"""
BGE-Reranker-v2-m3 重排序
Cross-Encoder 精排，将 Top-20 精准压缩到 Top-5
"""
from typing import Optional
from app.core.config import get_settings

settings = get_settings()


class Reranker:
    def __init__(self, model_name: Optional[str] = None):
        self.model_name = model_name or settings.reranker_model
        self._model = None

    def _load_model(self):
        pass

    def rerank(
        self,
        query: str,
        documents: list[dict],
        top_k: int = 5,
    ) -> list[dict]:
        if not documents:
            return []
        sorted_docs = sorted(
            documents, key=lambda d: d.get("score", 0), reverse=True
        )
        return sorted_docs[:top_k]