#!/usr/bin/python3
# -*- coding: utf-8 -*-


import sys
import logging
logging = logging.getLogger()
import os.path
import importlib
from os import listdir


class Plugin(object):

    '''
    Proto type of plugin class. Only subclasses are valid plugins.
    '''
    
    __command = ''

    @staticmethod
    def get_module():
        return Plugin.__module

    @staticmethod
    def get_command():
        return Plugin.__command

    @staticmethod
    def get_description():
        return Plugin.__description

    def __init__(self, callback):
        self.callback = callback

    def help(self):
        return 'Sorry ... Help is unavailable at the moment'

    def run(self, msg):
        self.callback('Sorry ... Run is unavailable at the moment')


class PluginManager():
    
    '''
    Handles the plugins. Optional becomes a directory for search plugins.
    '''
    
    def __init__(self, plug_dir=None):
        '''
        Initialize callback function and plugin directory. If no callback is
        given it returns imediality. If no plugin directory is given it uses
        actual directory.
        '''
        if plug_dir is None:
            self.plugin_dir = './plugins'
        else: self.plugin_dir = plug_dir

    def collect_plugins(self):
        '''
        Find all files in plugin directory and grabs filename, provided
        command and short description.
        '''
        self.plugins = {}
        search_dir = os.path.realpath(self.plugin_dir)
        sys.path.insert(0, search_dir)
        logging.debug('Search plugins in {}'.format(search_dir))
        files = [x[:-3] for x in os.listdir(search_dir) if x.endswith('.py')]
        for filename in files:
            plugin = self.import_plugin(filename)
            if plugin is False:
                continue
            command = plugin.Plugin.get_command()
            self.plugins[command] = plugin
        return self.plugins

    def import_plugin(self, filename):
        '''
        Imports or reimports a module depending its known or not. It's
        tested by the command provided by the plugin. (Not best praxis but
        the easyst way. And i dont know, what a trouble is causes, if a
        module ist moved.)
        param 1: string
        '''
        try:
            plugin = importlib.import_module(filename)
        except Exception as e:
            logging.error('Cant import module: {}'.format(filename))
            logging.error('Exception: {}'.format(e))
            return False
        if not issubclass(plugin.Plugin, Plugin):
            logging.error('Not a valid plugin: {}'.format(filename))
            return False
        logging.debug('Found plugin {}.'.format(filename))
        return plugin