import asyncio
from typing import Optional, Any
import firebase_admin
from firebase_admin import credentials, firestore as fs
from app.config import settings
from app.internal.logger import logger


def _init_firebase():
    if firebase_admin._apps:
        return firestore.client()

    if settings.gcp_credentials_path:
        cred = credentials.Certificate(settings.gcp_credentials_path)
    else:
        cred = credentials.ApplicationDefault()

    firebase_admin.initialize_app(cred)
    logger.info("Firebase initialised.")


_init_firebase()
db = fs.client(database_id=settings.firestore_database)


# ---------------------------------------------------------------------------
# Thin async wrappers — firebase-admin is synchronous, run in thread executor
# ---------------------------------------------------------------------------

async def doc_set(collection: str, doc_id: str, data: dict, merge: bool = True) -> None:
    ref = db.collection(collection).document(doc_id)
    await asyncio.to_thread(ref.set, data, merge=merge)


async def doc_get(collection: str, doc_id: str) -> Optional[dict]:
    ref = db.collection(collection).document(doc_id)
    snap = await asyncio.to_thread(ref.get)
    return snap.to_dict() if snap.exists else None


async def doc_update(collection: str, doc_id: str, data: dict) -> None:
    ref = db.collection(collection).document(doc_id)
    await asyncio.to_thread(ref.update, data)


async def collection_list(collection: str, **filters) -> list[dict]:
    """
    List all documents in a collection.
    Optional keyword filters: field=value pairs passed as equality where-clauses.
    """
    def _query():
        ref = db.collection(collection)
        for field, value in filters.items():
            ref = ref.where(field, "==", value)
        return [doc.to_dict() for doc in ref.stream()]

    return await asyncio.to_thread(_query)


async def collection_where(
    collection: str,
    conditions: list[tuple[str, str, Any]],
) -> list[dict]:
    """
    Query a collection with arbitrary where-clauses.
    conditions: list of (field, op, value) — e.g. [("ended_at", ">=", cutoff_dt)]
    Supports any Firestore operator: "==", "!=", "<", "<=", ">", ">=".
    """
    def _query():
        ref = db.collection(collection)
        for field, op, value in conditions:
            ref = ref.where(field, op, value)
        return [doc.to_dict() for doc in ref.stream()]

    return await asyncio.to_thread(_query)


async def doc_delete(collection: str, doc_id: str) -> None:
    ref = db.collection(collection).document(doc_id)
    await asyncio.to_thread(ref.delete)