import os
import platform


if os.name == "posix":
    if platform.system() == "Darwin":
        DEFAULT_SOCKET_DIRS = ("/tmp",)
    else:
        DEFAULT_SOCKET_DIRS = ("/var/run", "/var/lib")
else:
    DEFAULT_SOCKET_DIRS = ()


def list_path(root_dir):
    """List directory if exists.

    :param root_dir: str
    :return: list

    """
    res = []
    if os.path.isdir(root_dir):
        for name in os.listdir(root_dir):
            res.append(name)
    return res


def complete_path(curr_dir, last_dir):
    """Return the path to complete that matches the last entered component.

    If the last entered component is ~, expanded path would not
    match, so return all of the available paths.

    :param curr_dir: str
    :param last_dir: str
    :return: str

    """
    if not last_dir or curr_dir.startswith(last_dir):
        return curr_dir
    elif last_dir == '~':
        return os.path.join(last_dir, curr_dir)


def parse_path(root_dir):
    """Split path into head and last component for the completer.

    Also return position where last component starts.

    :param root_dir: str path
    :return: tuple of (string, string, int)

    """
    base_dir, last_dir, position = '', '', 0
    if root_dir:
        base_dir, last_dir = os.path.split(root_dir)
        position = -len(last_dir) if last_dir else 0
    return base_dir, last_dir, position


def suggest_path(root_dir):
    """List all files and subdirectories in a directory.

    If the directory is not specified, suggest root directory,
    user directory, current and parent directory.

    :param root_dir: string: directory to list
    :return: list

    """
    if not root_dir:
        return [os.path.abspath(os.sep), '~', os.curdir, os.pardir]

    if '~' in root_dir:
        root_dir = os.path.expanduser(root_dir)

    if not os.path.exists(root_dir):
        root_dir, _ = os.path.split(root_dir)

    return list_path(root_dir)


def dir_path_exists(path):
    """Check if the directory path exists for a given file.

    For example, for a file /home/user/.cache/mycli/log, check if
    /home/user/.cache/mycli exists.

    :param str path: The file path.
    :return: Whether or not the directory path exists.

    """
    return os.path.exists(os.path.dirname(path))


def guess_socket_location():
    """Try to guess the location of the default mysql socket file."""
    socket_dirs = filter(os.path.exists, DEFAULT_SOCKET_DIRS)
    for directory in socket_dirs:
        for r, dirs, files in os.walk(directory, topdown=True):
            for filename in files:
                name, ext = os.path.splitext(filename)
                if name.startswith("mysql") and ext in ('.socket', '.sock'):
                    return os.path.join(r, filename)
            dirs[:] = [d for d in dirs if d.startswith("mysql")]
    return None