nubia/internal/helpers.py

#!/usr/bin/env python3

# Copyright (c) Facebook, Inc. and its affiliates.
# All rights reserved.
#
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree.
#

import inspect
import re
import signal
import string
import subprocess
from collections import namedtuple
from typing import Iterable, Optional

import jellyfish


def add_command_arguments(parser, options):
    for option, extras in options.items():
        parser.add_argument("--{}".format(option), **extras)


async def try_await(result):
    """
    Await if awaitable, otherwise return.
    """
    if inspect.isawaitable(result):
        return await result
    return result


def run_process(process_arg_list, on_interrupt=None, working_dir=None):
    """
    This runs a process using subprocess python module but handles SIGINT
    properly. In case we received SIGINT (Ctrl+C) we will send a SIGTERM to
    terminate the subprocess and call the supplied callback.

    @param process_arg_list Is the list you would send to subprocess.Popen()
    @param on_interrupt     Is a python callable that will be called in case we
                            received SIGINT

    This may raise OSError if the command doesn't exist.

    @return the return code of this process after completion
    """
    assert isinstance(process_arg_list, list)
    old_handler = signal.getsignal(signal.SIGINT)
    process = subprocess.Popen(process_arg_list, cwd=working_dir)

    def handler(signum, frame):
        process.send_signal(signal.SIGTERM)
        # call the interrupted callack
        if on_interrupt:
            on_interrupt()

    # register the signal handler
    signal.signal(signal.SIGINT, handler)
    rv = process.wait()
    # after the process terminates, restore the original SIGINT handler
    # whatever it was.
    signal.signal(signal.SIGINT, old_handler)
    return rv


FullArgSpec = namedtuple(
    "FullArgSpec",
    (
        "args",
        "varargs",
        "varkw",
        "defaults",
        "kwonlyargs",
        "kwonlydefaults",
        "annotations",
    ),
)


def get_arg_spec(function):
    """
    Basic backport of python's 3 inspect.gefullargspec to python 2
    """

    def set_default_value(dictionary, key, value):
        if not dictionary.get(key, None):
            dictionary[key] = value

    if hasattr(inspect, "getfullargspec"):
        argspec = inspect.getfullargspec(function)._asdict()
        argspec["annotations"].update(getattr(function, "__annotations__", {}))
    else:
        argspec = inspect.getargspec(function)._asdict()
        # python 3 renamed keywords for varkw
        argspec["varkw"] = argspec.pop("keywords")
        argspec["annotations"] = getattr(function, "__annotations__", None)

    for field in ["args", "defaults", "kwonlyargs"]:
        set_default_value(argspec, field, [])
    for field in ["kwonlydefaults", "annotations"]:
        set_default_value(argspec, field, {})

    return FullArgSpec(**argspec)


def get_kwargs_for_function(function, **kwargs):
    arg_spec = get_arg_spec(function)
    return (
        dict(kwargs)
        if arg_spec.varkw
        else {k: v for k, v in kwargs.items() if k in arg_spec.args}
    )


def function_to_str(function, with_module=True, with_args=True):
    """
    Returns a nice string representation of a function
    """
    string = getattr(function, "__name__", str(function))
    if with_module:
        string = "{}.{}".format(function.__module__, string)
    if with_args:
        argspec = get_arg_spec(function)
        args_string = ", ".join(argspec.args)
        if argspec.varargs:
            args_string = "{}, *{}".format(args_string, argspec.varargs)
        if argspec.varkw:
            args_string = "{}, **{}".format(args_string, argspec.varkw)
        string = "{}({})".format(string, args_string)
    return string


def transform_name(name, from_char="_", to_char="-"):
    """
    Transforms a symbol from code into something more user friendly
    For instance:
        _foo_bar => foo-bar
        __special__ => special
    """
    name = name.strip()
    # transforms one or more underscores into dashes. Also remove any
    # trailing or leading one
    # e.g, some__very___special -> some-very-special
    name = re.sub(r"{}+".format(re.escape(from_char)), to_char, name)
    name = re.sub(r"^{c}|{c}$".format(c=re.escape(to_char)), "", name)
    if not name:
        raise ValueError('Invalid name "{}"'.format(name))
    return name


def transform_class_name(name):
    """
    Tranforms a camel-case class name into dashed name. This also swaps
    underscores if exists
    """
    new_name = transform_name(name)
    res = []
    for c in new_name:
        if c in string.ascii_uppercase and len(res) > 0:
            res.append("-")
            res.append(c.lower())
        else:
            res.append(c.lower())
    return "".join(res)


# TypeError. In this case the object is clearly not a subclass, so we
# override this behavior for returning False
def issubclass_(obj, class_):
    try:
        return issubclass(obj, class_)
    except (AttributeError, TypeError):
        return False


def catchall(func, *args):
    """
    Run the given function with the given arguments,
    and make sure it never crashes.
    Note: This still allows some BaseExceptions,
    like SystemExit and KeyboardInterrupt
    """
    try:
        func(*args)
    except Exception as e:
        print("Error logging to scuba: {}".format(str(e)))


def find_approx(cmd_input: str, cmd_map: Optional[Iterable[str]]) -> Iterable[str]:
    """Finds the closest command to the passed cmd, this is used in case we
    cannot find an exact match for the cmd
    We will use two methods, unique prefix match and levenshtein distance match
    """

    prefix_suggestions = set()
    levenshtein_suggestions = {}

    for another_command in cmd_map:
        if str(another_command).startswith(str(cmd_input).lower()):
            prefix_suggestions.add(another_command)
        #  removing single letter levenshtein suggestions
        #  such as `?`, `q` etc
        elif len(another_command) > 1:
            distance = jellyfish.damerau_levenshtein_distance(
                str(cmd_input).lower(), another_command
            )
            if distance <= 2:
                levenshtein_suggestions.update({another_command: distance})

    if prefix_suggestions:
        return sorted(prefix_suggestions)
    else:
        # sort suggestions by levenshtein distance and then by name
        return [
            k
            for k, _ in sorted(
                levenshtein_suggestions.items(), key=lambda i: (i[1], i[0])
            )
        ]


def suggestions_msg(suggestions: Optional[Iterable[str]]) -> str:
    if not suggestions:
        return ""
    else:
        return f", Did you mean {', '.join(suggestions[:-1])} or {suggestions[-1]}?"