addon_updater.py

# ##### BEGIN GPL LICENSE BLOCK #####
#
#  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.
#
# ##### END GPL LICENSE BLOCK #####


"""
See documentation for usage
https://github.com/CGCookie/blender-addon-updater
"""

__version__ = "1.1.1"

import errno
import traceback
import platform
import ssl
import urllib.request
import urllib
import os
import json
import zipfile
import shutil
import threading
import fnmatch
from datetime import datetime, timedelta

# Blender imports, used in limited cases.
import bpy
import addon_utils
from .common import *

# -----------------------------------------------------------------------------
# The main class
# -----------------------------------------------------------------------------
LEGACY_BRANCH = "blender_279"

class SingletonUpdater:
    """Addon updater service class.

    This is the singleton class to instance once and then reference where
    needed throughout the addon. It implements all the interfaces for running
    updates.
    """
    def __init__(self):

        self._engine = GithubEngine()
        self._user = None
        self._repo = None
        self._website = None
        self._current_version = None
        self._subfolder_path = None
        self._tags = list()
        self._tag_latest = None
        self._tag_names = list()
        self._latest_release = None
        self._use_releases = False
        self._include_branches = False
        self._include_branch_list = ['master']
        self._include_branch_auto_check = False
        self._manual_only = False
        self._version_min_update = None
        self._version_max_update = None

        # By default, backup current addon on update/target install.
        self._backup_current = True
        self._backup_ignore_patterns = None

        # Set patterns the files to overwrite during an update.
        self._overwrite_patterns = ["*.py", "*.pyc"]
        self._remove_pre_update_patterns = list()

        # By default, don't auto disable+re-enable the addon after an update,
        # as this is less stable/often won't fully reload all modules anyways.
        self._auto_reload_post_update = False

        # Settings for the frequency of automated background checks.
        self._check_interval_enabled = False
        self._check_interval_months = 0
        self._check_interval_days = 1
        self._check_interval_hours = 0
        self._check_interval_minutes = 0

        # runtime variables, initial conditions
        self._verbose = False
        self._use_print_traces = True
        self._fake_install = False
        self._async_checking = False  # only true when async daemon started
        self._update_ready = None
        self._update_link = None
        self._last_commit = None
        self._update_version = None
        self._source_zip = None
        self._check_thread = None
        self._select_link = None
        self.skip_tag = None
        self.legacy_blender = not is_bl_newer_than(2, 80) 
        self.using_development_build = False
        self.current_branch = None

        # Get data from the running blender module (addon).
        self._addon = __package__.lower()
        self._addon_package = __package__  # Must not change.
        self._updater_path = os.path.join(
            os.path.dirname(__file__),
            self._addon + "_updater"
        )
        self._addon_root = os.path.dirname(__file__)
        self._json = dict()
        self._error = None
        self._error_msg = None
        self._prefiltered_tag_count = 0

        # UI properties, not used within this module but still useful to have.

        # to verify a valid import, in place of placeholder import
        self.show_popups = True  # UI uses to show popups or not.
        self.invalid_updater = False

        # pre-assign basic select-link function
        def select_link_function(self, tag):
            return tag["zipball_url"]

        self._select_link = select_link_function

    def print_trace(self):
        """Print handled exception details when use_print_traces is set"""
        if self._use_print_traces:
            traceback.print_exc()

    def print_verbose(self, msg):
        """Print out a verbose logging message if verbose is true."""
        if not self._verbose:
            return
        print("{} addon: ".format(self.addon) + msg)

    # -------------------------------------------------------------------------
    # Getters and setters
    # -------------------------------------------------------------------------
    @property
    def addon(self):
        return self._addon

    @addon.setter
    def addon(self, value):
        self._addon = str(value)

    @property
    def api_url(self):
        return self._engine.api_url

    @api_url.setter
    def api_url(self, value):
        if not self.check_is_url(value):
            raise ValueError("Not a valid URL: " + value)
        self._engine.api_url = value

    @property
    def async_checking(self):
        return self._async_checking

    @property
    def auto_reload_post_update(self):
        return self._auto_reload_post_update

    @auto_reload_post_update.setter
    def auto_reload_post_update(self, value):
        try:
            self._auto_reload_post_update = bool(value)
        except:
            raise ValueError("auto_reload_post_update must be a boolean value")

    @property
    def backup_current(self):
        return self._backup_current

    @backup_current.setter
    def backup_current(self, value):
        if value is None:
            self._backup_current = False
        else:
            self._backup_current = value

    @property
    def backup_ignore_patterns(self):
        return self._backup_ignore_patterns

    @backup_ignore_patterns.setter
    def backup_ignore_patterns(self, value):
        if value is None:
            self._backup_ignore_patterns = None
        elif not isinstance(value, list):
            raise ValueError("Backup pattern must be in list format")
        else:
            self._backup_ignore_patterns = value

    @property
    def check_interval(self):
        return (
            self._check_interval_enabled,
            self._check_interval_months,
            self._check_interval_days,
            self._check_interval_hours,
            self._check_interval_minutes
        )

    @property
    def current_version(self):
        return self._current_version

    @current_version.setter
    def current_version(self, tuple_values):
        if tuple_values is None:
            self._current_version = None
            return
        elif type(tuple_values) is not tuple:
            try:
                tuple(tuple_values)
            except:
                raise ValueError("current_version must be a tuple of integers")
        for i in tuple_values:
            if type(i) is not int:
                raise ValueError("current_version must be a tuple of integers")
        self._current_version = tuple(tuple_values)

    @property
    def engine(self):
        return self._engine.name

    @engine.setter
    def engine(self, value):
        engine = value.lower()
        if engine == "github":
            self._engine = GithubEngine()
        elif engine == "gitlab":
            self._engine = GitlabEngine()
        elif engine == "bitbucket":
            self._engine = BitbucketEngine()
        else:
            raise ValueError("Invalid engine selection")

    @property
    def error(self):
        return self._error

    @property
    def error_msg(self):
        return self._error_msg

    @property
    def fake_install(self):
        return self._fake_install

    @fake_install.setter
    def fake_install(self, value):
        if not isinstance(value, bool):
            raise ValueError("fake_install must be a boolean value")
        self._fake_install = bool(value)

    # not currently used
    @property
    def include_branch_auto_check(self):
        return self._include_branch_auto_check

    @include_branch_auto_check.setter
    def include_branch_auto_check(self, value):
        try:
            self._include_branch_auto_check = bool(value)
        except:
            raise ValueError("include_branch_autocheck must be a boolean")

    @property
    def include_branch_list(self):
        return self._include_branch_list

    @include_branch_list.setter
    def include_branch_list(self, value):
        try:
            if value is None:
                if self.legacy_blender:
                    self._include_branch_list = [LEGACY_BRANCH]
                else:
                    self._include_branch_list = ['master']

            elif not isinstance(value, list) or len(value) == 0:
                raise ValueError("include_branch_list should be a list of valid branches")
            else:
                self._include_branch_list = value
        except:
            raise ValueError("include_branch_list should be a list of valid branches")

    @property
    def include_branches(self):
        return self._include_branches

    @include_branches.setter
    def include_branches(self, value):
        try:
            self._include_branches = bool(value)
        except:
            raise ValueError("include_branches must be a boolean value")

    @property
    def json(self):
        if len(self._json) == 0:
            self.set_updater_json()
        return self._json

    @property
    def latest_release(self):
        if self._latest_release is None:
            return None
        return self._latest_release

    @property
    def manual_only(self):
        return self._manual_only

    @manual_only.setter
    def manual_only(self, value):
        try:
            self._manual_only = bool(value)
        except:
            raise ValueError("manual_only must be a boolean value")

    @property
    def overwrite_patterns(self):
        return self._overwrite_patterns

    @overwrite_patterns.setter
    def overwrite_patterns(self, value):
        if value is None:
            self._overwrite_patterns = ["*.py", "*.pyc"]
        elif not isinstance(value, list):
            raise ValueError("overwrite_patterns needs to be in a list format")
        else:
            self._overwrite_patterns = value

    @property
    def private_token(self):
        return self._engine.token

    @private_token.setter
    def private_token(self, value):
        if value is None:
            self._engine.token = None
        else:
            self._engine.token = str(value)

    @property
    def remove_pre_update_patterns(self):
        return self._remove_pre_update_patterns

    @remove_pre_update_patterns.setter
    def remove_pre_update_patterns(self, value):
        if value is None:
            self._remove_pre_update_patterns = list()
        elif not isinstance(value, list):
            raise ValueError("remove_pre_update_patterns needs to be in a list format")
        else:
            self._remove_pre_update_patterns = value

    @property
    def repo(self):
        return self._repo

    @repo.setter
    def repo(self, value):
        try:
            self._repo = str(value)
        except:
            raise ValueError("repo must be a string value")

    @property
    def select_link(self):
        return self._select_link

    @select_link.setter
    def select_link(self, value):
        # ensure it is a function assignment, with signature:
        # input self, tag; returns link name
        if not hasattr(value, "__call__"):
            raise ValueError("select_link must be a function")
        self._select_link = value

    @property
    def stage_path(self):
        return self._updater_path

    @stage_path.setter
    def stage_path(self, value):
        if value is None:
            self.print_verbose("Aborting assigning stage_path, it's null")
            return
        elif value is not None and not os.path.exists(value):
            try:
                os.makedirs(value)
            except:
                self.print_verbose("Error trying to staging path")
                self.print_trace()
                return
        self._updater_path = value

    @property
    def subfolder_path(self):
        return self._subfolder_path

    @subfolder_path.setter
    def subfolder_path(self, value):
        self._subfolder_path = value

    @property
    def tags(self):
        if len(self._tags) == 0:
            return list()
        tag_names = list()
        for tag in self._tags:
            nm = tag["name"]
            if "label" in tag.keys():
                label = tag["label"]
                if label == LEGACY_BRANCH:
                    label = "Master (Blender 2.7x)"
            else:
                label = "Stable (" + nm + ")"
            tag_names.append((nm, label, "Select to install " + nm))
        return tag_names

    @property
    def tag_latest(self):
        if self._tag_latest is None:
            return None
        return self._tag_latest["name"]

    @property
    def update_link(self):
        return self._update_link

    @property
    def update_ready(self):
        return self._update_ready

    @property
    def update_version(self):
        return self._update_version

    @property
    def use_releases(self):
        return self._use_releases

    @use_releases.setter
    def use_releases(self, value):
        try:
            self._use_releases = bool(value)
        except:
            raise ValueError("use_releases must be a boolean value")

    @property
    def user(self):
        return self._user

    @user.setter
    def user(self, value):
        try:
            self._user = str(value)
        except:
            raise ValueError("User must be a string value")

    @property
    def verbose(self):
        return self._verbose

    @verbose.setter
    def verbose(self, value):
        try:
            self._verbose = bool(value)
            self.print_verbose("Verbose is enabled")
        except:
            raise ValueError("Verbose must be a boolean value")

    @property
    def use_print_traces(self):
        return self._use_print_traces

    @use_print_traces.setter
    def use_print_traces(self, value):
        try:
            self._use_print_traces = bool(value)
        except:
            raise ValueError("use_print_traces must be a boolean value")

    @property
    def version_max_update(self):
        return self._version_max_update

    @version_max_update.setter
    def version_max_update(self, value):
        if value is None:
            self._version_max_update = None
            return
        if not isinstance(value, tuple):
            raise ValueError("Version maximum must be a tuple")
        for subvalue in value:
            if type(subvalue) is not int:
                raise ValueError("Version elements must be integers")
        self._version_max_update = value

    @property
    def version_min_update(self):
        return self._version_min_update

    @version_min_update.setter
    def version_min_update(self, value):
        if value is None:
            self._version_min_update = None
            return
        if not isinstance(value, tuple):
            raise ValueError("Version minimum must be a tuple")
        for subvalue in value:
            if type(subvalue) != int:
                raise ValueError("Version elements must be integers")
        self._version_min_update = value

    @property
    def website(self):
        return self._website

    @website.setter
    def website(self, value):
        if not self.check_is_url(value):
            raise ValueError("Not a valid URL: " + value)
        self._website = value

    # -------------------------------------------------------------------------
    # Parameter validation related functions
    # -------------------------------------------------------------------------
    @staticmethod
    def check_is_url(url):
        if not ("http://" in url or "https://" in url):
            return False
        if "." not in url:
            return False
        return True

    def _get_tag_names(self):
        tag_names = list()
        self.get_tags()
        for tag in self._tags:
            tag_names.append(tag["name"])
        return tag_names

    def set_check_interval(
            self, enabled=False,
            months=0, days=14, hours=0, minutes=0
        ):

        """Set the time interval between automated checks, and if enabled.

        Has enabled = False as default to not check against frequency,
        if enabled, default is 2 weeks.
        """

        if type(enabled) is not bool:
            raise ValueError("Enable must be a boolean value")
        if type(months) is not int:
            raise ValueError("Months must be an integer value")
        if type(days) is not int:
            raise ValueError("Days must be an integer value")
        if type(hours) is not int:
            raise ValueError("Hours must be an integer value")
        if type(minutes) is not int:
            raise ValueError("Minutes must be an integer value")

        self._check_interval_enabled = enabled

        self._check_interval_months = months
        self._check_interval_days = days
        self._check_interval_hours = hours
        self._check_interval_minutes = minutes

    def __repr__(self):
        return "<Module updater from {}>".format(__file__)

    def __str__(self):
        return "Updater, with user: {}, repository: {}, url: {}".format(
            self._user, self._repo, self.form_repo_url()
        )

    # -------------------------------------------------------------------------
    # API-related functions
    # -------------------------------------------------------------------------
    def form_repo_url(self):
        return self._engine.form_repo_url(self)

    def form_tags_url(self):
        return self._engine.form_tags_url(self)
    
    def form_branch_list_url(self):
        return self._engine.form_branch_list_url(self)

    def form_branch_url(self, branch):
        return self._engine.form_branch_url(branch, self)

    def get_tags(self):
        request = self.form_tags_url()
        self.print_verbose("Getting tags from server")

        # get all tags, internet call
        # print("url:", request)
        all_tags = self._engine.parse_tags(self.get_api(request), self)
        if all_tags is not None:
            self._prefiltered_tag_count = len(all_tags)
        else:
            self._prefiltered_tag_count = 0
            all_tags = list()

        if len(all_tags) > 0:
            # only need the latest release 
            # all_tags = [all_tags[0]]
            self._tags = [all_tags[0]] + self._tags

        # pre-process to skip tags
        # if self.skip_tag is not None:
        #     self._tags = [tg for tg in all_tags if not self.skip_tag(self, tg)]
        # else:
        #     self._tags = all_tags
        
        # get additional branches too, if needed, and place in front
        # Does NO checking here whether branch is valid
        # if self._include_branches:
        #     temp_branches = self._include_branch_list.copy()
        #     for branch in temp_branches:
        #         request = self.form_branch_url(branch)
        #         include = {
        #             "name": branch,
        #             "label": branch,
        #             "zipball_url": request
        #         }
        #         self._tags.append(include)

        if self._tags is None:
            # some error occurred
            self._tag_latest = None
            self._tags = list()

        elif self._prefiltered_tag_count == 0 and not self._include_branches:
            self._tag_latest = None
            if self._error is None:  # if not None, could have had no internet
                self._error = "No releases found"
                self._error_msg = "No releases or tags found in repository"
            self.print_verbose("No releases or tags found in repository")

        elif self._prefiltered_tag_count == 0 and self._include_branches and len(self._include_branch_list) > 0:
            if not self._error:
                self._tag_latest = self._tags[0]
            branch = self._include_branch_list[0]
            self.print_verbose(
                "{} branch found, no releases: {}".format(branch, self._tags[0])
            )

        elif (
                (len(self._tags) - len(self._include_branch_list) == 0 and self._include_branches)
                or (len(self._tags) == 0 and not self._include_branches)
                and self._prefiltered_tag_count > 0
            ):
            self._tag_latest = None
            self._error = "No releases available"
            self._error_msg = "No versions found within compatible version range"
            self.print_verbose(self._error_msg)

        else:
            
            self._tag_latest = self._tags[0]
            self.print_verbose("Most recent tag found:" + str(self._tags[0]['name']))
            
        self._json["branches"] = self._tags
    
    def get_branches(self):
        self._include_branch_list.clear()
        self._tags.clear()

        request = self.form_branch_list_url()
        self.print_verbose("Getting branches from server " + request)
        all_branches = self.get_api(request)

        if all_branches is None:
            all_branches = list()

        for br in all_branches:
            branch = br["name"]
            include = self.get_branch_obj(branch, br["commit"]["sha"])

            if self.legacy_blender:
                if branch == LEGACY_BRANCH:
                    self._tags.append(include)
                    self._include_branch_list.append(branch)
            elif branch != LEGACY_BRANCH:
                if branch == "master": 
                    self._tags = [include] + self._tags
                else:
                    self._tags.append(include)
                self._include_branch_list.append(branch)

    def get_branch_obj(self, branch_name, last_commit):
        request_br = self.form_branch_url(branch_name)

        return {
            "name" : branch_name,
            "last_commit" : last_commit,
            "label" : branch_name,
            "zipball_url" : request_br
        }

    def get_raw(self, url):
        """All API calls to base url."""
        request = urllib.request.Request(url)
        try:
            context = ssl._create_unverified_context()
        except:
            # Some blender packaged python versions don't have this, largely
            # useful for local network setups otherwise minimal impact.
            context = None

        # Setup private request headers if appropriate.
        if self._engine.token is not None:
            if self._engine.name == "gitlab":
                request.add_header('PRIVATE-TOKEN', self._engine.token)
            else:
                self.print_verbose("Tokens not setup for engine yet")

        # Always set user agent.
        request.add_header('User-Agent', "Python/" + str(platform.python_version()))

        # Run the request.
        try:
            if context:
                result = urllib.request.urlopen(request, context=context)
            else:
                result = urllib.request.urlopen(request)
        except urllib.error.HTTPError as e:
            if str(e.code) == "403":
                self._error = "HTTP error (access denied)"
                self._error_msg = str(e.code) + " - server error response"
                print(self._error, self._error_msg)
            else:
                self._error = "HTTP error"
                self._error_msg = str(e.code)
                print(self._error, self._error_msg)
            self.print_trace()
            self._update_ready = None
        except urllib.error.URLError as e:
            reason = str(e.reason)
            if "TLSV1_ALERT" in reason or "SSL" in reason.upper():
                self._error = "Connection rejected, download manually"
                self._error_msg = reason
                print(self._error, self._error_msg)
            else:
                self._error = "URL error, check internet connection"
                self._error_msg = reason
                print(self._error, self._error_msg)
            self.print_trace()
            self._update_ready = None
            return None
        else:
            result_string = result.read()
            result.close()
            return result_string.decode()

    def get_api(self, url):
        """Result of all api calls, decoded into json format."""
        get = None
        get = self.get_raw(url)
        if get is not None:
            try:
                return json.JSONDecoder().decode(get)
            except Exception as e:
                self._error = "API response has invalid JSON format"
                self._error_msg = str(e.reason)
                self._update_ready = None
                print(self._error, self._error_msg)
                self.print_trace()
                return None
        else:
            return None

    def stage_repository(self, url):
        """Create a working directory and download the new files"""

        local = os.path.join(self._updater_path, "update_staging")
        error = None

        # Make/clear the staging folder, to ensure the folder is always clean.
        self.print_verbose("Preparing staging folder for download:\n" + str(local))
        if os.path.isdir(local):
            try:
                shutil.rmtree(local)
                os.makedirs(local)
            except:
                error = "failed to remove existing staging directory"
                self.print_trace()
        else:
            try:
                os.makedirs(local)
            except:
                error = "failed to create staging directory"
                self.print_trace()

        if error is not None:
            self.print_verbose("Error: Aborting update, " + error)
            self._error = "Update aborted, staging path error"
            self._error_msg = "Error: {}".format(error)
            return False

        if self._backup_current:
            self.create_backup()

        self.print_verbose("Now retrieving the new source zip")
        self._source_zip = os.path.join(local, "source.zip")
        self.print_verbose("Starting download update zip")
        try:
            request = urllib.request.Request(url)
            context = None
            if is_bl_newer_than(2, 77):
                context = ssl._create_unverified_context()

            # Setup private token if appropriate.
            if self._engine.token is not None:
                if self._engine.name == "gitlab":
                    request.add_header('PRIVATE-TOKEN', self._engine.token)
                else:
                    self.print_verbose("Tokens not setup for selected engine yet")

            # Always set user agent
            request.add_header('User-Agent', "Python/" + str(platform.python_version()))

            if context:
                self.url_retrieve(
                    urllib.request.urlopen(request, context=context), self._source_zip
                )
            else:
                self.url_retrieve(
                    urllib.request.urlopen(request), self._source_zip
                )
            # Add additional checks on file size being non-zero.
            self.print_verbose("Successfully downloaded update zip")
            return True
        except Exception as e:
            self._error = "Error retrieving download, bad link?"
            self._error_msg = "Error: {}".format(e)
            print("Error retrieving download, bad link?")
            print("Error: {}".format(e))
            self.print_trace()
            return False

    def create_backup(self):
        """Save a backup of the current installed addon prior to an update."""
        self.print_verbose("Backing up current addon folder")
        local = os.path.join(self._updater_path, "backup")
        tempdest = os.path.join(
            self._addon_root, os.pardir, self._addon + "_updater_backup_temp"
        )

        self.print_verbose("Backup destination path: " + str(local))

        if os.path.isdir(local):
            try:
                shutil.rmtree(local)
            except:
                self.print_verbose(
                    "Failed to removed previous backup folder, continuing")
                self.print_trace()

        # Remove the temp folder.
        # Shouldn't exist but could if previously interrupted.
        if os.path.isdir(tempdest):
            try:
                shutil.rmtree(tempdest)
            except:
                self.print_verbose("Failed to remove existing temp folder, continuing")
                self.print_trace()

        # Make a full addon copy, temporarily placed outside the addon folder.
        if self._backup_ignore_patterns is not None:
            try:
                shutil.copytree(
                    self._addon_root, tempdest,
                    ignore = shutil.ignore_patterns(*self._backup_ignore_patterns)
                )
            except:
                print("Failed to create backup, still attempting update.")
                self.print_trace()
                return
        else:
            try:
                shutil.copytree(self._addon_root, tempdest)
            except:
                print("Failed to create backup, still attempting update.")
                self.print_trace()
                return
        shutil.move(tempdest, local)

        # Save the date for future reference.
        now = datetime.now()
        self._json["backup_date"] = "{m}-{d}-{yr}".format(
            m=now.strftime("%B"), d=now.day, yr=now.year
        )
        self.save_updater_json()

    def restore_backup(self):
        """Restore the last backed up addon version, user initiated only"""
        self.print_verbose("Restoring backup, backing up current addon folder")
        backuploc = os.path.join(self._updater_path, "backup")
        tempdest = os.path.join(
            self._addon_root, os.pardir, self._addon + "_updater_backup_temp"
        )
        tempdest = os.path.abspath(tempdest)

        # Move instead contents back in place, instead of copy.
        shutil.move(backuploc, tempdest)
        shutil.rmtree(self._addon_root)
        os.rename(tempdest, self._addon_root)

        self._json["backup_date"] = ""
        self._json["just_restored"] = True
        self._json["just_updated"] = True
        self.save_updater_json()

        self.reload_addon()

    def unpack_staged_zip(self, clean=False):
        """Unzip the downloaded file, and validate contents"""
        if not os.path.isfile(self._source_zip):
            self.print_verbose("Error, update zip not found")
            self._error = "Install failed"
            self._error_msg = "Downloaded zip not found"
            return -1

        # Clear the existing source folder in case previous files remain.
        outdir = os.path.join(self._updater_path, "source")
        try:
            shutil.rmtree(outdir)
            self.print_verbose("Source folder cleared")
        except:
            self.print_trace()

        # Create parent directories if needed, would not be relevant unless
        # installing addon into another location or via an addon manager.
        try:
            os.mkdir(outdir)
        except Exception as err:
            print("Error occurred while making extract dir:")
            print(str(err))
            self.print_trace()
            self._error = "Install failed"
            self._error_msg = "Failed to make extract directory"
            return -1

        if not os.path.isdir(outdir):
            print("Failed to create source directory")
            self._error = "Install failed"
            self._error_msg = "Failed to create extract directory"
            return -1

        self.print_verbose(
            "Begin extracting source from zip:" + str(self._source_zip))
        with zipfile.ZipFile(self._source_zip, "r") as zfile:

            if not zfile:
                self._error = "Install failed"
                self._error_msg = "Resulting file is not a zip, cannot extract"
                self.print_verbose(self._error_msg)
                return -1

            # Now extract directly from the first subfolder (not root)
            # this avoids adding the first subfolder to the path length,
            # which can be too long if the download has the SHA in the name.
            zsep = '/'  # Not using os.sep, always the / value even on windows.
            for name in zfile.namelist():
                if zsep not in name:
                    continue
                top_folder = name[:name.index(zsep) + 1]
                if name == top_folder + zsep:
                    continue  # skip top level folder
                sub_path = name[name.index(zsep) + 1:]
                if name.endswith(zsep):
                    try:
                        os.mkdir(os.path.join(outdir, sub_path))
                        self.print_verbose(
                            "Extract - mkdir: " + os.path.join(outdir, sub_path)
                        )
                    except OSError as exc:
                        if exc.errno != errno.EEXIST:
                            self._error = "Install failed"
                            self._error_msg = "Could not create folder from zip"
                            self.print_trace()
                            return -1
                else:
                    with open(os.path.join(outdir, sub_path), "wb") as outfile:
                        data = zfile.read(name)
                        outfile.write(data)
                        self.print_verbose(
                            "Extract - create: " + os.path.join(outdir, sub_path)
                        )

        self.print_verbose("Extracted source")

        unpath = os.path.join(self._updater_path, "source")
        if not os.path.isdir(unpath):
            self._error = "Install failed"
            self._error_msg = "Extracted path does not exist"
            print("Extracted path does not exist: ", unpath)
            return -1

        if self._subfolder_path:
            self._subfolder_path.replace('/', os.path.sep)
            self._subfolder_path.replace('\\', os.path.sep)

        # Either directly in root of zip/one subfolder, or use specified path.
        if not os.path.isfile(os.path.join(unpath, "__init__.py")):
            dirlist = os.listdir(unpath)
            if len(dirlist) > 0:
                if self._subfolder_path == "" or self._subfolder_path is None:
                    unpath = os.path.join(unpath, dirlist[0])
                else:
                    unpath = os.path.join(unpath, self._subfolder_path)

            # Smarter check for additional sub folders for a single folder
            # containing the __init__.py file.
            if not os.path.isfile(os.path.join(unpath, "__init__.py")):
                print("Not a valid addon found")
                print("Paths:")
                print(dirlist)
                self._error = "Install failed"
                self._error_msg = "No __init__ file found in new source"
                return -1

        # Merge code with the addon directory, using blender default behavior,
        # plus any modifiers indicated by user (e.g. force remove/keep).
        self.deep_merge_directory(self._addon_root, unpath, clean)

        # Now save the json state.
        # Change to True to trigger the handler on other side if allowing
        # reloading within same blender session.
        self._json["just_updated"] = True
        self._json["using_development_build"] = self.using_development_build
        self._json["current_branch"] = self.current_branch
        self._json["last_commit"] = self._last_commit
        
        if self.legacy_blender:
            bpy.ops.wm.save_userpref()

        self.save_updater_json()
        self.reload_addon()
        self._update_ready = False
        return 0

    def deep_merge_directory(self, base, merger, clean=False):
        """Merge folder 'merger' into 'base' without deleting existing"""
        if not os.path.exists(base):
            self.print_verbose("Base path does not exist:" + str(base))
            return -1
        elif not os.path.exists(merger):
            self.print_verbose("Merger path does not exist")
            return -1

        # Path to be aware of and not overwrite/remove/etc.
        staging_path = os.path.join(self._updater_path, "update_staging")

        # If clean install is enabled, clear existing files ahead of time
        # note: will not delete the update.json, update folder, staging, or
        # staging but will delete all other folders/files in addon directory.
        error = None
        if clean:
            try:
                # Implement clearing of all folders/files, except the updater
                # folder and updater json.
                # Careful, this deletes entire subdirectories recursively...
                # Make sure that base is not a high level shared folder, but
                # is dedicated just to the addon itself.
                self.print_verbose("clean=True, clearing addon folder to fresh install state")

                # Remove root files and folders (except update folder).
                files = [
                    f for f in os.listdir(base)
                        if os.path.isfile(os.path.join(base, f))
                ]
                folders = [
                    f for f in os.listdir(base)
                        if os.path.isdir(os.path.join(base, f))
                ]

                for f in files:
                    os.remove(os.path.join(base, f))
                    self.print_verbose(
                        "Clean removing file {}".format(os.path.join(base, f))
                    )
                for f in folders:
                    if os.path.join(base, f) is self._updater_path:
                        continue
                    shutil.rmtree(os.path.join(base, f))
                    self.print_verbose(
                        "Clean removing folder and contents {}".format(os.path.join(base, f))
                    )

            except Exception as err:
                error = "failed to create clean existing addon folder"
                print(error, str(err))
                self.print_trace()

        # Walk through the base addon folder for rules on pre-removing
        # but avoid removing/altering backup and updater file.
        for path, dirs, files in os.walk(base):
            # Prune ie skip updater folder.
            dirs[:] = [
                d for d in dirs
                    if os.path.join(path, d) not in [self._updater_path]
            ]
            for file in files:
                for pattern in self.remove_pre_update_patterns:
                    if fnmatch.filter([file], pattern):
                        try:
                            fl = os.path.join(path, file)
                            os.remove(fl)
                            self.print_verbose("Pre-removed file " + file)
                        except OSError:
                            print("Failed to pre-remove " + file)
                            self.print_trace()

        # Walk through the temp addon sub folder for replacements
        # this implements the overwrite rules, which apply after
        # the above pre-removal rules. This also performs the
        # actual file copying/replacements.
        for path, dirs, files in os.walk(merger):
            # Verify structure works to prune updater sub folder overwriting.
            dirs[:] = [
                d for d in dirs
                    if os.path.join(path, d) not in [self._updater_path]
            ]
            rel_path = os.path.relpath(path, merger)
            dest_path = os.path.join(base, rel_path)
            if not os.path.exists(dest_path):
                os.makedirs(dest_path)
            for file in files:
                # Bring in additional logic around copying/replacing.
                # Blender default: overwrite .py's, don't overwrite the rest.
                dest_file = os.path.join(dest_path, file)
                srcFile = os.path.join(path, file)

                # Decide to replace if file already exists, and copy new over.
                if os.path.isfile(dest_file):
                    # Otherwise, check each file for overwrite pattern match.
                    replaced = False
                    for pattern in self._overwrite_patterns:
                        if fnmatch.filter([file], pattern):
                            replaced = True
                            break
                    if replaced:
                        os.remove(dest_file)
                        os.rename(srcFile, dest_file)
                        self.print_verbose(
                            "Overwrote file " + os.path.basename(dest_file))
                    else:
                        self.print_verbose(
                            "Pattern not matched to {}, not overwritten".format(
                                os.path.basename(dest_file)
                            )
                        )
                else:
                    # File did not previously exist, simply move it over.
                    os.rename(srcFile, dest_file)
                    self.print_verbose("New file " + os.path.basename(dest_file))

        # now remove the temp staging folder and downloaded zip
        try:
            shutil.rmtree(staging_path)
        except:
            error = (
                "Error: Failed to remove existing staging directory, "
                "consider manually removing "
            ) + staging_path

            self.print_verbose(error)
            self.print_trace()

    def reload_addon(self):
        # if post_update false, skip this function
        # else, unload/reload addon & trigger popup
        if not self._auto_reload_post_update:
            print("Restart blender to reload addon and complete update")
            return

        self.print_verbose("Reloading addon...")
        addon_utils.modules(refresh=True)
        bpy.utils.refresh_script_paths()

        # not allowed in restricted context, such as register module
        # toggle to refresh
        if "addon_disable" in dir(bpy.ops.wm):  # 2.7
            bpy.ops.wm.addon_disable(module=self._addon_package)
            bpy.ops.wm.addon_refresh()
            bpy.ops.wm.addon_enable(module=self._addon_package)
            print("2.7 reload complete")
        else:  # 2.8
            bpy.ops.preferences.addon_disable(module=self._addon_package)
            bpy.ops.preferences.addon_refresh()
            bpy.ops.preferences.addon_enable(module=self._addon_package)
            print("2.8 reload complete")

    # -------------------------------------------------------------------------
    # Other non-api functions and setups
    # -------------------------------------------------------------------------
    def restore_saved_branches(self):
        saved_json = self.json
        if "branches" in saved_json.keys():
            
            self._tags = saved_json["branches"]
            self._include_branch_list = []

            for tag in self._tags:
                if "last_commit" in tag:
                    self._include_branch_list.append(tag["name"])

        if "using_development_build" in saved_json.keys():
            self.using_development_build = saved_json["using_development_build"]
        if "current_branch" in saved_json.keys():
            self.current_branch = saved_json["current_branch"]
        if "last_commit" in saved_json.keys():
            self._last_commit = saved_json["last_commit"] 
            
        if "update_ready" in saved_json.keys():
            self._update_ready = saved_json["update_ready"]
            if self._update_ready:
                if self.using_development_build:
                    self.set_tag(self.current_branch)
                else:
                    self._tag_latest = self._tags[0]
                    self.set_tag(self.tag_latest)
        
    def clear_state(self):
        self._update_ready = None
        self._update_link = None
        self._last_commit = None
        self._update_version = None
        self._source_zip = None
        self._error = None
        self._error_msg = None

    def url_retrieve(self, url_file, filepath):
        """Custom urlretrieve implementation"""
        chunk = 1024 * 8
        f = open(filepath, "wb")
        while 1:
            data = url_file.read(chunk)
            if not data:
                # print("done.")
                break
            f.write(data)
            # print("Read %s bytes" % len(data))
        f.close()

    def version_tuple_from_text(self, text):
        """Convert text into a tuple of numbers (int).

        Should go through string and remove all non-integers, and for any
        given break split into a different section.
        """
        if text is None:
            return ()

        segments = list()
        tmp = ''
        for char in str(text):
            if not char.isdigit():
                if len(tmp) > 0:
                    segments.append(int(tmp))
                    tmp = ''
            else:
                tmp += char
        if len(tmp) > 0:
            segments.append(int(tmp))

        if len(segments) == 0:
            self.print_verbose("No version strings found text: " + str(text))
            if not self._include_branches:
                return ()
            else:
                return (text)
        return tuple(segments)

    def check_for_update_async(self, callback=None):
        """Called for running check in a background thread"""
        is_ready = (
            self._json is not None
            and "update_ready" in self._json
            and self._json["version_text"] != dict()
            and self._json["update_ready"])

        if is_ready:
            self._update_ready = True
            self._update_link = self._json["version_text"]["link"]
            self._update_version = str(self._json["version_text"]["version"])
            # Cached update.
            callback(True)
            return

        # do the check
        if not self._check_interval_enabled:
            return
        elif self._async_checking:
            self.print_verbose("Skipping async check, already started")
            # already running the bg thread
        elif self._update_ready is None:
            print("{} updater: Running background check for update".format(self.addon))
            self.start_async_check_update(False, callback)

    def check_for_update_now(self, callback=None):
        self._error = None
        self._error_msg = None
        self.print_verbose(
            "Check update now pressed, first getting current status")
        if self._async_checking:
            self.print_verbose("Skipping async check, already started")
            return  # already running the bg thread
        elif self._update_ready is None:
            self.start_async_check_update(True, callback)
        else:
            self._update_ready = None
            self.start_async_check_update(True, callback)

    def check_for_branches_now(self, callback=None):
        self._error = None
        self._error_msg = None
        self.print_verbose(
            "Check update branches pressed, first getting current status")
        if self._async_checking:
            self.print_verbose("Skipping async check, already started")
            return  # already running the bg thread
        elif self._update_ready is None:
            self.start_async_check_branches(callback)
        else:
            self._update_ready = None
            self.start_async_check_branches(callback)

    def check_for_branches_releases_now(self, callback=None):
        self._error = None
        self._error_msg = None
        self.print_verbose(
            "Check update pressed, first getting current status")
        if self._async_checking:
            self.print_verbose("Skipping async check, already started")
            return  # already running the bg thread
        elif self._update_ready is None:
            self.start_async_check_branches_releases(callback)
        else:
            self._update_ready = None
            self.start_async_check_branches_releases(callback)

    def check_for_update(self, update_last_check:bool = True, now=False):
        """Check for update not in a syncrhonous manner.

        This function is not async, will always return in sequential fashion
        but should have a parent which calls it in another thread.
        """
        self.print_verbose("Checking for update function")

        # clear the errors if any
        self._error = None
        self._error_msg = None

        # avoid running again in, just return past result if found
        # but if force now check, then still do it
        if self._update_ready is not None and not now:
            return (
                self._update_ready,
                self._update_version,
                self._update_link
            )

        if self._current_version is None:
            raise ValueError("current_version not yet defined")

        if self._repo is None:
            raise ValueError("repo not yet defined")

        if self._user is None:
            raise ValueError("username not yet defined")

        self.set_updater_json()  # self._json

        if not now and not self.past_interval_timestamp():
            self.print_verbose("Aborting check for updated, check interval not reached")
            return (False, None, None)

        # check if using tags or releases
        # note that if called the first time, this will pull tags from online
        if self._fake_install:
            self.print_verbose("fake_install = True, setting fake version as ready")
            self._update_ready = True
            self._update_version = "(999,999,999)"
            self._update_link = "http://127.0.0.1"

            return (
                self._update_ready,
                self._update_version,
                self._update_link
            )

        # Primary internet call, sets self._tags and self._tag_latest.
        self.get_tags()


        if update_last_check:
            self._json["last_check"] = str(datetime.now())
        self.save_updater_json()
        

        # Can be () or ('master') in addition to branches, and version tag.
        new_version = self.version_tuple_from_text(self.tag_latest)

        if len(self._tags) == 0:
            self._update_ready = False
            self._update_version = None
            self._update_link = None
            return (False, None, None)

        if not self._include_branches:
            link = self.select_link(self, self._tags[0])
        else:
            n = len(self._include_branch_list)
            if len(self._tags) == n:
                # effectively means no tags found on repo
                # so provide the first one as default
                link = self.select_link(self, self._tags[0])
            else:
                link = self.select_link(self, self._tags[n])

        if self.using_development_build:
            for tg in self._tags:
                if tg["name"] == self.current_branch:
                    if self._last_commit is not None and self._last_commit != tg["last_commit"]:
                        self._update_ready = True
                        self._update_version = new_version
                        self._update_link = link
                        self.save_updater_json()
                        print("use branch build(",self.current_branch,") there is update", new_version, "|", link)
                        return (True, new_version, link) 
                    self.print_verbose("use branch " + self.current_branch + " build no update")
            self.print_verbose("use branch build no update")
        else:
            if new_version > self._current_version:
                self._update_ready = True
                self._update_version = new_version
                self._update_link = link
                self.save_updater_json()
                print("use stable build(",self.current_branch,") there is update", new_version, "|", link)

                return (True, new_version, link)
            self.print_verbose("use stable build no update")

        # If no update, set ready to False from None to show it was checked.
        self._update_ready = False
        self._update_version = None
        self._update_link = None
        return (False, None, None)
    
    def check_for_branches(self, update_last_check:bool=True):
        """Check for update not in a syncrhonous manner.

        This function is not async, will always return in sequential fashion
        but should have a parent which calls it in another thread.
        """
        self.print_verbose("Checking for branches function")

        # clear the errors if any
        self._error = None
        self._error_msg = None

        # avoid running again in, just return past result if found
        # but if force now check, then still do it
        if self._update_ready is not None:
            self.print_verbose(
                "Aborting check for brannches, update ready=" + str(self._update_ready)
            )
            return (
                self._update_ready,
                self._update_version,
                self._update_link
            )

        self.set_updater_json()  # self._json

        if not self.past_interval_timestamp():
            self.print_verbose("Aborting check for brannches, check interval not reached")
            return (False, None, None)

        # check if using tags or releases
        # note that if called the first time, this will pull tags from online
        # if self._fake_install:
        #     self.print_verbose(
        #         "fake_install = True, setting fake version as ready")
        #     self._update_ready = True
        #     self._update_version = "(999,999,999)"
        #     self._update_link = "http://127.0.0.1"

        #     return (self._update_ready,
        #             self._update_version,
        #             self._update_link)

        # Primary internet call, sets self._tags and self._tag_latest.
        self.get_branches()

        if update_last_check:
            self._json["last_check"] = str(datetime.now())
        self.save_updater_json()

        if len(self._tags) == 0:
            self._update_ready = False
            self._update_version = None
            self._update_link = None
            return (False, None, None)

        link = self.select_link(self, self._tags[0]) # last selected branch
        
        self._update_ready = True
        self._update_link = link
        self.save_updater_json()

        return (True, "", link)


    def on_dev_mode_change(self, dev_mode):
        self.use_releases = not dev_mode
        self.include_branches = dev_mode
        self.clear_state()

        if dev_mode:
            if self.legacy_blender:
                self.get_branches()
                link = self.select_link(self, self._tags[0]) # last selected branch
                self._update_ready = True
                self._update_link = link
                self.save_updater_json()
            else:
                from . import addon_updater_ops 
                self.check_for_branches_now(addon_updater_ops.ui_refresh)


    def set_tag(self, name):
        """Assign the tag name and url to update to"""
        tg = None
        for tag in self._tags:
            if name == tag["name"]:
                tg = tag
                break
        self.using_development_build = name in self._include_branch_list
        self.current_branch = name
        
        if tg:
            new_version = self.version_tuple_from_text(self.tag_latest)
            self._update_version = new_version
            self._update_link = self.select_link(self, tg)
            if self.using_development_build:
                self._last_commit = tg["last_commit"]
            
        elif self._include_branches and name in self._include_branch_list:
            # scenario if reverting to a specific branch name instead of tag
            tg = name
            link = self.form_branch_url(tg)
            self._update_version = name  # this will break things
            self._update_link = link
        # print("download url", self._update_link)
        if not tg:
            raise ValueError("Version tag not found: " + name)

    def run_update(self, force=False, revert_tag=None, clean=False, callback=None):
        """Runs an install, update, or reversion of an addon from online source

        Arguments:
            force: Install assigned link, even if self.update_ready is False
            revert_tag: Version to install, if none uses detected update link
            clean: not used, but in future could use to totally refresh addon
            callback: used to run function on update completion
        """
        self._json["update_ready"] = False
        self._json["ignore"] = False  # clear ignore flag
        self._json["version_text"] = dict()

        # in case error
        prev_data = (self.using_development_build, self.current_branch)

        if revert_tag is not None:
            self.set_tag(revert_tag)
            self._update_ready = True

           
        print("self._update_link", self._update_link)
        # if True:
        #     return 0
        # clear the errors if any
        self._error = None
        self._error_msg = None

        self.print_verbose("Running update")

        if self._fake_install:
            # Change to True, to trigger the reload/"update installed" handler.
            self.print_verbose("fake_install=True")
            self.print_verbose("Just reloading and running any handler triggers")
            self._json["just_updated"] = True
            self.save_updater_json()
            if self._backup_current is True:
                self.create_backup()
            self.reload_addon()
            self._update_ready = False
            res = True  # fake "success" zip download flag

        elif not force:
            if not self._update_ready:
                self.print_verbose("Update stopped, new version not ready")
                if callback:
                    callback(
                        self._addon_package,
                        "Update stopped, new version not ready"
                    )
                return "Update stopped, new version not ready"
            elif self._update_link is None:
                # this shouldn't happen if update is ready
                self.print_verbose("Update stopped, update link unavailable")
                if callback:
                    callback(
                        self._addon_package,
                        "Update stopped, update link unavailable"
                    )
                return "Update stopped, update link unavailable"

            if revert_tag is None:
                self.print_verbose("Staging update")
            else:
                self.print_verbose("Staging install")

            res = self.stage_repository(self._update_link)
            if not res:
                print("Error in staging repository: " + str(res))
                # revert
                self._update_ready = False
                self.using_development_build = prev_data[0] 
                self.current_branch = prev_data[1]
                
                if callback is not None:
                    callback(self._addon_package, self._error_msg)
                return self._error_msg
            res = self.unpack_staged_zip(clean)
            if res < 0:
                if callback:
                    callback(self._addon_package, self._error_msg)
                return res

        else:
            if self._update_link is None:
                self.print_verbose("Update stopped, could not get link")
                return "Update stopped, could not get link"
            self.print_verbose("Forcing update")

            res = self.stage_repository(self._update_link)
            if not res:
                print("Error in staging repository: " + str(res))
                # revert
                self._update_ready = False
                self.using_development_build = prev_data[0] 
                self.current_branch = prev_data[1]
                
                if callback:
                    callback(self._addon_package, self._error_msg)
                return self._error_msg
            res = self.unpack_staged_zip(clean)
            if res < 0:
                return res
            # would need to compare against other versions held in tags

        # run the front-end's callback if provided
        if callback:
            callback(self._addon_package)

        # return something meaningful, 0 means it worked
        return 0

    def past_interval_timestamp(self):
        if not self._check_interval_enabled:
            return True  # ie this exact feature is disabled

        if "last_check" not in self._json or self._json["last_check"] == "":
            return True

        now = datetime.now()
        last_check = datetime.strptime(
            self._json["last_check"], "%Y-%m-%d %H:%M:%S.%f")
        offset = timedelta(
            days=self._check_interval_days + 30 * self._check_interval_months,
            hours=self._check_interval_hours,
            minutes=self._check_interval_minutes)

        delta = (now - offset) - last_check
        if delta.total_seconds() > 0:
            self.print_verbose("Time to check for updates!")
            return True

        print("Determined it's not yet time to check for updates", delta.total_seconds())
        return False

    def get_json_path(self):
        """Returns the full path to the JSON state file used by this updater.

        Will also rename old file paths to addon-specific path if found.
        """
        json_path = os.path.join(
            self._updater_path,
            "{}_updater_status.json".format(self._addon_package)
        )
        old_json_path = os.path.join(self._updater_path, "updater_status.json")

        # Rename old file if it exists.
        try:
            os.rename(old_json_path, json_path)
        except FileNotFoundError:
            pass
        except Exception as err:
            print("Other OS error occurred while trying to rename old JSON")
            print(err)
            self.print_trace()
        return json_path

    def set_updater_json(self):
        """Load or initialize JSON dictionary data for updater state"""
        if self._updater_path is None:
            raise ValueError("updater_path is not defined")
        elif not os.path.isdir(self._updater_path):
            os.makedirs(self._updater_path)

        jpath = self.get_json_path()
        if os.path.isfile(jpath):
            with open(jpath) as data_file:
                self._json = json.load(data_file)
                self.print_verbose("Read in JSON settings from file")
        else:
            self._json = {
                "last_check" : "",
                "backup_date" : "",
                "using_development_build" : self.using_development_build,
                "current_branch" : self.current_branch,
                "last_commit" : self._last_commit,
                "update_ready" : False,
                "ignore" : False,
                "just_restored" : False,
                "just_updated" : False,
                "version_text" : dict()
            }
            self.save_updater_json()

    def save_updater_json(self):
        """Trigger save of current json structure into file within addon"""
        if self._update_ready:
            if isinstance(self._update_version, tuple):
                self._json["update_ready"] = True
                self._json["version_text"]["link"] = self._update_link
                self._json["version_text"]["version"] = self._update_version
            else:
                self._json["update_ready"] = False
                self._json["version_text"] = dict()
        else:
            self._json["update_ready"] = False
            self._json["version_text"] = dict()

        jpath = self.get_json_path()
        if not os.path.isdir(os.path.dirname(jpath)):
            print(
                "State error: Directory does not exist, cannot save json: ",
                os.path.basename(jpath)
            )
            return
        try:
            with open(jpath, 'w') as outf:
                data_out = json.dumps(self._json, indent=4)
                outf.write(data_out)
        except:
            print("Failed to open/save data to json: ", jpath)
            self.print_trace()
        self.print_verbose("Wrote out updater JSON settings with content:")

    def json_reset_postupdate(self):
        self._json["just_updated"] = False
        self._json["update_ready"] = False
        self._json["version_text"] = dict()
        self.save_updater_json()

    def json_reset_restore(self):
        self._json["just_restored"] = False
        self._json["update_ready"] = False
        self._json["version_text"] = dict()
        self.save_updater_json()
        self._update_ready = None  # Reset so you could check update again.

    def ignore_update(self):
        self._json["ignore"] = True
        self.save_updater_json()

    # -------------------------------------------------------------------------
    # ASYNC related methods
    # -------------------------------------------------------------------------
    def start_async_check_update(self, now=False, callback=None):
        """Start a background thread which will check for updates"""
        if self._async_checking:
            return
        self.print_verbose("Starting background checking thread")
        check_thread = threading.Thread(
            target = self.async_check_update,
            args = (now, callback,)
        )
        check_thread.daemon = True
        self._check_thread = check_thread
        check_thread.start()

    def async_check_update(self, now, callback=None):
        """Perform update check, run as target of background thread"""
        self._async_checking = True
        self.print_verbose("Checking for update now in background")

        try:
            self.check_for_update(now=now)
        except Exception as exception:
            print("Checking for update error:")
            print(exception)
            self.print_trace()
            if not self._error:
                self._update_ready = False
                self._update_version = None
                self._update_link = None
                self._error = "Error occurred"
                self._error_msg = "Encountered an error while checking for updates"

        self._async_checking = False
        self._check_thread = None

        if callback:
            self.print_verbose("Finished check update, doing callback")
            callback(self._update_ready)
        self.print_verbose("BG thread: Finished check update, no callback")

    def stop_async_check_update(self):
        """Method to give impression of stopping check for update.

        Currently does nothing but allows user to retry/stop blocking UI from
        hitting a refresh button. This does not actually stop the thread, as it
        will complete after the connection timeout regardless. If the thread
        does complete with a successful response, this will be still displayed
        on next UI refresh (ie no update, or update available).
        """
        if self._check_thread is not None:
            self.print_verbose("Thread will end in normal course.")
            # however, "There is no direct kill method on a thread object."
            # better to let it run its course
            # self._check_thread.stop()
        self._async_checking = False
        self._error = None
        self._error_msg = None

    def start_async_check_branches(self, callback=None):
        """Start a background thread which will check for updates"""
        if self._async_checking:
            return
        self.print_verbose("Starting background checking thread")
        check_thread = threading.Thread(
            target=self.async_check_branches,
            args=(callback,)
        )
        check_thread.daemon = True
        self._check_thread = check_thread
        check_thread.start()

    def start_async_check_branches_releases(self, callback=None):
        """Start a background thread which will check for updates"""
        if self._async_checking:
            return
        self.print_verbose("Starting background checking thread")
        check_thread = threading.Thread(
            target = self.async_check_branches_releases,
            args = (callback,)
        )
        check_thread.daemon = True
        self._check_thread = check_thread
        check_thread.start()

    def async_check_branches_releases(self, callback=None):
        """Perform update check, run as target of background thread"""
        self._async_checking = True
        self.print_verbose("Checking for update now in background")

        try:
            self._update_ready = None
            self.check_for_branches(update_last_check=False)
            self._update_ready = None
            self.check_for_update(update_last_check=True)
        except Exception as exception:
            print("Checking for update error:")
            print(exception)
            self.print_trace()
            if not self._error:
                self._update_ready = False
                self._update_version = None
                self._update_link = None
                self._error = "Error occurred"
                self._error_msg = "Encountered an error while checking for updates"

        self._async_checking = False
        self._check_thread = None

        if callback:
            self.print_verbose("Finished check update, doing callback")
            callback(self._update_ready)
        self.print_verbose("BG thread: Finished check update, no callback")

    def async_check_branches(self, callback=None):
        """Perform update check, run as target of background thread"""
        self._async_checking = True
        self.print_verbose("Checking for update now in background")

        try:
            self.check_for_branches()
        except Exception as exception:
            print("Checking for update error:")
            print(exception)
            self.print_trace()
            if not self._error:
                self._update_ready = False
                self._update_version = None
                self._update_link = None
                self._error = "Error occurred"
                self._error_msg = "Encountered an error while checking for updates"

        self._async_checking = False
        self._check_thread = None

        if callback:
            self.print_verbose("Finished check update, doing callback")
            callback(self._update_ready)
        self.print_verbose("BG thread: Finished check update, no callback")

    def stop_async_check_update(self):
        """Method to give impression of stopping check for update.

        Currently does nothing but allows user to retry/stop blocking UI from
        hitting a refresh button. This does not actually stop the thread, as it
        will complete after the connection timeout regardless. If the thread
        does complete with a successful response, this will be still displayed
        on next UI refresh (ie no update, or update available).
        """
        if self._check_thread is not None:
            self.print_verbose("Thread will end in normal course.")
            # however, "There is no direct kill method on a thread object."
            # better to let it run its course
            # self._check_thread.stop()
        self._async_checking = False
        self._error = None
        self._error_msg = None

# -----------------------------------------------------------------------------
# Updater Engines
# -----------------------------------------------------------------------------

class BitbucketEngine:
    """Integration to Bitbucket API for git-formatted repositories"""

    def __init__(self):
        self.api_url = 'https://api.bitbucket.org'
        self.token = None
        self.name = "bitbucket"

    def form_repo_url(self, updater):
        return "{}/2.0/repositories/{}/{}".format(
            self.api_url, updater.user, updater.repo
        )

    def form_tags_url(self, updater):
        return self.form_repo_url(updater) + "/refs/tags?sort=-name"

    def form_branch_url(self, branch, updater):
        return self.get_zip_url(branch, updater)

    def get_zip_url(self, name, updater):
        return "https://bitbucket.org/{user}/{repo}/get/{name}.zip".format(
            user = updater.user,
            repo = updater.repo,
            name = name
        )

    def parse_tags(self, response, updater):
        if response is None:
            return list()
        return [
            {
                "name" : tag["name"],
                "zipball_url" : self.get_zip_url(tag["name"], updater)
            } for tag in response["values"]]


class GithubEngine:
    """Integration to Github API"""

    def __init__(self):
        self.api_url = 'https://api.github.com'
        self.token = None
        self.name = "github"

    def form_repo_url(self, updater):
        return "{}/repos/{}/{}".format(
            self.api_url, updater.user, updater.repo
        )

    def form_tags_url(self, updater):
        if updater.use_releases:
            return "{}/releases".format(self.form_repo_url(updater))
        else:
            return "{}/tags".format(self.form_repo_url(updater))

    def form_branch_list_url(self, updater):
        return "{}/branches".format(self.form_repo_url(updater))

    def form_branch_url(self, branch, updater):
        return "{}/zipball/{}".format(self.form_repo_url(updater), branch)

    def parse_tags(self, response, updater):
        if response is None:
            return list()
        return response


class GitlabEngine:
    """Integration to GitLab API"""

    def __init__(self):
        self.api_url = 'https://gitlab.com'
        self.token = None
        self.name = "gitlab"

    def form_repo_url(self, updater):
        return "{}/api/v4/projects/{}".format(self.api_url, updater.repo)

    def form_tags_url(self, updater):
        return "{}/repository/tags".format(self.form_repo_url(updater))

    def form_branch_list_url(self, updater):
        # does not validate branch name.
        return "{}/repository/branches".format(self.form_repo_url(updater))

    def form_branch_url(self, branch, updater):
        # Could clash with tag names and if it does, it will download TAG zip
        # instead of branch zip to get direct path, would need.
        return "{}/repository/archive.zip?sha={}".format(
            self.form_repo_url(updater), branch
        )

    def get_zip_url(self, sha, updater):
        return "{base}/repository/archive.zip?sha={sha}".format(
            base = self.form_repo_url(updater),
            sha = sha
        )

    # def get_commit_zip(self, id, updater):
    # 	return self.form_repo_url(updater)+"/repository/archive.zip?sha:"+id

    def parse_tags(self, response, updater):
        if response is None:
            return list()
        return [
            {
                "name" : tag["name"],
                "zipball_url" : self.get_zip_url(tag["commit"]["id"], updater)
            } for tag in response]


# -----------------------------------------------------------------------------
# The module-shared class instance,
# should be what's imported to other files
# -----------------------------------------------------------------------------

Updater = SingletonUpdater()