# -*- coding: utf-8 -*-
"""TF-IDF RAG - term frequency-inverse document frequency retrieval."""
from .base import BaseRAG, RAGResult
from loguru import logger


class TFIDFRAG(BaseRAG):
    def __init__(self, llm_client=None, llm_model="gpt-4o", **kwargs):
        self.embedding_model = None
        self.vector_store = None
        self.llm_client = llm_client
        self.llm_model = llm_model
        self.name = self.__class__.__name__
        self.vectorizer = None
        self.tfidf_matrix = None
        self._all_documents = []

    def index_documents(self, documents):
        self._all_documents = documents
        texts = [doc.page_content for doc in documents]
        from sklearn.feature_extraction.text import TfidfVectorizer
        self.vectorizer = TfidfVectorizer()
        self.tfidf_matrix = self.vectorizer.fit_transform(texts)
        logger.info("TF-IDF index built with {} documents, vocab size: {}".format(len(documents), len(self.vectorizer.vocabulary_)))

    def retrieve(self, query, k=10):
        if self.tfidf_matrix is None:
            return []
        
        from sklearn.metrics.pairwise import cosine_similarity
        query_vec = self.vectorizer.transform([query])
        scores = cosine_similarity(query_vec, self.tfidf_matrix).flatten()

        import numpy as np
        top_indices = np.argsort(scores)[::-1]

        results = []
        for idx in top_indices:
            if scores[idx] > 0:
                results.append((self._all_documents[idx], float(scores[idx])))

        return self._deduplicate_results(results, k)

    def generate(self, query, context):
        prompt = (
            "根据以下参考文档（TF-IDF关键词检索），回答问题。\n\n"
            "参考文档：\n{}\n\n"
            "问题：{}\n\n"
            "请详细回答。".format(context, query)
        )
        return self._call_llm(prompt)

    def query(self, query, k=10):
        import time
        start_total = time.time()
        
        t0 = time.time()
        docs = self.retrieve(query, k)
        retrieval_time = time.time() - t0

        context = self._format_context(docs)

        t1 = time.time()
        answer = self.generate(query, context)
        generation_time = time.time() - t1

        total_time = time.time() - start_total

        return RAGResult(
            answer=answer,
            retrieved_docs=docs,
            latency_retrieval=retrieval_time,
            latency_generation=generation_time,
            latency_total=total_time,
            metadata={"method": self.name, "num_context_tokens": len(context)},
        )