import inspect
import logging
import imp
import os.path


class IModuleLoader:
    def __init__(self, **params):
        self.set_params(**params)

    def set_params(self, **params):
        raise NotImplementedError

    def load(self, registrant):
        raise NotImplementedError


class FileLoader(IModuleLoader):
    def __init__(self, **params):
        IModuleLoader.__init__(self, **params)
        self.__logger = logging.getLogger("libraries.FileLoader")

    def set_params(self, **params):
        if "base_path" not in params:
            return
        elif "filename" not in params:
            return

        self.filename = params["filename"]
        self.base_path = params["base_path"]
        if self.base_path.endswith('/'):
            self.base_path = self.base_path[:-1]

    def load(self, registrant):
        self.module_registrant = registrant

        self._load_py_from_file(os.path.join(self.base_path, self.filename))

    def _build_id(self, filename, objname):
        filepath, filename = os.path.split(filename)

        relative_path = os.path.relpath(filepath, self.base_path)
        identifier = relative_path + '/' + objname
        if identifier.startswith('./'):
            identifier = identifier[2:]

        return identifier

    def _load_py_from_file(self, filename):
        """
        Opens "filename", inspects it and calls the registrant
        """
        self.__logger.debug('__load_py_from_file. START, file=%s' % (filename,))

        dirname, filename = os.path.split(filename)
        fn = os.path.splitext(filename)[0]
        exten_file = None
        module = None

        try:
            exten_file, filename, description = imp.find_module(fn, [dirname])
            module = imp.load_module(fn, exten_file, filename, description)
        except ImportError as msg:
            self.__logger.critical('__load_py_from_file. Filename: %s Exception, msg=%s' % (filename, msg))
            # raise msg
            pass
        except SyntaxError as msg:
            # incorrect python syntax in file
            self.__logger.critical('__load_py_from_file. Filename: %s Exception, msg=%s' % (filename, msg))
            # raise msg
            pass
        finally:
            if exten_file:
                exten_file.close()

        if module is None:
            return

        for objname in dir(module):
            obj = getattr(module, objname)
            self.__logger.debug('__load_py_from_file. inspecting=%s' % (objname,))
            if inspect.isclass(obj):
                if '__PLUGIN_MODULEMAN_MARK' in dir(obj):
                    if self.module_registrant:
                        self.module_registrant.register(self._build_id(filename, objname), obj)

        self.__logger.debug('__load_py_from_file. END, loaded file=%s' % (filename,))


class DirLoader(FileLoader):
    def __init__(self, **params):
        FileLoader.__init__(self, **params)
        self.__logger = logging.getLogger("libraries.DirLoader")

    def set_params(self, **params):
        if "base_dir" not in params:
            return
        elif "base_path" not in params:
            return

        self.base_dir = params["base_dir"]
        self.base_path = params["base_path"]
        if self.base_path.endswith('/'):
            self.base_path = self.base_path[:-1]

    def load(self, registrant):
        self.module_registrant = registrant
        self.structure = self.__load_all(self.base_dir)

    def _build_id(self, filename, objname):
        filepath, filename = os.path.split(filename)

        relative_path = os.path.relpath(filepath, os.path.join(self.base_path, self.base_dir))
        identifier = relative_path + '/' + objname
        if identifier.startswith('./'):
            identifier = identifier[2:]

        return identifier

    def __load_all(self, dir_name):
        """
        loads all plugins and creates a loaded list of scripts from directory plugins like:
        [ ( category,[script1, script2,...] ), (category2,[script1, (subcategory,[script1,script2]),...]) ]
        """
        walked = []

        current = os.path.join(self.base_path, dir_name)
        if os.path.isdir(current):
            dir_list = self.__walk_dir_tree(current)
            walked.append((current, dir_list))
            if self.module_registrant:
                self.module_registrant.end_loading()

        return walked

    def __walk_dir_tree(self, dirname):
        dir_list = []

        self.__logger.debug('__walk_dir_tree. START dir=%s', dirname)

        for f in os.listdir(dirname):
            current = os.path.join(dirname, f)
            if os.path.isfile(current) and f.endswith("py"):
                if self.module_registrant:
                    self._load_py_from_file(current)

                dir_list.append(current)
            elif os.path.isdir(current):
                ret = self.__walk_dir_tree(current)
                if ret:
                    dir_list.append((f, ret))

        return dir_list
