"""Abstract base classes related to import."""

from . import _fileloader2

from . import _bootstrap
from . import _bootstrap_external
from . import machinery
import abc

try:
    from importlib.abc import _register
except ImportError:
    # backporting _register (without caring about builtin or frozen modules)
    def _register(abstract_cls, *classes):
        for cls in classes:
            abstract_cls.register(cls)


try:
    from importlib.abc import Finder
except ImportError:

    class Finder(object):
        __metaclass__ = abc.ABCMeta
        """Legacy abstract base class for import finders.
    
        It may be subclassed for compatibility with legacy third party
        reimplementations of the import system.  Otherwise, finder
        implementations should derive from the more specific MetaPathFinder
        or PathEntryFinder ABCs.
        """

        @abc.abstractmethod
        def find_module(self, fullname, path=None):
            """An abstract method that should find a module.
            The fullname is a str and the optional path is a str or None.
            Returns a Loader object or None.
            """

try:
    from importlib.abc import MetaPathFinder
except ImportError:
    class MetaPathFinder(Finder):

        """Abstract base class for import finders on sys.meta_path."""

        # We don't define find_spec() here since that would break
        # hasattr checks we do to support backward compatibility.

        def find_module(self, fullname, path):
            """Return a loader for the module.

            If no module is found, return None.  The fullname is a str and
            the path is a list of strings or None.

            This method is deprecated in favor of finder.find_spec(). If find_spec()
            exists then backwards-compatible functionality is provided for this
            method.

            """
            if not hasattr(self, 'find_spec'):
                return None
            found = self.find_spec(fullname, path)
            return found.loader if found is not None else None

        def invalidate_caches(self):
            """An optional method for clearing the finder's cache, if any.
            This method is used by importlib.invalidate_caches().
            """

    _register(MetaPathFinder, machinery.PathFinder)

try:
    from importlib.abc import PathEntryFinder
except ImportError:
    class PathEntryFinder(Finder):

        """Abstract base class for path entry finders used by PathFinder."""

        # We don't define find_spec() here since that would break
        # hasattr checks we do to support backward compatibility.

        def find_loader(self, fullname):
            """Return (loader, namespace portion) for the path entry.

            The fullname is a str.  The namespace portion is a sequence of
            path entries contributing to part of a namespace package. The
            sequence may be empty.  If loader is not None, the portion will
            be ignored.

            The portion will be discarded if another path entry finder
            locates the module as a normal module or package.

            This method is deprecated in favor of finder.find_spec(). If find_spec()
            is provided than backwards-compatible functionality is provided.

            """
            if not hasattr(self, 'find_spec'):
                return None, []
            found = self.find_spec(fullname)
            if found is not None:
                if not found.submodule_search_locations:
                    portions = []
                else:
                    portions = found.submodule_search_locations
                return found.loader, portions
            else:
                return None, []

        find_module = _bootstrap_external._find_module_shim

        def invalidate_caches(self):
            """An optional method for clearing the finder's cache, if any.
            This method is used by PathFinder.invalidate_caches().
            """

    _register(PathEntryFinder, machinery.FileFinder)

try:
    from importlib.abc import Loader
except ImportError:
    class Loader(object):
        __metaclass__ = abc.ABCMeta
        """Abstract base class for import loaders."""

        def create_module(self, spec):
            """Return a module to initialize and into which to load.

            This method should raise ImportError if anything prevents it
            from creating a new module.  It may return None to indicate
            that the spec should create the new module.
            """
            # By default, defer to default semantics for the new module.
            return None

        # We don't define exec_module() here since that would break
        # hasattr checks we do to support backward compatibility.

        def load_module(self, fullname):
            """Return the loaded module.

            The module must be added to sys.modules and have import-related
            attributes set properly.  The fullname is a str.

            ImportError is raised on failure.

            This method is deprecated in favor of loader.exec_module(). If
            exec_module() exists then it is used to provide a backwards-compatible
            functionality for this method.

            """
            if not hasattr(self, 'exec_module'):
                raise ImportError
            return _bootstrap._load_module_shim(self, fullname)

        def module_repr(self, module):
            """Return a module's repr.

            Used by the module type when the method does not raise
            NotImplementedError.

            This method is deprecated.

            """
            # The exception will cause ModuleType.__repr__ to ignore this method.
            raise NotImplementedError

try:
    from importlib.abc import ResourceLoader
except ImportError:
    class ResourceLoader(Loader):

        """Abstract base class for loaders which can return data from their
        back-end storage.

        This ABC represents one of the optional protocols specified by PEP 302.

        """

        @abc.abstractmethod
        def get_data(self, path):
            """Abstract method which when implemented should return the bytes for
            the specified path.  The path must be a str."""
            raise IOError

try:
    from importlib.abc import InspectLoader
except ImportError:
    class InspectLoader(Loader):

        """Abstract base class for loaders which support inspection about the
        modules they can load.

        This ABC represents one of the optional protocols specified by PEP 302.

        """

        def is_package(self, fullname):
            """Optional method which when implemented should return whether the
            module is a package.  The fullname is a str.  Returns a bool.

            Raises ImportError if the module cannot be found.
            """
            raise ImportError

        def get_code(self, fullname):
            """Method which returns the code object for the module.

            The fullname is a str.  Returns a types.CodeType if possible, else
            returns None if a code object does not make sense
            (e.g. built-in module). Raises ImportError if the module cannot be
            found.
            """
            source = self.get_source(fullname)
            if source is None:
                return None
            return self.source_to_code(source)

        @abc.abstractmethod
        def get_source(self, fullname):
            """Abstract method which should return the source code for the
            module.  The fullname is a str.  Returns a str.

            Raises ImportError if the module cannot be found.
            """
            raise ImportError

        @staticmethod
        def source_to_code(data, path='<string>'):
            """Compile 'data' into a code object.

            The 'data' argument can be anything that compile() can handle. The'path'
            argument should be where the data was retrieved (when applicable)."""
            return compile(data, path, 'exec', dont_inherit=True)

        exec_module = _bootstrap_external._LoaderBasics.exec_module
        load_module = _bootstrap_external._LoaderBasics.load_module

    _register(InspectLoader, machinery.BuiltinImporter, machinery.FrozenImporter)

try:
    from importlib.abc import ExecutionLoader
except ImportError:
    class ExecutionLoader(InspectLoader):

        """Abstract base class for loaders that wish to support the execution of
        modules as scripts.

        This ABC represents one of the optional protocols specified in PEP 302.

        """

        @abc.abstractmethod
        def get_filename(self, fullname):
            """Abstract method which should return the value that __file__ is to be
            set to.

            Raises ImportError if the module cannot be found.
            """
            raise ImportError

        def get_code(self, fullname):
            """Method to return the code object for fullname.

            Should return None if not applicable (e.g. built-in module).
            Raise ImportError if the module cannot be found.
            """
            source = self.get_source(fullname)
            if source is None:
                return None
            try:
                path = self.get_filename(fullname)
            except ImportError:
                return self.source_to_code(source)
            else:
                return self.source_to_code(source, path)

    _register(ExecutionLoader, machinery.ExtensionFileLoader)


try:
    from importlib.abc import FileLoader
except ImportError:
    class FileLoader(_fileloader2.FileLoader, ResourceLoader, ExecutionLoader):

        """Abstract base class partially implementing the ResourceLoader and
        ExecutionLoader ABCs."""

    _register(FileLoader, machinery.SourceFileLoader,
                machinery.SourcelessFileLoader)


try:
    from importlib.abc import SourceLoader
except ImportError:
    class SourceLoader(_fileloader2.SourceLoader, ResourceLoader, ExecutionLoader):

        """Abstract base class for loading source code (and optionally any
        corresponding bytecode).

        To support loading from source code, the abstractmethods inherited from
        ResourceLoader and ExecutionLoader need to be implemented. To also support
        loading from bytecode, the optional methods specified directly by this ABC
        is required.

        Inherited abstractmethods not implemented in this ABC:

            * ResourceLoader.get_data
            * ExecutionLoader.get_filename

        """

        def path_mtime(self, path):
            """Return the (int) modification time for the path (str)."""
            if self.path_stats.__func__ is SourceLoader.path_stats:
                raise IOError
            return int(self.path_stats(path)['mtime'])

        def path_stats(self, path):
            """Return a metadata dict for the source pointed to by the path (str).
            Possible keys:
            - 'mtime' (mandatory) is the numeric timestamp of last source
              code modification;
            - 'size' (optional) is the size in bytes of the source code.
            """
            if self.path_mtime.__func__ is SourceLoader.path_mtime:
                raise IOError
            return {'mtime': self.path_mtime(path)}

        def set_data(self, path, data):
            """Write the bytes to the path (if possible).

            Accepts a str path and data as bytes.

            Any needed intermediary directories are to be created. If for some
            reason the file cannot be written because of permissions, fail
            silently.
            """

    _register(SourceLoader, machinery.SourceFileLoader)
