"""Lifecycle hook helpers for instrumenting tool instance transitions."""

import uuid
from datetime import datetime, timezone

from sqlalchemy.ext.asyncio import AsyncSession

from src.models.instance_event import InstanceEvent
from src.models.tool_instance import ToolInstance
from src.services.correlation import get_correlation_id
from src.services.event_bus import InstanceEventBus, InstanceEventPayload


def _build_payload(
    event_type: str,
    instance: ToolInstance,
    status: str | None = None,
    message: str | None = None,
    metadata: dict | None = None,
) -> InstanceEventPayload:
    """Construct a standard event payload."""
    return {
        "event": event_type,
        "instance_id": str(instance.id),
        "status": status or instance.status,
        "message": message,
        "metadata": metadata or {},
        "timestamp": datetime.now(timezone.utc).isoformat(),
        "correlation_id": get_correlation_id(),
    }


async def _write_audit_row(
    session: AsyncSession,
    instance: ToolInstance,
    event_type: str,
    created_by: uuid.UUID | None = None,
    status: str | None = None,
    message: str | None = None,
    metadata: dict | None = None,
) -> InstanceEvent:
    """Persist an instance_events audit row."""
    row = InstanceEvent(
        instance_id=instance.id,
        event_type=event_type.replace("instance.", ""),
        status=status or instance.status,
        message=message,
        created_by=created_by,
        event_metadata=metadata or {},
    )
    session.add(row)
    await session.commit()
    return row


async def publish_lifecycle_event(
    event_bus: InstanceEventBus,
    session: AsyncSession,
    instance: ToolInstance,
    event_type: str,
    created_by: uuid.UUID | None = None,
    status: str | None = None,
    message: str | None = None,
    metadata: dict | None = None,
) -> None:
    """Publish a lifecycle event and write an audit row after DB commit.

    Args:
        event_bus: The global event bus.
        session: Active async DB session.
        instance: The affected tool instance.
        event_type: One of instance.created, instance.started, etc.
        created_by: User ID for user-initiated actions; None for system.
        status: Optional status override.
        message: Optional human-readable message.
        metadata: Optional extra metadata.
    """
    payload = _build_payload(
        event_type=event_type,
        instance=instance,
        status=status,
        message=message,
        metadata=metadata,
    )

    # Write audit row
    await _write_audit_row(
        session=session,
        instance=instance,
        event_type=event_type,
        created_by=created_by,
        status=status or instance.status,
        message=message,
        metadata=metadata,
    )

    # Publish to bus
    await event_bus.publish(event_type, payload)