PlexKodiConnect/resources/lib/utils.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Various functions and decorators for PKC
"""
from __future__ import absolute_import, division, unicode_literals
from future import standard_library
standard_library.install_aliases()
from builtins import str
from builtins import object
from logging import getLogger
from sqlite3 import OperationalError
from datetime import datetime
from unicodedata import normalize
from threading import Lock
import urllib.request, urllib.parse, urllib.error
import urllib.parse as _urlparse
# Originally tried faster cElementTree, but does NOT work reliably with Kodi
import xml.etree.ElementTree as etree
# etree parse unsafe; make sure we're always receiving unicode
from . import defused_etree
from xml.etree.ElementTree import ParseError
from functools import wraps
import re
import gc
try:
    from multiprocessing.pool import ThreadPool
    SUPPORTS_POOL = True
except Exception:
    SUPPORTS_POOL = False


import xbmc
import xbmcaddon
import xbmcgui

from . import path_ops, variables as v

LOG = getLogger('PLEX.utils')

WINDOW = xbmcgui.Window(10000)
ADDON = xbmcaddon.Addon(id='plugin.video.plexkodiconnect')

# If several threads access  the settings.xml file concurrently, it gets
# corrupted
SETTINGS_LOCK = Lock()

# Grab Plex id from '...plex_id=XXXX....'
REGEX_PLEX_ID = re.compile(r'''plex_id=(\d+)''')
# Return the numbers at the end of an url like '.../.../XXXX'
REGEX_END_DIGITS = re.compile(r'''/(.+)/(\d+)$''')
REGEX_PLEX_DIRECT = re.compile(r'''\.plex\.direct:\d+$''')
# Plex API
REGEX_IMDB = re.compile(r'''/(tt\d+)''')
REGEX_TVDB = re.compile(r'''thetvdb:\/\/(.+?)\?''')
REGEX_TMDB = re.compile(r'''themoviedb:\/\/(.+?)\?''')
# Plex music
REGEX_MUSICPATH = re.compile(r'''^\^(.+)\$$''')
# Grab Plex id from an URL-encoded string
REGEX_PLEX_ID_FROM_URL = re.compile(r'''metadata%2F(\d+)''')

SAFE_URL_CHARACTERS = "%/:=&?~#+!$,;'@()*[]".encode('utf-8')
HTTP_DAV_FTP = re.compile(r'(http(s)?|dav(s)?|(s)?ftp)://((.+):(.+)@)?([\w\.]+)(:([\d]+))?/')

def garbageCollect():
    gc.collect(2)


def setGlobalProperty(key, val):
    xbmcgui.Window(10000).setProperty(
        'plugin.video.plexkodiconnect.{0}'.format(key), val)


def setGlobalBoolProperty(key, boolean):
    xbmcgui.Window(10000).setProperty(
        'plugin.video.plexkodiconnect.{0}'.format(key), boolean and '1' or '')


def getGlobalProperty(key):
    return xbmc.getInfoLabel(
        'Window(10000).Property(plugin.video.plexkodiconnect.{0})'.format(key))


def reboot_kodi(message=None):
    """
    Displays an OK prompt with 'Kodi will now restart to apply the changes'
    Kodi will then reboot.

    Set optional custom message
    """
    message = message or lang(33033)
    messageDialog(lang(29999), message)
    xbmc.executebuiltin('RestartApp')


def window(prop, value=None, clear=False, windowid=10000):
    """
    Get or set window property - thread safe!

    Returns unicode.

    Property and value may be string or unicode
    """
    if windowid != 10000:
        win = xbmcgui.Window(windowid)
    else:
        win = WINDOW

    if clear:
        win.clearProperty(prop)
    elif value is not None:
        win.setProperty(try_encode(prop), try_encode(value))
    else:
        return try_decode(win.getProperty(prop))


def settings(setting, value=None):
    """
    Get or add addon setting. Returns unicode

    setting and value can either be unicode or string
    """
    # We need to instantiate every single time to read changed variables!
    with SETTINGS_LOCK:
        addon = xbmcaddon.Addon(id='plugin.video.plexkodiconnect')
        if value is not None:
                # Takes string or unicode by default!
                addon.setSetting(try_encode(setting), try_encode(value))
        else:
            # Should return unicode by default, but just in case
            return try_decode(addon.getSetting(setting))


def lang(stringid):
    """
    Central string retrieval from strings.po. If not found within PKC,
    standard XBMC/Kodi strings are retrieved.
    Will return unicode
    """
    return (ADDON.getLocalizedString(stringid) or
            xbmc.getLocalizedString(stringid))


def messageDialog(heading, msg):
    """
    Shows a dialog using the Plex layout
    """
    from .windows import optionsdialog
    optionsdialog.show(heading, msg, lang(186))


def yesno_dialog(heading, msg):
    """
    Shows a dialog with a yes and a no button using the Plex layout.
    Returns True if the user selected yes, False otherwise
    """
    from .windows import optionsdialog
    return optionsdialog.show(heading, msg, lang(107), lang(106)) == 0


def dialog(typus, *args, **kwargs):
    """
    Displays xbmcgui Dialog. Pass a string as typus:
        'yesno', 'ok', 'notification', 'input', 'select', 'numeric'
    kwargs:
        heading='{plex}'        title bar (here PlexKodiConnect)
        message=lang(30128),    Dialog content. Don't use with 'OK', 'yesno'
        line1=str(),            For 'OK' and 'yesno' dialogs use line1...line3!
        time=5000,
        sound=True,
        nolabel=str(),          For 'yesno' dialogs
        yeslabel=str(),         For 'yesno' dialogs
    Icons:
        icon='{plex}'       Display Plex standard icon
        icon='{info}'       xbmcgui.NOTIFICATION_INFO
        icon='{warning}'    xbmcgui.NOTIFICATION_WARNING
        icon='{error}'      xbmcgui.NOTIFICATION_ERROR
    Input Types:
        type='{alphanum}'   xbmcgui.INPUT_ALPHANUM (standard keyboard)
        type='{numeric}'    xbmcgui.INPUT_NUMERIC (format: #)
        type='{date}'       xbmcgui.INPUT_DATE (format: DD/MM/YYYY)
        type='{time}'       xbmcgui.INPUT_TIME (format: HH:MM)
        type='{ipaddress}'  xbmcgui.INPUT_IPADDRESS (format: #.#.#.#)
        type='{password}'   xbmcgui.INPUT_PASSWORD
                            (return md5 hash of input, input is masked)
    Options:
        option='{password}' xbmcgui.PASSWORD_VERIFY (verifies an existing
                            (default) md5 hashed password)
        option='{hide}'     xbmcgui.ALPHANUM_HIDE_INPUT (masks input)
    """
    if 'icon' in kwargs:
        types = {
            '{plex}': 'special://home/addons/plugin.video.plexkodiconnect/icon.png',
            '{info}': xbmcgui.NOTIFICATION_INFO,
            '{warning}': xbmcgui.NOTIFICATION_WARNING,
            '{error}': xbmcgui.NOTIFICATION_ERROR
        }
        for key, value in types.items():
            kwargs['icon'] = kwargs['icon'].replace(key, value)
    if 'type' in kwargs:
        types = {
            '{alphanum}': xbmcgui.INPUT_ALPHANUM,
            '{numeric}': xbmcgui.INPUT_NUMERIC,
            '{date}': xbmcgui.INPUT_DATE,
            '{time}': xbmcgui.INPUT_TIME,
            '{ipaddress}': xbmcgui.INPUT_IPADDRESS,
            '{password}': xbmcgui.INPUT_PASSWORD
        }
        kwargs['type'] = types[kwargs['type']]
    if 'option' in kwargs:
        types = {
            '{password}': xbmcgui.PASSWORD_VERIFY,
            '{hide}': xbmcgui.ALPHANUM_HIDE_INPUT
        }
        kwargs['option'] = types[kwargs['option']]
    if 'heading' in kwargs:
        kwargs['heading'] = kwargs['heading'].replace("{plex}",
                                                      lang(29999))
    dia = xbmcgui.Dialog()
    types = {
        'yesno': dia.yesno,
        'ok': dia.ok,
        'notification': dia.notification,
        'input': dia.input,
        'select': dia.select,
        'numeric': dia.numeric,
        'contextmenu': dia.contextmenu
    }
    return types[typus](*args, **kwargs)


def ERROR(txt='', hide_tb=False, notify=False, cancel_sync=False):
    import sys
    short = str(sys.exc_info()[1])
    LOG.error('Error encountered: %s - %s', txt, short)
    if cancel_sync:
        from . import app
        app.APP.stop_threads(block=False)
    if hide_tb:
        return short

    import traceback
    trace = traceback.format_exc()
    LOG.error("_____________________________________________________________")
    for line in trace.splitlines():
        LOG.error('    ' + line)
    LOG.error("_____________________________________________________________")
    if notify:
        dialog('notification',
               heading='{plex}',
               message=short,
               icon='{error}')
    return short


def rreplace(s, old, new, occurrence=-1):
    """
    Replaces the string old [str, unicode] with new from the RIGHT given a
    string s.
    """
    li = s.rsplit(old, occurrence)
    return new.join(li)


class AttributeDict(dict):
    """
    Turns an etree xml response's xml.attrib into an object with attributes
    """
    def __getattr__(self, attr):
        return self.get(attr)

    def __setattr__(self, attr, value):
        self[attr] = value

    def __unicode__(self):
        return '<{0}:{1}:{2}>'.format(self.__class__.__name__,
                                      self.id,
                                      self.get('title', 'None'))

    def __repr__(self):
        return self.__unicode__().encode('utf-8')


def cast(func, value):
    """
    Cast the specified value to the specified type (returned by func). Currently
    this only support int, float, bool. Should be extended if needed.
    Parameters:
        func (func): Calback function to used cast to type (int, bool, float).
        value (any): value to be cast and returned.

    Returns None if something goes wrong
    """
    if value is None:
        return value
    elif func == bool:
        return bool(int(value))
    elif func == str:
        if isinstance(value, (int, float)):
            return str(value)
        elif isinstance(value, str):
            return value
        else:
            return value.decode('utf-8')
    elif func == str:
        if isinstance(value, (int, float)):
            return str(value)
        elif isinstance(value, str):
            return value
        else:
            return value.encode('utf-8')
    elif func == int:
        try:
            return int(value)
        except ValueError:
            try:
                # Converting e.g. '8.0' fails; need to convert to float first
                return int(float(value))
            except ValueError:
                return
    elif func == float:
        try:
            return float(value)
        except ValueError:
            return
    return func(value)


def extend_url(url, params):
    """
    Pass in an url [unicode] and params [dict]. Returns the extended url
        '<url><? or &><urllib.urlencode(params)>'
    in unicode
    """
    params = encode_dict(params) if params else {}
    params = urllib.parse.urlencode(params).decode('utf-8')
    if '?' in url:
        return '%s&%s' % (url, params)
    else:
        return '%s?%s' % (url, params)


def encode_dict(dictionary):
    """
    Pass in a dict. Will return the same dict with all keys and values encoded
    in utf-8 - as long as they are unicode. Ignores all non-unicode entries

    Useful for urllib.urlencode or urllib.(un)quote
    """
    for key, value in dictionary.items():
        if isinstance(key, str):
            dictionary[key.encode('utf-8')] = dictionary.pop(key)
        if isinstance(value, str):
            dictionary[key] = value.encode('utf-8')
    return dictionary


def parse_qs(qs, keep_blank_values=0, strict_parsing=0):
    """
    unicode-safe way to use urlparse.parse_qs(). Pass in the query string qs
    either as str or unicode
    Returns a dict with lists as values; all entires unicode
    """
    if isinstance(qs, str):
        qs = qs.encode('utf-8')
    qs = _urlparse.parse_qs(qs, keep_blank_values, strict_parsing)
    return {k.decode('utf-8'): [e.decode('utf-8') for e in v]
            for k, v in qs.items()}


def parse_qsl(qs, keep_blank_values=0, strict_parsing=0):
    """
    unicode-safe way to use urlparse.parse_qsl(). Pass in either str or unicode
    Returns a list of unicode tuples
    """
    if isinstance(qs, str):
        qs = qs.encode('utf-8')
    qs = _urlparse.parse_qsl(qs, keep_blank_values, strict_parsing)
    return [(x.decode('utf-8'), y.decode('utf-8')) for (x, y) in qs]


def urlparse(url, scheme='', allow_fragments=True):
    """
    unicode-safe way to use urlparse.urlparse(). Pass in either str or unicode
    CAREFUL: returns an encoded urlparse.ParseResult()!
    """
    if isinstance(url, str):
        url = url.encode('utf-8')
    return _urlparse.urlparse(url, scheme, allow_fragments)


def escape_path(path, safe_url_char=SAFE_URL_CHARACTERS):
    """
    Uses urllib.quote to escape to escape path [unicode]. See here for the
    reasoning whether a character is safe or not and whether or not it should
    be escaped:
        https://bugs.python.org/issue918368
    Letters, digits, and the characters '_.-' are never quoted. Choosing the
    "wrong" characters for a password for USERNAME:PASSWORD@host.com will get
    you in trouble (e.g. '@')
    Returns the escaped path as unicode
    """
    is_http_dav_ftp = HTTP_DAV_FTP.match(path)
    if is_http_dav_ftp:
        # If path seems to be a http(s), dav(s) or (s)ftp url, the escape path will be constructed
        # using RegExp and using safe_url_char as safe characters not to be escaped
        protocol = is_http_dav_ftp.group(1)
        user = is_http_dav_ftp.group(6)
        psswd = is_http_dav_ftp.group(7)
        if user and psswd:
            user = urllib.parse.quote(user.encode('utf-8'), safe=safe_url_char).decode('utf-8')
            psswd = urllib.parse.quote(psswd.encode('utf-8'), safe=safe_url_char).decode('utf-8')
        host = is_http_dav_ftp.group(8)
        port = is_http_dav_ftp.group(10)
        url_path = path.replace(is_http_dav_ftp.group(), '', 1)
        if url_path:
            url_path = urllib.parse.quote(path.replace(is_http_dav_ftp.group(), '', 1).encode('utf-8'),
                                    safe=safe_url_char).decode('utf-8')
        return protocol + \
               u'://' + \
               (user + u':' + psswd + u'@' if (user and psswd) else u'') + \
               host + \
               (u':' + port if port else u'') + \
               u'/' + \
               (url_path if url_path else u'')
    else:
        # If paths does not seem to be a http(s), dav(s) or (s)ftp url (e.g. plugin://)
        # escape path as before
        return urllib.parse.quote(path.encode('utf-8'),
                            safe=SAFE_URL_CHARACTERS).decode('utf-8')


def quote(s, safe='/'):
    """
    unicode-safe way to use urllib.quote(). Pass in either str or unicode
    Returns unicode
    """
    if isinstance(s, str):
        s = s.encode('utf-8')
    s = urllib.parse.quote(s, safe.encode('utf-8'))
    return s.decode('utf-8')


def quote_plus(s, safe=''):
    """
    unicode-safe way to use urllib.quote(). Pass in either str or unicode
    Returns unicode
    """
    if isinstance(s, str):
        s = s.encode('utf-8')
    s = urllib.parse.quote_plus(s, safe.encode('utf-8'))
    return s.decode('utf-8')


def unquote(s):
    """
    unicode-safe way to use urllib.unquote(). Pass in either str or unicode
    Returns unicode
    """
    if isinstance(s, str):
        s = s.encode('utf-8')
    s = urllib.parse.unquote(s)
    return s.decode('utf-8')


def try_encode(input_str, encoding='utf-8'):
    """
    Will try to encode input_str (in unicode) to encoding. This possibly
    fails with e.g. Android TV's Python, which does not accept arguments for
    string.encode()
    """
    if isinstance(input_str, str):
        # already encoded
        return input_str
    try:
        input_str = input_str.encode(encoding, "ignore")
    except TypeError:
        input_str = input_str.encode()
    return input_str


def try_decode(string, encoding='utf-8'):
    """
    Will try to decode string (encoded) using encoding. This possibly
    fails with e.g. Android TV's Python, which does not accept arguments for
    string.encode()
    """
    if isinstance(string, str):
        # already decoded
        return string
    try:
        string = string.decode(encoding, "ignore")
    except TypeError:
        string = string.decode()
    return string


def slugify(text):
    """
    Normalizes text (in unicode or string) to e.g. enable safe filenames.
    Returns unicode
    """
    if not isinstance(text, str):
        text = str(text)
    return str(normalize('NFKD', text).encode('ascii', 'ignore'))


def valid_filename(text):
    """
    Return a valid filename after passing it in [unicode].
    """
    # Get rid of all whitespace except a normal space
    text = re.sub(r'(?! )\s', '', text)
    # ASCII characters 0 to 31 (non-printable, just in case)
    text = re.sub(u'[\x00-\x1f]', '', text)
    if v.DEVICE == 'Windows':
        # Whitespace at the end of the filename is illegal
        text = text.strip()
        # Dot at the end of a filename is illegal
        text = re.sub(r'\.+$', '', text)
        # Illegal Windows characters
        text = re.sub(r'[/\\:*?"<>|\^]', '', text)
    elif v.DEVICE == 'MacOSX':
        # Colon is illegal
        text = re.sub(r':', '', text)
        # Files cannot begin with a dot
        text = re.sub(r'^\.+', '', text)
    else:
        # Linux
        text = re.sub(r'/', '', text)
    # Ensure that filename length is at most 255 chars (including 3 chars for
    # filename extension and 1 dot to separate the extension)
    text = text[:min(len(text), 251)]
    return text


def escape_html(string):
    """
    Escapes the following:
        < to &lt;
        > to &gt;
        & to &amp;
    """
    escapes = {
        '<': '&lt;',
        '>': '&gt;',
        '&': '&amp;'
    }
    for key, value in escapes.items():
        string = string.replace(key, value)
    return string


def delete_temporary_subtitles():
    """
    Permanently deletes all temporary subtitle files
    """
    for root, _, files in path_ops.walk(v.EXTERNAL_SUBTITLE_TEMP_PATH):
        for file in files:
            try:
                path_ops.remove(path_ops.path.join(root, file))
            except (OSError, IOError) as err:
                LOG.error('Could not delete temporary subtitle: %s, %s: %s',
                          root, file, err)


def wipe_database(reboot=True):
    """
    Deletes all Plex playlists as well as video nodes, then clears Kodi as well
    as Plex databases completely.
    Will also delete all cached artwork.
    """
    LOG.warn('Start wiping')
    from .library_sync.sections import delete_files
    from .library_sync.common import PLAYLIST_SYNC_ENABLED
    from . import kodi_db, plex_db
    delete_files()
    if PLAYLIST_SYNC_ENABLED:
        from .playlists import remove_synced_playlists
        remove_synced_playlists()
    try:
        with plex_db.PlexDB() as plexdb:
            if plexdb.songs_have_been_synced():
                LOG.info('Detected that music has also been synced - wiping music')
                music = True
            else:
                LOG.info('No music has been synced in the past - not wiping')
                music = False
    except OperationalError:
        # Plex DB completely empty yet. Wipe existing Kodi music only if we
        # expect to sync Plex music
        music = settings('enableMusic') == 'true'
    LOG.info("Resetting all cached artwork.")
    kodi_db.wipe_dbs(music)
    plex_db.wipe()

    # reset the install run flag
    settings('SyncInstallRunDone', value="false")
    settings('sections_asked_for_machine_identifier', value='')
    init_dbs()
    LOG.info('Wiping done')
    no_reboot = settings('kodi_db_has_been_wiped_clean') == 'true' or not reboot
    settings('kodi_db_has_been_wiped_clean', value='true')
    if not no_reboot:
        # Root cause is sqlite WAL mode - Kodi might still have DB access open
        LOG.warn('Need to restart Kodi before filling Kodi DB again')
        reboot_kodi()


def init_dbs():
    """
    Call e.g. on startup to ensure that Plex and Kodi DBs look like they should
    """
    from . import kodi_db, plex_db
    # Ensure that Plex DB is set-up
    plex_db.initialize()
    # Hack to speed up look-ups for actors (giant table!)
    kodi_db.create_kodi_db_indicees()
    kodi_db.setup_kodi_default_entries()
    with kodi_db.KodiVideoDB() as kodidb:
        # Setup the paths for addon-paths (even when using direct paths)
        kodidb.setup_path_table()
    LOG.info('Init DBs done')


def reset(ask_user=True):
    """
    User navigated to the PKC settings, Advanced, and wants to reset the Kodi
    database and possibly PKC entirely
    """
    # Are you sure you want to reset your local Kodi database?
    if ask_user and not yesno_dialog(lang(29999), lang(39600)):
        return
    from . import app
    # first stop any db sync
    app.APP.suspend_threads()
    # Reset all PlexKodiConnect Addon settings? (this is usually NOT
    # recommended and unnecessary!)
    if ask_user and yesno_dialog(lang(29999), lang(39603)):
        # Delete the settings
        LOG.info("Deleting: settings.xml")
        path_ops.remove("%ssettings.xml" % v.ADDON_PROFILE)

    # Wipe everything
    wipe_database()
    reboot_kodi()


def compare_version(current, minimum):
    """
    Returns True if current is >= then minimum. False otherwise. Returns True
    if there was no valid input for current!

    Input strings: e.g. "1.2.3"; always with Major, Minor and Patch!
    """
    try:
        curr_major, curr_minor, curr_patch = current.split(".")
    except ValueError:
        # there WAS no current DB, e.g. deleted.
        return True
    min_major, min_minor, min_patch = minimum.split(".")
    curr_major = int(curr_major)
    curr_minor = int(curr_minor)
    curr_patch = int(curr_patch)
    min_major = int(min_major)
    min_minor = int(min_minor)
    min_patch = int(min_patch)

    if curr_major > min_major:
        return True
    elif curr_major < min_major:
        return False

    if curr_minor > min_minor:
        return True
    elif curr_minor < min_minor:
        return False
    return curr_patch >= min_patch


def normalize_string(text):
    """
    For theme media, do not modify unless modified in TV Tunes
    """
    text = text.replace(":", "")
    text = text.replace("/", "-")
    text = text.replace("\\", "-")
    text = text.replace("<", "")
    text = text.replace(">", "")
    text = text.replace("*", "")
    text = text.replace("?", "")
    text = text.replace('|', "")
    text = text.strip()
    # Remove dots from the last character as windows can not have directories
    # with dots at the end
    text = text.rstrip('.')
    text = try_encode(normalize('NFKD', str(text, 'utf-8')))

    return text


def normalize_nodes(text):
    """
    For video nodes. Returns unicode
    """
    text = text.replace(":", "")
    text = text.replace("/", "-")
    text = text.replace("\\", "-")
    text = text.replace("<", "")
    text = text.replace(">", "")
    text = text.replace("*", "")
    text = text.replace("?", "")
    text = text.replace('|', "")
    text = text.replace('(', "")
    text = text.replace(')', "")
    text = text.strip()
    # Remove dots from the last character as windows can not have directories
    # with dots at the end
    text = text.rstrip('.')
    text = normalize('NFKD', str(text, 'utf-8'))
    return text


def indent(elem, level=0):
    """
    Prettifies xml trees. Pass the etree root in
    """
    try:
        i = "\n" + level * "  "
        if len(elem):
            if not elem.text or not elem.text.strip():
                elem.text = i + "  "
            if not elem.tail or not elem.tail.strip():
                elem.tail = i
            for elem in elem:
                indent(elem, level + 1)
            if not elem.tail or not elem.tail.strip():
                elem.tail = i
        else:
            if level and (not elem.tail or not elem.tail.strip()):
                elem.tail = i
    except Exception as err:
        LOG.info('Indentation failed with: %s', err)


class XmlKodiSetting(object):
    """
    Used to load a Kodi XML settings file from special://profile as an etree
    object to read settings or set them. Usage:
        with XmlKodiSetting(filename,
                            path=None,
                            force_create=False,
                            top_element=None) as xml:
            xml.get_setting('test')

    filename [str]:      filename of the Kodi settings file under
    path [str]:          if set, replace special://profile path with custom
                         path
    force_create:        will create the XML file if it does not exist
    top_element [str]:   Name of the top xml element; used if xml does not
                         yet exist

    Raises IOError if the file does not exist or is empty and force_create
    has been set to False.
    Raises utils.ParseError if the file could not be parsed by etree

    xml.write_xml        Set to True if we need to write the XML to disk
    """
    def __init__(self, filename, path=None, force_create=False,
                 top_element=None):
        self.filename = filename
        if path is None:
            self.path = path_ops.path.join(v.KODI_PROFILE, filename)
        else:
            self.path = path_ops.path.join(path, filename)
        self.force_create = force_create
        self.top_element = top_element
        self.tree = None
        self.root = None
        self.write_xml = False

    def __enter__(self):
        try:
            self.tree = defused_etree.parse(self.path)
        except IOError:
            # Document is blank or missing
            if self.force_create is False:
                LOG.debug('%s does not seem to exist; not creating', self.path)
                # This will abort __enter__
                self.__exit__(IOError('File not found'), None, None)
            # Create topmost xml entry
            self.tree = etree.ElementTree(etree.Element(self.top_element))
            self.write_xml = True
        except ParseError:
            LOG.error('Error parsing %s', self.path)
            # "Kodi cannot parse {0}. PKC will not function correctly. Please
            # visit {1} and correct your file!"
            messageDialog(lang(29999), lang(39716).format(
                self.filename,
                'http://kodi.wiki'))
            self.__exit__(ParseError('Error parsing XML'), None, None)
        self.root = self.tree.getroot()
        return self

    def __exit__(self, e_typ, e_val, trcbak):
        if e_typ:
            # re-raise any exception
            return False
        # Only safe to file if we did not botch anything
        if self.write_xml is True:
            self._remove_empty_elements()
            # Indent and make readable
            indent(self.root)
            # Safe the changed xml
            try:
                self.tree.write(self.path, encoding='utf-8')
            except IOError as err:
                LOG.error('Could not save xml %s. Error: %s',
                          self.filename, err)
                # Could not change the Kodi settings file {0}. PKC might not
                # work correctly. Error: {1}
                if not settings('%s_ioerror' % self.filename):
                    messageDialog(lang(29999),
                                  lang(30417).format(self.filename, err))
                    settings('%s_ioerror' % self.filename,
                             value='warning_shown')

    def _is_empty(self, element, empty_elements):
        empty = True
        for child in element:
            empty_child = True
            if list(child):
                empty_child = self._is_empty(child, empty_elements)
            if empty_child and (child.attrib or
                                (child.text and child.text.strip())):
                empty_child = False
            if empty_child:
                empty_elements.append((element, child))
            else:
                # At least one non-empty entry - hence we cannot delete the
                # original element itself
                empty = False
        return empty

    def _remove_empty_elements(self):
        """
        Deletes all empty XML elements, otherwise Kodi/PKC gets confused
        This is recursive, so an empty element with empty children will also
        get deleted
        """
        empty_elements = []
        self._is_empty(self.root, empty_elements)
        for element, child in empty_elements:
            element.remove(child)

    @staticmethod
    def _set_sub_element(element, subelement):
        """
        Returns an etree element's subelement. Creates one if not exist
        """
        answ = element.find(subelement)
        if answ is None:
            answ = etree.SubElement(element, subelement)
        return answ

    def get_setting(self, node_list):
        """
        node_list is a list of node names starting from the outside, ignoring
        the outter advancedsettings.
        Example nodelist=['video', 'busydialogdelayms'] for the following xml
        would return the etree Element:

            <busydialogdelayms>750</busydialogdelayms>

        for the following example xml:

        <advancedsettings>
            <video>
                <busydialogdelayms>750</busydialogdelayms>
            </video>
        </advancedsettings>

        Returns the etree element or None if not found
        """
        element = self.root
        for node in node_list:
            element = element.find(node)
            if element is None:
                break
        return element

    def set_setting(self, node_list, value=None, attrib=None, append=False):
        """
        node_list is a list of node names starting from the outside, ignoring
        the outter advancedsettings.
        Example nodelist=['video', 'busydialogdelayms'] for the following xml
        would return the etree Element:

            <busydialogdelayms>750</busydialogdelayms>

        for the following example xml:

        <advancedsettings>
            <video>
                <busydialogdelayms>750</busydialogdelayms>
            </video>
        </advancedsettings>

        value, e.g. '750' will be set accordingly, returning the new
        etree Element. Advancedsettings might be generated if it did not exist
        already

        If the dict attrib is set, the Element's attributs will be appended
        accordingly

        If append is True, the last element of node_list with value and attrib
        will always be added. WARNING: this will set self.write_xml to True!

        Returns the (last) etree element
        """
        attrib = attrib or {}
        value = value or ''
        if not append:
            old = self.get_setting(node_list)
            if (old is not None and
                    ((old.text is not None and old.text.strip() == value) or
                     (old.text is None and value == '')) and
                    (old.attrib or {}) == attrib):
                # Already set exactly these values
                return old
        LOG.debug('Adding etree to: %s, value: %s, attrib: %s, append: %s',
                  node_list, value, attrib, append)
        self.write_xml = True
        element = self.root
        nodes = node_list[:-1] if append else node_list
        for node in nodes:
            element = self._set_sub_element(element, node)
        if append:
            element = etree.SubElement(element, node_list[-1])
        # Write new values
        element.text = value
        if attrib:
            for key, attribute in attrib.items():
                element.set(key, attribute)
        return element


def process_method_on_list(method_to_run, items):
    """
    helper method that processes a method on each item with pooling if the
    system supports it
    """
    all_items = []
    if SUPPORTS_POOL:
        pool = ThreadPool()
        try:
            all_items = pool.map(method_to_run, items)
        except Exception:
            # catch exception to prevent threadpool running forever
            ERROR(notify=True)
        pool.close()
        pool.join()
    else:
        all_items = [method_to_run(item) for item in items]
    all_items = [_f for _f in all_items if _f]
    return all_items


###############################################################################
# WRAPPERS

def catch_exceptions(warnuser=False):
    """
    Decorator for methods to catch exceptions and log them. Useful for e.g.
    librarysync threads using itemtypes.py, because otherwise we would not
    get informed of crashes

    warnuser=True:      sets the window flag 'plex_scancrashed' to true
                        which will trigger a Kodi infobox to inform user
    """
    def decorate(func):
        """
        Decorator construct
        """
        @wraps(func)
        def wrapper(*args, **kwargs):
            """
            Wrapper construct
            """
            try:
                return func(*args, **kwargs)
            except Exception as err:
                LOG.error('%s has crashed. Error: %s', func.__name__, err)
                import traceback
                LOG.error("Traceback:\n%s", traceback.format_exc())
                if warnuser:
                    window('plex_scancrashed', value='true')
                return
        return wrapper
    return decorate


def log_time(func):
    """
    Decorator for functions and methods to log the time it took to run the code
    """
    @wraps(func)
    def wrapper(*args, **kwargs):
        starttotal = datetime.now()
        result = func(*args, **kwargs)
        elapsedtotal = datetime.now() - starttotal
        LOG.info('It took %s to run the function %s',
                 elapsedtotal, func.__name__)
        return result
    return wrapper