#!/usr/bin/env python3

# SàT plugin for attaching 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/>.

from collections import namedtuple
import mimetypes
from pathlib import Path
import shutil
import tempfile
from typing import Callable, Optional

from twisted.internet import defer

from sat.core import exceptions
from sat.core.constants import Const as C
from sat.core.core_types import SatXMPPEntity
from sat.core.i18n import _
from sat.core.log import getLogger
from sat.tools import utils
from sat.tools import image


log = getLogger(__name__)


PLUGIN_INFO = {
    C.PI_NAME: "File Attach",
    C.PI_IMPORT_NAME: "ATTACH",
    C.PI_TYPE: C.PLUG_TYPE_MISC,
    C.PI_MODES: C.PLUG_MODE_BOTH,
    C.PI_DEPENDENCIES: ["UPLOAD"],
    C.PI_MAIN: "AttachPlugin",
    C.PI_HANDLER: "no",
    C.PI_DESCRIPTION: _("""Attachments handler"""),
}


AttachmentHandler = namedtuple('AttachmentHandler', ['can_handle', 'attach', 'priority'])


class AttachPlugin:

    def __init__(self, host):
        log.info(_("plugin Attach initialization"))
        self.host = host
        self._u = host.plugins["UPLOAD"]
        host.trigger.add("sendMessage", self._send_message_trigger)
        host.trigger.add("sendMessageComponent", self._send_message_trigger)
        self._attachments_handlers = {'clear': [], 'encrypted': []}
        self.register(self.default_can_handle, self.default_attach, False, -1000)

    def register(self, can_handle, attach, encrypted=False, priority=0):
        """Register an attachments handler

        @param can_handle(callable, coroutine, Deferred): a method which must return True
            if this plugin can handle the upload, otherwise next ones will be tried.
            This method will get client and mess_data as arguments, before the XML is
            generated
        @param attach(callable, coroutine, Deferred): attach the file
            this method will get client and mess_data as arguments, after XML is
            generated. Upload operation must be handled
            hint: "UPLOAD" plugin can be used
        @param encrypted(bool): True if the handler manages encrypted files
            A handler can be registered twice if it handle both encrypted and clear
            attachments
        @param priority(int): priority of this handler, handler with higher priority will
            be tried first
        """
        handler = AttachmentHandler(can_handle, attach, priority)
        handlers = (
            self._attachments_handlers['encrypted']
            if encrypted else self._attachments_handlers['clear']
        )
        if handler in handlers:
            raise exceptions.InternalError(
                'Attachment handler has been registered twice, this should never happen'
            )

        handlers.append(handler)
        handlers.sort(key=lambda h: h.priority, reverse=True)
        log.debug(f"new attachments handler: {handler}")

    async def attach_files(self, client, data):
        """Main method to attach file

        It will do generic pre-treatment, and call the suitable attachments handler
        """
        # we check attachment for pre-treatment like large image resizing
        # media_type will be added if missing (and if it can be guessed from path)
        attachments = data["extra"][C.KEY_ATTACHMENTS]
        tmp_dirs_to_clean = []
        for attachment in attachments:
            if attachment.get(C.KEY_ATTACHMENTS_RESIZE, False):
                path = Path(attachment["path"])
                try:
                    media_type = attachment[C.KEY_ATTACHMENTS_MEDIA_TYPE]
                except KeyError:
                    media_type = mimetypes.guess_type(path, strict=False)[0]
                    if media_type is None:
                        log.warning(
                            _("Can't resize attachment of unknown type: {attachment}")
                            .format(attachment=attachment))
                        continue
                    attachment[C.KEY_ATTACHMENTS_MEDIA_TYPE] = media_type

                main_type = media_type.split('/')[0]
                if main_type == "image":
                    report = image.check(self.host, path)
                    if report['too_large']:
                        tmp_dir = Path(tempfile.mkdtemp())
                        tmp_dirs_to_clean.append(tmp_dir)
                        new_path = tmp_dir / path.name
                        await image.resize(
                            path, report["recommended_size"], dest=new_path)
                        attachment["path"] = new_path
                        log.info(
                            _("Attachment {path!r} has been resized at {new_path!r}")
                            .format(path=str(path), new_path=str(new_path)))
                else:
                    log.warning(
                        _("Can't resize attachment of type {main_type!r}: {attachment}")
                        .format(main_type=main_type, attachment=attachment))

        if client.encryption.is_encryption_requested(data):
            handlers = self._attachments_handlers['encrypted']
        else:
            handlers = self._attachments_handlers['clear']

        for handler in handlers:
            can_handle = await utils.as_deferred(handler.can_handle, client, data)
            if can_handle:
                break
        else:
            raise exceptions.NotFound(
                _("No plugin can handle attachment with {destinee}").format(
                destinee = data['to']
            ))

        await utils.as_deferred(handler.attach, client, data)

        for dir_path in tmp_dirs_to_clean:
            log.debug(f"Cleaning temporary directory at {dir_path}")
            shutil.rmtree(dir_path)

        return data

    async def upload_files(
        self,
        client: SatXMPPEntity,
        data: dict,
        upload_cb: Optional[Callable] = None
    ):
        """Upload file, and update attachments

        invalid attachments will be removed
        @param client:
        @param data(dict): message data
        @param upload_cb(coroutine, Deferred, None): method to use for upload
            if None, upload method from UPLOAD plugin will be used.
            Otherwise, following kwargs will be used with the cb:
                - client
                - filepath
                - filename
                - options
            the method must return a tuple similar to UPLOAD plugin's upload method,
            it must contain:
                - progress_id
                - a deferred which fire download URL
        """
        if upload_cb is None:
            upload_cb = self._u.upload

        uploads_d = []
        to_delete = []
        attachments = data["extra"]["attachments"]

        for attachment in attachments:
            if "url" in attachment and not "path" in attachment:
                log.debug(f"attachment is external, we don't upload it: {attachment}")
                continue
            try:
                # we pop path because we don't want it to be stored, as the file can be
                # only in a temporary location
                path = Path(attachment.pop("path"))
            except KeyError:
                log.warning("no path in attachment: {attachment}")
                to_delete.append(attachment)
                continue

            if "url" in attachment:
                url = attachment.pop('url')
                log.warning(
                    f"unexpected URL in attachment: {url!r}\nattachment: {attachment}"
                )

            try:
                name = attachment["name"]
            except KeyError:
                name = attachment["name"] = path.name

            attachment["size"] = path.stat().st_size

            extra = {
                "attachment": attachment
            }
            progress_id = attachment.pop("progress_id", None)
            if progress_id:
                extra["progress_id"] = progress_id
            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 upload, this is dangerous!"))

            __, upload_d = await upload_cb(
                client=client,
                filepath=path,
                filename=name,
                extra=extra,
            )
            uploads_d.append(upload_d)

        for attachment in to_delete:
            attachments.remove(attachment)

        upload_results = await defer.DeferredList(uploads_d)
        for idx, (success, ret) in enumerate(upload_results):
            attachment = attachments[idx]

            if not success:
                # ret is a failure here
                log.warning(f"error while uploading {attachment}: {ret}")
                continue

            attachment["url"] = ret

        return data

    def _attach_files(self, data, client):
        return defer.ensureDeferred(self.attach_files(client, data))

    def _send_message_trigger(
        self, client, mess_data, pre_xml_treatments, post_xml_treatments):
        if mess_data['extra'].get(C.KEY_ATTACHMENTS):
            post_xml_treatments.addCallback(self._attach_files, client=client)
        return True

    async def default_can_handle(self, client, data):
        return True

    async def default_attach(self, client, data):
        await self.upload_files(client, data)
        # TODO: handle xhtml-im
        body_elt = data["xml"].body
        if body_elt is None:
            body_elt = data["xml"].addElement("body")
        attachments = data["extra"][C.KEY_ATTACHMENTS]
        if attachments:
            body_links = '\n'.join(a['url'] for a in attachments)
            if str(body_elt).strip():
                # if there is already a body, we add a line feed before the first link
                body_elt.addContent('\n')
            body_elt.addContent(body_links)