from langchain.embeddings.base import Embeddings
from langchain.vectorstores.faiss import FAISS
import threading
from contextlib import contextmanager
from collections import OrderedDict
from typing import List, Any, Union, Tuple


class ThreadSafeObject:
    def __init__(self, key: Union[str, Tuple], obj: Any = None, pool: "CachePool" = None):
        self._obj = obj
        self._key = key
        self._pool = pool
        self._lock = threading.RLock()
        self._loaded = threading.Event()

    def __repr__(self) -> str:
        cls = type(self).__name__
        return f"<{cls}: key: {self.key}, obj: {self._obj}>"

    @property
    def key(self):
        return self._key

    @contextmanager
    def acquire(self, owner: str = "", msg: str = "") -> FAISS:
        owner = owner or f"thread {threading.get_native_id()}"
        try:
            self._lock.acquire()
            if self._pool is not None:
                self._pool._cache.move_to_end(self.key)
            yield self._obj
        finally:
            self._lock.release()

    def start_loading(self):
        self._loaded.clear()

    def finish_loading(self):
        self._loaded.set()

    def wait_for_loading(self):
        self._loaded.wait()

    @property
    def obj(self):
        return self._obj

    @obj.setter
    def obj(self, val: Any):
        self._obj = val


class CachePool:
    def __init__(self, cache_num: int = -1):
        self._cache_num = cache_num
        self._cache = OrderedDict()
        self.atomic = threading.RLock()

    def keys(self) -> List[str]:
        return list(self._cache.keys())

    def _check_count(self):
        if isinstance(self._cache_num, int) and self._cache_num > 0:
            while len(self._cache) > self._cache_num:
                self._cache.popitem(last=False)

    def get(self, key: str) -> ThreadSafeObject:
        if cache := self._cache.get(key):
            cache.wait_for_loading()
            return cache

    def set(self, key: str, obj: ThreadSafeObject) -> ThreadSafeObject:
        self._cache[key] = obj
        self._check_count()
        return obj

    def pop(self, key: str = None) -> ThreadSafeObject:
        if key is None:
            return self._cache.popitem(last=False)
        else:
            return self._cache.pop(key, None)

    def acquire(self, key: Union[str, Tuple], owner: str = "", msg: str = ""):
        cache = self.get(key)
        if cache is None:
            raise RuntimeError(f"请求的资源 {key} 不存在")
        elif isinstance(cache, ThreadSafeObject):
            self._cache.move_to_end(key)
            return cache.acquire(owner=owner, msg=msg)
        else:
            return cache

    def load_kb_embeddings(
            self,
            local_model_path,
            embed_device
    ) -> Embeddings:
        return embeddings_pool.load_embeddings(local_model_path=local_model_path, device=embed_device)


class EmbeddingsPool(CachePool):
    def load_embeddings(self, local_model_path, device) -> Embeddings:
        self.atomic.acquire()
        key = (local_model_path, device)
        if not self.get(key):
            item = ThreadSafeObject(key, pool=self)
            self.set(key, item)
            with item.acquire(msg="初始化"):
                self.atomic.release()
                from langchain.embeddings.huggingface import HuggingFaceEmbeddings
                embeddings = HuggingFaceEmbeddings(model_name=local_model_path,
                                                    model_kwargs={'device': device})
                item.obj = embeddings
                item.finish_loading()
        else:
            self.atomic.release()
        return self.get(key).obj


embeddings_pool = EmbeddingsPool(cache_num=1)

import numpy as np

def normalize(embeddings: List[List[float]]) -> np.ndarray:
    '''
    sklearn.preprocessing.normalize 的替代（使用 L2），避免安装 scipy, scikit-learn
    '''
    norm = np.linalg.norm(embeddings, axis=1)
    norm = np.reshape(norm, (norm.shape[0], 1))
    norm = np.tile(norm, (1, len(embeddings[0])))
    return np.divide(embeddings, norm)


class EmbeddingsFunAdapter(Embeddings):
    def __init__(self, embed_local_model_path, device):
        self.embed_local_model_path = embed_local_model_path
        self.device = device

    def embed_documents(self, texts: List[str]) -> List[List[float]]:
        embeddings = embeddings_pool.load_embeddings(
                            model=self.embed_local_model_path, 
                            device=self.device).embed_documents(texts)
        return normalize(embeddings).tolist()

    def embed_query(self, text: str) -> List[float]:
        embeddings =  embeddings_pool.load_embeddings(
                            local_model_path=self.embed_local_model_path, 
                            device=self.device
                        ).embed_documents([text])
        query_embed = embeddings[0]
        query_embed_2d = np.reshape(query_embed, (1, -1))  # 将一维数组转换为二维数组
        normalized_query_embed = normalize(query_embed_2d)
        return normalized_query_embed[0].tolist()  # 将结果转换为一维数组并返回



def embed_documents(
        docs,
        local_model_path,
        device
):

    texts = [x.page_content for x in docs]
    metadatas = [x.metadata for x in docs]

    embeddings_model = embeddings_pool.load_embeddings(local_model_path=local_model_path, device=device)
    embeddings = embeddings_model.embed_documents(texts)
    if embeddings is not None:
        return {
            "texts": texts,
            "embeddings": embeddings,
            "metadatas": metadatas,
        }



class KnowledgeFile:
    def __init__(
            self,
            filename: str,
            knowledge_base_name: str
    ):
        self.kb_name = knowledge_base_name
        self.filename = filename


def torch_gc():
    try:
        import torch
        if torch.cuda.is_available():
            # with torch.cuda.device(DEVICE):
            torch.cuda.empty_cache()
            torch.cuda.ipc_collect()
        elif torch.backends.mps.is_available():
            try:
                from torch.mps import empty_cache
                empty_cache()
            except Exception as e:
                msg = ("如果您使用的是 macOS 建议将 pytorch 版本升级至 2.0.0 或更高版本，"
                       "以支持及时清理 torch 产生的内存占用。")
    except Exception:
        ...