#   Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import hashlib
import os
import os.path as osp
import shutil
import subprocess
import tarfile
import time
import zipfile

import requests
from tqdm import tqdm

from .log import logger

__all__ = ['get_path_from_url']

DOWNLOAD_RETRY_LIMIT = 3


def _is_url(path):
    """
    Whether path is URL.
    Args:
        path (string): URL string or not.
    """
    return path.startswith('http://') or path.startswith('https://')


def _map_path(url, root_dir):
    # parse path after download under root_dir
    fname = osp.split(url)[-1]
    fpath = fname
    return osp.join(root_dir, fpath)


def _get_unique_endpoints(trainer_endpoints):
    # Sorting is to avoid different environmental variables for each card
    trainer_endpoints.sort()
    ips = set()
    unique_endpoints = set()
    for endpoint in trainer_endpoints:
        ip = endpoint.split(":")[0]
        if ip in ips:
            continue
        ips.add(ip)
        unique_endpoints.add(endpoint)
    logger.debug("unique_endpoints {}".format(unique_endpoints))
    return unique_endpoints


def get_path_from_url(url,
                      root_dir,
                      md5sum=None,
                      check_exist=True,
                      decompress=True,
                      method='get'):
    """ Download from given url to root_dir.
    if file or directory specified by url is exists under
    root_dir, return the path directly, otherwise download
    from url and decompress it, return the path.
    Args:
        url (str): download url
        root_dir (str): root dir for downloading, it should be
                        WEIGHTS_HOME or DATASET_HOME
        md5sum (str): md5 sum of download package
        decompress (bool): decompress zip or tar file. Default is `True`
        method (str): which download method to use. Support `wget` and `get`. Default is `get`.
    Returns:
        str: a local path to save downloaded models & weights & datasets.
    """

    from paddle.distributed import ParallelEnv

    assert _is_url(url), "downloading from {} not a url".format(url)
    # parse path after download to decompress under root_dir
    fullpath = _map_path(url, root_dir)
    # Mainly used to solve the problem of downloading data from different 
    # machines in the case of multiple machines. Different ips will download 
    # data, and the same ip will only download data once.
    unique_endpoints = _get_unique_endpoints(ParallelEnv().trainer_endpoints[:])
    if osp.exists(fullpath) and check_exist and _md5check(fullpath, md5sum):
        logger.debug("Found {}".format(fullpath))
    else:
        if ParallelEnv().current_endpoint in unique_endpoints:
            fullpath = _download(url, root_dir, md5sum, method=method)
        else:
            while not os.path.exists(fullpath):
                time.sleep(1)

    if ParallelEnv().current_endpoint in unique_endpoints:
        if decompress and (tarfile.is_tarfile(fullpath) or
                           zipfile.is_zipfile(fullpath)):
            fullpath = _decompress(fullpath)

    return fullpath


def _get_download(url, fullname):
    # using requests.get method
    fname = osp.basename(fullname)
    try:
        req = requests.get(url, stream=True)
    except Exception as e:  # requests.exceptions.ConnectionError
        logger.debug("Downloading {} from {} failed with exception {}".format(
            fname, url, str(e)))
        return False

    if req.status_code != 200:
        raise RuntimeError("Downloading from {} failed with code "
                           "{}!".format(url, req.status_code))

    # For protecting download interupted, download to
    # tmp_fullname firstly, move tmp_fullname to fullname
    # after download finished
    tmp_fullname = fullname + "_tmp"
    total_size = req.headers.get('content-length')
    with open(tmp_fullname, 'wb') as f:
        if total_size:
            with tqdm(total=(int(total_size)), unit='B', unit_scale=True) as pbar:
                for chunk in req.iter_content(chunk_size=1024):
                    f.write(chunk)
                    pbar.update(len(chunk))
        else:
            for chunk in req.iter_content(chunk_size=1024):
                if chunk:
                    f.write(chunk)
    shutil.move(tmp_fullname, fullname)

    return fullname


def _wget_download(url, fullname):
    # using wget to download url
    tmp_fullname = fullname + "_tmp"
    # –user-agent
    command = 'wget -O {} -t {} {}'.format(tmp_fullname, DOWNLOAD_RETRY_LIMIT,
                                           url)
    subprc = subprocess.Popen(
        command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    _ = subprc.communicate()

    if subprc.returncode != 0:
        raise RuntimeError(
            '{} failed. Please make sure `wget` is installed or {} exists'.
            format(command, url))

    shutil.move(tmp_fullname, fullname)

    return fullname


_download_methods = {
    'get': _get_download,
    'wget': _wget_download,
}


def _download(url, path, md5sum=None, method='get'):
    """
    Download from url, save to path.
    url (str): download url
    path (str): download to given path
    md5sum (str): md5 sum of download package
    method (str): which download method to use. Support `wget` and `get`. Default is `get`.
    """
    assert method in _download_methods, 'make sure `{}` implemented'.format(
        method)

    if not osp.exists(path):
        os.makedirs(path)

    fname = osp.split(url)[-1]
    fullname = osp.join(path, fname)
    retry_cnt = 0

    logger.debug("Downloading {} from {}".format(fname, url))
    while not (osp.exists(fullname) and _md5check(fullname, md5sum)):
        if retry_cnt < DOWNLOAD_RETRY_LIMIT:
            retry_cnt += 1
        else:
            raise RuntimeError("Download from {} failed. "
                               "Retry limit reached".format(url))

        if not _download_methods[method](url, fullname):
            time.sleep(1)
            continue

    return fullname


def _md5check(fullname, md5sum=None):
    if md5sum is None:
        return True

    logger.debug("File {} md5 checking...".format(fullname))
    md5 = hashlib.md5()
    with open(fullname, 'rb') as f:
        for chunk in iter(lambda: f.read(4096), b""):
            md5.update(chunk)
    calc_md5sum = md5.hexdigest()

    if calc_md5sum != md5sum:
        logger.debug("File {} md5 check failed, {}(calc) != "
                     "{}(base)".format(fullname, calc_md5sum, md5sum))
        return False
    return True


def _decompress(fname):
    """
    Decompress for zip and tar file
    """
    logger.debug("Decompressing {}...".format(fname))

    # For protecting decompressing interupted,
    # decompress to fpath_tmp directory firstly, if decompress
    # successed, move decompress files to fpath and delete
    # fpath_tmp and remove download compress file.

    if tarfile.is_tarfile(fname):
        uncompressed_path = _uncompress_file_tar(fname)
    elif zipfile.is_zipfile(fname):
        uncompressed_path = _uncompress_file_zip(fname)
    else:
        raise TypeError("Unsupport compress file type {}".format(fname))

    return uncompressed_path


def _uncompress_file_zip(filepath):
    files = zipfile.ZipFile(filepath, 'r')
    file_list = files.namelist()

    file_dir = os.path.dirname(filepath)

    if _is_a_single_file(file_list):
        rootpath = file_list[0]
        uncompressed_path = os.path.join(file_dir, rootpath)

        for item in file_list:
            files.extract(item, file_dir)

    elif _is_a_single_dir(file_list):
        rootpath = os.path.splitext(file_list[0])[0].split(os.sep)[0]
        uncompressed_path = os.path.join(file_dir, rootpath)

        for item in file_list:
            files.extract(item, file_dir)

    else:
        rootpath = os.path.splitext(filepath)[0].split(os.sep)[-1]
        uncompressed_path = os.path.join(file_dir, rootpath)
        if not os.path.exists(uncompressed_path):
            os.makedirs(uncompressed_path)
        for item in file_list:
            files.extract(item, os.path.join(file_dir, rootpath))

    files.close()

    return uncompressed_path


def _uncompress_file_tar(filepath, mode="r:*"):
    files = tarfile.open(filepath, mode)
    file_list = files.getnames()

    file_dir = os.path.dirname(filepath)

    if _is_a_single_file(file_list):
        rootpath = file_list[0]
        uncompressed_path = os.path.join(file_dir, rootpath)
        for item in file_list:
            files.extract(item, file_dir)
    elif _is_a_single_dir(file_list):
        rootpath = os.path.splitext(file_list[0])[0].split(os.sep)[-1]
        uncompressed_path = os.path.join(file_dir, rootpath)
        for item in file_list:
            files.extract(item, file_dir)
    else:
        rootpath = os.path.splitext(filepath)[0].split(os.sep)[-1]
        uncompressed_path = os.path.join(file_dir, rootpath)
        if not os.path.exists(uncompressed_path):
            os.makedirs(uncompressed_path)

        for item in file_list:
            files.extract(item, os.path.join(file_dir, rootpath))

    files.close()

    return uncompressed_path


def _is_a_single_file(file_list):
    if len(file_list) == 1 and file_list[0].find(os.sep) < -1:
        return True
    return False


def _is_a_single_dir(file_list):
    new_file_list = []
    for file_path in file_list:
        if '/' in file_path:
            file_path = file_path.replace('/', os.sep)
        elif '\\' in file_path:
            file_path = file_path.replace('\\', os.sep)
        new_file_list.append(file_path)

    file_name = new_file_list[0].split(os.sep)[0]
    for i in range(1, len(new_file_list)):
        if file_name != new_file_list[i].split(os.sep)[0]:
            return False
    return True
