"""In-app notifications for the mobile client."""
from datetime import datetime, timezone

from bson import ObjectId
from pymongo import DESCENDING

from ..core.db_connector import notifications_collection


def _ensure_indexes():
    try:
        notifications_collection.create_index(
            [("user_id", 1), ("created_at", DESCENDING)]
        )
        notifications_collection.create_index([("user_id", 1), ("is_read", 1)])
    except Exception:
        pass


_ensure_indexes()


def _serialize(doc, user_id=None):
    if not doc:
        return None
    read_by = [str(u) for u in doc.get("read_by", [])]
    uid = str(user_id) if user_id is not None else ""
    created = doc.get("created_at")
    return {
        "id": str(doc["_id"]),
        "title": doc.get("title") or "",
        "message": doc.get("message") or "",
        "type": doc.get("type") or "info",
        "created_at": created.isoformat() if created else datetime.now(timezone.utc).isoformat(),
        "is_read": uid in read_by if uid else bool(doc.get("is_read")),
    }


def list_notifications(user_id, limit=50):
    uid = str(user_id)
    cursor = notifications_collection.find(
        {"$or": [{"user_id": uid}, {"user_id": {"$exists": False}}, {"broadcast": True}]}
    ).sort("created_at", DESCENDING).limit(limit)
    return [_serialize(doc, uid) for doc in cursor]


def mark_read(user_id, notification_id):
    uid = str(user_id)
    try:
        oid = ObjectId(notification_id)
    except Exception:
        return False
    result = notifications_collection.update_one(
        {"_id": oid},
        {"$addToSet": {"read_by": uid}, "$set": {"is_read": True}},
    )
    return result.matched_count > 0


def mark_all_read(user_id):
    uid = str(user_id)
    notifications_collection.update_many(
        {"$or": [{"user_id": uid}, {"broadcast": True}]},
        {"$addToSet": {"read_by": uid}},
    )
    return True


def delete_notification(user_id, notification_id):
    uid = str(user_id)
    try:
        oid = ObjectId(notification_id)
    except Exception:
        return False
    result = notifications_collection.delete_one(
        {"_id": oid, "$or": [{"user_id": uid}, {"broadcast": True}]}
    )
    return result.deleted_count > 0