"""Hook-based history recording — standard hooks that call record_history().

Registers action hooks for entity lifecycle events:
- entity.after_create  → record_history(action='create', snapshot_after=...)
- entity.after_update  → record_history(action='update', snapshot_before=..., snapshot_after=..., changes=...)
- entity.after_delete  → record_history(action='delete', snapshot_before=...)

Plugins can register their own entity types by calling:
    register_history_hooks(reg, 'task', 'task.after_create', 'task.after_update', 'task.after_delete')

This is explicit, traceable, and testable — no SQLAlchemy event listeners.
"""

from __future__ import annotations

import logging
import uuid
from typing import Any

from sqlalchemy.ext.asyncio import AsyncSession

from app.core.hooks import HookRegistry, get_hook_registry
from app.services.entity_history_service import record_history

logger = logging.getLogger(__name__)


def register_history_hooks(
    reg: HookRegistry,
    entity_type: str,
    after_create_hook: str,
    after_update_hook: str,
    after_delete_hook: str,
    owner_tag: str | None = None,
) -> None:
    """Register standard history-recording hooks for an entity type.

    Args:
        owner_tag: Plugin name that owns these hooks. Used for targeted
            deregistration in on_deactivate() via unregister_actions_by_owner().

    Each hook receives kwargs: db, tenant_id, user_id, and either:
    - after_create: snapshot_after (the created entity dict)
    - after_update: snapshot_before, snapshot_after, changes
    - after_delete: snapshot_before
    """

    async def _on_create(
        snapshot_after: dict[str, Any],
        *,
        db: AsyncSession,
        tenant_id: uuid.UUID,
        user_id: uuid.UUID | None = None,
        **kwargs: Any,
    ) -> None:
        entity_id = _extract_entity_id(snapshot_after)
        if entity_id is None:
            logger.warning("history_hooks: cannot extract entity_id from snapshot for %s", entity_type)
            return
        await record_history(
            db, tenant_id, user_id, entity_type, entity_id,
            action="create", snapshot_after=snapshot_after,
        )

    async def _on_update(
        snapshot_after: dict[str, Any],
        *,
        db: AsyncSession,
        tenant_id: uuid.UUID,
        user_id: uuid.UUID | None = None,
        snapshot_before: dict[str, Any] | None = None,
        changes: dict[str, Any] | None = None,
        **kwargs: Any,
    ) -> None:
        entity_id = _extract_entity_id(snapshot_after) or (
            _extract_entity_id(snapshot_before) if snapshot_before else None
        )
        if entity_id is None:
            logger.warning("history_hooks: cannot extract entity_id for %s update", entity_type)
            return
        await record_history(
            db, tenant_id, user_id, entity_type, entity_id,
            action="update",
            snapshot_before=snapshot_before,
            snapshot_after=snapshot_after,
            changes=changes,
        )

    async def _on_delete(
        snapshot_before: dict[str, Any] | None = None,
        *,
        db: AsyncSession,
        tenant_id: uuid.UUID,
        user_id: uuid.UUID | None = None,
        entity_id: uuid.UUID | None = None,
        **kwargs: Any,
    ) -> None:
        eid = entity_id or (_extract_entity_id(snapshot_before) if snapshot_before else None)
        if eid is None:
            logger.warning("history_hooks: cannot extract entity_id for %s delete", entity_type)
            return
        await record_history(
            db, tenant_id, user_id, entity_type, eid,
            action="delete", snapshot_before=snapshot_before,
        )

    reg.register_action(after_create_hook, _on_create, priority=90, owner_tag=owner_tag)
    reg.register_action(after_update_hook, _on_update, priority=90, owner_tag=owner_tag)
    reg.register_action(after_delete_hook, _on_delete, priority=90, owner_tag=owner_tag)
    logger.debug("History hooks registered for: %s", entity_type)


def _extract_entity_id(snapshot: dict[str, Any] | None) -> uuid.UUID | None:
    """Extract entity UUID from a snapshot dict."""
    if snapshot is None:
        return None
    raw_id = snapshot.get("id")
    if raw_id is None:
        return None
    if isinstance(raw_id, uuid.UUID):
        return raw_id
    try:
        return uuid.UUID(str(raw_id))
    except (ValueError, TypeError):
        return None


def register_default_history_hooks() -> None:
    """Register history hooks for Core entity types only.

    Called during app startup after the hook registry is initialized.
    Plugin entities (task, calendar_entry, dms_file, mail) register
    their own hooks in on_activate(). See P0-8 fix.
    """
    # Contact hooks are registered by ContactsPlugin.on_activate() with
    # owner_tag="contacts" — do not register them here to avoid double
    # registration. This function remains for future Core entities that
    # have no plugin.


def reset_history_hooks_for_testing() -> None:
    """Clear all history hooks — for unit tests only."""
    reg = get_hook_registry()
    # The hook registry's _reset_for_testing clears everything
    reg._reset_for_testing()