openlp/openlp/core/lib/pluginmanager.py

# -*- coding: utf-8 -*-
# vim: autoindent shiftwidth=4 expandtab textwidth=80 tabstop=4 softtabstop=4
"""
OpenLP - Open Source Lyrics Projection
Copyright (c) 2008 Raoul Snyman
Portions copyright (c) 2008 - 2009 Martin Thompson, Tim Bentley,

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; version 2 of the License.

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., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA
"""
import os
import sys
import logging

from openlp.core.lib import Plugin, EventManager

class PluginManager(object):
    """
    This is the Plugin manager, which loads all the plugins,
    and executes all the hooks, as and when necessary.
    """
    global log
    log = logging.getLogger(u'PluginMgr')
    log.info(u'Plugin manager loaded')

    def __init__(self, dir):
        """
        The constructor for the plugin manager.
        Passes the controllers on to the plugins for them to interact with via their ServiceItems
        """
        log.info(u'Plugin manager initing')
        if not dir in sys.path:
            log.debug(u'Inserting %s into sys.path', dir)
            sys.path.insert(0, dir)
        self.basepath = os.path.abspath(dir)
        log.debug(u'Base path %s ', self.basepath)
        self.plugins = []
        # this has to happen after the UI is sorted self.find_plugins(dir)
        log.info(u'Plugin manager done init')

    def find_plugins(self, dir, plugin_helpers, eventmanager):
        """
        Scan the directory dir for objects inheriting from openlp.plugin
        """
        self.plugin_helpers = plugin_helpers
        startdepth = len(os.path.abspath(dir).split(os.sep))
        log.debug(u'find plugins %s at depth %d' %( unicode(dir), startdepth))

        for root, dirs, files in os.walk(dir):
            for name in files:
                if name.endswith(u'.py') and not name.startswith(u'__'):
                    path = os.path.abspath(os.path.join(root, name))
                    thisdepth = len(path.split(os.sep))
                    if thisdepth-startdepth > 2:
                        # skip anything lower down
                        continue
                    modulename, pyext = os.path.splitext(path)
                    prefix = os.path.commonprefix([self.basepath, path])
                    # hack off the plugin base path
                    modulename = modulename[len(prefix) + 1:]
                    modulename = modulename.replace(os.path.sep, '.')
                    # import the modules
                    log.debug(u'Importing %s from %s. Depth %d' % (modulename, path, thisdepth))
                    try:
                        __import__(modulename, globals(), locals(), [])
                    except ImportError, e:
                        log.error(u'Failed to import module %s on path %s for reason %s', modulename, path,  sys.exc_info()[1])
        self.plugin_classes = Plugin.__subclasses__()
        self.plugins = []
        plugin_objects = []
        for p in self.plugin_classes:
            try:
                plugin = p(self.plugin_helpers)
                log.debug(u'loaded plugin %s with helpers'%unicode(p))
                log.debug(u'Plugin: %s', unicode(p))
                if plugin.check_pre_conditions():
                    log.debug(u'Appending %s ',  unicode(p))
                    plugin_objects.append(plugin)
                    eventmanager.register(plugin)
            except TypeError:
                log.error(u'loaded plugin %s has no helpers'%unicode(p))
        self.plugins = sorted(plugin_objects, self.order_by_weight)

    def order_by_weight(self, x, y):
        return cmp(x.weight, y.weight)

    def hook_media_manager(self, mediatoolbox):
        """
        Loop through all the plugins. If a plugin has a valid media manager item,
        add it to the media manager.
        """
        for plugin in self.plugins:
            media_manager_item = plugin.get_media_manager_item()
            if media_manager_item is not None:
                log.debug(u'Inserting media manager item from %s' % plugin.name)
                mediatoolbox.addItem(media_manager_item, plugin.icon, media_manager_item.title)

    def hook_settings_tabs(self, settingsform=None):
        """
        Loop through all the plugins. If a plugin has a valid settings tab item,
        add it to the settings tab.
        """
        for plugin in self.plugins:
            settings_tab = plugin.get_settings_tab()
            if settings_tab is not None:
                log.debug(u'Inserting settings tab item from %s' % plugin.name)
                settingsform.addTab(settings_tab)
            else:
                log.debug(u'No settings in %s' % plugin.name)

    def hook_import_menu(self, import_menu):
        """
        Loop through all the plugins and give them an opportunity to add an item
        to the import menu.
        """
        for plugin in self.plugins:
            plugin.add_import_menu_item(import_menu)

    def hook_export_menu(self, export_menu):
        """
        Loop through all the plugins and give them an opportunity to add an item
        to the export menu.
        """
        for plugin in self.plugins:
            plugin.add_export_menu_item(export_menu)

    def initialise_plugins(self):
        """
        Loop through all the plugins and give them an opportunity to add an item
        to the export menu.
        """
        for plugin in self.plugins:
            plugin.initialise()