# -*- coding: utf-8 -*-
# pylint: disable=I0011
""" rTorrent Proxy.

    Copyright (c) 2009, 2010, 2011 The PyroScope Project <pyroscope.project@gmail.com>
"""
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
from __future__ import with_statement
from __future__ import absolute_import

import sys
import time
import errno
import shlex
import fnmatch
import logging
import operator
from collections import namedtuple

from pyrobase.parts import Bunch
from pyrocore import config, error
from pyrocore.util import os, xmlrpc, load_config, traits, fmt, matching
from pyrocore.torrent import engine


class CommaLexer(shlex.shlex):
    """Helper to split argument lists."""

    def __init__(self, text):
        shlex.shlex.__init__(self, fmt.to_utf8(text), None, True)
        self.whitespace += ','
        self.whitespace_split = True
        self.commenters = ''


class RtorrentItem(engine.TorrentProxy):
    """ A single download item.
    """

    def __init__(self, engine_, fields):
        """ Initialize download item.
        """
        super(RtorrentItem, self).__init__()
        self._engine = engine_
        self._fields = dict(fields)


    def _make_it_so(self, command, calls, *args, **kwargs):
        """ Perform some error-checked XMLRPC calls.
        """
        observer = kwargs.pop('observer', False)
        args = (self._fields["hash"],) + args
        try:
            for call in calls:
                self._engine.LOG.debug("%s%s torrent #%s (%s)" % (
                    command[0].upper(), command[1:], self._fields["hash"], call))
                if call.startswith(':') or call[:2].endswith('.'):
                    namespace = self._engine._rpc
                else:
                    namespace = self._engine._rpc.d
                result = getattr(namespace, call.lstrip(':'))(*args)
                if observer:
                    observer(result)
        except xmlrpc.ERRORS as exc:
            raise error.EngineError("While %s torrent #%s: %s" % (command, self._fields["hash"], exc))


    def _get_files(self, attrs=None):
        """ Get a list of all files in this download; each entry has the
            attributes C{path} (relative to root), C{size} (in bytes),
            C{mtime}, C{prio} (0=off, 1=normal, 2=high), C{created},
            and C{opened}.

            This is UNCACHED, use C{fetch("files")} instead.

            @param attrs: Optional list of additional attributes to fetch.
        """
        try:
            # Get info for all files
            f_multicall = self._engine._rpc.f.multicall
            f_params = [self._fields["hash"], 0,
                "f.path=", "f.size_bytes=", "f.last_touched=",
                "f.priority=", "f.is_created=", "f.is_open=",
            ]
            for attr in (attrs or []):
                f_params.append("f.%s=" % attr)
            rpc_result = f_multicall(*tuple(f_params))
        except xmlrpc.ERRORS as exc:
            raise error.EngineError("While %s torrent #%s: %s" % (
                "getting files for", self._fields["hash"], exc))
        else:
            #self._engine.LOG.debug("files result: %r" % rpc_result)

            # Return results
            result = [Bunch(
                path=i[0], size=i[1], mtime=i[2] / 1000000.0,
                prio=i[3], created=i[4], opened=i[5],
            ) for i in rpc_result]

            if attrs:
                for idx, attr in enumerate(attrs):
                    if attr.startswith("get_"):
                        attr = attr[4:]
                    for item, rpc_item in zip(result, rpc_result):
                        item[attr] = rpc_item[6+idx]

            return result


    def _memoize(self, name, getter, *args, **kwargs):
        """ Cache a stable expensive-to-get item value for later (optimized) retrieval.
        """
        field = "custom_m_" + name
        cached = self.fetch(field)
        if cached:
            value = cached
        else:
            value = getter(*args, **kwargs)
            self._make_it_so("caching %s=%r for" % (name, value,), ["custom.set"], field[7:], value)
            self._fields[field] = value
        return value


    def _get_kind(self, limit):
        """ Get a set of dominant file types. The files must contribute
            at least C{limit}% to the item's total size.
        """
        histo = self.fetch("custom_kind")

        if histo:
            # Parse histogram from cached field
            histo = [i.split("%_") for i in str(histo).split()]
            histo = [(int(val, 10), ext) for val, ext in histo]
            ##self._engine.LOG.debug("~~~~~~~~~~ cached histo = %r" % histo)
        else:
            # Get filetypes
            histo = traits.get_filetypes(self.fetch("files"),
                path=operator.attrgetter("path"), size=operator.attrgetter("size"))

            # Set custom cache field with value formatted like "80%_flac 20%_jpg" (sorted by percentage)
            histo_str = ' '.join(("%d%%_%s" % i).replace(' ', '_') for i in histo)
            self._make_it_so("setting kind cache %r on" % (histo_str,), ["custom.set"], "kind", histo_str)
            self._fields["custom_kind"] = histo_str

        # Return all non-empty extensions that make up at least <limit>% of total size
        return set(ext for val, ext in histo if ext and val >= limit)


    def as_dict(self):
        """ Return known fields.
        """
        return self._fields.copy()


    def fetch(self, name, engine_name=None):
        """ Get a field on demand.
        """
        # TODO: Get each on-demand field in a multicall for all other items, since
        # we likely need it anyway; another (more easy) way would be to pre-fetch dynamically
        # with the list of fields from filters and output formats
        try:
            return self._fields[name]
        except KeyError:
            if isinstance(name, (int, long)):
                name = "custom_%d" % name

            if name == "done":
                val = float(self.fetch("completed_chunks")) / self.fetch("size_chunks")
            elif name == "files":
                val = self._get_files()
            elif name.startswith("kind_") and name[5:].isdigit():
                val = self._get_kind(int(name[5:], 10))
            elif name.startswith("d_") or name.startswith("d."):
                val = self.fetch('=' + (engine_name or name)[2:])
            elif name.startswith("custom_"):
                key = name[7:]
                try:
                    if len(key) == 1 and key in "12345":
                        val = getattr(self._engine._rpc.d, "custom"+key)(self._fields["hash"])
                    else:
                        val = self._engine._rpc.d.custom(self._fields["hash"], key)
                except xmlrpc.ERRORS as exc:
                    raise error.EngineError("While accessing field %r: %s" % (name, exc))
            else:
                getter_name = engine_name if engine_name else RtorrentEngine.PYRO2RT_MAPPING.get(name, name)
                if getter_name[0] == '=':
                    getter_name = getter_name[1:]
                else:
                    getter_name = "get_" + getter_name
                getter = getattr(self._engine._rpc.d, getter_name)

                try:
                    val = getter(self._fields["hash"])
                except xmlrpc.ERRORS as exc:
                    raise error.EngineError("While accessing field %r: %s" % (name, exc))

            # TODO: Currently, NOT caching makes no sense; in a demon, it does!
            #if isinstance(FieldDefinition.FIELDS.get(name), engine.ConstantField):
            self._fields[name] = val

            return val


    def datapath(self):
        """ Get an item's data path.
        """
        path = self._fields['path']
        if not path:  # stopped item with no base_dir?
            path = self.fetch('directory')
            if path and not self._fields['is_multi_file']:
                path = os.path.join(path, self._fields['name'])
        return os.path.expanduser(fmt.to_unicode(path))


    def announce_urls(self, default=[]):  # pylint: disable=dangerous-default-value
        """ Get a list of all announce URLs.
            Returns `default` if no trackers are found at all.
        """
        try:
            response = self._engine._rpc.t.multicall(self._fields["hash"], 0, "t.url=", "t.is_enabled=")
        except xmlrpc.ERRORS as exc:
            raise error.EngineError("While getting announce URLs for #%s: %s" % (self._fields["hash"], exc))

        if response:
            return [i[0] for i in response if i[1]]
        else:
            return default


    def start(self):
        """ (Re-)start downloading or seeding.
        """
        self._make_it_so("starting", ["open", "start"])


    def stop(self):
        """ Stop and close download.
        """
        self._make_it_so("stopping", ["stop", "close"])


    def ignore(self, flag):
        """ Set ignore status.
        """
        self._make_it_so("setting ignore status for", ["ignore_commands.set"], int(flag))


    def set_prio(self, prio):
        """ Set priority (0-3).
        """
        self._make_it_so("setting priority for", ["priority.set"], max(0, min(int(prio), 3)))


    def tag(self, tags):
        """ Add or remove tags.
        """
        # Get tag list and add/remove given tags
        tags = tags.lower()
        previous = self.tagged
        tagset = previous.copy()
        for tag in tags.replace(',', ' ').split():
            if tag.startswith('-'):
                tagset.discard(tag[1:])
            elif tag.startswith('+'):
                tagset.add(tag[1:])
            else:
                tagset.add(tag)

        # Write back new tagset, if changed
        tagset.discard('')
        if tagset != previous:
            tagset = ' '.join(sorted(tagset))
            self._make_it_so("setting tags %r on" % (tagset,), ["custom.set"], "tags", tagset)
            self._fields["custom_tags"] = tagset


    def set_throttle(self, name):
        """ Assign to throttle group.
        """
        if name.lower() == "null":
            name = "NULL"
        if name.lower() == "none":
            name = ''

        if name not in self._engine.known_throttle_names:
            if self._engine._rpc.throttle.up.max(xmlrpc.NOHASH, name) == -1:
                if self._engine._rpc.throttle.down.max(xmlrpc.NOHASH, name) == -1:
                    raise error.UserError("Unknown throttle name '{}'".format(name))
            self._engine.known_throttle_names.add(name)

        if (name or "NONE") == self.throttle:
            self._engine.LOG.debug("Keeping throttle %r on torrent #%s" % (self.throttle, self._fields["hash"]))
            return

        active = self.is_active
        if active:
            self._engine.LOG.debug("Torrent #%s stopped for throttling" % (self._fields["hash"],))
            self.stop()
        self._make_it_so("setting throttle %r on" % (name,), ["throttle_name.set"], name)
        if active:
            self._engine.LOG.debug("Torrent #%s restarted after throttling" % (self._fields["hash"],))
            self.start()


    def set_custom(self, key, value=None):
        """ Set a custom value. C{key} might have the form "key=value" when value is C{None}.
        """
        # Split combined key/value
        if value is None:
            try:
                key, value = key.split('=', 1)
            except (ValueError, TypeError) as exc:
                raise error.UserError("Bad custom field assignment %r, probably missing a '=' (%s)" % (key, exc))

        # Check identifier rules
        if not key:
            raise error.UserError("Custom field name cannot be empty!")
        elif len(key) == 1 and key in "12345":
            method, args = "custom"+key+".set", (value,)
        elif not (key[0].isalpha() and key.replace("_", "").isalnum()):
            raise error.UserError("Bad custom field name %r (must only contain a-z, A-Z, 0-9 and _)" % (key,))
        else:
            method, args = "custom.set", (key, value)

        # Make the assignment
        self._make_it_so("setting custom_%s = %r on" % (key, value), [method], *args)
        self._fields["custom_"+key] = value


    def hash_check(self):
        """ Hash check a download.
        """
        self._make_it_so("hash-checking", ["check_hash"])


    def execute(self, commands):
        """ Execute XMLRPC command(s).
        """
        try:
            commands = [i.strip() for i in commands.split(' ; ')]
        except (TypeError, AttributeError):
            pass # assume an iterable

        results = {}
        for command in commands:
            try:
                method, args = command.split('=', 1)
                args = tuple(CommaLexer(args))
            except (ValueError, TypeError) as exc:
                raise error.UserError("Bad command %r, probably missing a '=' (%s)" % (command, exc))

            def print_result(data):
                "Helper to print XMLRPC call results"
                args_list = ''
                if args:
                    args_list = '"' + '","'.join(args) + '"'
                print('%s\t%s\t%s=%s' % (self._fields["hash"], data, method.lstrip(':'), args_list))

            def store_result(data):
                "Helper to collect XMLRPC call results"
                results[method.lstrip(':')] = data

            observer = None
            if method.startswith('>'):
                observer = print_result
                method = method.lstrip('>')
            elif method.startswith('!'):
                observer = store_result
                method = method.lstrip('!')
            if not (method.startswith(':') or method[:2].endswith('.')):
                method = 'd.' + method
            self._make_it_so("executing command on", [method], *args, observer=observer)

        return results


    def delete(self):
        """ Remove torrent from client.
        """
        self.stop()
        self._make_it_so("removing metafile of", ["delete_tied"])
        self._make_it_so("erasing", ["erase"])


    #TODO: def set_files_priority(self, pattern, prio)
    # Set priority of selected files
    # NOTE: need to call d.update_priorities after f.priority.set!


    def purge(self):
        """ Delete PARTIAL data files and remove torrent from client.
        """
        def partial_file(item):
            "Filter out partial files"
            #print "???", repr(item)
            return item.completed_chunks < item.size_chunks

        self.cull(file_filter=partial_file, attrs=["get_completed_chunks", "get_size_chunks"])


    def cull(self, file_filter=None, attrs=None):
        """ Delete ALL data files and remove torrent from client.

            @param file_filter: Optional callable for selecting a subset of all files.
                The callable gets a file item as described for RtorrentItem._get_files
                and must return True for items eligible for deletion.
            @param attrs: Optional list of additional attributes to fetch for a filter.
        """
        dry_run = 0 # set to 1 for testing

        def remove_with_links(path):
            "Remove a path including any symlink chains leading to it."
            rm_paths = []
            while os.path.islink(path):
                target = os.readlink(path)
                rm_paths.append(path)
                path = target

            if os.path.exists(path):
                rm_paths.append(path)
            else:
                self._engine.LOG.debug("Real path '%s' doesn't exist,"
                    " but %d symlink(s) leading to it will be deleted..." % (path, len(rm_paths)))

            # Remove the link chain, starting at the real path
            # (this prevents losing the chain when there's permission problems)
            for rm_path in reversed(rm_paths):
                is_dir = os.path.isdir(rm_path) and not os.path.islink(rm_path)
                self._engine.LOG.debug("Deleting '%s%s'" % (rm_path, '/' if is_dir else ''))
                if not dry_run:
                    try:
                        (os.rmdir if is_dir else os.remove)(rm_path)
                    except OSError as exc:
                        if exc.errno == errno.ENOENT:
                            # Seems this disappeared somehow inbetween (race condition)
                            self._engine.LOG.info("Path '%s%s' disappeared before it could be deleted"
                                                  % (rm_path, '/' if is_dir else ''))
                        else:
                            raise

            return rm_paths

        # Assemble doomed files and directories
        files, dirs = set(), set()
        base_path = os.path.expanduser(self.directory)
        item_files = list(self._get_files(attrs=attrs))

        if not self.directory:
            raise error.EngineError("Directory for item #%s is empty,"
                " you might want to add a filter 'directory=!'" % (self._fields["hash"],))
        if not os.path.isabs(base_path):
            raise error.EngineError("Directory '%s' for item #%s is not absolute, which is a bad idea;"
                " fix your .rtorrent.rc, and use 'directory.default.set = /...'"
                % (self.directory, self._fields["hash"],))
        if self.fetch("=is_multi_file") and os.path.isdir(self.directory):
            dirs.add(self.directory)

        for item_file in item_files:
            if file_filter and not file_filter(item_file):
                continue
            #print repr(item_file)
            path = os.path.join(base_path, item_file.path)
            files.add(path)
            if '/' in item_file.path:
                dirs.add(os.path.dirname(path))

        # Delete selected files
        if not dry_run:
            self.stop()
        for path in sorted(files):
            ##self._engine.LOG.debug("Deleting file '%s'" % (path,))
            remove_with_links(path)

        # Prune empty directories (longer paths first)
        doomed = files | dirs
        for path in sorted(dirs, reverse=True):
            residue = set(os.listdir(path) if os.path.exists(path) else [])
            ignorable = set(i for i in residue
                if any(fnmatch.fnmatch(i, pat) for pat in config.waif_pattern_list)
                #or os.path.join(path, i) in doomed
            )
            ##print "---", residue - ignorable
            if residue and residue != ignorable:
                self._engine.LOG.info("Keeping non-empty directory '%s' with %d %s%s!" % (
                    path, len(residue),
                    "entry" if len(residue) == 1 else "entries",
                    (" (%d ignorable)" % len(ignorable)) if ignorable else "",
                ))
            else:
                ##print "---", ignorable
                for waif in ignorable:# - doomed:
                    waif = os.path.join(path, waif)
                    self._engine.LOG.debug("Deleting waif '%s'" % (waif,))
                    if not dry_run:
                        try:
                            os.remove(waif)
                        except EnvironmentError as exc:
                            self._engine.LOG.warn("Problem deleting waif '%s' (%s)" % (waif, exc))

                ##self._engine.LOG.debug("Deleting empty directory '%s'" % (path,))
                doomed.update(remove_with_links(path))

        # Delete item from engine
        if not dry_run:
            self.delete()


    def flush(self):
        """ Write volatile data to disk.
        """
        self._make_it_so("saving session data of", ["save_resume"])


class RtorrentEngine(engine.TorrentEngine):
    """ The rTorrent backend proxy.
    """
    # keys we read from rTorrent's configuration
    RTORRENT_RC_KEYS = ("scgi_local", "scgi_port")

    # mapping from new to old commands, and thus our config keys
    RTORRENT_RC_ALIASES = {
        "network.scgi.open_local": "scgi_local",
        "network.scgi.open_port": "scgi_port",
    }

    # rTorrent names of fields that never change
    CONSTANT_FIELDS = set((
        "hash", "name", "is_private", "is_multi_file", "tracker_size", "size_bytes",
    ))

    # rTorrent names of fields that need to be pre-fetched
    CORE_FIELDS = CONSTANT_FIELDS | set((
        "complete", "tied_to_file",
    ))

    # rTorrent names of fields that get fetched in multi-call
    PREFETCH_FIELDS = CORE_FIELDS | set((
        "is_open", "is_active",
        "ratio", "up_rate", "up_total", "down_rate", "down_total",
        "base_path", "custom=m_alias",
        "custom=tm_completed", "custom=tm_loaded", "custom=tm_started",
    ))

    # mapping of our names to rTorrent names (only those that differ)
    PYRO2RT_MAPPING = dict(
        is_complete="complete",
        is_ignored="ignore_commands",
        down="down_rate",
        up="up_rate",
        path="base_path",
        metafile="tied_to_file",
        size="size_bytes",
        prio="priority",
        throttle="throttle_name",
        custom_m_alias="custom=m_alias",
        custom_tm_completed="custom=tm_completed",
        custom_tm_loaded="custom=tm_loaded",
        custom_tm_started="custom=tm_started",
    )

    # inverse mapping of rTorrent names to ours
    RT2PYRO_MAPPING = dict((v, k) for k, v in PYRO2RT_MAPPING.items())


    def __init__(self):
        """ Initialize proxy.
        """
        super(RtorrentEngine, self).__init__()
        self.versions = (None, None)
        self.version_info = (0,)
        self.startup = time.time()
        self._rpc = None
        self._session_dir = None
        self._download_dir = None
        self._item_cache = {}
        self.known_throttle_names = {'', 'NULL'}


    def load_config(self, namespace=None, rcfile=None):
        """ Load file given in "rcfile".
        """
        if namespace is None:
            namespace = config
        if namespace.scgi_url:
            return  # already have the connection to rTorrent

        # Get and check config file name
        if not rcfile:
            rcfile = getattr(config, "rtorrent_rc", None)
        if not rcfile:
            raise error.UserError("No 'rtorrent_rc' path defined in configuration!")
        if not os.path.isfile(rcfile):
            raise error.UserError("Config file %r doesn't exist!" % (rcfile,))

        # Parse the file
        self.LOG.debug("Loading rtorrent config from %r" % (rcfile,))
        rc_vals = Bunch(scgi_local='', scgi_port = '')
        with open(rcfile) as handle:
            continued = False
            for line in handle.readlines():
                # Skip comments, continuations, and empty lines
                line = line.strip()
                continued, was_continued = line.endswith('\\'), continued
                if not line or was_continued or line.startswith("#"):
                    continue

                # Be lenient about errors, after all it's not our own config file
                try:
                    key, val = line.split("=", 1)
                except ValueError:
                    self.LOG.warning("Ignored invalid line %r in %r!" % (line, rcfile))
                    continue
                key, val = key.strip(), val.strip()
                key = self.RTORRENT_RC_ALIASES.get(key, key).replace('.', '_')

                # Copy values we're interested in
                if key in self.RTORRENT_RC_KEYS:
                    self.LOG.debug("rtorrent.rc: %s = %s" % (key, val))
                    rc_vals[key] = val

        # Validate fields
        if rc_vals.scgi_local:
            rc_vals.scgi_local = os.path.expanduser(rc_vals.scgi_local)
            if rc_vals.scgi_local.startswith('/'):
                rc_vals.scgi_local = "scgi://" + rc_vals.scgi_local
        if rc_vals.scgi_port and not rc_vals.scgi_port.startswith("scgi://"):
            rc_vals.scgi_port = "scgi://" + rc_vals.scgi_port

        # Prefer UNIX domain sockets over TCP sockets
        namespace.scgi_url = rc_vals.scgi_local or rc_vals.scgi_port


    def __repr__(self):
        """ Return a representation of internal state.
        """
        if self._rpc:
            # Connected state
            return "%s connected to %s [%s, up %s] via %r" % (
                self.__class__.__name__, self.engine_id, self.engine_software,
                fmt.human_duration(self.uptime, 0, 2, True).strip(), config.scgi_url,
            )
        else:
            # Unconnected state
            self.load_config()
            return "%s connectable via %r" % (
                self.__class__.__name__, config.scgi_url,
            )


    @property
    def uptime(self):
        """ rTorrent's uptime.
        """
        return time.time() - self.startup


    def _resolve_viewname(self, viewname):
        """ Check for special view names and return existing rTorrent one.
        """
        if viewname == "-":
            try:
                # Only works with rTorrent-PS at this time!
                viewname = self.open().ui.current_view()
            except xmlrpc.ERRORS as exc:
                raise error.EngineError("Can't get name of current view: %s" % (exc))

        return viewname


    def open(self):
        """ Open connection.
        """
        # Only connect once
        if self._rpc is not None:
            return self._rpc

        # Get connection URL from rtorrent.rc
        self.load_config()

        # Reading abilities are on the downfall, so...
        if not config.scgi_url:
            raise error.UserError("You need to configure a XMLRPC connection, read"
                " https://pyrocore.readthedocs.io/en/latest/setup.html")

        # Connect and get instance ID (also ensures we're connectable)
        self._rpc = xmlrpc.RTorrentProxy(config.scgi_url)
        self.versions, self.version_info = self._rpc._set_mappings()
        self.engine_id = self._rpc.session.name()
        time_usec = self._rpc.system.time_usec()

        # Make sure xmlrpc-c works as expected
        if time_usec < 2**32:
            self.LOG.warn("Your xmlrpc-c is broken (64 bit integer support missing,"
                " %r returned instead)" % (type(time_usec),))

        # Get other manifest values
        self.engine_software = "rTorrent %s/%s" % self.versions

        if "+ssh:" in config.scgi_url:
            self.startup = int(self._rpc.system.startup_time() or time.time())
        else:
            self._session_dir = self._rpc.session.path()
            if not self._session_dir:
                raise error.UserError("You need a session directory, read"
                    " https://pyrocore.readthedocs.io/en/latest/setup.html")
            if not os.path.exists(self._session_dir):
                raise error.UserError("Non-existing session directory %r" % self._session_dir)
            self._download_dir = os.path.expanduser(self._rpc.directory.default())
            if not os.path.exists(self._download_dir):
                raise error.UserError("Non-existing download directory %r" % self._download_dir)
            self.startup = os.path.getmtime(os.path.join(self._session_dir, "rtorrent.lock"))

        # Return connection
        self.LOG.debug(repr(self))
        return self._rpc


    def multicall(self, viewname, fields):
        """ Query the given fields of items in the given view.

            The result list contains named tuples,
            so you can access the fields directly by their name.
        """
        commands = tuple('d.{}='.format(x) for x in fields)
        result_type = namedtuple('DownloadItem', [x.replace('.', '_') for x in fields])
        items = self.open().d.multicall(viewname, *commands)
        return [result_type(*x) for x in items]


    def log(self, msg):
        """ Log a message in the torrent client.
        """
        self.open().log(0, msg)


    def item(self, infohash, prefetch=None, cache=False):
        """ Fetch a single item by its info hash.
        """
        return next(self.items(infohash, prefetch, cache))


    def items(self, view=None, prefetch=None, cache=True):
        """ Get list of download items.

            @param view: Name of the view.
            @param prefetch: OPtional list of field names to fetch initially.
            @param cache: Cache items for the given view?
        """
        # TODO: Cache should be by hash.
        # Then get the initial data when cache is empty,
        # else get a list of hashes from the view, make a diff
        # to what's in the cache, fetch the rest. Getting the
        # fields for one hash might be done by a special view
        # (filter: $d.hash == hashvalue)

        if view is None:
            view = engine.TorrentView(self, "default")
        elif isinstance(view, basestring):
            view = engine.TorrentView(self, self._resolve_viewname(view))
        else:
            view.viewname = self._resolve_viewname(view.viewname)

        if not cache or view.viewname not in self._item_cache:
            # Map pyroscope names to rTorrent ones
            if prefetch:
                prefetch = self.CORE_FIELDS | set((self.PYRO2RT_MAPPING.get(i, i) for i in prefetch))
            else:
                prefetch = self.PREFETCH_FIELDS

            # Fetch items
            items = []
            try:
                # Prepare multi-call arguments
                args = ["d.%s%s" % ("" if field.startswith("is_") else "get_", field)
                    for field in prefetch
                ]

                infohash = view._check_hash_view()
                if infohash:
                    multi_call = self.open().system.multicall
                    args = [dict(methodName=field.rsplit('=', 1)[0],
                                 params=[infohash] + (field.rsplit('=', 1)[1].split(',') if '=' in field else []))
                            for field in args]
                    raw_items = [[i[0] for i in multi_call(args)]]
                else:
                    multi_call = self.open().d.multicall
                    args = [view.viewname] + [field if '=' in field else field + '=' for field in args]
                    if view.matcher and int(config.fast_query):
                        pre_filter = matching.unquote_pre_filter(view.matcher.pre_filter())
                        self.LOG.info("!!! pre-filter: {}".format(pre_filter or 'N/A'))
                        if pre_filter:
                            multi_call = self.open().d.multicall.filtered
                            args.insert(1, pre_filter)
                    raw_items = multi_call(*tuple(args))

                ##self.LOG.debug("multicall %r" % (args,))
                ##import pprint; self.LOG.debug(pprint.pformat(raw_items))
                self.LOG.debug("Got %d items with %d attributes from %r [%s]" % (
                    len(raw_items), len(prefetch), self.engine_id, multi_call))

                for item in raw_items:
                    items.append(RtorrentItem(self, zip(
                        [self.RT2PYRO_MAPPING.get(i, i) for i in prefetch], item
                    )))
                    yield items[-1]
            except xmlrpc.ERRORS as exc:
                raise error.EngineError("While getting download items from %r: %s" % (self, exc))

            # Everything yielded, store for next iteration
            if cache:
                self._item_cache[view.viewname] = items
        else:
            # Yield prefetched results
            for item in self._item_cache[view.viewname]:
                yield item


    def show(self, items, view=None, append=False, disjoin=False):
        """ Visualize a set of items (search result), and return the view name.
        """
        proxy = self.open()
        view = self._resolve_viewname(view or "rtcontrol")

        if append and disjoin:
            raise error.EngineError("Cannot BOTH append to / disjoin from view '{}'".format(view))

        # Add view if needed
        if view not in proxy.view.list():
            proxy.view.add(xmlrpc.NOHASH, view)

        # Clear view and show it
        if not append and not disjoin:
            proxy.view.filter(xmlrpc.NOHASH, view, "false=")
            proxy.d.multicall2(xmlrpc.NOHASH, 'default', 'd.views.remove=' + view)
        proxy.ui.current_view.set(view)

        # Add items
        # TODO: should be a "system.multicall"
        for item in items:
            if disjoin:
                proxy.d.views.remove(item.hash, view)
                proxy.view.set_not_visible(item.hash, view)
            else:
                proxy.d.views.push_back_unique(item.hash, view)
                proxy.view.set_visible(item.hash, view)

        return view


def run():
    """ Module level test.
    """
    logging.basicConfig(level=logging.DEBUG)
    load_config.ConfigLoader().load()
    config.debug = True
    print(repr(config.engine.item(sys.argv[1])))


if __name__ == "__main__":
    run()
