import sys
import boto3
from pathlib import Path
from llama_index.core import Settings
from llama_index.core.storage.docstore import SimpleDocumentStore
from llama_index.retrievers.bm25 import BM25Retriever
from llama_index.core.retrievers import QueryFusionRetriever

from config import aws_access_key_id, aws_secret_access_key


class AppState:
    _instance = None
    retriever_bm25 = None

    def __new__(cls):
        if cls._instance is None:
            cls._instance = super(AppState, cls).__new__(cls)
        return cls._instance


# Параметри S3
BUCKET_NAME = "legal-position"
PREFIX_RETRIEVER = "Save_Index/"
LOCAL_DIR = Path("Save_Index_Local")

# Створюємо глобальний екземпляр стану
app_state = AppState()


def initialize_s3_client():
    return boto3.client(
        "s3",
        aws_access_key_id=aws_access_key_id,
        aws_secret_access_key=aws_secret_access_key,
        region_name="eu-north-1"
    )


def download_s3_file(s3_client, bucket_name, s3_key, local_path):
    s3_client.download_file(bucket_name, s3_key, str(local_path))
    print(f"Завантажено: {s3_key} -> {local_path}")


def download_s3_folder(s3_client, bucket_name, prefix, local_dir):
    response = s3_client.list_objects_v2(Bucket=bucket_name, Prefix=prefix)
    if 'Contents' in response:
        for obj in response['Contents']:
            s3_key = obj['Key']
            if s3_key.endswith('/'):
                continue
            local_file_path = local_dir / Path(s3_key).relative_to(prefix)
            local_file_path.parent.mkdir(parents=True, exist_ok=True)
            s3_client.download_file(bucket_name, s3_key, str(local_file_path))
            print(f"Завантажено: {s3_key} -> {local_file_path}")


def initialize_components():
    try:
        persist_path = Path("Save_Index_Local")

        if not persist_path.exists():
            raise FileNotFoundError(f"Directory not found: {persist_path}")

        required_files = ['docstore_es_filter.json', 'bm25_retriever_es']
        missing_files = [f for f in required_files if not (persist_path / f).exists()]

        if missing_files:
            raise FileNotFoundError(f"Missing required files: {', '.join(missing_files)}")

        docstore = SimpleDocumentStore.from_persist_path(str(persist_path / "docstore_es_filter.json"))
        bm25_retriever = BM25Retriever.from_persist_dir(str(persist_path / "bm25_retriever_es"))

        # Зберігаємо retriever_bm25 в глобальному стані
        app_state.retriever_bm25 = QueryFusionRetriever(
            [bm25_retriever],
            similarity_top_k=Settings.similarity_top_k,
            num_queries=1,
            use_async=True,
        )
        return True
    except Exception as e:
        print(f"Error initializing components: {str(e)}", file=sys.stderr)
        return False