import os
import stat

path = '/tmp/pytest'
bytes_path = os.fsencode(path)
os.mkdir(dirname)


# Filename used for testing
if os.name == 'java':
    # Jython disallows @ in module names
    TESTFN = '$test'
else:
    TESTFN = '@test'

# Disambiguate TESTFN for parallel testing, while letting it remain a valid
# module name.
TESTFN = "{}_{}_tmp".format(TESTFN, os.getpid())

_can_symlink = None
def can_symlink():
    global _can_symlink
    if _can_symlink is not None:
        return _can_symlink
    symlink_path = TESTFN + "can_symlink"
    try:
        os.symlink(TESTFN, symlink_path)
        can = True
    except (OSError, NotImplementedError, AttributeError):
        can = False
    else:
        os.remove(symlink_path)
    _can_symlink = can
    return can
    

def _create_file(filename, content=b'content'):
    with open(filename, "xb", 0) as fp:
        fp.write(content)

def create_file(name="file.txt"):
    _path = bytes_path if isinstance(name, bytes) else path
    filename = os.path.join(_path, name)
    _create_file(filename, b'python')
    return filename
        
        
def get_entries(names):
    entries = dict((entry.name, entry)
                   for entry in os.scandir(path))
    assert sorted(entries.keys()) == names
    return entries


def assert_stat_equal(stat1, stat2, skip_fields):
    if skip_fields:
        for attr in dir(stat1):
            if not attr.startswith("st_"):
                continue
            if attr in ("st_dev", "st_ino", "st_nlink"):
                continue
            assert getattr(stat1, attr) == getattr(stat2, attr) == (stat1, stat2, attr)
    else:
        assert stat1 == stat2


def check_entry(entry, name, is_dir, is_file, is_symlink):
    assert isinstance(entry, os.DirEntry)
    assert entry.name == name
    assert entry.path == os.path.join(path, name)
    assert entry.inode() == os.stat(entry.path, follow_symlinks=False).st_ino

    entry_stat = os.stat(entry.path)
    assert entry.is_dir() == stat.S_ISDIR(entry_stat.st_mode)
    assert entry.is_file() == stat.S_ISREG(entry_stat.st_mode)
    assert entry.is_symlink() == os.path.islink(entry.path)

    entry_lstat = os.stat(entry.path, follow_symlinks=False)
    assert entry.is_dir(follow_symlinks=False) == stat.S_ISDIR(entry_lstat.st_mode)
    assert entry.is_file(follow_symlinks=False) == stat.S_ISREG(entry_lstat.st_mode)

    assert_stat_equal(entry.stat(),
                           entry_stat,
                           os.name == 'nt' and not is_symlink)
    assert_stat_equal(entry.stat(follow_symlinks=False),
                           entry_lstat,
                           os.name == 'nt')
                               
                               
link = hasattr(os, 'link')
symlink = can_symlink()
dirname = os.path.join(path, "dir")
os.mkdir(dirname)

filename = create_file("file.txt")
if link:
    os.link(filename, os.path.join(path, "link_file.txt"))
if symlink:
    os.symlink(dirname, os.path.join(path, "symlink_dir"), target_is_directory=True)
    os.symlink(filename, os.path.join(path, "symlink_file.txt"))

names = ['dir', 'file.txt']
if link:
    names.append('link_file.txt')
if symlink:
    names.extend(('symlink_dir', 'symlink_file.txt'))
entries = get_entries(names)

entry = entries['dir']
check_entry(entry, 'dir', True, False, False)

entry = entries['file.txt']
check_entry(entry, 'file.txt', False, True, False)

if link:
    entry = entries['link_file.txt']
    check_entry(entry, 'link_file.txt', False, True, False)

if symlink:
    entry = entries['symlink_dir']
    check_entry(entry, 'symlink_dir', True, False, True)

    entry = entries['symlink_file.txt']
    check_entry(entry, 'symlink_file.txt', False, True, True)