#!/usr/bin/env python3

# SAT plugin for downloading files
# Copyright (C) 2009-2021 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import hashlib
from pathlib import Path
from typing import Any, Dict, Optional, Union, Tuple, Callable
from urllib.parse import unquote, urlparse

import treq
from twisted.internet import defer
from twisted.words.protocols.jabber import error as jabber_error

from libervia.backend.core import exceptions
from libervia.backend.core.constants import Const as C
from libervia.backend.core.core_types import SatXMPPEntity
from libervia.backend.core.i18n import D_, _
from libervia.backend.core.log import getLogger
from libervia.backend.tools import xml_tools
from libervia.backend.tools import stream
from libervia.backend.tools.common import data_format
from libervia.backend.tools.web import treq_client_no_ssl

log = getLogger(__name__)


PLUGIN_INFO = {
    C.PI_NAME: "File Download",
    C.PI_IMPORT_NAME: "DOWNLOAD",
    C.PI_TYPE: C.PLUG_TYPE_MISC,
    C.PI_MODES: C.PLUG_MODE_BOTH,
    C.PI_MAIN: "DownloadPlugin",
    C.PI_HANDLER: "no",
    C.PI_DESCRIPTION: _("""File download management"""),
}


class DownloadPlugin(object):

    def __init__(self, host):
        log.info(_("plugin Download initialization"))
        self.host = host
        host.bridge.add_method(
            "file_download",
            ".plugin",
            in_sign="ssss",
            out_sign="s",
            method=self._file_download,
            async_=True,
        )
        host.bridge.add_method(
            "file_download_complete",
            ".plugin",
            in_sign="ssss",
            out_sign="s",
            method=self._file_download_complete,
            async_=True,
        )
        self._download_callbacks = {}
        self._scheme_callbacks = {}
        self.register_scheme('http', self.download_http)
        self.register_scheme('https', self.download_http)

    def _file_download(
            self, attachment_s: str, dest_path: str, extra_s: str, profile: str
    ) -> defer.Deferred:
        d = defer.ensureDeferred(self.file_download(
            self.host.get_client(profile),
            data_format.deserialise(attachment_s),
            Path(dest_path),
            data_format.deserialise(extra_s)
        ))
        d.addCallback(lambda ret: data_format.serialise(ret))
        return d

    async def file_download(
        self,
        client: SatXMPPEntity,
        attachment: Dict[str, Any],
        dest_path: Path,
        extra: Optional[Dict[str, Any]] = None
    ) -> Dict[str, Any]:
        """Download a file using best available method

        parameters are the same as for [download]
        @return (dict): action dictionary, with progress id in case of success, else xmlui
            message
        """
        try:
            progress_id, __ = await self.download(client, attachment, dest_path, extra)
        except Exception as e:
            if (isinstance(e, jabber_error.StanzaError)
                and e.condition == 'not-acceptable'):
                reason = e.text
            else:
                reason = str(e)
            msg = D_("Can't download file: {reason}").format(reason=reason)
            log.warning(msg)
            return {
                "xmlui": xml_tools.note(
                    msg, D_("Can't download file"), C.XMLUI_DATA_LVL_WARNING
                ).toXml()
            }
        else:
            return {"progress": progress_id}

    def _file_download_complete(
            self, attachment_s: str, dest_path: str, extra_s: str, profile: str
    ) -> defer.Deferred:
        d = defer.ensureDeferred(self.file_download_complete(
            self.host.get_client(profile),
            data_format.deserialise(attachment_s),
            Path(dest_path),
            data_format.deserialise(extra_s)
        ))
        d.addCallback(lambda path: str(path))
        return d

    async def file_download_complete(
        self,
        client: SatXMPPEntity,
        attachment: Dict[str, Any],
        dest_path: Path,
        extra: Optional[Dict[str, Any]] = None
    ) -> str:
        """Helper method to fully download a file and return its path

        parameters are the same as for [download]
        @return (str): path to the downloaded file
            use empty string to store the file in cache
        """
        __, download_d = await self.download(client, attachment, dest_path, extra)
        dest_path = await download_d
        return dest_path

    async def download_uri(
        self,
        client: SatXMPPEntity,
        uri: str,
        dest_path: Union[Path, str],
        extra: Optional[Dict[str, Any]] = None
    ) -> Tuple[str, defer.Deferred]:
        if extra is None:
            extra = {}
        uri_parsed = urlparse(uri, 'http')
        if dest_path:
            dest_path = Path(dest_path)
            cache_uid = None
        else:
            filename = Path(unquote(uri_parsed.path)).name.strip() or C.FILE_DEFAULT_NAME
            # we don't use Path.suffixes because we don't want to have more than 2
            # suffixes, but we still want to handle suffixes like "tar.gz".
            stem, *suffixes = filename.rsplit('.', 2)
            # we hash the URL to have an unique identifier, and avoid double download
            url_hash = hashlib.sha256(uri_parsed.geturl().encode()).hexdigest()
            cache_uid = f"{stem}_{url_hash}"
            cache_data = client.cache.get_metadata(cache_uid)
            if cache_data is not None:
                # file is already in cache, we return it
                download_d = defer.succeed(cache_data['path'])
                return '', download_d
            else:
                # the file is not in cache
                unique_name = '.'.join([cache_uid] + suffixes)
                with client.cache.cache_data(
                    "DOWNLOAD", cache_uid, filename=unique_name) as f:
                    # we close the file and only use its name, the file will be opened
                    # by the registered callback
                    dest_path = Path(f.name)

        # should we check certificates?
        check_certificate = self.host.memory.param_get_a(
            "check_certificate", "Connection", profile_key=client.profile)
        if not check_certificate:
            extra['ignore_tls_errors'] = True
            log.warning(
                _("certificate check disabled for download, this is dangerous!"))

        try:
            callback = self._scheme_callbacks[uri_parsed.scheme]
        except KeyError:
            raise exceptions.NotFound(f"Can't find any handler for uri {uri}")
        else:
            try:
                progress_id, download_d = await callback(
                    client, uri_parsed, dest_path, extra)
            except Exception as e:
                log.warning(_(
                    "Can't download URI {uri}: {reason}").format(
                    uri=uri, reason=e))
                if cache_uid is not None:
                    client.cache.remove_from_cache(cache_uid)
                elif dest_path.exists():
                    dest_path.unlink()
                raise e
            download_d.addCallback(lambda __: dest_path)
            return progress_id, download_d


    async def download(
        self,
        client: SatXMPPEntity,
        attachment: Dict[str, Any],
        dest_path: Union[Path, str],
        extra: Optional[Dict[str, Any]] = None
    ) -> Tuple[str, defer.Deferred]:
        """Download a file from URI using suitable method

        @param uri: URI to the file to download
        @param dest_path: where the file must be downloaded
            if empty string, the file will be stored in local path
        @param extra: options depending on scheme handler
            Some common options:
                - ignore_tls_errors(bool): True to ignore SSL/TLS certificate verification
                  used only if HTTPS transport is needed
        @return: ``progress_id`` and a Deferred which fire download URL when download is
            finished.
            ``progress_id`` can be empty string if the file already exist and is not
            downloaded again (can happen if cache is used with empty ``dest_path``).
        """
        uri = attachment.get("uri")
        if uri:
            return await self.download_uri(client, uri, dest_path, extra)
        else:
            for source in attachment.get("sources", []):
                source_type = source.get("type")
                if not source_type:
                    log.warning(
                        "source type is missing for source: {source}\nattachment: "
                        f"{attachment}"
                    )
                    continue
                try:
                    cb = self._download_callbacks[source_type]
                except KeyError:
                    log.warning(
                        f"no source handler registered for {source_type!r}"
                    )
                else:
                    try:
                        return await cb(client, attachment, source, dest_path, extra)
                    except exceptions.CancelError as e:
                        # the handler can't or doesn't want to handle this source
                        log.debug(
                            f"Following source handling by {cb} has been cancelled ({e}):"
                            f"{source}"
                        )

        log.warning(
            "no source could be handled, we can't download the attachment:\n"
            f"{attachment}"
        )
        raise exceptions.FeatureNotFound("no handler could manage the attachment")

    def register_download_handler(
        self,
        source_type: str,
        callback: Callable[
            [
                SatXMPPEntity, Dict[str, Any], Dict[str, Any], Union[str, Path],
                Dict[str, Any]
            ],
            Tuple[str, defer.Deferred]
        ]
    ) -> None:
        """Register a handler to manage a type of attachment source

        @param source_type: ``type`` of source handled
            This is usually the namespace of the protocol used
        @param callback: method to call to manage the source.
            Call arguments are the same as for [download], with an extra ``source`` dict
            which is used just after ``attachment`` to give a quick reference to the
            source used.
            The callabke must return a tuple with:
                - progress ID
                - a Deferred which fire whant the file is fully downloaded
        """
        if source_type is self._download_callbacks:
            raise exceptions.ConflictError(
                f"The is already a callback registered for source type {source_type!r}"
            )
        self._download_callbacks[source_type] = callback

    def register_scheme(self, scheme: str, download_cb: Callable) -> None:
        """Register an URI scheme handler

        @param scheme: URI scheme this callback is handling
        @param download_cb: callback to download a file
            arguments are:
                - (SatXMPPClient) client
                - (urllib.parse.SplitResult) parsed URI
                - (Path) destination path where the file must be downloaded
                - (dict) options
            must return a tuple with progress_id and a Deferred which fire when download
            is finished
        """
        if scheme in self._scheme_callbacks:
            raise exceptions.ConflictError(
                f"A method with scheme {scheme!r} is already registered"
            )
        self._scheme_callbacks[scheme] = download_cb

    def unregister(self, scheme):
        try:
            del self._scheme_callbacks[scheme]
        except KeyError:
            raise exceptions.NotFound(f"No callback registered for scheme {scheme!r}")

    def errback_download(self, file_obj, download_d, resp):
        """Set file_obj and download deferred appropriatly after a network error

        @param file_obj(SatFile): file where the download must be done
        @param download_d(Deferred): deffered which must be fired on complete download
        @param resp(treq.response.IResponse): treq response
        """
        msg = f"HTTP error ({resp.code}): {resp.phrase.decode()}"
        file_obj.close(error=msg)
        download_d.errback(exceptions.NetworkError(msg))

    async def download_http(self, client, uri_parsed, dest_path, options):
        url = uri_parsed.geturl()

        if options.get('ignore_tls_errors', False):
            log.warning(
                "TLS certificate check disabled, this is highly insecure"
            )
            treq_client = treq_client_no_ssl
        else:
            treq_client = treq

        head_data = await treq_client.head(url)
        try:
            content_length = int(head_data.headers.getRawHeaders('content-length')[0])
        except (KeyError, TypeError, IndexError):
            content_length = None
            log.debug(f"No content lenght found at {url}")
        file_obj = stream.SatFile(
            self.host,
            client,
            dest_path,
            mode="wb",
            size = content_length,
        )

        progress_id = file_obj.uid

        resp = await treq_client.get(url, unbuffered=True)
        if resp.code == 200:
            d = treq.collect(resp, file_obj.write)
            d.addBoth(lambda _: file_obj.close())
        else:
            d = defer.Deferred()
            self.errback_download(file_obj, d, resp)
        return progress_id, d