def mainloop(self):
        """ The main loop.
        """
        if not self.args:
            self.parser.error("No metafiles given, nothing to do!")

        if 1 < sum(bool(i) for i in (self.options.no_ssl, self.options.reannounce, self.options.reannounce_all)):
            self.parser.error("Conflicting options --no-ssl, --reannounce and --reannounce-all!")

        # Set filter criteria for metafiles
        filter_url_prefix = None
        if self.options.reannounce:
            # <scheme>://<netloc>/<path>?<query>
            filter_url_prefix = urlparse.urlsplit(self.options.reannounce, allow_fragments=False)
            filter_url_prefix = urlparse.urlunsplit((
                filter_url_prefix.scheme, filter_url_prefix.netloc, '/', '', '' # bogus pylint: disable=E1103
            ))
            self.LOG.info("Filtering for metafiles with announce URL prefix %r..." % filter_url_prefix)

        if self.options.reannounce_all:
            self.options.reannounce = self.options.reannounce_all
        else:
            # When changing the announce URL w/o changing the domain, don't change the info hash!
            self.options.no_cross_seed = True

        # Resolve tracker alias, if URL doesn't look like an URL
        if self.options.reannounce and not urlparse.urlparse(self.options.reannounce).scheme:
            tracker_alias, idx = self.options.reannounce, "0"
            if '.' in tracker_alias:
                tracker_alias, idx = tracker_alias.split('.', 1)
            try:
                idx = int(idx, 10)
                _, tracker_url = config.lookup_announce_alias(tracker_alias)
                self.options.reannounce = tracker_url[idx]
            except (KeyError, IndexError, TypeError, ValueError) as exc:
                raise error.UserError("Unknown tracker alias or bogus URL %r (%s)!" % (
                    self.options.reannounce, exc))

        # go through given files
        bad = 0
        changed = 0
        for filename in self.args:
            try:
                # Read and remember current content
                metainfo = bencode.bread(filename)
                old_metainfo = bencode.bencode(metainfo)
            except (EnvironmentError, KeyError, bencode.BencodeError) as exc:
                self.LOG.warning("Skipping bad metafile %r (%s: %s)" % (filename, type(exc).__name__, exc))
                bad += 1
            else:
                # Check metafile integrity
                try:
                    metafile.check_meta(metainfo)
                except ValueError as exc:
                    self.LOG.warn("Metafile %r failed integrity check: %s" % (filename, exc,))
                    if not self.options.no_skip:
                        continue

                # Skip any metafiles that don't meet the pre-conditions
                if filter_url_prefix and not metainfo['announce'].startswith(filter_url_prefix):
                    self.LOG.warn("Skipping metafile %r no tracked by %r!" % (filename, filter_url_prefix,))
                    continue

                # Keep resume info safe
                libtorrent_resume = {}
                if "libtorrent_resume" in metainfo:
                    try:
                        libtorrent_resume["bitfield"] = metainfo["libtorrent_resume"]["bitfield"]
                    except KeyError:
                        pass # nothing to remember

                    libtorrent_resume["files"] = copy.deepcopy(metainfo["libtorrent_resume"]["files"])

                # Change private flag?
                if self.options.make_private and not metainfo["info"].get("private", 0):
                    self.LOG.info("Setting private flag...")
                    metainfo["info"]["private"] = 1
                if self.options.make_public and metainfo["info"].get("private", 0):
                    self.LOG.info("Clearing private flag...")
                    del metainfo["info"]["private"]

                # Remove non-standard keys?
                if self.options.clean or self.options.clean_all or self.options.clean_xseed:
                    metafile.clean_meta(metainfo, including_info=not self.options.clean, logger=self.LOG.info)

                # Restore resume info?
                if self.options.clean_xseed:
                    if libtorrent_resume:
                        self.LOG.info("Restoring key 'libtorrent_resume'...")
                        metainfo.setdefault("libtorrent_resume", {})
                        metainfo["libtorrent_resume"].update(libtorrent_resume)
                    else:
                        self.LOG.warn("No resume information found!")

                # Clean rTorrent data?
                if self.options.clean_rtorrent:
                    for key in self.RT_RESUMT_KEYS:
                        if key in metainfo:
                            self.LOG.info("Removing key %r..." % (key,))
                            del metainfo[key]

                # Change announce URL?
                if self.options.reannounce:
                    metainfo['announce'] = self.options.reannounce
                    if "announce-list" in metainfo:
                        del metainfo["announce-list"]

                    if not self.options.no_cross_seed:
                        # Enforce unique hash per tracker
                        metainfo["info"]["x_cross_seed"] = hashlib.md5(self.options.reannounce).hexdigest()
                if self.options.no_ssl:
                    # We're assuming here the same (default) port is used
                    metainfo['announce'] = (metainfo['announce']
                        .replace("https://", "http://").replace(":443/", ":80/"))

                # Change comment or creation date?
                if self.options.comment is not None:
                    if self.options.comment:
                        metainfo["comment"] = self.options.comment
                    elif "comment" in metainfo:
                        del metainfo["comment"]
                if self.options.bump_date:
                    metainfo["creation date"] = int(time.time())
                if self.options.no_date and "creation date" in metainfo:
                    del metainfo["creation date"]

                # Add fast-resume data?
                if self.options.hashed:
                    try:
                        metafile.add_fast_resume(metainfo, self.options.hashed.replace("{}", metainfo["info"]["name"]))
                    except EnvironmentError as exc:
                        self.fatal("Error making fast-resume data (%s)" % (exc,))
                        raise

                # Set specific keys?
                metafile.assign_fields(metainfo, self.options.set)
                replace_fields(metainfo, self.options.regex)

                # Write new metafile, if changed
                new_metainfo = bencode.bencode(metainfo)
                if new_metainfo != old_metainfo:
                    if self.options.output_directory:
                        filename = os.path.join(self.options.output_directory, os.path.basename(filename))
                        self.LOG.info("Writing %r..." % filename)

                        if not self.options.dry_run:
                            bencode.bwrite(filename, metainfo)
                            if "libtorrent_resume" in metainfo:
                                # Also write clean version
                                filename = filename.replace(".torrent", "-no-resume.torrent")
                                del metainfo["libtorrent_resume"]
                                self.LOG.info("Writing %r..." % filename)
                                bencode.bwrite(filename, metainfo)
                    else:
                        self.LOG.info("Changing %r..." % filename)

                        if not self.options.dry_run:
                            # Write to temporary file
                            tempname = os.path.join(
                                os.path.dirname(filename),
                                '.' + os.path.basename(filename),
                            )
                            self.LOG.debug("Writing %r..." % tempname)
                            bencode.bwrite(tempname, metainfo)

                            # Replace existing file
                            if os.name != "posix":
                                # cannot rename to existing target on WIN32
                                os.remove(filename)

                            try:
                                os.rename(tempname, filename)
                            except EnvironmentError as exc:
                                # TODO: Try to write directly, keeping a backup!
                                raise error.LoggableError("Can't rename tempfile %r to %r (%s)" % (
                                    tempname, filename, exc
                                ))

                    changed += 1

        # Print summary
        if changed:
            self.LOG.info("%s %d metafile(s)." % (
                "Would've changed" if self.options.dry_run else "Changed", changed
            ))
        if bad:
            self.LOG.warn("Skipped %d bad metafile(s)!" % (bad))