import os
import shutil

from configs.model_config import KB_ROOT_PATH, CACHED_VS_NUM, EMBEDDING_MODEL, EMBEDDING_DEVICE
from server.knowledge_base.kb_service.base import KBService, SupportedVSType
from functools import lru_cache
from server.knowledge_base.utils import get_vs_path, load_embeddings, KnowledgeFile
from langchain.vectorstores import FAISS
from langchain.embeddings.base import Embeddings
from langchain.embeddings.huggingface import HuggingFaceEmbeddings
from typing import List
from langchain.docstore.document import Document
from server.utils import torch_gc
import numpy as np


# make HuggingFaceEmbeddings hashable
def _embeddings_hash(self):
    return hash(self.model_name)
HuggingFaceEmbeddings.__hash__ = _embeddings_hash


_VECTOR_STORE_TICKS = {}


@lru_cache(CACHED_VS_NUM)
def load_vector_store(
        knowledge_base_name: str,
        embed_model: str = EMBEDDING_MODEL,
        embed_device: str = EMBEDDING_DEVICE,
        embeddings: Embeddings = None,
        tick: int = 0,  # tick will be changed by upload_doc etc. and make cache refreshed.
):
    print(f"loading vector store in '{knowledge_base_name}'.")
    vs_path = get_vs_path(knowledge_base_name)
    if embeddings is None:
        embeddings = load_embeddings(embed_model, embed_device)
    search_index = FAISS.load_local(vs_path, embeddings)
    return search_index


def refresh_vs_cache(kb_name: str):
    """
    make vector store cache refreshed when next loading
    """
    _VECTOR_STORE_TICKS[kb_name] = _VECTOR_STORE_TICKS.get(kb_name, 0) + 1


def delete_doc_from_faiss(vector_store: FAISS, ids: List[str]):
    overlapping = set(ids).intersection(vector_store.index_to_docstore_id.values())
    if not overlapping:
        raise ValueError("ids do not exist in the current object")
    _reversed_index = {v: k for k, v in vector_store.index_to_docstore_id.items()}
    index_to_delete = [_reversed_index[i] for i in ids]
    vector_store.index.remove_ids(np.array(index_to_delete, dtype=np.int64))
    for _id in index_to_delete:
        del vector_store.index_to_docstore_id[_id]
    # Remove items from docstore.
    overlapping2 = set(ids).intersection(vector_store.docstore._dict)
    if not overlapping2:
        raise ValueError(f"Tried to delete ids that does not  exist: {ids}")
    for _id in ids:
        vector_store.docstore._dict.pop(_id)
    return vector_store


class FaissKBService(KBService):
    vs_path: str
    kb_path: str

    def vs_type(self) -> str:
        return SupportedVSType.FAISS

    @staticmethod
    def get_vs_path(knowledge_base_name: str):
        return os.path.join(FaissKBService.get_kb_path(knowledge_base_name), "vector_store")

    @staticmethod
    def get_kb_path(knowledge_base_name: str):
        return os.path.join(KB_ROOT_PATH, knowledge_base_name)

    def do_init(self):
        self.kb_path = FaissKBService.get_kb_path(self.kb_name)
        self.vs_path = FaissKBService.get_vs_path(self.kb_name)

    def do_create_kb(self):
        if not os.path.exists(self.vs_path):
            os.makedirs(self.vs_path)

    def do_drop_kb(self):
        shutil.rmtree(self.kb_path)

    def do_search(self,
                  query: str,
                  top_k: int,
                  embeddings: Embeddings,
                  ) -> List[Document]:
        search_index = load_vector_store(self.kb_name,
                                         embeddings=embeddings,
                                         tick=_VECTOR_STORE_TICKS.get(self.kb_name))
        docs = search_index.similarity_search(query, k=top_k)
        return docs

    def do_add_doc(self,
                   docs: List[Document],
                   embeddings: Embeddings,
                   ):
        if os.path.exists(self.vs_path) and "index.faiss" in os.listdir(self.vs_path):
            vector_store = FAISS.load_local(self.vs_path, embeddings)
            vector_store.add_documents(docs)
            torch_gc()
        else:
            if not os.path.exists(self.vs_path):
                os.makedirs(self.vs_path)
            vector_store = FAISS.from_documents(
                docs, embeddings)  # docs 为Document列表
            torch_gc()
        vector_store.save_local(self.vs_path)
        refresh_vs_cache(self.kb_name)

    def do_delete_doc(self,
                  kb_file: KnowledgeFile):
        embeddings = self._load_embeddings()
        if os.path.exists(self.vs_path) and "index.faiss" in os.listdir(self.vs_path):
            vector_store = FAISS.load_local(self.vs_path, embeddings)
            ids = [k for k, v in vector_store.docstore._dict.items() if v.metadata["source"] == kb_file.filepath]
            if len(ids) == 0:
                return None
            vector_store = delete_doc_from_faiss(vector_store, ids)
            vector_store.save_local(self.vs_path)
            refresh_vs_cache(self.kb_name)
            return True
        else:
            return None

    def do_clear_vs(self):
        shutil.rmtree(self.vs_path)
        os.makedirs(self.vs_path)