"""Source provider for a content root managed by git version control."""
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

import os

from ... import types as t

from ...git import (
    Git,
)

from ...encoding import (
    to_bytes,
)

from ...util import (
    SubprocessError,
)

from . import (
    SourceProvider,
)


class GitSource(SourceProvider):
    """Source provider for a content root managed by git version control."""
    @staticmethod
    def is_content_root(path):  # type: (str) -> bool
        """Return True if the given path is a content root for this provider."""
        return os.path.exists(os.path.join(path, '.git'))

    def get_paths(self, path):  # type: (str) -> t.List[str]
        """Return the list of available content paths under the given path."""
        paths = self.__get_paths(path)

        try:
            submodule_paths = Git(path).get_submodule_paths()
        except SubprocessError:
            if path == self.root:
                raise

            # older versions of git require submodule commands to be executed from the top level of the working tree
            # git version 2.18.1 (centos8) does not have this restriction
            # git version 1.8.3.1 (centos7) does
            # fall back to using the top level directory of the working tree only when needed
            # this avoids penalizing newer git versions with a potentially slower analysis due to additional submodules
            rel_path = os.path.relpath(path, self.root) + os.path.sep

            submodule_paths = Git(self.root).get_submodule_paths()
            submodule_paths = [os.path.relpath(p, rel_path) for p in submodule_paths if p.startswith(rel_path)]

        for submodule_path in submodule_paths:
            paths.extend(os.path.join(submodule_path, p) for p in self.__get_paths(os.path.join(path, submodule_path)))

        # git reports submodule directories as regular files
        paths = [p for p in paths if p not in submodule_paths]

        return paths

    @staticmethod
    def __get_paths(path):  # type: (str) -> t.List[str]
        """Return the list of available content paths under the given path."""
        git = Git(path)
        paths = git.get_file_names(['--cached', '--others', '--exclude-standard'])
        deleted_paths = git.get_file_names(['--deleted'])
        paths = sorted(set(paths) - set(deleted_paths))

        # directory symlinks are reported by git as regular files but they need to be treated as directories
        paths = [path + os.path.sep if os.path.isdir(to_bytes(path)) else path for path in paths]

        return paths