#!/usr/bin/python -tt
#
# Copyright (c) 2011 Intel, Inc.
#
# 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, sys

from mic import msger
from mic import pluginbase
from mic.utils import errors


__ALL__ = ['PluginMgr', 'pluginmgr']

PLUGIN_TYPES = ["imager", "source"] # TODO  "hook"


class PluginMgr(object):
    plugin_dirs = {}

    # make the manager class as singleton
    _instance = None
    def __new__(cls, *args, **kwargs):
        if not cls._instance:
            cls._instance = super(PluginMgr, cls).__new__(cls, *args, **kwargs)

        return cls._instance

    def __init__(self):
        mic_path = os.path.dirname(__file__)
        eos = mic_path.find('scripts') + len('scripts')
        scripts_path = mic_path[:eos]

        self.plugin_dir = scripts_path + "/lib/mic/plugins"

    def append_dirs(self, dirs):
        for path in dirs:
            self._add_plugindir(path)

        # load all the plugins AGAIN
        self._load_all()

    def _add_plugindir(self, path):
        path = os.path.abspath(os.path.expanduser(path))

        if not os.path.isdir(path):
            msger.warning("Plugin dir is not a directory or does not exist: %s"\
                          % path)
            return

        if path not in self.plugin_dirs:
            self.plugin_dirs[path] = False
            # the value True/False means "loaded"

    def _load_all(self):
        for (pdir, loaded) in self.plugin_dirs.iteritems():
            if loaded: continue

            sys.path.insert(0, pdir)
            for mod in [x[:-3] for x in os.listdir(pdir) if x.endswith(".py")]:
                if mod and mod != '__init__':
                    if mod in sys.modules:
                        #self.plugin_dirs[pdir] = True
                        msger.warning("Module %s already exists, skip" % mod)
                    else:
                        try:
                            pymod = __import__(mod)
                            self.plugin_dirs[pdir] = True
                            msger.debug("Plugin module %s:%s imported"\
                                        % (mod, pymod.__file__))
                        except ImportError, err:
                            msg = 'Failed to load plugin %s/%s: %s' \
                                % (os.path.basename(pdir), mod, err)
                            msger.warning(msg)

            del(sys.path[0])

    def get_plugins(self, ptype):
        """ the return value is dict of name:class pairs """

        if ptype not in PLUGIN_TYPES:
            raise errors.CreatorError('%s is not valid plugin type' % ptype)

        self._add_plugindir(os.path.join(self.plugin_dir, ptype))
        self._load_all()

        return pluginbase.get_plugins(ptype)

    def get_source_plugin_methods(self, source_name, methods):
        """
        The methods param is a dict with the method names to find.  On
        return, the dict values will be filled in with pointers to the
        corresponding methods.  If one or more methods are not found,
        None is returned.
        """
        return_methods = None
        for _source_name, klass in self.get_plugins('source').iteritems():
            if _source_name == source_name:
                for _method_name in methods.keys():
                    if not hasattr(klass, _method_name):
                        msger.warning("Unimplemented %s source interface for: %s"\
                                      % (_method_name, _source_name))
                        return None
                    func = getattr(klass, _method_name)
                    methods[_method_name] = func
                    return_methods = methods
        return return_methods

pluginmgr = PluginMgr()