import json
from dataclasses import asdict
from functools import lru_cache

from pydantic_settings import BaseSettings


class Settings(BaseSettings):
    """Configuration for the retrieval and generation system"""

    api_title: str = "NEXUS API"
    api_version: str = "0.1.0"
    chunk_size: int = 512
    chunk_overlap: int = 256

    embedding_model: str = "text-embedding-ada-002"
    rerank_model: str = "cross-encoder/ms-marco-MiniLM-L-6-v2"
    llm_model: str = "gpt-4o"
    openai_api_key: str | None = None

    use_colbert: bool = True
    colbert_model: str = "answerdotai/answerai-colbert-small-v1"
    colbert_top_k: int = 20
    colbert_only: bool = False

    bm25_top_k: int = 20
    final_top_k: int = 5
    bm25_weight: float = 0.50
    colbert_weight: float = 0.50
    use_reranking: bool = True

    index_path: str = "./data/indexes/rag_index"
    colbert_index_path: str = "./data/indexes/colbert_index"
    markdown_directory: str = "./Markdown_files"

    def save(self, path: str):
        """Save config to JSON"""
        with open(path, "w") as f:
            json.dump(asdict(self), f, indent=2)

    @classmethod
    def load(cls, path: str):
        """Load config from JSON"""
        with open(path) as f:
            return cls(**json.load(f))


@lru_cache
def get_settings():
    return Settings()