"""Create Mixin."""

from typing import Any

from sqlalchemy import Connection, event
from sqlalchemy.orm import Mapper

from ..contexts import get_user_id
from ..utils import current_timestamp, try_creatable


class CreateMixin:
    """Mixin for models with creation tracking.

    AUTOMATIC BEHAVIOR on any model creation:
    - created_at: Set to current timestamp in SYSTEM_TIMEZONE
    - created_by: Set from ctx_user_id context

    To control automatic updates:
    ```python
    disable_on_create()
    enable_on_create()
    ```

    The actual columns are defined in the model itself
    based on what exists in the database schema.

    A model using this mixin may have one or more of:
    - created_at: When the record was created
    - created_by: User ID who created the record
    """

    def _on_create(self) -> None:
        """Automatically set creation fields."""
        try_creatable(self)
        if hasattr(self, 'created_at') and self.created_at is None:
            self.created_at = current_timestamp()
        if hasattr(self, 'created_by') and self.created_by is None:
            self.created_by = get_user_id()


_on_create_enabled = True


def disable_on_create() -> None:
    """Disable automatic creation fields."""
    global _on_create_enabled
    if not _on_create_enabled:
        return

    try:
        event.remove(CreateMixin, 'before_insert', _on_create)
    except Exception:
        pass

    _on_create_enabled = False


def enable_on_create() -> None:
    """Enable automatic creation fields."""
    global _on_create_enabled
    if _on_create_enabled:
        return

    event.listen(CreateMixin, 'before_insert', _on_create, propagate=True)
    _on_create_enabled = True


def _on_create(mapper: Mapper, connection: Connection, target: Any) -> None:
    """Automatically set creation fields."""
    target._on_create()


# Register listener at module import time
event.listen(CreateMixin, 'before_insert', _on_create, propagate=True)