import logging
from tqdm import tqdm, trange
from abc import ABC, abstractmethod
from typing import Any, Union, List, Dict, Literal, Optional

import queue
import multiprocessing as mp
from multiprocessing import Queue

import math
import gc
import torch
import numpy as np
from transformers import is_torch_npu_available

try:
    import torch_musa
except Exception:
    pass

logger = logging.getLogger(__name__)


class AbsEmbedder(ABC):
    """
    Base class for embedder.
    Extend this class and implement :meth:`encode_queries`, :meth:`encode_corpus`, :meth:`encode` for custom embedders.

    Args:
        model_name_or_path (str): If it's a path to a local model, it loads the model from the path. Otherwise tries to download and
            load a model from HuggingFace Hub with the name.
        normalize_embeddings (bool, optional): If True, normalize the embedding vector. Defaults to :data:`True`.
        use_fp16 (bool, optional): If true, use half-precision floating-point to speed up computation with a slight performance 
            degradation. Defaults to :data:`True`.
        query_instruction_for_retrieval: (Optional[str], optional): Query instruction for retrieval tasks, which will be used with
            with :attr:`query_instruction_format`. Defaults to :data:`None`.
        query_instruction_format: (str, optional): The template for :attr:`query_instruction_for_retrieval`. Defaults to :data:`"{}{}"`.
        devices (Optional[Union[str, int, List[str], List[int]]], optional): Devices to use for model inference. Defaults to :data:`None`.
        batch_size (int, optional): Batch size for inference. Defaults to :data:`256`.
        query_max_length (int, optional): Maximum length for query. Defaults to :data:`512`.
        passage_max_length (int, optional): Maximum length for passage. Defaults to :data:`512`.
        convert_to_numpy (bool, optional): If True, the output embedding will be a Numpy array. Otherwise, it will be a Torch Tensor. 
            Defaults to :data:`True`.
        kwargs (Dict[Any], optional): Additional parameters for HuggingFace Transformers config or children classes.
    """

    def __init__(
        self,
        model_name_or_path: str,
        normalize_embeddings: bool = True,
        use_fp16: bool = True,
        query_instruction_for_retrieval: Optional[str] = None,
        query_instruction_format: str = "{}{}",  # specify the format of query_instruction_for_retrieval
        devices: Optional[Union[str, int, List[str], List[int]]] = None,
        # inference
        batch_size: int = 256,
        query_max_length: int = 512,
        passage_max_length: int = 512,
        convert_to_numpy: bool = True,
        **kwargs: Any,
    ):
        self.model_name_or_path = model_name_or_path
        self.normalize_embeddings = normalize_embeddings
        self.use_fp16 = use_fp16
        self.query_instruction_for_retrieval = query_instruction_for_retrieval
        self.query_instruction_format = query_instruction_format
        self.target_devices = self.get_target_devices(devices)

        self.batch_size = batch_size
        self.query_max_length = query_max_length
        self.passage_max_length = passage_max_length
        self.convert_to_numpy = convert_to_numpy

        for k in kwargs:
            setattr(self, k, kwargs[k])

        self.kwargs = kwargs

        # tokenizer and model are initialized in the child class
        self.tokenizer = None
        self.model = None
        self.pool = None

    def stop_self_pool(self):
        if self.pool is not None:
            self.stop_multi_process_pool(self.pool)
            self.pool = None
        try:
            self.model.to('cpu')
            torch.cuda.empty_cache()
        except:
            pass
        if gc is not None and callable(gc.collect):
            gc.collect()

    @staticmethod
    def get_target_devices(devices: Union[str, int, List[str], List[int]]) -> List[str]:
        """

        Args:
            devices (Union[str, int, List[str], List[int]]): specified devices, can be `str`, `int`, list of `str`, or list of `int`.

        Raises:
            ValueError: Devices should be a string or an integer or a list of strings or a list of integers.

        Returns:
            List[str]: A list of target devices in format.
        """
        if devices is None:
            if torch.cuda.is_available():
                return [f"cuda:{i}" for i in range(torch.cuda.device_count())]
            elif is_torch_npu_available():
                return [f"npu:{i}" for i in range(torch.npu.device_count())]
            elif hasattr(torch, "musa") and torch.musa.is_available():
                return [f"musa:{i}" for i in range(torch.musa.device_count())]
            elif torch.backends.mps.is_available():
                try:
                    return [f"mps:{i}" for i in range(torch.mps.device_count())]
                except:
                    return ["mps"]
            else:
                return ["cpu"]
        elif isinstance(devices, str):
            return [devices]
        elif isinstance(devices, int):
            if hasattr(torch, "musa") and torch.musa.is_available():
                return [f"musa:{devices}"]
            else:
                return [f"cuda:{devices}"]
        elif isinstance(devices, list):
            if isinstance(devices[0], str):
                return devices
            elif isinstance(devices[0], int):
                if hasattr(torch, "musa") and torch.musa.is_available():
                    return [f"musa:{device}" for device in devices]
                else:
                    return [f"cuda:{device}" for device in devices]
            else:
                raise ValueError("devices should be a string or an integer or a list of strings or a list of integers.")
        else:
            raise ValueError("devices should be a string or an integer or a list of strings or a list of integers.")

    @staticmethod
    def get_detailed_instruct(instruction_format: str, instruction: str, sentence: str):
        """Combine the instruction and sentence along with the instruction format.

        Args:
            instruction_format (str): Format for instruction.
            instruction (str): The text of instruction.
            sentence (str): The sentence to concatenate with.

        Returns:
            str: The complete sentence with instruction
        """
        if "\\n" in instruction_format:
            instruction_format = instruction_format.replace("\\n", "\n")
        return instruction_format.format(instruction, sentence)

    def encode_queries(
        self,
        queries: Union[List[str], str],
        batch_size: Optional[int] = None,
        max_length: Optional[int] = None,
        convert_to_numpy: Optional[bool] = None,
        **kwargs: Any
    ):
        """encode the queries using the instruction if provided.

        Args:
            queries (Union[List[str], str]): Input queries to encode.
            batch_size (Optional[int], optional): Number of sentences for each iter. Defaults to :data:`None`.
            max_length (Optional[int], optional): Maximum length of tokens. Defaults to :data:`None`.
            convert_to_numpy (Optional[bool], optional): If True, the output embedding will be a Numpy array. Otherwise, it will 
                be a Torch Tensor. Defaults to :data:`None`.

        Returns:
            Union[torch.Tensor, np.ndarray]: Return the embedding vectors in a numpy array or tensor.
        """
        if batch_size is None: batch_size = self.batch_size
        if max_length is None: max_length = self.query_max_length
        if convert_to_numpy is None: convert_to_numpy = self.convert_to_numpy

        return self.encode(
            queries,
            batch_size=batch_size,
            max_length=max_length,
            convert_to_numpy=convert_to_numpy,
            instruction=self.query_instruction_for_retrieval,
            instruction_format=self.query_instruction_format,
            **kwargs
        )

    def encode_corpus(
        self,
        corpus: Union[List[str], str],
        batch_size: Optional[int] = None,
        max_length: Optional[int] = None,
        convert_to_numpy: Optional[bool] = None,
        **kwargs: Any
    ):
        """encode the corpus using the instruction if provided.

        Args:
            corpus (Union[List[str], str]): Input corpus to encode.
            batch_size (Optional[int], optional): Number of sentences for each iter. Defaults to :data:`None`.
            max_length (Optional[int], optional): Maximum length of tokens. Defaults to :data:`None`.
            convert_to_numpy (Optional[bool], optional): If True, the output embedding will be a Numpy array. Otherwise, it will 
                be a Torch Tensor. Defaults to :data:`None`.

        Returns:
            Union[torch.Tensor, np.ndarray]: Return the embedding vectors in a numpy array or tensor.
        """
        passage_instruction_for_retrieval = self.kwargs.get("passage_instruction_for_retrieval", None)
        passage_instruction_format = self.kwargs.get("passage_instruction_format", "{}{}")

        if batch_size is None: batch_size = self.batch_size
        if max_length is None: max_length = self.passage_max_length
        if convert_to_numpy is None: convert_to_numpy = self.convert_to_numpy

        return self.encode(
            corpus,
            batch_size=batch_size,
            max_length=max_length,
            convert_to_numpy=convert_to_numpy,
            instruction=passage_instruction_for_retrieval,
            instruction_format=passage_instruction_format,
            **kwargs
        )

    def encode(
        self,
        sentences: Union[List[str], str],
        batch_size: Optional[int] = None,
        max_length: Optional[int] = None,
        convert_to_numpy: Optional[bool] = None,
        instruction: Optional[str] = None,
        instruction_format: Optional[str] = None,
        **kwargs: Any
    ):
        """encode the input sentences with the embedding model.

        Args:
            sentences (Union[List[str], str]): Input sentences to encode.
            batch_size (Optional[int], optional): Number of sentences for each iter. Defaults to :data:`None`.
            max_length (Optional[int], optional): Maximum length of tokens. Defaults to :data:`None`.
            convert_to_numpy (Optional[bool], optional): If True, the output embedding will be a Numpy array. Otherwise, it will 
                be a Torch Tensor. Defaults to :data:`None`.
            instruction (Optional[str], optional): The text of instruction. Defaults to :data:`None`.
            instruction_format (Optional[str], optional): Format for instruction. Defaults to :data:`None`.

        Returns:
            Union[torch.Tensor, np.ndarray]: return the embedding vectors in a numpy array or tensor.
        """
        if batch_size is None: batch_size = self.batch_size
        if max_length is None: max_length = self.passage_max_length
        if convert_to_numpy is None: convert_to_numpy = self.convert_to_numpy

        if instruction is not None:
            if isinstance(sentences, str):
                sentences = self.get_detailed_instruct(instruction_format, instruction, sentences)
            else:
                sentences = [self.get_detailed_instruct(instruction_format, instruction, sentence) for sentence in
                             sentences]

        if isinstance(sentences, str) or len(self.target_devices) == 1:
            return self.encode_single_device(
                sentences,
                batch_size=batch_size,
                max_length=max_length,
                convert_to_numpy=convert_to_numpy,
                device=self.target_devices[0],
                **kwargs
            )

        if self.pool is None:
            self.pool = self.start_multi_process_pool(AbsEmbedder._encode_multi_process_worker)
        embeddings = self.encode_multi_process(
            sentences,
            self.pool,
            batch_size=batch_size,
            max_length=max_length,
            convert_to_numpy=convert_to_numpy,
            **kwargs
        )
        return embeddings

    def __del__(self):
        self.stop_self_pool()

    @abstractmethod
    def encode_single_device(
        self,
        sentences: Union[List[str], str],
        batch_size: int = 256,
        max_length: int = 512,
        convert_to_numpy: bool = True,
        device: Optional[str] = None,
        **kwargs: Any,
    ):
        """
        This method should encode sentences and return embeddings on a single device.
        """
        pass

    # adapted from https://github.com/UKPLab/sentence-transformers/blob/1802076d4eae42ff0a5629e1b04e75785d4e193b/sentence_transformers/SentenceTransformer.py#L807
    def start_multi_process_pool(
        self,
        process_target_func: Any,
    ) -> Dict[Literal["input", "output", "processes"], Any]:
        """
        Starts a multi-process pool to process the encoding with several independent processes
        via :meth:`SentenceTransformer.encode_multi_process <sentence_transformers.SentenceTransformer.encode_multi_process>`.

        This method is recommended if you want to encode on multiple GPUs or CPUs. It is advised
        to start only one process per GPU. This method works together with encode_multi_process
        and stop_multi_process_pool.

        Returns:
            Dict[str, Any]: A dictionary with the target processes, an input queue, and an output queue.
        """
        if self.model is None:
            raise ValueError("Model is not initialized.")

        logger.info("Start multi-process pool on devices: {}".format(", ".join(map(str, self.target_devices))))

        self.model.to("cpu")
        self.model.share_memory()
        ctx = mp.get_context("spawn")
        input_queue = ctx.Queue()
        output_queue = ctx.Queue()
        processes = []

        for device_id in tqdm(self.target_devices, desc='initial target device'):
            p = ctx.Process(
                target=process_target_func,
                args=(device_id, self, input_queue, output_queue),
                daemon=True,
            )
            p.start()
            processes.append(p)

        return {"input": input_queue, "output": output_queue, "processes": processes}

    # adapted from https://github.com/UKPLab/sentence-transformers/blob/1802076d4eae42ff0a5629e1b04e75785d4e193b/sentence_transformers/SentenceTransformer.py#L976
    @staticmethod
    def _encode_multi_process_worker(
        target_device: str, model: 'AbsEmbedder', input_queue: Queue, results_queue: Queue
    ) -> None:
        """
        Internal working process to encode sentences in multi-process setup
        """
        while True:
            try:
                chunk_id, sentences, kwargs = (
                    input_queue.get()
                )
                embeddings = model.encode_single_device(
                    sentences,
                    device=target_device,
                    **kwargs
                )

                results_queue.put([chunk_id, embeddings])
            except queue.Empty:
                break

    # copied from https://github.com/UKPLab/sentence-transformers/blob/1802076d4eae42ff0a5629e1b04e75785d4e193b/sentence_transformers/SentenceTransformer.py#L857
    @staticmethod
    def stop_multi_process_pool(pool: Dict[Literal["input", "output", "processes"], Any]) -> None:
        """
        Stops all processes started with start_multi_process_pool.

        Args:
            pool (Dict[str, object]): A dictionary containing the input queue, output queue, and process list.

        Returns:
            None
        """
        for p in pool["processes"]:
            p.terminate()

        for p in pool["processes"]:
            p.join()
            p.close()

        pool["input"].close()
        pool["output"].close()
        pool = None

    # adapted from https://github.com/UKPLab/sentence-transformers/blob/1802076d4eae42ff0a5629e1b04e75785d4e193b/sentence_transformers/SentenceTransformer.py#L877
    def encode_multi_process(
        self,
        sentences: List[str],
        pool: Dict[Literal["input", "output", "processes"], Any],
        **kwargs
    ):
        chunk_size = math.ceil(len(sentences) / len(pool["processes"]))

        input_queue = pool["input"]
        last_chunk_id = 0
        chunk = []

        for sentence in sentences:
            chunk.append(sentence)
            if len(chunk) >= chunk_size:
                input_queue.put(
                    [last_chunk_id, chunk, kwargs]
                )
                last_chunk_id += 1
                chunk = []

        if len(chunk) > 0:
            input_queue.put([last_chunk_id, chunk, kwargs])
            last_chunk_id += 1

        output_queue = pool["output"]
        results_list = sorted(
            [output_queue.get() for _ in trange(last_chunk_id, desc="Chunks")],
            key=lambda x: x[0],
        )
        embeddings = self._concatenate_results_from_multi_process([result[1] for result in results_list])
        return embeddings

    def _concatenate_results_from_multi_process(self, results_list: List[Union[torch.Tensor, np.ndarray, Any]]):
        """concatenate and return the results from all the processes

        Args:
            results_list (List[Union[torch.Tensor, np.ndarray, Any]]): A list of results from all the processes.

        Raises:
            NotImplementedError: Unsupported type for results_list

        Returns:
            Union[torch.Tensor, np.ndarray]: return the embedding vectors in a numpy array or tensor.
        """
        if isinstance(results_list[0], torch.Tensor):
            # move all tensors to the same device
            results_list = [res.to(self.target_devices[0]) for res in results_list]
            return torch.cat(results_list, dim=0)
        elif isinstance(results_list[0], np.ndarray):
            return np.concatenate(results_list, axis=0)
        else:
            raise NotImplementedError("Unsupported type for results_list")
