"""
Roleplaying base system for Evennia

Contribution - Griatch, 2015

This module contains the ContribRPObject, ContribRPRoom and
ContribRPCharacter typeclasses.  If you inherit your
objects/rooms/character from these (or make them the defaults) from
these you will get the following features:

    - Objects/Rooms will get the ability to have poses and will report
    the poses of items inside them (the latter most useful for Rooms).
    - Characters will get poses and also sdescs (short descriptions)
    that will be used instead of their keys. They will gain commands
    for managing recognition (custom sdesc-replacement), masking
    themselves as well as an advanced free-form emote command.

To use, simply import the typclasses you want from this module and use
them to create your objects, or set them to default.

In more detail, This RP base system introduces the following features
to a game, common to many RP-centric games:

    - emote system using director stance emoting (names/sdescs).
        This uses a customizable replacement noun (/me, @ etc) to
        represent you in the emote. You can use /sdesc, /nick, /key or
        /alias to reference objects in the room. You can use any
        number of sdesc sub-parts to differentiate a local sdesc, or
        use /1-sdesc etc to differentiate them. The emote also
        identifies nested says.
    - sdesc obscuration of real character names for use in emotes
        and in any referencing such as object.search().  This relies
        on an SdescHandler `sdesc` being set on the Character and
        makes use of a custom Character.get_display_name hook. If
        sdesc is not set, the character's `key` is used instead. This
        is particularly used in the emoting system.
    - recog system to assign your own nicknames to characters, can then
        be used for referencing. The user may recog a user and assign
        any personal nick to them. This will be shown in descriptions
        and used to reference them. This is making use of the nick
        functionality of Evennia.
    - masks to hide your identity (using a simple lock).
    - pose system to set room-persistent poses, visible in room
        descriptions and when looking at the person/object.  This is a
        simple Attribute that modifies how the characters is viewed when
        in a room as sdesc + pose.
    - in-emote says, including seamless integration with language
        obscuration routine (such as contrib/rplanguage.py)

Examples:

> look
Tavern
The tavern is full of nice people

*A tall man* is standing by the bar.

Above is an example of a player with an sdesc "a tall man". It is also
an example of a static *pose*: The "standing by the bar" has been set
by the player of the tall man, so that people looking at him can tell
at a glance what is going on.

> emote /me looks at /tall and says "Hello!"

I see:
    Griatch looks at Tall man and says "Hello".
Tall man (assuming his name is Tom) sees:
    The godlike figure looks at Tom and says "Hello".

Verbose Installation Instructions:

    1. In typeclasses/character.py:
       Import the `ContribRPCharacter` class:
           `from evennia.contrib.rpsystem import ContribRPCharacter`
       Inherit ContribRPCharacter:
           Change "class Character(DefaultCharacter):" to
           `class Character(ContribRPCharacter):`
       If you have any overriden calls in `at_object_creation(self)`:
           Add `super(Character,self).at_object_creation()` as the top line.
    2. In `typeclasses/rooms.py`:
           Import the `ContribRPRoom` class:
           `from evennia.contrib.rpsystem import ContribRPRoom`
       Inherit `ContribRPRoom`:
           Change `class Character(DefaultRoom):` to
           `class Character(ContribRPRoom):`
    3. In `typeclasses/objects.py`
           Import the `ContribRPObject` class:
           `from evennia.contrib.rpsystem import ContribRPObject`
       Inherit `ContribRPObject`:
           Change `class Character(DefaultObject):` to
           `class Character(ContribRPObject):`
    4. Reload the server (@reload or from console: "evennia reload")
    5. Force typeclass updates as required. Example for your character:
           @type/reset/force me = typeclasses.characters.Character

"""
from builtins import object

import re
from re import escape as re_escape
import itertools
from django.conf import settings
from evennia import DefaultObject, DefaultCharacter, ObjectDB
from evennia import Command, CmdSet
from evennia import ansi
from evennia.utils.utils import lazy_property, make_iter, variable_from_module

_AT_SEARCH_RESULT = variable_from_module(*settings.SEARCH_AT_RESULT.rsplit('.', 1))
#------------------------------------------------------------
# Emote parser
#------------------------------------------------------------

# Settings

# The prefix is the (single-character) symbol used to find the start
# of a object reference, such as /tall (note that
# the system will understand multi-word references like '/a tall man' too).
_PREFIX = "/"

# The num_sep is the (single-character) symbol used to separate the
# sdesc from the number when  trying to separate identical sdescs from
# one another. This is the same syntax used in the rest of Evennia, so
# by default, multiple "tall" can be separated by entering 1-tall,
# 2-tall etc.
_NUM_SEP = "-"

# Texts

_EMOTE_NOMATCH_ERROR = \
"""|RNo match for |r{ref}|R.|n"""

_EMOTE_MULTIMATCH_ERROR = \
"""|RMultiple possibilities for {ref}:
    |r{reflist}|n"""

_RE_FLAGS = re.MULTILINE + re.IGNORECASE + re.UNICODE

_RE_PREFIX = re.compile(r"^%s" % _PREFIX, re.UNICODE)

# This regex will return groups (num, word), where num is an optional counter to
# separate multimatches from one another and word is the first word in the
# marker. So entering "/tall man" will return groups ("", "tall")
# and "/2-tall man" will return groups ("2", "tall").
_RE_OBJ_REF_START = re.compile(r"%s(?:([0-9]+)%s)*(\w+)" %
                    (_PREFIX, _NUM_SEP), _RE_FLAGS)

_RE_LEFT_BRACKETS = re.compile(r"\{+", _RE_FLAGS)
_RE_RIGHT_BRACKETS = re.compile(r"\}+", _RE_FLAGS)
# Reference markers are used internally when distributing the emote to
# all that can see it. They are never seen by players and are on the form {#dbref}.
_RE_REF = re.compile(r"\{+\#([0-9]+)\}+")

# This regex is used to quickly reference one self in an emote.
_RE_SELF_REF = re.compile(r"/me|@", _RE_FLAGS)

# regex for non-alphanumberic end of a string
_RE_CHAREND = re.compile(r"\W+$", _RE_FLAGS)

# reference markers for language
_RE_REF_LANG = re.compile(r"\{+\##([0-9]+)\}+")
# language says in the emote are on the form "..." or langname"..." (no spaces).
# this regex returns in groups (langname, say), where langname can be empty.
_RE_LANGUAGE = re.compile(r"(?:\((\w+)\))*(\".+?\")")

# the emote parser works in two steps:
#  1) convert the incoming emote into an intermediary
#     form with all object references mapped to ids.
#  2) for every person seeing the emote, parse this
#     intermediary form into the one valid for that char.

class EmoteError(Exception):
    pass


class SdescError(Exception):
    pass


class RecogError(Exception):
    pass


class LanguageError(Exception):
    pass


def _dummy_process(text, *args, **kwargs):
    "Pass-through processor"
    return text


# emoting mechanisms


def ordered_permutation_regex(sentence):
    """
    Builds a regex that matches 'ordered permutations' of a sentence's
    words.

    Args:
        sentence (str): The sentence to build a match pattern to

    Returns:
        regex (re object): Compiled regex object represented the
            possible ordered permutations of the sentence, from longest to
            shortest.
    Example:
         The sdesc_regex for an sdesc of " very tall man" will
         result in the following allowed permutations,
         regex-matched in inverse order of length (case-insensitive):
         "the very tall man", "the very tall", "very tall man",
         "very tall", "the very", "tall man", "the", "very", "tall",
         and "man".
         We also add regex to make sure it also accepts num-specifiers,
         like /2-tall.

    """
    # escape {#nnn} markers from sentence, replace with nnn
    sentence = _RE_REF.sub(r"\1", sentence)
    # escape {##nnn} markers, replace with nnn
    sentence = _RE_REF_LANG.sub(r"\1", sentence)
    # escape self-ref marker from sentence
    sentence = _RE_SELF_REF.sub(r"", sentence)

    # ordered permutation algorithm
    words = sentence.split()
    combinations = itertools.product((True, False), repeat=len(words))
    solution = []
    for combination in combinations:
        comb = []
        for iword, word in enumerate(words):
            if combination[iword]:
                comb.append(word)
            elif comb:
                break
        if comb:
            solution.append(_PREFIX + r"[0-9]*%s*%s(?=\W|$)+" % (_NUM_SEP, re_escape(" ".join(comb)).rstrip("\\")))

    # combine into a match regex, first matching the longest down to the shortest components
    regex = r"|".join(sorted(set(solution), key=len, reverse=True))
    return regex

def regex_tuple_from_key_alias(obj):
    """
    This will build a regex tuple for any object, not just from those
    with sdesc/recog handlers. It's used as a legacy mechanism for
    being able to mix this contrib with objects not using sdescs, but
    note that creating the ordered permutation regex dynamically for
    every object will add computational overhead.

    Args:
        obj (Object): This object's key and eventual aliases will
            be used to build the tuple.

    Returns:
        regex_tuple (tuple): A tuple
            (ordered_permutation_regex, obj, key/alias)

    """
    return (re.compile(ordered_permutation_regex(" ".join([obj.key] + obj.aliases.all())), _RE_FLAGS),
            obj,
            obj.key)


def parse_language(speaker, emote):
    """
    Parse the emote for language. This is
    used with a plugin for handling languages.

    Args:
        speaker (Object): The object speaking.
        emote (str): An emote possibly containing
            language references.

    Returns:
        (emote, mapping) (tuple): A tuple where the
            `emote` is the emote string with all says
            (including quotes) replaced with reference
            markers on the form {##n} where n is a running
            number. The `mapping` is a dictionary between
            the markers and a tuple (langname, saytext), where
            langname can be None.
    Raises:
        LanguageError: If an invalid language was specified.

    Notes:
        Note that no errors are raised if the wrong language identifier
        is given.
        This data, together with the identity of the speaker, is
        intended to be used by the "listener" later, since with this
        information the language skill of the speaker can be offset to
        the language skill of the listener to determine how much
        information is actually conveyed.

    """
    # escape mapping syntax on the form {##id} if it exists already in emote,
    # if so it is replaced with just "id".
    emote = _RE_REF_LANG.sub(r"\1", emote)

    errors = []
    mapping = {}
    for imatch, say_match in enumerate(reversed(list(_RE_LANGUAGE.finditer(emote)))):
        # process matches backwards to be able to replace
        # in-place without messing up indexes for future matches
        # note that saytext includes surrounding "...".
        langname, saytext = say_match.groups()
        istart, iend = say_match.start(), say_match.end()
        # the key is simply the running match in the emote
        key = "##%i" % imatch
        # replace say with ref markers in emote
        emote = emote[:istart] + "{%s}" % key + emote[iend:]
        mapping[key] = (langname, saytext)

    if errors:
        # catch errors and report
        raise LanguageError("\n".join(errors))

    # at this point all says have been replaced with {##nn} markers
    # and mapping maps 1:1 to this.
    return emote, mapping


def parse_sdescs_and_recogs(sender, candidates, string, search_mode=False):
    """
    Read a raw emote and parse it into an intermediary
    format for distributing to all observers.

    Args:
        sender (Object): The object sending the emote. This object's
            recog data will be considered in the parsing.
        candidates (iterable): A list of objects valid for referencing
            in the emote.
    string (str): The string (like an emote) we want to analyze for keywords.
    search_mode (bool, optional): If `True`, the "emote" is a query string
        we want to analyze. If so, the return value is changed.

    Returns:
        (emote, mapping) (tuple): If `search_mode` is `False`
            (default), a tuple where the emote is the emote string, with
            all references replaced with internal-representation {#dbref}
            markers and mapping is a dictionary `{"#dbref":obj, ...}`.
        result (list): If `search_mode` is `True` we are
            performing a search query on `string`, looking for a specific
            object. A list with zero, one or more matches.

    Raises:
        EmoteException: For various ref-matching errors.

    Notes:
        The parser analyzes and should understand the following
        _PREFIX-tagged structures in the emote:
        - self-reference (/me)
        - recogs (any part of it) stored on emoter, matching obj in `candidates`.
        - sdesc (any part of it) from any obj in `candidates`.
        - N-sdesc, N-recog separating multi-matches (1-tall, 2-tall)
        - says, "..." are

    """
    # Load all candidate regex tuples [(regex, obj, sdesc/recog),...]
    candidate_regexes = \
            ([(_RE_SELF_REF, sender, sender.sdesc.get())] if hasattr(sender, "sdesc") else [])+ \
            ([sender.recog.get_regex_tuple(obj) for obj in candidates] if hasattr(sender, "recog") else []) + \
            [obj.sdesc.get_regex_tuple()
                    for obj in candidates if hasattr(obj, "sdesc")] + \
            [regex_tuple_from_key_alias(obj)   # handle objects without sdescs
                    for obj in candidates if not (hasattr(obj, "recog") and
                                                  hasattr(obj, "sdesc"))]

    # filter out non-found data
    candidate_regexes = [tup for tup in candidate_regexes if tup]

    # escape mapping syntax on the form {#id} if it exists already in emote,
    # if so it is replaced with just "id".
    string = _RE_REF.sub(r"\1", string)
    # escape loose { } brackets since this will clash with formatting
    string = _RE_LEFT_BRACKETS.sub("{{", string)
    string = _RE_RIGHT_BRACKETS.sub("}}", string)

    # we now loop over all references and analyze them
    mapping = {}
    errors = []
    obj = None
    nmatches = 0
    for marker_match in reversed(list(_RE_OBJ_REF_START.finditer(string))):
        # we scan backwards so we can replace in-situ without messing
        # up later occurrences. Given a marker match, query from
        # start index forward for all candidates.

        # first see if there is a number given (e.g. 1-tall)
        num_identifier, _ = marker_match.groups("") # return "" if no match, rather than None
        istart0 = marker_match.start()
        istart = istart0

        # loop over all candidate regexes and match against the string following the match
        matches = ((reg.match(string[istart:]), obj, text) for reg, obj, text in candidate_regexes)

        # score matches by how long part of the string was matched
        matches = [(match.end() if match else -1, obj, text) for match, obj, text in matches]
        maxscore = max(score for score, obj, text in matches)

        # we have a valid maxscore, extract all matches with this value
        bestmatches = [(obj, text) for score, obj, text in matches if maxscore == score != -1]
        nmatches = len(bestmatches)

        if not nmatches:
            # no matches
            obj = None
            nmatches = 0
        elif nmatches == 1:
            # an exact match.
            obj = bestmatches[0][0]
            nmatches = 1
        elif all(bestmatches[0][0].id == obj.id for obj, text in bestmatches):
            # multi-match but all matches actually reference the same
            # obj (could happen with clashing recogs + sdescs)
            obj = bestmatches[0][0]
            nmatches = 1
        else:
            # multi-match.
            # was a numerical identifier given to help us separate the multi-match?
            inum = min(max(0, int(num_identifier) - 1), nmatches-1) if num_identifier else None
            if inum is not None:
                # A valid inum is given. Use this to separate data.
                obj = bestmatches[inum][0]
                nmatches = 1
            else:
                # no identifier given - a real multimatch.
                obj = bestmatches

        if search_mode:
            # single-object search mode. Don't continue loop.
            break
        elif nmatches == 0:
            errors.append(_EMOTE_NOMATCH_ERROR.format(ref=marker_match.group()))
        elif nmatches == 1:
            key = "#%i" % obj.id
            string = string[:istart0] + "{%s}" % key + string[istart + maxscore:]
            mapping[key] = obj
        else:
            refname = marker_match.group()
            reflist = ["%s%s%s (%s%s)" % (inum+1, _NUM_SEP,
                    _RE_PREFIX.sub("", refname), text,
                    " (%s)" % sender.key if sender == ob else "")
                    for inum, (ob, text) in enumerate(obj)]
            errors.append(_EMOTE_MULTIMATCH_ERROR.format(
                          ref=marker_match.group(), reflist="\n    ".join(reflist)))
    if search_mode:
        # return list of object(s) matching
        if nmatches == 0:
            return []
        elif nmatches == 1:
            return [obj]
        else:
            return [tup[0] for tup in obj]

    if errors:
        # make sure to not let errors through.
        raise EmoteError("\n".join(errors))

    # at this point all references have been replaced with {#xxx} markers and the mapping contains
    # a 1:1 mapping between those inline markers and objects.
    return string, mapping


def send_emote(sender, receivers, emote, anonymous_add="first"):
    """
    Main access function for distribute an emote.

    Args:
        sender (Object): The one sending the emote.
        receivers (iterable): Receivers of the emote. These
            will also form the basis for which sdescs are
            'valid' to use in the emote.
        emote (str): The raw emote string as input by emoter.
        anonymous_add (str or None, optional): If `sender` is not
            self-referencing in the emote, this will auto-add
            `sender`'s data to the emote. Possible values are
            - None: No auto-add at anonymous emote
            - 'last': Add sender to the end of emote as [sender]
            - 'first': Prepend sender to start of emote.

    """
    try:
        emote, obj_mapping = parse_sdescs_and_recogs(sender, receivers, emote)
        emote, language_mapping = parse_language(sender, emote)
    except (EmoteError, LanguageError) as err:
        # handle all error messages, don't hide actual coding errors
        sender.msg(err.message)
        return
    # we escape the object mappings since we'll do the language ones first
    # (the text could have nested object mappings).
    emote = _RE_REF.sub(r"{{#\1}}", emote)

    if anonymous_add and not "#%i" % sender.id in obj_mapping:
        # no self-reference in the emote - add to the end
        key = "#%i" % sender.id
        obj_mapping[key] = sender
        if anonymous_add == 'first':
            possessive = "" if emote.startswith('\'') else " "
            emote = "%s%s%s" % ("{{%s}}" % key, possessive, emote)
        else:
            emote = "%s [%s]" % (emote, "{{%s}}" % key)

    # broadcast emote to everyone
    for receiver in receivers:
        # first handle the language mapping, which always produce different keys ##nn
        receiver_lang_mapping = {}
        try:
            process_language = receiver.process_language
        except AttributeError:
            process_language = _dummy_process
        for key, (langname, saytext) in language_mapping.iteritems():
            # color says
            receiver_lang_mapping[key] = process_language(saytext, sender, langname)
        # map the language {##num} markers. This will convert the escaped sdesc markers on
        # the form {{#num}} to {#num} markers ready to sdescmat in the next step.
        sendemote = emote.format(**receiver_lang_mapping)

        # handle sdesc mappings. we make a temporary copy that we can modify
        try:
            process_sdesc = receiver.process_sdesc
        except AttributeError:
            process_sdesc = _dummy_process

        try:
            process_recog = receiver.process_recog
        except AttributeError:
            process_recog = _dummy_process

        try:
            recog_get = receiver.recog.get
            receiver_sdesc_mapping = dict((ref, process_recog(recog_get(obj), obj)) for ref, obj in obj_mapping.items())
        except AttributeError:
            receiver_sdesc_mapping = dict((ref, process_sdesc(obj.sdesc.get(), obj)
                            if hasattr(obj, "sdesc") else process_sdesc(obj.key, obj))
                            for ref, obj in obj_mapping.items())
        # make sure receiver always sees their real name
        rkey = "#%i" % receiver.id
        if rkey in receiver_sdesc_mapping:
            receiver_sdesc_mapping[rkey] = process_sdesc(receiver.key, receiver)

        # do the template replacement of the sdesc/recog {#num} markers
        receiver.msg(sendemote.format(**receiver_sdesc_mapping))

#------------------------------------------------------------
# Handlers for sdesc and recog
#------------------------------------------------------------

class SdescHandler(object):
    """
    This Handler wraps all operations with sdescs. We
    need to use this since we do a lot preparations on
    sdescs when updating them, in order for them to be
    efficient to search for and query.

    The handler stores data in the following Attributes

        _sdesc   - a string
        _regex  - an empty dictionary

    """
    def __init__(self, obj):
        """
        Initialize the handler

        Args:
            obj (Object): The entity on which this handler is stored.

        """
        self.obj = obj
        self.sdesc = ""
        self.sdesc_regex = ""
        self._cache()

    def _cache(self):
        """
        Cache data from storage

        """
        self.sdesc = self.obj.attributes.get("_sdesc", default="")
        sdesc_regex = self.obj.attributes.get("_sdesc_regex", default="")
        self.sdesc_regex = re.compile(sdesc_regex, _RE_FLAGS)

    def add(self, sdesc, max_length=60):
        """
        Add a new sdesc to object, replacing the old one.

        Args:
            sdesc (str): The sdesc to set. This may be stripped
                of control sequences before setting.
            max_length (int, optional): The max limit of the sdesc.

        Returns:
            sdesc (str): The actually set sdesc.

        Raises:
            SdescError: If the sdesc is empty, can not be set or is
            longer than `max_length`.

        """
        # strip emote components from sdesc
        sdesc = _RE_REF.sub(r"\1",
                _RE_REF_LANG.sub(r"\1",
                _RE_SELF_REF.sub(r"",
                _RE_LANGUAGE.sub(r"",
                _RE_OBJ_REF_START.sub(r"", sdesc)))))

        # make an sdesc clean of ANSI codes
        cleaned_sdesc = ansi.strip_ansi(sdesc)

        if not cleaned_sdesc:
            raise SdescError("Short desc cannot be empty.")

        if len(cleaned_sdesc) > max_length:
            raise SdescError("Short desc can max be %i chars long (was %i chars)." % (max_length, len(cleaned_sdesc)))

        # store to attributes
        sdesc_regex = ordered_permutation_regex(cleaned_sdesc)
        self.obj.attributes.add("_sdesc", sdesc)
        self.obj.attributes.add("_sdesc_regex", sdesc_regex)
        # local caching
        self.sdesc = sdesc
        self.sdesc_regex = re.compile(sdesc_regex, _RE_FLAGS)

        return sdesc

    def get(self):
        """
        Simple getter. The sdesc should never be allowed to
        be empty, but it is we must fall back to the key.

        """
        return self.sdesc or self.obj.key

    def get_regex_tuple(self):
        """
        Return data for sdesc/recog handling

        Returns:
            tup (tuple): tuple (sdesc_regex, obj, sdesc)

        """
        return self.sdesc_regex, self.obj, self.sdesc


class RecogHandler(object):
    """
    This handler manages the recognition mapping
    of an Object.

    The handler stores data in Attributes as dictionaries of
    the following names:

        _recog_ref2recog
        _recog_obj2recog
        _recog_obj2regex

    """
    def __init__(self, obj):
        """
        Initialize the handler

        Args:
            obj (Object): The entity on which this handler is stored.

        """
        self.obj = obj
        # mappings
        self.ref2recog = {}
        self.obj2regex = {}
        self.obj2recog = {}
        self._cache()

    def _cache(self):
        """
        Load data to handler cache
        """
        self.ref2recog = self.obj.attributes.get("_recog_ref2recog", default={})
        obj2regex = self.obj.attributes.get("_recog_obj2regex", default={})
        obj2recog = self.obj.attributes.get("_recog_obj2recog", default={})
        self.obj2regex = dict((obj, re.compile(regex, _RE_FLAGS))
                            for obj, regex in obj2regex.items() if obj)
        self.obj2recog = dict((obj, recog)
                            for obj, recog in obj2recog.items() if obj)

    def add(self, obj, recog, max_length=60):
        """
        Assign a custom recog (nick) to the given object.

        Args:
            obj (Object): The object ot associate with the recog
                string. This is usually determined from the sdesc in the
                room by a call to parse_sdescs_and_recogs, but can also be
                given.
            recog (str): The replacement string to use with this object.
            max_length (int, optional): The max length of the recog string.

        Returns:
            recog (str): The (possibly cleaned up) recog string actually set.

        Raises:
            SdescError: When recog could not be set or sdesc longer
                than `max_length`.

        """
        # strip emote components from recog
        recog = _RE_REF.sub(r"\1",
                _RE_REF_LANG.sub(r"\1",
                _RE_SELF_REF.sub(r"",
                _RE_LANGUAGE.sub(r"",
                _RE_OBJ_REF_START.sub(r"", recog)))))

        # make an recog clean of ANSI codes
        cleaned_recog = ansi.strip_ansi(recog)

        if not cleaned_recog:
            raise SdescError("Recog string cannot be empty.")

        if len(cleaned_recog) > max_length:
            raise RecogError("Recog string cannot be longer than %i chars (was %i chars)" % (max_length, len(cleaned_recog)))

        # mapping #dbref:obj
        key = "#%i" % obj.id
        self.obj.attributes.get("_recog_ref2recog", default={})[key] = recog
        self.obj.attributes.get("_recog_obj2recog", default={})[obj] = recog
        regex = ordered_permutation_regex(cleaned_recog)
        self.obj.attributes.get("_recog_obj2regex", default={})[obj] = regex
        # local caching
        self.ref2recog[key] = recog
        self.obj2recog[obj] = recog
        self.obj2regex[obj] = re.compile(regex, _RE_FLAGS)
        return recog

    def get(self, obj):
        """
        Get recog replacement string, if one exists, otherwise
        get sdesc and as a last resort, the object's key.

        Args:
            obj (Object): The object, whose sdesc to replace
        Returns:
            recog (str): The replacement string to use.

        Notes:
            This method will respect a "enable_recog" lock set on
            `obj` (True by default) in order to turn off recog
            mechanism. This is useful for adding masks/hoods etc.
        """
        if obj.access(self.obj, "enable_recog", default=True):
            # check an eventual recog_masked lock on the object
            # to avoid revealing masked characters. If lock
            # does not exist, pass automatically.
            return self.obj2recog.get(obj, obj.sdesc.get()
                        if hasattr(obj, "sdesc") else obj.key)
        else:
            # recog_mask log not passed, disable recog
            return obj.sdesc.get() if hasattr(obj, "sdesc") else obj.key

    def remove(self, obj):
        """
        Clear recog for a given object.

        Args:
            obj (Object): The object for which to remove recog.
        """
        if obj in self.obj2recog:
            del self.obj.db._recog_obj2recog[obj]
            del self.obj.db._recog_obj2regex[obj]
            del self.obj.db._recog_ref2recog["#%i" % obj.id]
        self._cache()

    def get_regex_tuple(self, obj):
        """
        Returns:
            rec (tuple): Tuple (recog_regex, obj, recog)
        """
        if obj in self.obj2recog and obj.access(self.obj, "enable_recog", default=True):
            return self.obj2regex[obj], obj, self.obj2regex[obj]
        return None

#------------------------------------------------------------
# RP Commands
#------------------------------------------------------------


class RPCommand(Command):
    "simple parent"
    def parse(self):
        "strip extra whitespace"
        self.args = self.args.strip()


class CmdEmote(RPCommand):  # replaces the main emote
    """
    Emote an action, allowing dynamic replacement of
    text in the emote.

    Usage:
      emote text

    Example:
      emote /me looks around.
      emote With a flurry /me attacks /tall man with his sword.
      emote "Hello", /me says.

    Describes an event in the world. This allows the use of /ref
    markers to replace with the short descriptions or recognized
    strings of objects in the same room. These will be translated to
    emotes to match each person seeing it. Use "..." for saying
    things and langcode"..." without spaces to say something in
    a different language.

    """
    key = "emote"
    aliases = [":"]
    locks = "cmd:all()"

    def func(self):
        "Perform the emote."
        if not self.args:
            self.caller.msg("What do you want to do?")
        else:
            # we also include ourselves here.
            emote = self.args
            targets = self.caller.location.contents
            if not emote.endswith((".", "?", "!")):  # If emote is not punctuated,
                emote = "%s." % emote  # add a full-stop for good measure.
            send_emote(self.caller, targets, emote, anonymous_add='first')


class CmdSay(RPCommand): # replaces standard say
    """
    speak as your character

    Usage:
      say <message>

    Talk to those in your current location.
    """

    key = "say"
    aliases = ['"', "'"]
    locks = "cmd:all()"

    def func(self):

        "Run the say command"

        caller = self.caller

        if not self.args:
            caller.msg("Say what?")
            return

        # calling the speech hook on the location
        speech = caller.location.at_say(caller, self.args)
        # preparing the speech with sdesc/speech parsing.
        speech = "/me says, \"{speech}\"".format(speech=speech)
        targets = self.caller.location.contents
        send_emote(self.caller, targets, speech, anonymous_add=None)


class CmdSdesc(RPCommand): # set/look at own sdesc
    """
    Assign yourself a short description (sdesc).

    Usage:
      sdesc <short description>

    Assigns a short description to yourself.

    """
    key = "sdesc"
    locks = "cmd:all()"

    def func(self):
        "Assign the sdesc"
        caller = self.caller
        if not self.args:
            caller.msg("Usage: sdesc <sdesc-text>")
            return
        else:
            # strip non-alfanum chars from end of sdesc
            sdesc = _RE_CHAREND.sub("", self.args)
            try:
                sdesc = caller.sdesc.add(sdesc)
            except SdescError, err:
                caller.msg(err)
                return
            caller.msg("%s's sdesc was set to '%s'." % (caller.key, sdesc))


class CmdPose(RPCommand): # set current pose and default pose
    """
    Set a static pose

    Usage:
        pose <pose>
        pose default <pose>
        pose reset
        pose obj = <pose>
        pose default obj = <pose>
        pose reset obj =

    Examples:
        pose leans against the tree
        pose is talking to the barkeep.
        pose box = is sitting on the floor.

    Set a static pose. This is the end of a full sentence that starts
    with your sdesc. If no full stop is given, it will be added
    automatically. The default pose is the pose you get when using
    pose reset. Note that you can use sdescs/recogs to reference
    people in your pose, but these always appear as that person's
    sdesc in the emote, regardless of who is seeing it.

    """
    key = "pose"

    def parse(self):
        """
        Extract the "default" alternative to the pose.
        """
        args = self.args.strip()
        default = args.startswith("default")
        reset = args.startswith("reset")
        if default:
            args = re.sub(r"^default", "", args)
        if reset:
            args = re.sub(r"^reset", "", args)
        target = None
        if "=" in args:
            target, args = [part.strip() for part in args.split("=", 1)]

        self.target = target
        self.reset = reset
        self.default = default
        self.args = args.strip()

    def func(self):
        "Create the pose"
        caller = self.caller
        pose = self.args
        target = self.target
        if not pose and not self.reset:
            caller.msg("Usage: pose <pose-text> OR pose obj = <pose-text>")
            return

        if not pose.endswith("."):
            pose = "%s." % pose
        if target:
            # affect something else
            target = caller.search(target)
            if not target:
                return
            if not target.access(caller, "edit"):
                caller.msg("You can't pose that.")
                return
        else:
            target = caller

        if not target.attributes.has("pose"):
            caller.msg("%s cannot be posed." % target.key)
            return

        target_name = target.sdesc.get() if hasattr(target, "sdesc") else target.key
        # set the pose
        if self.reset:
            pose = target.db.pose_default
            target.db.pose = pose
        elif self.default:
            target.db.pose_default = pose
            caller.msg("Default pose is now '%s %s'." % (target_name, pose))
            return
        else:
            # set the pose. We do one-time ref->sdesc mapping here.
            parsed, mapping = parse_sdescs_and_recogs(caller, caller.location.contents, pose)
            mapping = dict((ref, obj.sdesc.get() if hasattr(obj, "sdesc") else obj.key)
                            for ref, obj in mapping.iteritems())
            pose = parsed.format(**mapping)

            if len(target_name) + len(pose) > 60:
                caller.msg("Your pose '%s' is too long." % pose)
                return

            target.db.pose = pose

        caller.msg("Pose will read '%s %s'." % (target_name, pose))


class CmdRecog(RPCommand): # assign personal alias to object in room
    """
    Recognize another person in the same room.

    Usage:
      recog sdesc as alias
      forget alias

    Example:
        recog tall man as Griatch
        forget griatch

    This will assign a personal alias for a person, or
    forget said alias.

    """
    key = "recog"
    aliases = ["recognize", "forget"]

    def parse(self):
        "Parse for the sdesc as alias structure"
        if " as " in self.args:
            self.sdesc, self.alias = [part.strip() for part in self.args.split(" as ", 2)]
        elif self.args:
            # try to split by space instead
            try:
                self.sdesc, self.alias = [part.strip() for part in self.args.split(None, 1)]
            except ValueError:
                self.sdesc, self.alias = self.args.strip(), ""

    def func(self):
        "Assign the recog"
        caller = self.caller
        if not self.args:
            caller.msg("Usage: recog <sdesc> as <alias> or forget <alias>")
            return
        sdesc = self.sdesc
        alias = self.alias.rstrip(".?!")
        prefixed_sdesc = sdesc if sdesc.startswith(_PREFIX) else _PREFIX + sdesc
        candidates = caller.location.contents
        matches = parse_sdescs_and_recogs(caller, candidates, prefixed_sdesc, search_mode=True)
        nmatches = len(matches)
        # handle 0, 1 and >1 matches
        if nmatches == 0:
            caller.msg(_EMOTE_NOMATCH_ERROR.format(ref=sdesc))
        elif nmatches > 1:
            reflist = ["%s%s%s (%s%s)" % (inum+1, _NUM_SEP,
                _RE_PREFIX.sub("", sdesc), caller.recog.get(obj),
                " (%s)" % caller.key if caller == obj else "")
                    for inum, obj in enumerate(matches)]
            caller.msg(_EMOTE_MULTIMATCH_ERROR.format(ref=sdesc,reflist="\n    ".join(reflist)))
        else:
            obj = matches[0]
            if not obj.access(self.obj, "enable_recog", default=True):
                # don't apply recog if object doesn't allow it (e.g. by being masked).
                caller.msg("Can't recognize someone who is masked.")
                return
            if self.cmdstring == "forget":
                # remove existing recog
                caller.recog.remove(obj)
                caller.msg("%s will now know only '%s'." % (caller.key, obj.recog.get(obj)))
            else:
                sdesc = obj.sdesc.get() if hasattr(obj, "sdesc") else obj.key
                try:
                    alias = caller.recog.add(obj, alias)
                except RecogError, err:
                    caller.msg(err)
                    return
                caller.msg("%s will now remember |w%s|n as |w%s|n." % (caller.key, sdesc, alias))


class CmdMask(RPCommand):
    """
    Wear a mask

    Usage:
        mask <new sdesc>
        unmask

    This will put on a mask to hide your identity. When wearing
    a mask, your sdesc will be replaced by the sdesc you pick and
    people's recognitions of you will be disabled.

    """
    key = "mask"
    aliases = ["unmask"]

    def func(self):
        caller = self.caller
        if self.cmdstring == "mask":
            # wear a mask
            if not self.args:
                caller.msg("Usage: (un)wearmask sdesc")
                return
            if caller.db.unmasked_sdesc:
                caller.msg("You are already wearing a mask.")
                return
            sdesc = _RE_CHAREND.sub("", self.args)
            sdesc = "%s |H[masked]|n" % sdesc
            if len(sdesc) > 60:
                caller.msg("Your masked sdesc is too long.")
                return
            caller.db.unmasked_sdesc = caller.sdesc.get()
            caller.locks.add("enable_recog:false()")
            caller.sdesc.add(sdesc)
            caller.msg("You wear a mask as '%s'." % sdesc)
        else:
            #unmask
            old_sdesc = caller.db.unmasked_sdesc
            if not old_sdesc:
                caller.msg("You are not wearing a mask.")
                return
            del caller.db.unmasked_sdesc
            caller.locks.remove("enable_recog")
            caller.sdesc.add(old_sdesc)
            caller.msg("You remove your mask and is again '%s'." % old_sdesc)


class RPSystemCmdSet(CmdSet):
    """
    Mix-in for adding rp-commands to default cmdset.
    """
    def at_cmdset_creation(self):
        self.add(CmdEmote())
        self.add(CmdSay())
        self.add(CmdSdesc())
        self.add(CmdPose())
        self.add(CmdRecog())
        self.add(CmdMask())


#------------------------------------------------------------
# RP typeclasses
#------------------------------------------------------------

class ContribRPObject(DefaultObject):
    """
    This class is meant as a mix-in or parent for objects in an
    rp-heavy game. It implements the base functionality for poses.
    """

    def at_object_creation(self):
        """
        Called at initial creation.
        """
        super(ContribRPObject, self).at_object_creation

        # emoting/recog data
        self.db.pose = ""
        self.db.pose_default = "is here."

    def search(self, searchdata,
               global_search=False,
               use_nicks=True,
               typeclass=None,
               location=None,
               attribute_name=None,
               quiet=False,
               exact=False,
               candidates=None,
               nofound_string=None,
               multimatch_string=None,
               use_dbref=None):
        """
        Returns an Object matching a search string/condition, taking
        sdescs into account.

        Perform a standard object search in the database, handling
        multiple results and lack thereof gracefully. By default, only
        objects in the current `location` of `self` or its inventory are searched for.

        Args:
            searchdata (str or obj): Primary search criterion. Will be matched
                against `object.key` (with `object.aliases` second) unless
                the keyword attribute_name specifies otherwise.
                **Special strings:**
                - `#<num>`: search by unique dbref. This is always
                   a global search.
                - `me,self`: self-reference to this object
                - `<num>-<string>` - can be used to differentiate
                   between multiple same-named matches
            global_search (bool): Search all objects globally. This is overruled
                by `location` keyword.
            use_nicks (bool): Use nickname-replace (nicktype "object") on `searchdata`.
            typeclass (str or Typeclass, or list of either): Limit search only
                to `Objects` with this typeclass. May be a list of typeclasses
                for a broader search.
            location (Object or list): Specify a location or multiple locations
                to search. Note that this is used to query the *contents* of a
                location and will not match for the location itself -
                if you want that, don't set this or use `candidates` to specify
                exactly which objects should be searched.
            attribute_name (str): Define which property to search. If set, no
                key+alias search will be performed. This can be used
                to search database fields (db_ will be automatically
                appended), and if that fails, it will try to return
                objects having Attributes with this name and value
                equal to searchdata. A special use is to search for
                "key" here if you want to do a key-search without
                including aliases.
            quiet (bool): don't display default error messages - this tells the
                search method that the user wants to handle all errors
                themselves. It also changes the return value type, see
                below.
            exact (bool): if unset (default) - prefers to match to beginning of
                string rather than not matching at all. If set, requires
                exact mathing of entire string.
            candidates (list of objects): this is an optional custom list of objects
                to search (filter) between. It is ignored if `global_search`
                is given. If not set, this list will automatically be defined
                to include the location, the contents of location and the
                caller's contents (inventory).
            nofound_string (str):  optional custom string for not-found error message.
            multimatch_string (str): optional custom string for multimatch error header.
            use_dbref (bool or None): If None, only turn off use_dbref if we are of a lower
                permission than Builders. Otherwise, honor the True/False value.

        Returns:
            match (Object, None or list): will return an Object/None if `quiet=False`,
                otherwise it will return a list of 0, 1 or more matches.

        Notes:
            To find Players, use eg. `evennia.player_search`. If
            `quiet=False`, error messages will be handled by
            `settings.SEARCH_AT_RESULT` and echoed automatically (on
            error, return will be `None`). If `quiet=True`, the error
            messaging is assumed to be handled by the caller.

        """
        is_string = isinstance(searchdata, basestring)

        if is_string:
            # searchdata is a string; wrap some common self-references
            if searchdata.lower() in ("here", ):
                return [self.location] if quiet else self.location
            if searchdata.lower() in ("me", "self",):
                return [self] if quiet else self

        if use_nicks:
            # do nick-replacement on search
            searchdata = self.nicks.nickreplace(searchdata, categories=("object", "player"), include_player=True)

        if(global_search or (is_string and searchdata.startswith("#") and
                    len(searchdata) > 1 and searchdata[1:].isdigit())):
            # only allow exact matching if searching the entire database
            # or unique #dbrefs
            exact = True
        elif candidates is None:
            # no custom candidates given - get them automatically
            if location:
                # location(s) were given
                candidates = []
                for obj in make_iter(location):
                    candidates.extend(obj.contents)
            else:
                # local search. Candidates are taken from
                # self.contents, self.location and
                # self.location.contents
                location = self.location
                candidates = self.contents
                if location:
                    candidates = candidates + [location] + location.contents
                else:
                    # normally we don't need this since we are
                    # included in location.contents
                    candidates.append(self)

        # the sdesc-related substitution
        is_builder = self.locks.check_lockstring(self, "perm(Builders)")
        use_dbref = is_builder if use_dbref is None else use_dbref
        search_obj = lambda string: ObjectDB.objects.object_search(string,
                                                 attribute_name=attribute_name,
                                                 typeclass=typeclass,
                                                 candidates=candidates,
                                                 exact=exact,
                                                 use_dbref=use_dbref)

        if candidates:
            candidates = parse_sdescs_and_recogs(self, candidates,
                        _PREFIX + searchdata, search_mode=True)
            results = []
            for candidate in candidates:
                # we search by candidate keys here; this allows full error
                # management and use of all kwargs - we will use searchdata
                # in eventual error reporting later (not their keys). Doing
                # it like this e.g. allows for use of the typeclass kwarg
                # limiter.
                results.extend(search_obj(candidate.key))

            if not results and is_builder:
                # builders get a chance to search only by key+alias
                results = search_obj(searchdata)
        else:
            # global searches / #drefs end up here. Global searches are
            # only done in code, so is controlled, #dbrefs are turned off
            # for non-Builders.
            results = search_obj(searchdata)

        if quiet:
            return results
        return  _AT_SEARCH_RESULT(results, self, query=searchdata,
                nofound_string=nofound_string, multimatch_string=multimatch_string)

    def get_display_name(self, looker, **kwargs):
        """
        Displays the name of the object in a viewer-aware manner.

        Args:
            looker (TypedObject): The object or player that is looking
                at/getting inforamtion for this object.

        Kwargs:
            pose (bool): Include the pose (if available) in the return.

        Returns:
            name (str): A string of the sdesc containing the name of the object,
            if this is defined.
                including the DBREF if this user is privileged to control
                said object.

        Notes:
            The RPObject version doesn't add color to its display.

        """
        idstr = "(#%s)" % self.id if self.access(looker, access_type='control') else ""
        if looker == self:
            sdesc = self.key
        else:
            try:
                recog = looker.recog.get(self)
            except AttributeError:
                recog = None
            sdesc = recog or (hasattr(self, "sdesc") and self.sdesc.get()) or self.key
        pose = " %s" % (self.db.pose or "") if kwargs.get("pose", False) else ""
        return "%s%s%s" % (sdesc, idstr, pose)

    def return_appearance(self, looker):
        """
        This formats a description. It is the hook a 'look' command
        should call.

        Args:
            looker (Object): Object doing the looking.
        """
        if not looker:
            return ""
        # get and identify all objects
        visible = (con for con in self.contents if con != looker and
                                                    con.access(looker, "view"))
        exits, users, things = [], [], []
        for con in visible:
            key = con.get_display_name(looker, pose=True)
            if con.destination:
                exits.append(key)
            elif con.has_player:
                users.append(key)
            else:
                things.append(key)
        # get description, build string
        string = "|c%s|n\n" % self.get_display_name(looker, pose=True)
        desc = self.db.desc
        if desc:
            string += "%s" % desc
        if exits:
            string += "\n|wExits:|n " + ", ".join(exits)
        if users or things:
            string += "\n " + "\n ".join(users + things)
        return string


class ContribRPRoom(ContribRPObject):
    """
    Dummy inheritance for rooms.
    """
    pass


class ContribRPCharacter(DefaultCharacter, ContribRPObject):
    """
    This is a character class that has poses, sdesc and recog.
    """
    # Handlers
    @lazy_property
    def sdesc(self):
        return SdescHandler(self)

    @lazy_property
    def recog(self):
        return RecogHandler(self)

    def get_display_name(self, looker, **kwargs):
        """
        Displays the name of the object in a viewer-aware manner.

        Args:
            looker (TypedObject): The object or player that is looking
                at/getting inforamtion for this object.

        Kwargs:
            pose (bool): Include the pose (if available) in the return.

        Returns:
            name (str): A string of the sdesc containing the name of the object,
            if this is defined.
                including the DBREF if this user is privileged to control
                said object.

        Notes:
            The RPCharacter version of this method colors its display to make
            characters stand out from other objects.

        """
        idstr = "(#%s)" % self.id if self.access(looker, access_type='control') else ""
        if looker == self:
            sdesc = self.key
        else:
            try:
                recog = looker.recog.get(self)
            except AttributeError:
                recog = None
            sdesc = recog or (hasattr(self, "sdesc") and self.sdesc.get()) or self.key
        pose = " %s" % (self.db.pose or "is here.") if kwargs.get("pose", False) else ""
        return "|c%s|n%s%s" % (sdesc, idstr, pose)

    def at_object_creation(self):
        """
        Called at initial creation.
        """
        super(ContribRPCharacter, self).at_object_creation()

        self.db._sdesc = ""
        self.db._sdesc_regex = ""

        self.db._recog_ref2recog = {}
        self.db._recog_obj2regex = {}
        self.db._recog_obj2recog = {}

        self.cmdset.add(RPSystemCmdSet, permanent=True)
        # initializing sdesc
        self.sdesc.add("A normal person")

    def process_sdesc(self, sdesc, obj, **kwargs):
        """
        Allows to customize how your sdesc is displayed (primarily by
        changing colors).

        Args:
            sdesc (str): The sdesc to display.
            obj (Object): The object to which the adjoining sdesc
                belongs. If this object is equal to yourself, then
                you are viewing yourself (and sdesc is your key).
                This is not used by default.

        Returns:
            sdesc (str): The processed sdesc ready
                for display.

        """
        return "|b%s|n" % sdesc

    def process_recog(self, recog, obj, **kwargs):
        """
        Allows to customize how a recog string is displayed.

        Args:
            recog (str): The recog string. It has already been
                translated from the original sdesc at this point.
            obj (Object): The object the recog:ed string belongs to.
                This is not used by default.

        Returns:
            recog (str): The modified recog string.

        """
        return self.process_sdesc(recog, obj)

    def process_language(self, text, speaker, language, **kwargs):
        """
        Allows to process the spoken text, for example
        by obfuscating language based on your and the
        speaker's language skills. Also a good place to
        put coloring.

        Args:
            text (str): The text to process.
            speaker (Object): The object delivering the text.
            language (str): An identifier string for the language.

        Return:
            text (str): The optionally processed text.

        Notes:
            This is designed to work together with a string obfuscator
            such as the `obfuscate_language` or `obfuscate_whisper` in
            the evennia.contrib.rplanguage module.

        """
        return "%s|w%s|n" % ("|W(%s)" % language if language else "", text)

        #from evennia.contrib import rplanguage
        #return "|w%s|n" % rplanguage.obfuscate_language(text, level=1.0)
