import os
import subprocess
import tarfile

from .file_finder import scm_find_files


def _git_toplevel(path):
    try:
        with open(os.devnull, 'wb') as devnull:
            out = subprocess.check_output([
                'git', 'rev-parse', '--show-toplevel',
            ], cwd=(path or '.'), universal_newlines=True, stderr=devnull)
        return os.path.normcase(os.path.realpath(out.strip()))
    except subprocess.CalledProcessError:
        # git returned error, we are not in a git repo
        return None
    except OSError:
        # git command not found, probably
        return None


def _git_ls_files_and_dirs(toplevel):
    # use git archive instead of git ls-file to honor
    # export-ignore git attribute
    cmd = ['git', 'archive', '--prefix', toplevel + os.path.sep, 'HEAD']
    proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, cwd=toplevel)
    tf = tarfile.open(fileobj=proc.stdout, mode='r|*')
    git_files = set()
    git_dirs = set([toplevel])
    for member in tf.getmembers():
        name = os.path.normcase(member.name).replace('/', os.path.sep)
        if member.type == tarfile.DIRTYPE:
            git_dirs.add(name)
        else:
            git_files.add(name)
    return git_files, git_dirs


def git_find_files(path=''):
    toplevel = _git_toplevel(path)
    if not toplevel:
        return []
    git_files, git_dirs = _git_ls_files_and_dirs(toplevel)
    return scm_find_files(path, git_files, git_dirs)
