_published: int = 0
# Investigation Commands
class CreateInvestigationCommand(Command):
"""Command to create a new investigation."""
query: str
data_sources: Optional[list[str]] = None
priority: str = "medium"
class UpdateInvestigationCommand(Command):
"""Command to update investigation status."""
investigation_id: str
status: str
results: Optional[Dict[str, Any]] = None
class CancelInvestigationCommand(Command):
"""Command to cancel an investigation."""
investigation_id: str
reason: Optional[str] = None
# Agent Commands
class ExecuteAgentTaskCommand(Command):
"""Command to execute an agent task."""
agent_name: str
task_type: str
payload: Dict[str, Any]
timeout: Optional[float] = None
# Chat Commands
class SendChatMessageCommand(Command):
"""Command to send a chat message."""
session_id: str
message: str
context: Optional[Dict[str, Any]] = None
class CommandHandler(ABC, Generic[T]):
"""
Base class for command handlers.
Implements the handler pattern for processing commands.
"""
@abstractmethod
async def handle(self, command: T) -> CommandResult:
"""
Handle a command.
Args:
command: Command to handle
Returns:
Command execution result
"""
pass
@abstractmethod
def can_handle(self, command: Command) -> bool:
"""
Check if this handler can handle the command.
Args:
command: Command to check
Returns:
True if handler can process this command
"""
pass
class CreateInvestigationHandler(CommandHandler[CreateInvestigationCommand]):
"""Handler for creating investigations."""
def __init__(self, event_bus: EventBus):
"""
Initialize handler.
Args:
event_bus: Event bus for publishing events
"""
self.event_bus = event_bus
self.logger = get_logger(__name__)
async def handle(self, command: CreateInvestigationCommand) -> CommandResult:
"""Create a new investigation."""
try:
investigation_id = str(uuid.uuid4())
# In a real implementation, this would:
# 1. Validate the command
# 2. Create the investigation in the write model
# 3. Publish events
# Publish investigation created event
await self.event_bus.publish(
EventType.INVESTIGATION_CREATED,
{
"investigation_id": investigation_id,
"query": command.query,
"user_id": command.user_id,
"data_sources": command.data_sources,
"priority": command.priority
},
{"command_id": command.command_id}
)
self.logger.info(f"Investigation {investigation_id} created")
return CommandResult(
success=True,
command_id=command.command_id,
data={"investigation_id": investigation_id},
events_published=1
)
except Exception as e:
self.logger.error(f"Failed to create investigation: {e}")
return CommandResult(
success=False,
command_id=command.command_id,
error=str(e)
)
def can_handle(self, command: Command) -> bool:
"""Check if this handler can handle the command."""
return isinstance(command, CreateInvestigationCommand)
class CommandBus:
"""
Command bus for routing commands to appropriate handlers.
Implements the mediator pattern for command processing.
"""
def __init__(self, event_bus: EventBus):
"""
Initialize command bus.
Args:
event_bus: Event bus for publishing events
"""
self.event_bus = event_bus
self._handlers: list[CommandHandler] = []
self._middleware: list[CommandMiddleware] = []
# Statistics
self._stats = {
"commands_processed": 0,
"commands_succeeded": 0,
"commands_failed": 0
}
# Register default handlers
self._register_default_handlers()
def _register_default_handlers(self):
"""Register default command handlers."""
self.register_handler(CreateInvestigationHandler(self.event_bus))
def register_handler(self, handler: CommandHandler):
"""
Register a command handler.
Args:
handler: Handler to register
"""
self._handlers.append(handler)
logger.info(f"Registered command handler: {handler.__class__.__name__}")
def register_middleware(self, middleware: 'CommandMiddleware'):
"""
Register command middleware.
Args:
middleware: Middleware to register
"""
self._middleware.append(middleware)
logger.info(f"Registered command middleware: {middleware.__class__.__name__}")
async def execute(self, command: Command) -> CommandResult:
"""
Execute a command.
Args:
command: Command to execute
Returns:
Command execution result
"""
self._stats["commands_processed"] += 1
try:
# Apply middleware
for middleware in self._middleware:
command = await middleware.before_execute(command)
# Find handler
handler = None
for h in self._handlers:
if h.can_handle(command):
handler = h
break
if not handler:
raise ValueError(f"No handler found for command: {type(command).__name__}")
# Execute command
result = await handler.handle(command)
# Apply middleware to result
for middleware in reversed(self._middleware):
result = await middleware.after_execute(command, result)
if result.success:
self._stats["commands_succeeded"] += 1
else:
self._stats["commands_failed"] += 1
return result
except Exception as e:
logger.error(f"Command execution failed: {e}")
self._stats["commands_failed"] += 1
return CommandResult(
success=False,
command_id=command.command_id,
error=str(e)
)
def get_stats(self) -> Dict[str, Any]:
"""Get command bus statistics."""
return {
**self._stats,
"handlers_registered": len(self._handlers),
"middleware_registered": len(self._middleware),
"success_rate": (
self._stats["commands_succeeded"] / self._stats["commands_processed"]
if self._stats["commands_processed"] > 0 else 0
)
}
class CommandMiddleware(ABC):
"""Base class for command middleware."""
@abstractmethod
async def before_execute(self, command: Command) -> Command:
"""
Process command before execution.
Args:
command: Command to process
Returns:
Processed command
"""
pass
@abstractmethod
async def after_execute(
self,
command: Command,
result: CommandResult
) -> CommandResult:
"""
Process result after execution.
Args:
command: Executed command
result: Execution result
Returns:
Processed result
"""
pass
class LoggingMiddleware(CommandMiddleware):
"""Middleware for logging commands."""
def __init__(self):
self.logger = get_logger(__name__)
async def before_execute(self, command: Command) -> Command:
"""Log command execution."""
self.logger.info(
f"Executing command {command.__class__.__name__} "
f"(id: {command.command_id})"
)
return command
async def after_execute(
self,
command: Command,
result: CommandResult
) -> CommandResult:
"""Log command result."""
if result.success:
self.logger.info(
f"Command {command.command_id} succeeded "
f"(events: {result.events_published})"
)
else:
self.logger.error(
f"Command {command.command_id} failed: {result.error}"
)
return result
class ValidationMiddleware(CommandMiddleware):
"""Middleware for validating commands."""
async def before_execute(self, command: Command) -> Command:
"""Validate command."""
# Perform validation
if hasattr(command, 'validate'):
command.validate()
return command
async def after_execute(
self,
command: Command,
result: CommandResult
) -> CommandResult:
"""No post-processing needed."""
return result |