__author__ = "Christopher Tomkins-Tinch"
__copyright__ = "Copyright 2015, Christopher Tomkins-Tinch"
__email__ = "tomkinsc@broadinstitute.org"
__license__ = "MIT"

import os
import re
import collections
import shutil
import email.utils
from contextlib import contextmanager

# module-specific
from snakemake.remote import AbstractRemoteProvider, DomainObject
from snakemake.exceptions import HTTPFileException, WorkflowError
from snakemake.logging import logger


try:
    # third-party modules
    import requests
except ImportError as e:
    raise WorkflowError(
        "The Python 3 package 'requests' "
        + "must be installed to use HTTP(S) remote() file functionality. %s" % e.msg
    )


class RemoteProvider(AbstractRemoteProvider):
    def __init__(
        self, *args, keep_local=False, stay_on_remote=False, is_default=False, **kwargs
    ):
        super(RemoteProvider, self).__init__(
            *args,
            keep_local=keep_local,
            stay_on_remote=stay_on_remote,
            is_default=is_default,
            **kwargs
        )

    @property
    def default_protocol(self):
        """The protocol that is prepended to the path when no protocol is specified."""
        return "https://"

    @property
    def available_protocols(self):
        """List of valid protocols for this remote provider."""
        return ["http://", "https://"]

    def remote(self, value, *args, insecure=None, **kwargs):
        if isinstance(value, str):
            values = [value]
        elif isinstance(value, collections.abc.Iterable):
            values = value
        else:
            raise TypeError(
                "Invalid type ({}) passed to remote: {}".format(type(value), value)
            )

        for i, file in enumerate(values):
            match = re.match("^(https?)://.+", file)
            if match:
                (protocol,) = match.groups()
                if protocol == "https" and insecure:
                    raise SyntaxError(
                        "insecure=True cannot be used with a https:// url"
                    )
                if protocol == "http" and insecure not in [None, False]:
                    raise SyntaxError(
                        "insecure=False cannot be used with a http:// url"
                    )
            else:
                if insecure:
                    values[i] = "http://" + file
                else:
                    values[i] = "https://" + file

        return super(RemoteProvider, self).remote(values, *args, **kwargs)


class RemoteObject(DomainObject):
    """ This is a class to interact with an HTTP server.
    """

    def __init__(
        self,
        *args,
        keep_local=False,
        provider=None,
        additional_request_string="",
        allow_redirects=True,
        **kwargs
    ):
        super(RemoteObject, self).__init__(
            *args,
            keep_local=keep_local,
            provider=provider,
            allow_redirects=allow_redirects,
            **kwargs
        )
        self.additional_request_string = additional_request_string

    # === Implementations of abstract class members ===

    @contextmanager  # makes this a context manager. after 'yield' is __exit__()
    def httpr(self, verb="GET", stream=False):
        # if args have been provided to remote(), use them over those given to RemoteProvider()
        args_to_use = self.provider.args
        if len(self.args):
            args_to_use = self.args

        # use kwargs passed in to remote() to override those given to the RemoteProvider()
        # default to the host and port given as part of the file, falling back to one specified
        # as a kwarg to remote() or the RemoteProvider (overriding the latter with the former if both)
        kwargs_to_use = {}
        kwargs_to_use["username"] = None
        kwargs_to_use["password"] = None
        kwargs_to_use["auth"] = None

        for k, v in self.provider.kwargs.items():
            kwargs_to_use[k] = v
        for k, v in self.kwargs.items():
            kwargs_to_use[k] = v

        # Check that in case authentication kwargs are provided, they are either ("username", "password") combination
        # or "auth", but not both.
        if (
            kwargs_to_use["username"]
            and kwargs_to_use["password"]
            and kwargs_to_use["auth"]
        ):
            raise TypeError(
                "Authentication accepts either username and password or requests.auth object"
            )
        # If "username" and "password" kwargs are provided, use those to construct a tuple for "auth". Neither
        # requests.head() nor requests.get() accept them as-is.
        if kwargs_to_use["username"] and kwargs_to_use["password"]:
            kwargs_to_use["auth"] = (
                kwargs_to_use["username"],
                kwargs_to_use["password"],
            )
        # Delete "username" and "password" from kwargs
        del kwargs_to_use["username"]
        del kwargs_to_use["password"]

        url = self.remote_file() + self.additional_request_string

        if verb.upper() == "GET":
            r = requests.get(url, *args_to_use, stream=stream, **kwargs_to_use)
        if verb.upper() == "HEAD":
            r = requests.head(url, *args_to_use, **kwargs_to_use)

        yield r
        r.close()

    def exists(self):
        if self._matched_address:
            with self.httpr(verb="HEAD") as httpr:
                # if a file redirect was found
                if httpr.status_code in range(300, 308):
                    raise HTTPFileException(
                        "The file specified appears to have been moved (HTTP %s), check the URL or try adding 'allow_redirects=True' to the remote() file object: %s"
                        % (httpr.status_code, httpr.url)
                    )
                return httpr.status_code == requests.codes.ok
            return False
        else:
            raise HTTPFileException(
                "The file cannot be parsed as an HTTP path in form 'host:port/abs/path/to/file': %s"
                % self.local_file()
            )

    def mtime(self):
        if self.exists():
            with self.httpr(verb="HEAD") as httpr:

                file_mtime = self.get_header_item(httpr, "last-modified", default=None)
                logger.debug("HTTP last-modified: {}".format(file_mtime))

                epochTime = 0

                if file_mtime is not None:
                    modified_tuple = email.utils.parsedate_tz(file_mtime)
                    if modified_tuple is None:
                        logger.debug(
                            "HTTP last-modified not in RFC2822 format: `{}`".format(
                                file_mtime
                            )
                        )
                    else:
                        epochTime = email.utils.mktime_tz(modified_tuple)

                return epochTime
        else:
            raise HTTPFileException(
                "The file does not seem to exist remotely: %s" % self.remote_file()
            )

    def size(self):
        if self.exists():
            with self.httpr(verb="HEAD") as httpr:

                content_size = int(
                    self.get_header_item(httpr, "content-size", default=0)
                )

                return content_size
        else:
            return self._iofile.size_local

    def download(self, make_dest_dirs=True):
        with self.httpr(stream=True) as httpr:
            if self.exists():
                # Find out if the source file is gzip compressed in order to keep
                # compression intact after the download.
                # Per default requests decompresses .gz files.
                # More detials can be found here: https://stackoverflow.com/questions/25749345/how-to-download-gz-files-with-requests-in-python-without-decoding-it?noredirect=1&lq=1
                # Since data transferred with HTTP compression need to be decompressed automatically
                # check the header and decode if the content is encoded.
                if (
                    not self.name.endswith(".gz")
                    and httpr.headers.get("Content-Encoding") == "gzip"
                ):
                    # Decode non-gzipped sourcefiles automatically.
                    # This is needed to decompress uncompressed files that are compressed
                    # for the transfer by HTTP compression.
                    httpr.raw.decode_content = True
                # if the destination path does not exist
                if make_dest_dirs:
                    os.makedirs(os.path.dirname(self.local_path), exist_ok=True)
                    with open(self.local_path, "wb") as f:
                        shutil.copyfileobj(httpr.raw, f)
                    os.sync()  # ensure flush to disk
            else:
                raise HTTPFileException(
                    "The file does not seem to exist remotely: %s" % self.remote_file()
                )

    def upload(self):
        raise HTTPFileException(
            "Upload is not permitted for the HTTP remote provider. Is an output set to HTTP.remote()?"
        )

    def get_header_item(self, httpr, header_name, default):
        """
            Since HTTP header capitalization may differ, this returns
            a header value regardless of case
        """

        header_value = default
        for k, v in httpr.headers.items():
            if k.lower() == header_name:
                header_value = v
        return header_value

    @property
    def list(self):
        raise HTTPFileException(
            "The HTTP Remote Provider does not currently support list-based operations like glob_wildcards()."
        )
