from functools import lru_cache

import chromadb
from chromadb.api.models.Collection import Collection

from src.config import settings


@lru_cache(maxsize=1)
def get_chroma_client() -> chromadb.ClientAPI:
    return chromadb.PersistentClient(path=str(settings.chroma_db_path))


def get_collection() -> Collection:
    client = get_chroma_client()
    return client.get_or_create_collection(
        name=settings.chroma_collection_name,
        metadata={"hnsw:space": "cosine"},
    )


def add_chunks(
    ids: list[str],
    documents: list[str],
    embeddings: list[list[float]],
    metadatas: list[dict],
) -> None:
    collection = get_collection()
    # ChromaDB has a batch limit; process in batches of 5000
    batch_size = 5000
    for i in range(0, len(ids), batch_size):
        collection.add(
            ids=ids[i : i + batch_size],
            documents=documents[i : i + batch_size],
            embeddings=embeddings[i : i + batch_size],
            metadatas=metadatas[i : i + batch_size],
        )


def query_chunks(
    query_embedding: list[float],
    n_results: int = 5,
    where: dict | None = None,
) -> dict:
    collection = get_collection()
    kwargs = {
        "query_embeddings": [query_embedding],
        "n_results": n_results,
        "include": ["documents", "metadatas", "distances"],
    }
    if where:
        kwargs["where"] = where
    return collection.query(**kwargs)


def delete_by_book_id(book_id: str) -> None:
    collection = get_collection()
    collection.delete(where={"book_id": book_id})


def get_collection_count() -> int:
    collection = get_collection()
    return collection.count()