"""
.. todo::
    doc
"""

__all__ = [
    "cached_path",
    "get_filepath",
    "get_cache_path",
    "split_filename_suffix",
    "get_from_cache",
]

import os
import re
import shutil
import tempfile
from pathlib import Path
from urllib.parse import urlparse

import requests
from requests import HTTPError
from tqdm import tqdm

from ..core import logger

PRETRAINED_BERT_MODEL_DIR = {
    'en': 'bert-base-cased.zip',
    'en-large-cased-wwm': 'bert-large-cased-wwm.zip',
    'en-large-uncased-wwm': 'bert-large-uncased-wwm.zip',

    'en-large-uncased': 'bert-large-uncased.zip',
    'en-large-cased': 'bert-large-cased.zip',

    'en-base-uncased': 'bert-base-uncased.zip',
    'en-base-cased': 'bert-base-cased.zip',

    'en-base-cased-mrpc': 'bert-base-cased-finetuned-mrpc.zip',

    'en-distilbert-base-uncased': 'distilbert-base-uncased.zip',

    'multi-base-cased': 'bert-base-multilingual-cased.zip',
    'multi-base-uncased': 'bert-base-multilingual-uncased.zip',

    'cn': 'bert-chinese-wwm.zip',
    'cn-base': 'bert-base-chinese.zip',
    'cn-wwm': 'bert-chinese-wwm.zip',
    'cn-wwm-ext': "bert-chinese-wwm-ext.zip"
}

PRETRAINED_ELMO_MODEL_DIR = {
    'en': 'elmo_en_Medium.zip',
    'en-small': "elmo_en_Small.zip",
    'en-original-5.5b': 'elmo_en_Original_5.5B.zip',
    'en-original': 'elmo_en_Original.zip',
    'en-medium': 'elmo_en_Medium.zip'
}

PRETRAIN_STATIC_FILES = {
    'en': 'glove.840B.300d.zip',

    'en-glove-6b-50d': 'glove.6B.50d.zip',
    'en-glove-6b-100d': 'glove.6B.100d.zip',
    'en-glove-6b-200d': 'glove.6B.200d.zip',
    'en-glove-6b-300d': 'glove.6B.300d.zip',
    'en-glove-42b-300d': 'glove.42B.300d.zip',
    'en-glove-840b-300d': 'glove.840B.300d.zip',
    'en-glove-twitter-27b-25d': 'glove.twitter.27B.25d.zip',
    'en-glove-twitter-27b-50d': 'glove.twitter.27B.50d.zip',
    'en-glove-twitter-27b-100d': 'glove.twitter.27B.100d.zip',
    'en-glove-twitter-27b-200d': 'glove.twitter.27B.200d.zip',

    'en-word2vec-300': "GoogleNews-vectors-negative300.txt.gz",

    'en-fasttext-wiki': "wiki-news-300d-1M.vec.zip",
    'en-fasttext-crawl': "crawl-300d-2M.vec.zip",

    'cn': "tencent_cn.zip",
    'cn-tencent': "tencent_cn.zip",
    'cn-fasttext': "cc.zh.300.vec.gz",
    'cn-sgns-literature-word': 'sgns.literature.word.txt.zip',
    'cn-char-fastnlp-100d': "cn_char_fastnlp_100d.zip",
    'cn-bi-fastnlp-100d': "cn_bi_fastnlp_100d.zip",
    "cn-tri-fastnlp-100d": "cn_tri_fastnlp_100d.zip"
}

DATASET_DIR = {
    # Classification, English
    'aclImdb': "imdb.zip",
    "yelp-review-full": "yelp_review_full.tar.gz",
    "yelp-review-polarity": "yelp_review_polarity.tar.gz",
    "sst-2": "SST-2.zip",
    "sst": "SST.zip",

    # Classification, Chinese
    "chn-senti-corp": "chn_senti_corp.zip",
    "weibo-senti-100k": "WeiboSenti100k.zip",
    "thuc-news": "THUCNews.zip",

    # Matching, English
    "mnli": "MNLI.zip",
    "snli": "SNLI.zip",
    "qnli": "QNLI.zip",
    "rte": "RTE.zip",

    # Matching, Chinese
    "cn-xnli": "XNLI.zip",

    # Sequence Labeling, Chinese
    "msra-ner": "MSRA_NER.zip",
    "peopledaily": "peopledaily.zip",
    "weibo-ner": "weibo_NER.zip",

    # Chinese Word Segmentation
    "cws-pku": 'cws_pku.zip',
    "cws-cityu": "cws_cityu.zip",
    "cws-as": 'cws_as.zip',
    "cws-msra": 'cws_msra.zip',

    # Summarization, English
    "ext-cnndm": "ext-cnndm.zip",

    # Question & answer
    "cmrc2018": "cmrc2018.zip"

}

PRETRAIN_MAP = {'elmo': PRETRAINED_ELMO_MODEL_DIR,
                "bert": PRETRAINED_BERT_MODEL_DIR,
                "static": PRETRAIN_STATIC_FILES}

#  用于扩展fastNLP的下载
FASTNLP_EXTEND_DATASET_URL = 'fastnlp_dataset_url.txt'
FASTNLP_EXTEND_EMBEDDING_URL = {'elmo': 'fastnlp_elmo_url.txt',
                         'bert':'fastnlp_bert_url.txt',
                         'static': 'fastnlp_static_url.txt'
}


def cached_path(url_or_filename: str, cache_dir: str = None, name=None) -> Path:
    """
    给定一个url，尝试通过url中的解析出来的文件名字filename到{cache_dir}/{name}/{filename}下寻找这个文件，
    
    1. 如果cache_dir=None, 则cache_dir=~/.fastNLP/; 否则cache_dir=cache_dir
    2. 如果name=None, 则没有中间的{name}这一层结构；否者中间结构就为{name}

    如果有该文件，就直接返回路径
    
    如果没有该文件，则尝试用传入的url下载

    或者文件名(可以是具体的文件名，也可以是文件夹)，先在cache_dir下寻找该文件是否存在，如果不存在则去下载, 并
    将文件放入到cache_dir中.

    :param str url_or_filename: 文件的下载url或者文件名称。
    :param str cache_dir: 文件的缓存文件夹。如果为None，将使用"~/.fastNLP"这个默认路径
    :param str name: 中间一层的名称。如embedding, dataset
    :return:
    """
    if cache_dir is None:
        data_cache = Path(get_cache_path())
    else:
        data_cache = cache_dir

    if name:
        data_cache = os.path.join(data_cache, name)

    parsed = urlparse(url_or_filename)

    if parsed.scheme in ("http", "https"):
        # URL, so get it from the cache (downloading if necessary)
        return get_from_cache(url_or_filename, Path(data_cache))
    elif parsed.scheme == "" and Path(os.path.join(data_cache, url_or_filename)).exists():
        # File, and it exists.
        return Path(os.path.join(data_cache, url_or_filename))
    elif parsed.scheme == "":
        # File, but it doesn't exist.
        raise FileNotFoundError("file {} not found in {}.".format(url_or_filename, data_cache))
    else:
        # Something unknown
        raise ValueError(
            "unable to parse {} as a URL or as a local path".format(url_or_filename)
        )


def get_filepath(filepath):
    """
    如果filepath为文件夹，
    
        如果内含多个文件, 返回filepath
        
        如果只有一个文件, 返回filepath + filename

    如果filepath为文件
        
        返回filepath

    :param str filepath: 路径
    :return:
    """
    if os.path.isdir(filepath):
        files = os.listdir(filepath)
        if len(files) == 1:
            return os.path.join(filepath, files[0])
        else:
            return filepath
    elif os.path.isfile(filepath):
        return filepath
    else:
        raise FileNotFoundError(f"{filepath} is not a valid file or directory.")


def get_cache_path():
    """
    获取fastNLP默认cache的存放路径, 如果将FASTNLP_CACHE_PATH设置在了环境变量中，将使用环境变量的值，使得不用每个用户都去下载。

    :return str:  存放路径
    """
    if 'FASTNLP_CACHE_DIR' in os.environ:
        fastnlp_cache_dir = os.environ.get('FASTNLP_CACHE_DIR')
        if os.path.isdir(fastnlp_cache_dir):
            return fastnlp_cache_dir
        else:
            raise NotADirectoryError(f"{os.environ['FASTNLP_CACHE_DIR']} is not a directory.")
    fastnlp_cache_dir = os.path.expanduser(os.path.join("~", ".fastNLP"))
    return fastnlp_cache_dir


def _get_base_url(name):
    """
    根据name返回下载的url地址。

    :param str name: 支持dataset和embedding两种
    :return:
    """
    # 返回的URL结尾必须是/
    environ_name = "FASTNLP_{}_URL".format(name.upper())

    if environ_name in os.environ:
        url = os.environ[environ_name]
        if url.endswith('/'):
            return url
        else:
            return url + '/'
    else:
        URLS = {
            'embedding': "http://212.129.155.247/embedding/",
            "dataset": "http://212.129.155.247/dataset/"
        }
        if name.lower() not in URLS:
            raise KeyError(f"{name} is not recognized.")
        return URLS[name.lower()]


def _get_embedding_url(embed_type, name):
    """
    给定embedding类似和名称，返回下载url

    :param str embed_type: 支持static, bert, elmo。即embedding的类型
    :param str name: embedding的名称, 例如en, cn, based等
    :return: str, 下载的url地址
    """
    #  从扩展中寻找下载的url
    _filename = FASTNLP_EXTEND_EMBEDDING_URL.get(embed_type, None)
    if _filename:
        url = _read_extend_url_file(_filename, name)
        if url:
            return url
    embed_map = PRETRAIN_MAP.get(embed_type, None)
    if embed_map:
        filename = embed_map.get(name, None)
        if filename:
            url = _get_base_url('embedding') + filename
            return url
        raise KeyError("There is no {}. Only supports {}.".format(name, list(embed_map.keys())))
    else:
        raise KeyError(f"There is no {embed_type}. Only supports bert, elmo, static")

def _read_extend_url_file(filename, name)->str:
    """
    filename中的内容使用制表符隔开，第一列是名称，第二列是下载的url地址

    :param str filename: 在默认的路径下寻找file这个文件
    :param str name: 需要寻找的资源的名称
    :return: str or None
    """
    cache_dir = get_cache_path()
    filepath = os.path.join(cache_dir, filename)
    if os.path.exists(filepath):
        with open(filepath, 'r', encoding='utf-8') as f:
            for line in f:
                line = line.strip()
                if line:
                    parts = line.split('\t')
                    if len(parts) == 2:
                        if name == parts[0]:
                            return parts[1]
    return None

def _get_dataset_url(name):
    """
    给定dataset的名称，返回下载url

    :param str name: 给定dataset的名称，比如imdb, sst-2等
    :return: str
    """
    #  从扩展中寻找下载的url
    url = _read_extend_url_file(FASTNLP_EXTEND_DATASET_URL, name)
    if url:
        return url

    filename = DATASET_DIR.get(name, None)
    if filename:
        url = _get_base_url('dataset') + filename
        return url
    else:
        raise KeyError(f"There is no {name}.")


def split_filename_suffix(filepath):
    """
    给定filepath 返回对应的name和suffix. 如果后缀是多个点，仅支持.tar.gz类型
    
    :param filepath: 文件路径
    :return: filename, suffix
    """
    filename = os.path.basename(filepath)
    if filename.endswith('.tar.gz'):
        return filename[:-7], '.tar.gz'
    return os.path.splitext(filename)


def get_from_cache(url: str, cache_dir: Path = None) -> Path:
    """
    尝试在cache_dir中寻找url定义的资源; 如果没有找到; 则从url下载并将结果放在cache_dir下，缓存的名称由url的结果推断而来。会将下载的
    文件解压，将解压后的文件全部放在cache_dir文件夹中。

    如果从url中下载的资源解压后有多个文件，则返回目录的路径; 如果只有一个资源文件，则返回具体的路径。
    
    :param url: 资源的 url
    :param cache_dir: cache 目录
    :return: 路径
    """
    cache_dir.mkdir(parents=True, exist_ok=True)

    filename = re.sub(r".+/", "", url)
    dir_name, suffix = split_filename_suffix(filename)

    # 寻找与它名字匹配的内容, 而不关心后缀
    match_dir_name = match_file(dir_name, cache_dir)
    if match_dir_name:
        dir_name = match_dir_name
    cache_path = cache_dir / dir_name

    # get cache path to put the file
    if cache_path.exists():
        return get_filepath(cache_path)

    # make HEAD request to check ETag TODO ETag可以用来判断资源是否已经更新了，之后需要加上
    # response = requests.head(url, headers={"User-Agent": "fastNLP"})
    # if response.status_code != 200:
    #     raise IOError(
    #         f"HEAD request failed for url {url} with status code {response.status_code}."
    #     )

    # add ETag to filename if it exists
    # etag = response.headers.get("ETag")

    if not cache_path.exists():
        # Download to temporary file, then copy to cache dir once finished.
        # Otherwise you get corrupt cache entries if the download gets interrupted.
        # GET file object
        req = requests.get(url, stream=True, headers={"User-Agent": "fastNLP"})
        if req.status_code == 200:
            success = False
            fd, temp_filename = tempfile.mkstemp()
            uncompress_temp_dir = None
            try:
                content_length = req.headers.get("Content-Length")
                total = int(content_length) if content_length is not None else None
                progress = tqdm(unit="B", total=total, unit_scale=1)
                logger.info("%s not found in cache, downloading to %s" % (url, temp_filename))

                with open(temp_filename, "wb") as temp_file:
                    for chunk in req.iter_content(chunk_size=1024 * 16):
                        if chunk:  # filter out keep-alive new chunks
                            progress.update(len(chunk))
                            temp_file.write(chunk)
                progress.close()
                logger.info(f"Finish download from {url}")

                # 开始解压
                if suffix in ('.zip', '.tar.gz', '.gz'):
                    uncompress_temp_dir = tempfile.mkdtemp()
                    logger.debug(f"Start to uncompress file to {uncompress_temp_dir}")
                    if suffix == '.zip':
                        unzip_file(Path(temp_filename), Path(uncompress_temp_dir))
                    elif suffix == '.gz':
                        ungzip_file(temp_filename, uncompress_temp_dir, dir_name)
                    else:
                        untar_gz_file(Path(temp_filename), Path(uncompress_temp_dir))
                    filenames = os.listdir(uncompress_temp_dir)
                    if len(filenames) == 1:
                        if os.path.isdir(os.path.join(uncompress_temp_dir, filenames[0])):
                            uncompress_temp_dir = os.path.join(uncompress_temp_dir, filenames[0])

                    cache_path.mkdir(parents=True, exist_ok=True)
                    logger.debug("Finish un-compressing file.")
                else:
                    uncompress_temp_dir = temp_filename
                    cache_path = str(cache_path) + suffix

                # 复制到指定的位置
                logger.info(f"Copy file to {cache_path}")
                if os.path.isdir(uncompress_temp_dir):
                    for filename in os.listdir(uncompress_temp_dir):
                        if os.path.isdir(os.path.join(uncompress_temp_dir, filename)):
                            shutil.copytree(os.path.join(uncompress_temp_dir, filename), cache_path / filename)
                        else:
                            shutil.copyfile(os.path.join(uncompress_temp_dir, filename), cache_path / filename)
                else:
                    shutil.copyfile(uncompress_temp_dir, cache_path)
                success = True
            except Exception as e:
                logger.error(e)
                raise e
            finally:
                if not success:
                    if cache_path.exists():
                        if cache_path.is_file():
                            os.remove(cache_path)
                        else:
                            shutil.rmtree(cache_path)
                os.close(fd)
                os.remove(temp_filename)
                if os.path.isdir(uncompress_temp_dir):
                    shutil.rmtree(uncompress_temp_dir)
                elif os.path.isfile(uncompress_temp_dir):
                    os.remove(uncompress_temp_dir)
            return get_filepath(cache_path)
        else:
            raise HTTPError(f"Status code:{req.status_code}. Fail to download from {url}.")


def unzip_file(file: Path, to: Path):
    # unpack and write out in CoNLL column-like format
    from zipfile import ZipFile

    with ZipFile(file, "r") as zipObj:
        # Extract all the contents of zip file in current directory
        zipObj.extractall(to)


def untar_gz_file(file: Path, to: Path):
    import tarfile

    with tarfile.open(file, 'r:gz') as tar:
        tar.extractall(to)


def ungzip_file(file: str, to: str, filename:str):
    import gzip

    g_file = gzip.GzipFile(file)
    with open(os.path.join(to, filename), 'wb+') as f:
        f.write(g_file.read())
    g_file.close()


def match_file(dir_name: str, cache_dir: Path) -> str:
    """
    匹配的原则是: 在cache_dir下的文件与dir_name完全一致, 或除了后缀以外和dir_name完全一致。
    如果找到了两个匹配的结果将报错. 如果找到了则返回匹配的文件的名称; 没有找到返回空字符串

    :param dir_name: 需要匹配的名称
    :param cache_dir: 在该目录下找匹配dir_name是否存在
    :return str: 做为匹配结果的字符串
    """
    files = os.listdir(cache_dir)
    matched_filenames = []
    for file_name in files:
        if re.match(dir_name + '$', file_name) or re.match(dir_name + '\\..*', file_name):
            matched_filenames.append(file_name)
    if len(matched_filenames) == 0:
        return ''
    elif len(matched_filenames) == 1:
        return matched_filenames[-1]
    else:
        raise RuntimeError(f"Duplicate matched files:{matched_filenames}, this should be caused by a bug.")
