import logging
import hashlib
from urllib import url2pathname

from libtorrent import bdecode, bencode
from twisted.internet.defer import Deferred
from twisted.internet.error import DNSLookupError, ConnectError, ConnectionLost
from twisted.web import http, resource
from twisted.web.server import NOT_DONE_YET

from Tribler.Core.exceptions import HttpError
from Tribler.Core.TorrentDef import TorrentDef
import Tribler.Core.Utilities.json_util as json
from Tribler.Core.Utilities.utilities import fix_torrent, http_get, parse_magnetlink


class TorrentInfoEndpoint(resource.Resource):
    """
    This endpoint is responsible for handing all requests regarding torrent info in Tribler.
    """

    def __init__(self, session):
        resource.Resource.__init__(self)
        self.session = session
        self._logger = logging.getLogger(self.__class__.__name__)

    def finish_request(self, request):
        try:
            request.finish()
        except RuntimeError:
            self._logger.warning("Writing response failed, probably the client closed the connection already.")

    def render_GET(self, request):
        """
        .. http:get:: /torrentinfo

        A GET request to this endpoint will return information from a torrent found at a provided URI.
        This URI can either represent a file location, a magnet link or a HTTP(S) url.
        - torrent: the URI of the torrent file that should be downloaded. This parameter is required.

            **Example request**:

                .. sourcecode:: none

                    curl -X PUT http://localhost:8085/torrentinfo?torrent=file:/home/me/test.torrent

            **Example response**:

                .. sourcecode:: javascript

                    {"metainfo": <torrent metainfo dictionary>}
        """
        metainfo_deferred = Deferred()

        def on_got_metainfo(metainfo):
            if not isinstance(metainfo, dict) or 'info' not in metainfo:
                self._logger.warning("Received metainfo is not a valid dictionary")
                request.setResponseCode(http.INTERNAL_SERVER_ERROR)
                request.write(json.dumps({"error": 'invalid response'}))
                self.finish_request(request)
                return

            infohash = hashlib.sha1(bencode(metainfo['info'])).digest()

            # Check if the torrent is already in the downloads
            metainfo['download_exists'] = infohash in self.session.lm.downloads

            # Update the torrent database with metainfo if it is an unnamed torrent
            if self.session.lm.torrent_db:
                self.session.lm.torrent_db.update_torrent_with_metainfo(infohash, metainfo)

            # Save the torrent to our store
            try:
                self.session.save_collected_torrent(infohash, bencode(metainfo))
            except TypeError:
                # Note: in libtorrent 1.1.1, bencode throws a TypeError which is a known bug
                pass

            request.write(json.dumps({"metainfo": metainfo}, ensure_ascii=False))
            self.finish_request(request)

        def on_metainfo_timeout(_):
            if not request.finished:
                request.setResponseCode(http.REQUEST_TIMEOUT)
                request.write(json.dumps({"error": "timeout"}))
            # If the above request.write failed, the request will have already been finished
            if not request.finished:
                self.finish_request(request)

        def on_lookup_error(failure):
            failure.trap(ConnectError, DNSLookupError, HttpError, ConnectionLost)
            request.setResponseCode(http.INTERNAL_SERVER_ERROR)
            request.write(json.dumps({"error": failure.getErrorMessage()}))
            self.finish_request(request)

        if 'uri' not in request.args or len(request.args['uri']) == 0:
            request.setResponseCode(http.BAD_REQUEST)
            return json.dumps({"error": "uri parameter missing"})

        uri = unicode(request.args['uri'][0], 'utf-8')
        if uri.startswith('file:'):
            try:
                filename = url2pathname(uri[5:].encode('utf-8') if isinstance(uri, unicode) else uri[5:])
                metainfo_deferred.callback(bdecode(fix_torrent(filename)))
            except TypeError:
                request.setResponseCode(http.INTERNAL_SERVER_ERROR)
                return json.dumps({"error": "error while decoding torrent file"})
        elif uri.startswith('http'):
            def _on_loaded(metadata):
                metainfo_deferred.callback(bdecode(metadata))
            http_get(uri.encode('utf-8')).addCallback(_on_loaded).addErrback(on_lookup_error)
        elif uri.startswith('magnet'):
            infohash = parse_magnetlink(uri)[1]
            if infohash is None:
                request.setResponseCode(http.BAD_REQUEST)
                return json.dumps({"error": "missing infohash"})

            if self.session.has_collected_torrent(infohash):
                try:
                    tdef = TorrentDef.load_from_memory(self.session.get_collected_torrent(infohash))
                except ValueError as exc:
                    request.setResponseCode(http.INTERNAL_SERVER_ERROR)
                    return json.dumps({"error": "invalid torrent file: %s" % str(exc)})
                on_got_metainfo(tdef.get_metainfo())
                return NOT_DONE_YET

            self.session.lm.ltmgr.get_metainfo(uri, callback=metainfo_deferred.callback, timeout=20,
                                               timeout_callback=on_metainfo_timeout, notify=True)
        else:
            request.setResponseCode(http.BAD_REQUEST)
            return json.dumps({"error": "invalid uri"})

        metainfo_deferred.addCallback(on_got_metainfo)

        return NOT_DONE_YET
