# coding=utf-8
#
# Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2019 All Rights Reserved
#
# Licensed under CLOUD LINUX LICENSE AGREEMENT
# http://cloudlinux.com/docs/LICENSE.TXT

import importlib.util
import inspect
import logging
import os
import sys

from lvestats.core.plugin import LveStatsPlugin


class PluginLoader(object):

    def check_incorrect_symlink(self, path):
        """
        Check correcting symlink. If symlink incorrect return True
        :param str path: path to file or symlink
        :return bool:
        """
        if os.path.islink(path) and not os.path.exists(os.path.realpath(path)):
            self.log.warning('Incorrect symlink %s', path)
            return True

    def __init__(self, plugins_folder):
        self.log = logging.getLogger(__name__)
        classes_loaded = []

        if os.path.isdir(plugins_folder):
            file_names = (fn for fn in os.listdir(plugins_folder) if fn.endswith('.py'))

            for file_name in file_names:
                try:
                    module_name, _ = os.path.splitext(file_name)
                    full_path = os.path.join(plugins_folder, file_name)
                    if self.check_incorrect_symlink(full_path):
                        continue
                    spec = importlib.util.spec_from_file_location(module_name, full_path)
                    if spec is None:
                        self.log.error('Unable to find spec for %s', file_name)
                        continue
                    module = importlib.util.module_from_spec(spec)
                    spec.loader.exec_module(module)
                    # Load only subclasses of LveStatsPlugin
                    classes = [x for x in list(module.__dict__.values())
                               if inspect.isclass(x) and issubclass(x, LveStatsPlugin) and x is not LveStatsPlugin]
                    if not classes:
                        self.log.error('No classes to load found in %s', file_name)
                        continue
                    classes_loaded.extend(classes)
                    sys.modules[module.__name__] = module
                except Exception as ex:
                    self.log.exception('Unable to load %s due to exception %s', file_name, ex)

        self.plugins = classes_loaded