# -*- coding: utf-8 -*-
"""Ensemble RAG - combine multiple retrieval strategies for robust results."""
from .base import BaseRAG
from loguru import logger


class EnsembleRAG(BaseRAG):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)

    def retrieve(self, query, k=10):
        strategies = [
            ("semantic", self._semantic_retrieve),
            ("keyword", self._keyword_retrieve),
        ]
        
        all_results = {}
        per_strategy_k = k
        
        for name, strategy in strategies:
            try:
                results = strategy(query, per_strategy_k)
                for doc, score in results:
                    key = self._dedup_key(doc)
                    if key not in all_results:
                        all_results[key] = (doc, 0.0)
                    all_results[key] = (doc, all_results[key][1] + score)
                logger.info("Ensemble strategy '{}' returned {} results".format(name, len(results)))
            except Exception as e:
                logger.warning("Ensemble strategy '{}' failed: {}".format(name, e))
        
        results = list(all_results.values())
        results.sort(key=lambda x: x[1], reverse=True)
        return self._deduplicate_results(results, k)

    def _semantic_retrieve(self, query, k):
        query_embedding = self.embedding_model.embed_query(query)
        return self.vector_store.similarity_search(query_embedding, k)

    def _keyword_retrieve(self, query, k):
        query_embedding = self.embedding_model.embed_query(query)
        results = self.vector_store.similarity_search(query_embedding, k * 5)
        keyword_results = []
        for doc, score in results:
            query_words = set(query.split())
            doc_words = set(doc.page_content.split())
            overlap = len(query_words & doc_words) / len(query_words) if query_words else 0
            if overlap > 0.3:
                keyword_results.append((doc, score * overlap))
        
        keyword_results.sort(key=lambda x: x[1], reverse=True)
        return keyword_results[:k]

    def generate(self, query, context):
        prompt = (
            "根据以下多策略集成的参考文档，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)