#   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 os
import sys
import os.path as osp
import shutil
import requests
import hashlib
import tarfile
import zipfile
import time
from collections import OrderedDict

try:
    from tqdm import tqdm
except:

    class tqdm(object):
        def __init__(self, total=None):
            self.total = total
            self.n = 0

        def update(self, n):
            self.n += n
            if self.total is None:
                sys.stderr.write("\r{0:.1f} bytes".format(self.n))
            else:
                sys.stderr.write("\r{0:.1f}%".format(100 * self.n / float(
                    self.total)))
            sys.stderr.flush()

        def __enter__(self):
            return self

        def __exit__(self, exc_type, exc_val, exc_tb):
            sys.stderr.write('\n')


import logging
logger = logging.getLogger(__name__)

__all__ = ['get_weights_path_from_url']

WEIGHTS_HOME = osp.expanduser("~/.cache/paddle/hapi/weights")

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 get_weights_path_from_url(url, md5sum=None):
    """Get weights path from WEIGHT_HOME, if not exists,
    download it from url.

    Args:
        url (str): download url
        md5sum (str): md5 sum of download package
    
    Returns:
        str: a local path to save downloaded weights.

    Examples:
        .. code-block:: python

            from paddle.utils.download import get_weights_path_from_url

            resnet18_pretrained_weight_url = 'https://paddle-hapi.bj.bcebos.com/models/resnet18.pdparams'
            local_weight_path = get_weights_path_from_url(resnet18_pretrained_weight_url)

    """
    path = get_path_from_url(url, WEIGHTS_HOME, md5sum)
    return path


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.info("unique_endpoints {}".format(unique_endpoints))
    return unique_endpoints


def get_path_from_url(url,
                      root_dir,
                      md5sum=None,
                      check_exist=True,
                      decompress=True):
    """ 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
    
    Returns:
        str: a local path to save downloaded models & weights & datasets.
    """

    from paddle.fluid.dygraph.parallel 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.info("Found {}".format(fullpath))
    else:
        if ParallelEnv().current_endpoint in unique_endpoints:
            fullpath = _download(url, root_dir, md5sum)
        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 _download(url, path, md5sum=None):
    """
    Download from url, save to path.

    url (str): download url
    path (str): download to given path
    """
    if not osp.exists(path):
        os.makedirs(path)

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

    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))

        logger.info("Downloading {} from {}".format(fname, url))

        try:
            req = requests.get(url, stream=True)
        except Exception as e:  # requests.exceptions.ConnectionError
            logger.info(
                "Downloading {} from {} failed {} times with exception {}".
                format(fname, url, retry_cnt + 1, str(e)))
            time.sleep(1)
            continue

        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) + 1023) // 1024) as pbar:
                    for chunk in req.iter_content(chunk_size=1024):
                        f.write(chunk)
                        pbar.update(1)
            else:
                for chunk in req.iter_content(chunk_size=1024):
                    if chunk:
                        f.write(chunk)
        shutil.move(tmp_fullname, fullname)

    return fullname


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

    logger.info("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.info("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.info("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)[-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 _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