# coding=utf-8
"""
Imports the proper readline for the platform and provides utility functions for it
"""
import sys

try:
    from enum34 import Enum
except ImportError:
    from enum import Enum

# Prefer statically linked gnureadline if available (for macOS compatibility due to issues with libedit)
try:
    import gnureadline as readline
except ImportError:
    # Try to import readline, but allow failure for convenience in Windows unit testing
    # Note: If this actually fails, you should install readline on Linux or Mac or pyreadline on Windows
    try:
        # noinspection PyUnresolvedReferences
        import readline
    except ImportError:
        pass


# Check what implementation of readline we are using
class RlType(Enum):
    GNU = 1
    PYREADLINE = 2
    NONE = 3


rl_type = RlType.NONE

# The order of this check matters since importing pyreadline will also show readline in the modules list
if 'pyreadline' in sys.modules:
    rl_type = RlType.PYREADLINE

elif 'gnureadline' in sys.modules or 'readline' in sys.modules:
    rl_type = RlType.GNU

    # Load the readline lib so we can access members of it
    import ctypes
    readline_lib = ctypes.CDLL(readline.__file__)


def rl_force_redisplay() -> None:
    """
    Causes readline to redraw prompt and input line
    """
    if not sys.stdout.isatty():
        return
    if rl_type == RlType.GNU:
        # rl_forced_update_display() is the proper way to redraw the prompt and line, but we
        # have to use ctypes to do it since Python's readline API does not wrap the function
        readline_lib.rl_forced_update_display()

        # After manually updating the display, readline asks that rl_display_fixed be set to 1 for efficiency
        display_fixed = ctypes.c_int.in_dll(readline_lib, "rl_display_fixed")
        display_fixed.value = 1

    elif rl_type == RlType.PYREADLINE:
        # noinspection PyProtectedMember
        readline.rl.mode._print_prompt()