# Copyright 2012-2015, Andrey Kislyuk and argcomplete contributors.
# Licensed under the Apache License. See https://github.com/kislyuk/argcomplete for more info.

from __future__ import absolute_import, division, print_function, unicode_literals

import argparse
import contextlib
import os
import subprocess
import sys
from . import my_shlex as shlex
from .compat import USING_PYTHON2, str, sys_encoding, ensure_str, ensure_bytes

_DEBUG = "_ARC_DEBUG" in os.environ

debug_stream = sys.stderr


def debug(*args):
    if _DEBUG:
        print(file=debug_stream, *args)

BASH_FILE_COMPLETION_FALLBACK = 79
BASH_DIR_COMPLETION_FALLBACK = 80

safe_actions = (argparse._StoreAction,
                argparse._StoreConstAction,
                argparse._StoreTrueAction,
                argparse._StoreFalseAction,
                argparse._AppendAction,
                argparse._AppendConstAction,
                argparse._CountAction)

from . import completers
from .my_argparse import IntrospectiveArgumentParser, action_is_satisfied, action_is_open


@contextlib.contextmanager
def mute_stdout():
    stdout = sys.stdout
    sys.stdout = open(os.devnull, "w")
    try:
        yield
    finally:
        sys.stdout = stdout


@contextlib.contextmanager
def mute_stderr():
    stderr = sys.stderr
    sys.stderr = open(os.devnull, "w")
    try:
        yield
    finally:
        sys.stderr.close()
        sys.stderr = stderr


class ArgcompleteException(Exception):
    pass


def split_line(line, point=None):
    if point is None:
        point = len(line)
    lexer = shlex.shlex(line, posix=True, punctuation_chars=True)
    words = []

    def split_word(word):
        # TODO: make this less ugly
        point_in_word = len(word) + point - lexer.instream.tell()
        if isinstance(lexer.state, (str, bytes)) and lexer.state in lexer.whitespace:
            point_in_word += 1
        if point_in_word > len(word):
            debug("In trailing whitespace")
            words.append(word)
            word = ""
        prefix, suffix = word[:point_in_word], word[point_in_word:]
        prequote = ""
        # posix
        if lexer.state is not None and lexer.state in lexer.quotes:
            prequote = lexer.state
        # non-posix
        # if len(prefix) > 0 and prefix[0] in lexer.quotes:
        #    prequote, prefix = prefix[0], prefix[1:]

        first_colon_pos = lexer.first_colon_pos if ":" in word else None

        return prequote, prefix, suffix, words, first_colon_pos

    while True:
        try:
            word = lexer.get_token()
            if word == lexer.eof:
                # TODO: check if this is ever unsafe
                # raise ArgcompleteException("Unexpected end of input")
                return "", "", "", words, None
            if lexer.instream.tell() >= point:
                debug("word", word, "split, lexer state: '{s}'".format(s=lexer.state))
                return split_word(word)
            words.append(word)
        except ValueError:
            debug("word", lexer.token, "split (lexer stopped, state: '{s}')".format(s=lexer.state))
            if lexer.instream.tell() >= point:
                return split_word(lexer.token)
            else:
                raise ArgcompleteException("Unexpected internal state. Please report this bug at https://github.com/kislyuk/argcomplete/issues.")


def default_validator(completion, prefix):
    return completion.startswith(prefix)


class CompletionFinder(object):
    """
    Inherit from this class if you wish to override any of the stages below. Otherwise, use ``argcomplete.autocomplete()``
    directly (it's a convenience instance of this class). It has the same signature as
    :meth:`CompletionFinder.__call__()`.
    """
    def __init__(self, argument_parser=None, always_complete_options=True, exclude=None, validator=None,
                 print_suppressed=False):
        self._parser = argument_parser
        self.always_complete_options = always_complete_options
        self.exclude = exclude
        if validator is None:
            validator = default_validator
        self.validator = validator
        self.print_suppressed = print_suppressed
        self.completing = False
        self._display_completions = {}

    def __call__(self, argument_parser, always_complete_options=True, exit_method=os._exit, output_stream=None,
                 exclude=None, validator=None, print_suppressed=False):
        """
        :param argument_parser: The argument parser to autocomplete on
        :type argument_parser: :class:`argparse.ArgumentParser`
        :param always_complete_options:
            Whether or not to autocomplete options even if an option string opening character (normally ``-``) has not
            been entered
        :type always_complete_options: boolean
        :param exit_method:
            Method used to stop the program after printing completions. Defaults to :meth:`os._exit`. If you want to
            perform a normal exit that calls exit handlers, use :meth:`sys.exit`.
        :type exit_method: callable
        :param exclude: List of strings representing options to be omitted from autocompletion
        :type exclude: iterable
        :param validator:
            Function to filter all completions through before returning (called with two string arguments, completion
            and prefix; return value is evaluated as a boolean)
        :type validator: callable
        :param print_suppressed:
            Whether or not to autocomplete options that have the ``help=argparse.SUPPRESS`` keyword argument set.
        :type print_suppressed: boolean

        .. note::
            If you are not subclassing CompletionFinder to override its behaviors,
            use ``argcomplete.autocomplete()`` directly. It has the same signature as this method.

        Produces tab completions for ``argument_parser``. See module docs for more info.

        Argcomplete only executes actions if their class is known not to have side effects. Custom action classes can be
        added to argcomplete.safe_actions, if their values are wanted in the ``parsed_args`` completer argument, or their
        execution is otherwise desirable.
        """
        self.__init__(argument_parser, always_complete_options, exclude, validator, print_suppressed)

        if "_ARGCOMPLETE" not in os.environ:
            # not an argument completion invocation
            return

        global debug_stream
        try:
            debug_stream = os.fdopen(9, "w")
        except:
            debug_stream = sys.stderr

        if output_stream is None:
            try:
                output_stream = os.fdopen(8, "wb")
            except:
                debug("Unable to open fd 8 for writing, quitting")
                exit_method(1)

        # print("", stream=debug_stream)
        # for v in "COMP_CWORD", "COMP_LINE", "COMP_POINT", "COMP_TYPE", "COMP_KEY", "_ARGCOMPLETE_COMP_WORDBREAKS", "COMP_WORDS":
        #     print(v, os.environ[v], stream=debug_stream)

        ifs = os.environ.get("_ARGCOMPLETE_IFS", "\013")
        if len(ifs) != 1:
            debug("Invalid value for IFS, quitting [{v}]".format(v=ifs))
            exit_method(1)

        comp_line = os.environ["COMP_LINE"]
        comp_point = int(os.environ["COMP_POINT"])

        # Adjust comp_point for wide chars
        if USING_PYTHON2:
            comp_point = len(comp_line[:comp_point].decode(sys_encoding))
        else:
            comp_point = len(comp_line.encode(sys_encoding)[:comp_point].decode(sys_encoding))

        comp_line = ensure_str(comp_line)
        cword_prequote, cword_prefix, cword_suffix, comp_words, first_colon_pos = split_line(comp_line, comp_point)

        if os.environ["_ARGCOMPLETE"] == "2":
            # Shell hook recognized the first word as the interpreter; discard it
            comp_words.pop(0)

        debug("\nLINE: '{l}'\nPREQUOTE: '{pq}'\nPREFIX: '{p}'".format(l=comp_line, pq=cword_prequote, p=cword_prefix),
              "\nSUFFIX: '{s}'".format(s=cword_suffix),
              "\nWORDS:", comp_words)

        completions = self._get_completions(comp_words, cword_prefix, cword_prequote, first_colon_pos)

        debug("\nReturning completions:", completions)
        output_stream.write(ifs.join(completions).encode(sys_encoding))
        output_stream.flush()
        debug_stream.flush()
        exit_method(0)

    def _get_completions(self, comp_words, cword_prefix, cword_prequote, first_colon_pos):
        active_parsers = self._patch_argument_parser()

        parsed_args = argparse.Namespace()
        self.completing = True

        if USING_PYTHON2:
            # Python 2 argparse only properly works with byte strings.
            comp_words = [ensure_bytes(word) for word in comp_words]

        try:
            debug("invoking parser with", comp_words[1:])
            with mute_stderr():
                a = self._parser.parse_known_args(comp_words[1:], namespace=parsed_args)
            debug("parsed args:", a)
        except BaseException as e:
            debug("\nexception", type(e), str(e), "while parsing args")

        self.completing = False

        # key: complete word, value: description.

        completions = self.collect_completions(active_parsers, parsed_args, cword_prefix, debug)
        completions = self.filter_completions(completions)
        completions = self.quote_completions(completions, cword_prequote, first_colon_pos)
        return completions

    def _patch_argument_parser(self):
        """
        Since argparse doesn't support much introspection, we monkey-patch it to replace the parse_known_args method and
        all actions with hooks that tell us which action was last taken or about to be taken, and let us have the parser
        figure out which subparsers need to be activated (then recursively monkey-patch those).
        We save all active ArgumentParsers to extract all their possible option names later.
        """
        self.active_parsers = []
        self.visited_positionals = []

        completer = self

        def patch(parser):
            completer.visited_positionals.append(parser)
            completer.active_parsers.append(parser)

            if isinstance(parser, IntrospectiveArgumentParser):
                return

            classname = "MonkeyPatchedIntrospectiveArgumentParser"
            if USING_PYTHON2:
                classname = bytes(classname)
            parser.__class__ = type(classname, (IntrospectiveArgumentParser, parser.__class__), {})

            for action in parser._actions:

                if hasattr(action, "_orig_class"):
                    continue

                # TODO: accomplish this with super
                class IntrospectAction(action.__class__):
                    def __call__(self, parser, namespace, values, option_string=None):
                        debug("Action stub called on", self)
                        debug("\targs:", parser, namespace, values, option_string)
                        debug("\torig class:", self._orig_class)
                        debug("\torig callable:", self._orig_callable)

                        if not completer.completing:
                            self._orig_callable(parser, namespace, values, option_string=option_string)
                        elif self._orig_class == argparse._SubParsersAction:
                            debug("orig class is a subparsers action: patching and running it")
                            patch(self._name_parser_map[values[0]])
                            self._orig_callable(parser, namespace, values, option_string=option_string)
                        elif self._orig_class in safe_actions:
                            if not self.option_strings:
                                completer.visited_positionals.append(self)

                            self._orig_callable(parser, namespace, values, option_string=option_string)

                action._orig_class = action.__class__
                action._orig_callable = action.__call__
                action.__class__ = IntrospectAction

        patch(self._parser)

        debug("Active parsers:", self.active_parsers)
        debug("Visited positionals:", self.visited_positionals)

        return self.active_parsers

    def _get_subparser_completions(self, parser, cword_prefix):
        def filter_aliases(metavar, dest, prefix):
            if not metavar:
                return dest if dest and dest.startswith(prefix) else ""

            # metavar combines dest and aliases with ",".
            a = metavar.replace(",", "").split()
            return " ".join(x for x in a if x.startswith(prefix))

        for action in parser._get_subactions():
            subcmd_with_aliases = filter_aliases(action.metavar, action.dest, cword_prefix)
            if subcmd_with_aliases:
                self._display_completions[subcmd_with_aliases] = action.help

        completions = [subcmd for subcmd in parser.choices.keys() if subcmd.startswith(cword_prefix)]
        return completions

    def _get_option_completions(self, parser, cword_prefix):
        self._display_completions.update(
            [[" ".join(ensure_str(x) for x in action.option_strings if ensure_str(x).startswith(cword_prefix)), action.help]
             for action in parser._actions
             if action.option_strings])

        option_completions = []
        for action in parser._actions:
            if action.help == argparse.SUPPRESS and not self.print_suppressed:
                continue
            if not isinstance(action, argparse._SubParsersAction):
                for option in action.option_strings:
                    if ensure_str(option).startswith(cword_prefix):
                        option_completions.append(ensure_str(option))
        return option_completions

    def _complete_active_option(self, parser, next_positional, cword_prefix, parsed_args, completions):
        debug("Active actions (L={l}): {a}".format(l=len(parser.active_actions), a=parser.active_actions))

        # Only run completers if current word does not start with - (is not an optional)
        if len(cword_prefix) > 0 and cword_prefix[0] in parser.prefix_chars:
            return completions

        for active_action in parser.active_actions:
            if not active_action.option_strings:  # action is a positional
                if action_is_satisfied(active_action) and not action_is_open(active_action):
                    debug("Skipping", active_action)
                    continue

            debug("Activating completion for", active_action, active_action._orig_class)
            # completer = getattr(active_action, "completer", DefaultCompleter())
            completer = getattr(active_action, "completer", None)

            if completer is None and active_action.choices is not None:
                if not isinstance(active_action, argparse._SubParsersAction):
                    completer = completers.ChoicesCompleter(active_action.choices)

            if completer:
                if len(active_action.option_strings) > 0:  # only for optionals
                    if not action_is_satisfied(active_action):
                        # This means the current action will fail to parse if the word under the cursor is not given
                        # to it, so give it exclusive control over completions (flush previous completions)
                        debug("Resetting completions because", active_action, "is unsatisfied")
                        self._display_completions = {}
                        completions = []
                if callable(completer):
                    completions_from_callable = [c for c in completer(
                        prefix=cword_prefix, action=active_action, parsed_args=parsed_args)
                        if self.validator(c, cword_prefix)]

                    if completions_from_callable:
                        completions += completions_from_callable
                        if isinstance(completer, completers.ChoicesCompleter):
                            self._display_completions.update(
                                [[x, active_action.help] for x in completions_from_callable])
                        else:
                            self._display_completions.update(
                                [[x, ""] for x in completions_from_callable])
                else:
                    debug("Completer is not callable, trying the readline completer protocol instead")
                    for i in range(9999):
                        next_completion = completer.complete(cword_prefix, i)
                        if next_completion is None:
                            break
                        if self.validator(next_completion, cword_prefix):
                            self._display_completions.update({next_completion: ""})
                            completions.append(next_completion)
                debug("Completions:", completions)
            elif not isinstance(active_action, argparse._SubParsersAction):
                debug("Completer not available, falling back")
                try:
                    # TODO: what happens if completions contain newlines? How do I make compgen use IFS?
                    bashcomp_cmd = ["bash", "-c", "compgen -A file -- '{p}'".format(p=cword_prefix)]
                    comp = subprocess.check_output(bashcomp_cmd).decode(sys_encoding).splitlines()
                    if comp:
                        self._display_completions.update([[x, ""] for x in comp])
                        completions += comp
                except subprocess.CalledProcessError:
                    pass

        return completions

    def collect_completions(self, active_parsers, parsed_args, cword_prefix, debug):
        """
        Visits the active parsers and their actions, executes their completers or introspects them to collect their
        option strings. Returns the resulting completions as a list of strings.

        This method is exposed for overriding in subclasses; there is no need to use it directly.
        """
        completions = []

        debug("all active parsers:", active_parsers)
        active_parser = active_parsers[-1]
        debug("active_parser:", active_parser)
        if self.always_complete_options or (len(cword_prefix) > 0 and cword_prefix[0] in active_parser.prefix_chars):
            completions += self._get_option_completions(active_parser, cword_prefix)
        debug("optional options:", completions)

        next_positional = self._get_next_positional()
        debug("next_positional:", next_positional)

        if isinstance(next_positional, argparse._SubParsersAction):
            completions += self._get_subparser_completions(next_positional, cword_prefix)

        completions = self._complete_active_option(active_parser, next_positional, cword_prefix, parsed_args,
                                                   completions)
        debug("active options:", completions)
        debug("display completions:", self._display_completions)

        return completions

    def _get_next_positional(self):
        """
        Get the next positional action if it exists.
        """
        active_parser = self.active_parsers[-1]
        last_positional = self.visited_positionals[-1]

        all_positionals = active_parser._get_positional_actions()
        if not all_positionals:
            return None

        if active_parser == last_positional:
            return all_positionals[0]

        i = 0
        for i in range(len(all_positionals)):
            if all_positionals[i] == last_positional:
                break

        if i + 1 < len(all_positionals):
            return all_positionals[i + 1]

        return None

    def filter_completions(self, completions):
        """
        Ensures collected completions are Unicode text, de-duplicates them, and excludes those specified by ``exclude``.
        Returns the filtered completions as an iterable.

        This method is exposed for overriding in subclasses; there is no need to use it directly.
        """
        # On Python 2, we have to make sure all completions are unicode objects before we continue and output them.
        # Otherwise, because python disobeys the system locale encoding and uses ascii as the default encoding, it will try
        # to implicitly decode string objects using ascii, and fail.
        completions = [ensure_str(c) for c in completions]

        # De-duplicate completions and remove excluded ones
        if self.exclude is None:
            self.exclude = set()
        seen = set(self.exclude)
        return [c for c in completions if c not in seen and not seen.add(c)]

    def quote_completions(self, completions, cword_prequote, first_colon_pos):
        """
        If the word under the cursor started with a quote (as indicated by a nonempty ``cword_prequote``), escapes
        occurrences of that quote character in the completions, and adds the quote to the beginning of each completion.
        Otherwise, escapes all characters that bash splits words on (``COMP_WORDBREAKS``), and removes portions of
        completions before the first colon if (``COMP_WORDBREAKS``) contains a colon.

        If there is only one completion, and it doesn't end with a **continuation character** (``/``, ``:``, or ``=``),
        adds a space after the completion.

        This method is exposed for overriding in subclasses; there is no need to use it directly.
        """
        comp_wordbreaks = ensure_str(os.environ.get("_ARGCOMPLETE_COMP_WORDBREAKS",
                                                    os.environ.get("COMP_WORDBREAKS",
                                                                   " \t\"'@><=;|&(:.")))

        punctuation_chars = "();<>|&!`"
        for char in punctuation_chars:
            if char not in comp_wordbreaks:
                comp_wordbreaks += char

        # If the word under the cursor was quoted, escape the quote char and add the leading quote back in.
        # Otherwise, escape all COMP_WORDBREAKS chars.
        if cword_prequote == "":
            # Bash mangles completions which contain colons if COMP_WORDBREAKS contains a colon.
            # This workaround has the same effect as __ltrim_colon_completions in bash_completion.
            if ":" in comp_wordbreaks and first_colon_pos:
                completions = [c[first_colon_pos+1:] for c in completions]

            for wordbreak_char in comp_wordbreaks:
                completions = [c.replace(wordbreak_char, "\\"+wordbreak_char) for c in completions]
        else:
            if cword_prequote == '"':
                for char in "`$!":
                    completions = [c.replace(char, "\\"+char) for c in completions]
            completions = [cword_prequote+c.replace(cword_prequote, "\\"+cword_prequote) for c in completions]

        # Note: similar functionality in bash is turned off by supplying the "-o nospace" option to complete.
        # We can't use that functionality because bash is not smart enough to recognize continuation characters (/) for
        # which no space should be added.
        continuation_chars = "=/:"
        if len(completions) == 1 and completions[0][-1] not in continuation_chars:
            if cword_prequote == "" and not completions[0].endswith(" "):
                completions[0] += " "

        return completions

    def rl_complete(self, text, state):
        """
        Alternate entry point for using the argcomplete completer in a readline-based REPL. See also
        `rlcompleter <https://docs.python.org/2/library/rlcompleter.html#completer-objects>`_.
        Usage:

        .. code-block:: python

            import argcomplete, argparse, readline
            parser = argparse.ArgumentParser()
            ...
            completer = argcomplete.CompletionFinder(parser)
            readline.set_completer_delims("")
            readline.set_completer(completer.rl_complete)
            readline.parse_and_bind("tab: complete")
            result = input("prompt> ")

        (Use ``raw_input`` instead of ``input`` on Python 2, or use `eight <https://github.com/kislyuk/eight>`_).
        """
        if state == 0:
            cword_prequote, cword_prefix, cword_suffix, comp_words, first_colon_pos = split_line(text)
            comp_words.insert(0, sys.argv[0])
            matches = self._get_completions(comp_words, cword_prefix, cword_prequote, first_colon_pos)
            self._rl_matches = [text + match[len(cword_prefix):] for match in matches]

        if state < len(self._rl_matches):
            return self._rl_matches[state]
        else:
            return None

    def get_display_completions(self):
        """
        This function returns a mapping of option names to their help strings for displaying to the user

        Usage:

        .. code-block:: python

            def display_completions(substitution, matches, longest_match_length):
                _display_completions = argcomplete.autocomplete.get_display_completions()
                print("")
                if _display_completions:
                    help_len = [len(x) for x in _display_completions.values() if x]

                    if help_len:
                        maxlen = max([len(x) for x in _display_completions])
                        print("\\n".join("{0:{2}} -- {1}".format(k, v, maxlen)
                                        for k, v in sorted(_display_completions.items())))
                    else:
                        print("    ".join(k for k in sorted(_display_completions)))
                else:
                    print(" ".join(x for x in sorted(matches)))

                import readline
                print("cli /> {0}".format(readline.get_line_buffer()), end="")
                readline.redisplay()

            ...
            readline.set_completion_display_matches_hook(display_completions)

        """
        return self._display_completions

autocomplete = CompletionFinder()
autocomplete.__doc__ = """ Use this to access argcomplete. See :meth:`argcomplete.CompletionFinder.__call__()`. """


def warn(*args):
    """
    Prints **args** to standard error when running completions. This will interrupt the user's command line interaction;
    use it to indicate an error condition that is preventing your completer from working.
    """
    print("\n", file=debug_stream, *args)