evennia/src/utils/utils.py

"""
General helper functions that don't fit neatly under any given category.

They provide some useful string and conversion methods that might
be of use when designing your own game.

"""

import os
import sys
import imp
import types
import math
import re
import textwrap
import datetime
import random
import traceback
from inspect import ismodule
from collections import defaultdict
from twisted.internet import threads, defer, reactor
from django.conf import settings

try:
    import cPickle as pickle
except ImportError:
    import pickle

ENCODINGS = settings.ENCODINGS
_GA = object.__getattribute__
_SA = object.__setattr__
_DA = object.__delattr__


def is_iter(iterable):
    """
    Checks if an object behaves iterably. However,
    strings are not accepted as iterable (although
    they are actually iterable), since string iterations
    are usually not what we want to do with a string.
    """
    # use a try..except here to avoid a property
    # lookup when using this from a typeclassed entity
    try:
        _GA(iterable, '__iter__')
        return True
    except AttributeError:
        return False


def make_iter(obj):
    "Makes sure that the object is always iterable."
    return not hasattr(obj, '__iter__') and [obj] or obj


def fill(text, width=78, indent=0):
    """
    Safely wrap text to a certain number of characters.

    text: (str) The text to wrap.
    width: (int) The number of characters to wrap to.
    indent: (int) How much to indent new lines (the first line
                  will not be indented)
    """
    if not text:
        return ""
    indent = " " * indent
    return textwrap.fill(str(text), width, subsequent_indent=indent)


def crop(text, width=78, suffix="[...]"):
    """
    Crop text to a certain width, adding suffix to show the line
    continues. Cropping will be done so that the suffix will also fit
    within the given width.
    """
    ltext = len(to_str(text))
    if ltext <= width:
        return text
    else:
        lsuffix = len(suffix)
        return "%s%s" % (text[:width - lsuffix], suffix)


def dedent(text):
    """
    Safely clean all whitespace at the left
    of a paragraph. This is useful for preserving
    triple-quoted string indentation while still
    shifting it all to be next to the left edge of
    the display.
    """
    if not text:
        return ""
    return textwrap.dedent(text)


def list_to_string(inlist, endsep="and", addquote=False):
    """
    This pretty-formats a list as string output, adding
    an optional alternative separator to the second to last entry.
    If addquote is True, the outgoing strings will be surrounded by quotes.

    Examples:
     no endsep:
        [1,2,3] -> '1, 2, 3'
     with endsep=='and':
        [1,2,3] -> '1, 2 and 3'
     with addquote and endsep
        [1,2,3] -> '"1", "2" and "3"'
    """
    if not inlist:
        return ""
    if addquote:
        if len(inlist) == 1:
            return "\"%s\"" % inlist[0]
        return ", ".join("\"%s\"" % v for v in inlist[:-1]) + " %s %s" % (endsep, "\"%s\"" % inlist[-1])
    else:
        if len(inlist) == 1:
            return str(inlist[0])
        return ", ".join(str(v) for v in inlist[:-1]) + " %s %s" % (endsep, inlist[-1])


def wildcard_to_regexp(instring):
    """
    Converts a player-supplied string that may have wildcards in it to regular
    expressions. This is useful for name matching.

    instring: (string) A string that may potentially contain wildcards (* or ?).
    """
    regexp_string = ""

    # If the string starts with an asterisk, we can't impose the beginning of
    # string (^) limiter.
    if instring[0] != "*":
        regexp_string += "^"

    # Replace any occurances of * or ? with the appropriate groups.
    regexp_string += instring.replace("*", "(.*)").replace("?", "(.{1})")

    # If there's an asterisk at the end of the string, we can't impose the
    # end of string ($) limiter.
    if instring[-1] != "*":
        regexp_string += "$"

    return regexp_string


def time_format(seconds, style=0):
    """
    Function to return a 'prettified' version of a value in seconds.

    Style 0: 1d 08:30
    Style 1: 1d
    Style 2: 1 day, 8 hours, 30 minutes, 10 seconds
    """
    if seconds < 0:
        seconds = 0
    else:
        # We'll just use integer math, no need for decimal precision.
        seconds = int(seconds)

    days = seconds / 86400
    seconds -= days * 86400
    hours = seconds / 3600
    seconds -= hours * 3600
    minutes = seconds / 60
    seconds -= minutes * 60

    if style is 0:
        """
        Standard colon-style output.
        """
        if days > 0:
            retval = '%id %02i:%02i' % (days, hours, minutes,)
        else:
            retval = '%02i:%02i' % (hours, minutes,)

        return retval
    elif style is 1:
        """
        Simple, abbreviated form that only shows the highest time amount.
        """
        if days > 0:
            return '%id' % (days,)
        elif hours > 0:
            return '%ih' % (hours,)
        elif minutes > 0:
            return '%im' % (minutes,)
        else:
            return '%is' % (seconds,)
    elif style is 2:
        """
        Full-detailed, long-winded format. We ignore seconds.
        """
        days_str = hours_str = minutes_str = seconds_str = ''
        if days > 0:
            if days == 1:
                days_str = '%i day, ' % days
            else:
                days_str = '%i days, ' % days
        if days or hours > 0:
            if hours == 1:
                hours_str = '%i hour, ' % hours
            else:
                hours_str = '%i hours, ' % hours
        if hours or minutes > 0:
            if minutes == 1:
                minutes_str = '%i minute ' % minutes
            else:
                minutes_str = '%i minutes ' % minutes
        retval = '%s%s%s' % (days_str, hours_str, minutes_str)
    elif style is 3:
        """
        Full-detailed, long-winded format. Includes seconds.
        """
        days_str = hours_str = minutes_str = seconds_str = ''
        if days > 0:
            if days == 1:
                days_str = '%i day, ' % days
            else:
                days_str = '%i days, ' % days
        if days or hours > 0:
            if hours == 1:
                hours_str = '%i hour, ' % hours
            else:
                hours_str = '%i hours, ' % hours
        if hours or minutes > 0:
            if minutes == 1:
                minutes_str = '%i minute ' % minutes
            else:
                minutes_str = '%i minutes ' % minutes
        if minutes or seconds > 0:
            if seconds == 1:
                seconds_str = '%i second ' % seconds
            else:
                seconds_str = '%i seconds ' % seconds
        retval = '%s%s%s%s' % (days_str, hours_str, minutes_str, seconds_str)

    return retval


def datetime_format(dtobj):
    """
    Takes a datetime object instance (e.g. from django's DateTimeField)
    and returns a string describing how long ago that date was.

    """

    year, month, day = dtobj.year, dtobj.month, dtobj.day
    hour, minute, second = dtobj.hour, dtobj.minute, dtobj.second
    now = datetime.datetime.now()

    if year < now.year:
        # another year
        timestring = str(dtobj.date())
    elif dtobj.date() < now.date():
        # another date, same year
        timestring = "%02i-%02i" % (day, month)
    elif hour < now.hour - 1:
        # same day, more than 1 hour ago
        timestring = "%02i:%02i" % (hour, minute)
    else:
        # same day, less than 1 hour ago
        timestring = "%02i:%02i:%02i" % (hour, minute, second)
    return timestring


def host_os_is(osname):
    """
    Check to see if the host OS matches the query.
    """
    if os.name == osname:
        return True
    return False


def get_evennia_version():
    """
    Check for the evennia version info.
    """
    try:
        f = open(settings.BASE_PATH + os.sep + "VERSION.txt", 'r')
        return "%s-r%s" % (f.read().strip(), os.popen("hg id -i").read().strip())
    except IOError:
        return "Unknown version"


def pypath_to_realpath(python_path, file_ending='.py'):
    """
    Converts a path on dot python form (e.g. 'src.objects.models') to
    a system path ($BASE_PATH/src/objects/models.py). Calculates all paths as
    absoulte paths starting from the evennia main directory.
    """
    pathsplit = python_path.strip().split('.')
    if not pathsplit:
        return python_path
    path = settings.BASE_PATH
    for directory in pathsplit:
        path = os.path.join(path, directory)
    if file_ending:
        return "%s%s" % (path, file_ending)
    return path


def dbref(dbref, reqhash=True):
    """
    Converts/checks if input is a valid dbref.
    If reqhash is set, only input strings on the form '#N', where N is an
    integer is accepted. Otherwise strings '#N', 'N' and integers N are all
    accepted.
     Output is the integer part.
    """
    if reqhash:
        return (int(dbref.lstrip('#')) if (isinstance(dbref, basestring) and
                                           dbref.startswith("#") and
                                           dbref.lstrip('#').isdigit())
                                       else None)
    elif isinstance(dbref, basestring):
        dbref = dbref.lstrip('#')
        return int(dbref) if dbref.isdigit() else None
    return dbref if isinstance(dbref, int) else None


def to_unicode(obj, encoding='utf-8', force_string=False):
    """
    This decodes a suitable object to the unicode format. Note that
    one needs to encode it back to utf-8 before writing to disk or
    printing. Note that non-string objects are let through without
    conversion - this is important for e.g. Attributes. Use
    force_string to enforce conversion of objects to string. .
    """

    if force_string and not isinstance(obj, basestring):
        # some sort of other object. Try to
        # convert it to a string representation.
        if hasattr(obj, '__str__'):
            obj = obj.__str__()
        elif hasattr(obj, '__unicode__'):
            obj = obj.__unicode__()
        else:
            # last resort
            obj = str(obj)

    if isinstance(obj, basestring) and not isinstance(obj, unicode):
        try:
            obj = unicode(obj, encoding)
            return obj
        except UnicodeDecodeError:
            for alt_encoding in ENCODINGS:
                try:
                    obj = unicode(obj, alt_encoding)
                    return obj
                except UnicodeDecodeError:
                    pass
        raise Exception("Error: '%s' contains invalid character(s) not in %s." % (obj, encoding))
    return obj


def to_str(obj, encoding='utf-8', force_string=False):
    """
    This encodes a unicode string back to byte-representation,
    for printing, writing to disk etc. Note that non-string
    objects are let through without modification - this is
    required e.g. for Attributes. Use force_string to force
    conversion of objects to strings.
    """

    if force_string and not isinstance(obj, basestring):
        # some sort of other object. Try to
        # convert it to a string representation.
        try:
            obj = str(obj)
        except Exception:
            obj = unicode(obj)

    if isinstance(obj, basestring) and isinstance(obj, unicode):
        try:
            obj = obj.encode(encoding)
            return obj
        except UnicodeEncodeError:
            for alt_encoding in ENCODINGS:
                try:
                    obj = obj.encode(encoding)
                    return obj
                except UnicodeEncodeError:
                    pass
        raise Exception("Error: Unicode could not encode unicode string '%s'(%s) to a bytestring. " % (obj, encoding))
    return obj


def validate_email_address(emailaddress):
    """
    Checks if an email address is syntactically correct.

    (This snippet was adapted from
    http://commandline.org.uk/python/email-syntax-check.)
    """

    emailaddress = r"%s" % emailaddress

    domains = ("aero", "asia", "biz", "cat", "com", "coop",
               "edu", "gov", "info", "int", "jobs", "mil", "mobi", "museum",
               "name", "net", "org", "pro", "tel", "travel")

    # Email address must be more than 7 characters in total.
    if len(emailaddress) < 7:
        return False  # Address too short.

    # Split up email address into parts.
    try:
        localpart, domainname = emailaddress.rsplit('@', 1)
        host, toplevel = domainname.rsplit('.', 1)
    except ValueError:
        return False  # Address does not have enough parts.

    # Check for Country code or Generic Domain.
    if len(toplevel) != 2 and toplevel not in domains:
        return False  # Not a domain name.

    for i in '-_.%+.':
        localpart = localpart.replace(i, "")
    for i in '-_.':
        host = host.replace(i, "")

    if localpart.isalnum() and host.isalnum():
        return True  # Email address is fine.
    else:
        return False  # Email address has funny characters.


def inherits_from(obj, parent):
    """
    Takes an object and tries to determine if it inherits at any distance
    from parent. What differs this function from e.g. isinstance()
    is that obj may be both an instance and a class, and parent
    may be an instance, a class, or the python path to a class (counting
    from the evennia root directory).
    """

    if callable(obj):
        # this is a class
        obj_paths = ["%s.%s" % (mod.__module__, mod.__name__) for mod in obj.mro()]
    else:
        obj_paths = ["%s.%s" % (mod.__module__, mod.__name__) for mod in obj.__class__.mro()]

    if isinstance(parent, basestring):
        # a given string path, for direct matching
        parent_path = parent
    elif callable(parent):
        # this is a class
        parent_path = "%s.%s" % (parent.__module__, parent.__name__)
    else:
        parent_path = "%s.%s" % (parent.__class__.__module__, parent.__class__.__name__)
    return any(1 for obj_path in obj_paths if obj_path == parent_path)


def server_services():
    """
    Lists all services active on the Server. Observe that
    since services are launced in memory, this function will
    only return any results if called from inside the game.
    """
    from src.server.sessionhandler import SESSIONS
    if hasattr(SESSIONS, "server") and hasattr(SESSIONS.server, "services"):
        server = SESSIONS.server.services.namedServices
    else:
        # This function must be called from inside the evennia process.
        server = {}
    del SESSIONS
    return server


def uses_database(name="sqlite3"):
    """
    Checks if the game is currently using a given database. This is a
    shortcut to having to use the full backend name

    name - one of 'sqlite3', 'mysql', 'postgresql_psycopg2' or 'oracle'
    """
    try:
        engine = settings.DATABASES["default"]["ENGINE"]
    except KeyError:
        engine = settings.DATABASE_ENGINE
    return engine == "django.db.backends.%s" % name


def delay(delay=2, retval=None, callback=None):
    """
    Delay the return of a value.
    Inputs:
      delay (int) - the delay in seconds
      retval (any) - this will be returned by this function after a delay
      callback (func(retval)) - if given, this will be called with retval
                                after delay seconds
    Returns:
      deferred that will fire with to_return after delay seconds
    """
    d = defer.Deferred()
    callb = callback or d.callback
    reactor.callLater(delay, callb, retval)
    return d


_TYPECLASSMODELS = None
_OBJECTMODELS = None
def clean_object_caches(obj):
    """
    Clean all object caches on the given object
    """
    global _TYPECLASSMODELS, _OBJECTMODELS
    if not _TYPECLASSMODELS:
        from src.typeclasses import models as _TYPECLASSMODELS
    #if not _OBJECTMODELS:
    #    from src.objects import models as _OBJECTMODELS

    #print "recaching:", obj
    if not obj:
        return
    obj = hasattr(obj, "dbobj") and obj.dbobj or obj
    # contents cache
    try:
        _SA(obj, "_contents_cache", None)
    except AttributeError:
        pass

    # on-object property cache
    [_DA(obj, cname) for cname in obj.__dict__.keys()
                     if cname.startswith("_cached_db_")]
    try:
        hashid = _GA(obj, "hashid")
        _TYPECLASSMODELS._ATTRIBUTE_CACHE[hashid] = {}
    except AttributeError:
        pass


_PPOOL = None
_PCMD = None
_PROC_ERR = "A process has ended with a probable error condition: process ended by signal 9."
def run_async(to_execute, *args, **kwargs):
    """
    Runs a function or executes a code snippet asynchronously.

    Inputs:
    to_execute (callable) - if this is a callable, it will
            be executed with *args and non-reserver *kwargs as
            arguments.
            The callable will be executed using ProcPool, or in
            a thread if ProcPool is not available.

    reserved kwargs:
        'at_return' -should point to a callable with one argument.
                    It will be called with the return value from
                    to_execute.
        'at_return_kwargs' - this dictionary which be used as keyword
                             arguments to the at_return callback.
        'at_err' - this will be called with a Failure instance if
                       there is an error in to_execute.
        'at_err_kwargs' - this dictionary will be used as keyword
                          arguments to the at_err errback.

    *args   - these args will be used
              as arguments for that function. If to_execute is a string
              *args are not used.
    *kwargs - these kwargs will be used
              as keyword arguments in that function. If a string, they
              instead are used to define the executable environment
              that should be available to execute the code in to_execute.

    run_async will relay executed code to a thread or procpool.

    Use this function with restrain and only for features/commands
    that you know has no influence on the cause-and-effect order of your
    game (commands given after the async function might be executed before
    it has finished). Accessing the same property from different threads
    can lead to unpredicted behaviour if you are not careful (this is called a
    "race condition").

    Also note that some databases, notably sqlite3, don't support access from
    multiple threads simultaneously, so if you do heavy database access from
    your to_execute under sqlite3 you will probably run very slow or even get
    tracebacks.

    """

    # handle special reserved input kwargs
    callback = kwargs.pop("at_return", None)
    errback = kwargs.pop("at_err", None)
    callback_kwargs = kwargs.pop("at_return_kwargs", {})
    errback_kwargs = kwargs.pop("at_err_kwargs", {})

    if callable(to_execute):
        # no process pool available, fall back to old deferToThread mechanism.
        deferred = threads.deferToThread(to_execute, *args, **kwargs)
    else:
        # no appropriate input for this server setup
        raise RuntimeError("'%s' could not be handled by run_async" % to_execute)

    # attach callbacks
    if callback:
        deferred.addCallback(callback, **callback_kwargs)
    deferred.addErrback(errback, **errback_kwargs)


def check_evennia_dependencies():
    """
    Checks the versions of Evennia's dependencies.

    Returns False if a show-stopping version mismatch is found.
    """
    # defining the requirements
    python_min = '2.6'
    twisted_min = '10.0'
    django_min = '1.4'
    south_min = '0.7'
    nt_stop_python_min = '2.7'

    errstring = ""
    no_error = True

    # Python
    pversion = ".".join([str(num) for num in sys.version_info if type(num) == int])
    if pversion < python_min:
        errstring += "\n WARNING: Python %s used. Evennia recommends version %s or higher (but not 3.x)." % (pversion, python_min)
    if os.name == 'nt' and pversion < nt_stop_python_min:
        errstring += "\n WARNING: Python %s used. Windows requires Python %s or higher in order to" % (pversion, nt_stop_python_min)
        errstring += " restart/stop the server from the command line."
        errstring += "\n          (You need to restart/stop from inside the game.)"
    # Twisted
    try:
        import twisted
        tversion = twisted.version.short()
        if tversion < twisted_min:
            errstring += "\n WARNING: Twisted %s found. Evennia recommends version %s or higher." % (twisted.version.short(), twisted_min)
    except ImportError:
        errstring += "\n ERROR: Twisted does not seem to be installed."
        no_error = False
    # Django
    try:
        import django
        dversion = ".".join([str(num) for num in django.VERSION if type(num) == int])
        if dversion < django_min:
            errstring += "\n ERROR: Django version %s found. Evennia requires version %s or higher." % (dversion, django_min)
            no_error = False
    except ImportError:
        errstring += "\n ERROR: Django does not seem to be installed."
        no_error = False
    # South
    try:
        import south
        sversion = south.__version__
        if sversion < south_min:
            errstring += "\n WARNING: South version %s found. Evennia recommends version %s or higher." % (sversion, south_min)
        if sversion == "0.8.3":
            errstring += "\n ERROR: South version %s found. This has a known bug and will not work. Please upgrade." % sversion
            no_error = False
    except ImportError:
        pass
    # IRC support
    if settings.IRC_ENABLED:
        try:
            import twisted.words
            twisted.words  # set to avoid debug info about not-used import
        except ImportError:
            errstring += "\n ERROR: IRC is enabled, but twisted.words is not installed. Please install it."
            errstring += "\n   Linux Debian/Ubuntu users should install package 'python-twisted-words', others"
            errstring += "\n   can get it from http://twistedmatrix.com/trac/wiki/TwistedWords."
            no_error = False
    errstring = errstring.strip()
    if errstring:
        print "%s\n %s\n%s" % ("-"*78, errstring, '-'*78)
    return no_error


def has_parent(basepath, obj):
    "Checks if basepath is somewhere in objs parent tree."
    try:
        return any(cls for cls in obj.__class__.mro()
                   if basepath == "%s.%s" % (cls.__module__, cls.__name__))
    except (TypeError, AttributeError):
        # this can occur if we tried to store a class object, not an
        # instance. Not sure if one should defend against this.
        return False


def mod_import(module):
    """
    A generic Python module loader.

    Args:
        module - this can be either a Python path (dot-notation like
                 src.objects.models), an absolute path
                 (e.g. /home/eve/evennia/src/objects.models.py)
                 or an already import module object (e.g. models)
    Returns:
        an imported module. If the input argument was already a model,
        this is returned as-is, otherwise the path is parsed and imported.
    Error:
        returns None. The error is also logged.
    """

    def log_trace(errmsg=None):
        """
        Log a traceback to the log. This should be called
        from within an exception. errmsg is optional and
        adds an extra line with added info.
        """
        from twisted.python import log
        print errmsg

        tracestring = traceback.format_exc()
        if tracestring:
            for line in tracestring.splitlines():
                log.msg('[::] %s' % line)
        if errmsg:
            try:
                errmsg = to_str(errmsg)
            except Exception, e:
                errmsg = str(e)
            for line in errmsg.splitlines():
                log.msg('[EE] %s' % line)

    if not module:
        return None

    if isinstance(module, types.ModuleType):
        # if this is already a module, we are done
        mod = module
    else:
        # first try to import as a python path
        try:
            mod = __import__(module, fromlist=["None"])
        except ImportError, ex:
            # check just where the ImportError happened (it could have been
            # an erroneous import inside the module as well). This is the
            # trivial way to do it ...
            if str(ex) != "Import by filename is not supported.":
                #log_trace("ImportError inside module '%s': '%s'" % (module, str(ex)))
                raise

            # error in this module. Try absolute path import instead

            if not os.path.isabs(module):
                module = os.path.abspath(module)
            path, filename = module.rsplit(os.path.sep, 1)
            modname = re.sub(r"\.py$", "", filename)

            try:
                result = imp.find_module(modname, [path])
            except ImportError:
                log_trace("Could not find module '%s' (%s.py) at path '%s'" % (modname, modname, path))
                return
            try:
                mod = imp.load_module(modname, *result)
            except ImportError:
                log_trace("Could not find or import module %s at path '%s'" % (modname, path))
                mod = None
            # we have to close the file handle manually
            result[0].close()
    return mod


def all_from_module(module):
    """
    Return all global-level variables from a module as a dict
    """
    mod = mod_import(module)
    return dict((key, val) for key, val in mod.__dict__.items()
                            if not (key.startswith("_") or ismodule(val)))


def variable_from_module(module, variable=None, default=None):
    """
    Retrieve a variable or list of variables from a module. The variable(s)
    must be defined globally in the module. If no variable is given (or a
    list entry is None), a random variable is extracted from the module.

    If module cannot be imported or given variable not found, default
    is returned.

    Args:
      module (string or module)- python path, absolute path or a module
      variable (string or iterable) - single variable name or iterable of
                                      variable names to extract
      default (string) - default value to use if a variable fails
                         to be extracted.
    Returns:
      a single value or a list of values depending on the type of
        'variable' argument. Errors in lists are replaced by the
        'default' argument.
    """

    if not module:
        return default
    mod = mod_import(module)

    result = []
    for var in make_iter(variable):
        if var:
            # try to pick a named variable
            result.append(mod.__dict__.get(var, default))
        else:
            # random selection
            mvars = [val for key, val in mod.__dict__.items()
                            if not (key.startswith("_") or ismodule(val))]
            result.append((mvars and random.choice(mvars)) or default)
    if len(result) == 1:
        return result[0]
    return result


def string_from_module(module, variable=None, default=None):
    """
    This is a wrapper for variable_from_module that requires return
    value to be a string to pass. It's primarily used by login screen.
    """
    val = variable_from_module(module, variable=variable, default=default)
    if isinstance(val, basestring):
        return val
    elif is_iter(val):
        return [(isinstance(v, basestring) and v or default) for v in val]
    return default


def init_new_player(player):
    """
    Helper method to call all hooks, set flags etc on a newly created
    player (and potentially their character, if it exists already)
    """
    # the FIRST_LOGIN flags are necessary for the system to call
    # the relevant first-login hooks.
    #if player.character:
    #    player.character.db.FIRST_LOGIN = True
    player.db.FIRST_LOGIN = True


def string_similarity(string1, string2):
    """
    This implements a "cosine-similarity" algorithm as described for example in
       Proceedings of the 22nd International Conference on Computation
       Linguistics (Coling 2008), pages 593-600, Manchester, August 2008
    The measure-vectors used is simply a "bag of words" type histogram
    (but for letters).

    The function returns a value 0...1 rating how similar the two strings
    are. The strings can contain multiple words.
    """
    vocabulary = set(list(string1 + string2))
    vec1 = [string1.count(v) for v in vocabulary]
    vec2 = [string2.count(v) for v in vocabulary]
    try:
        return float(sum(vec1[i] * vec2[i] for i in range(len(vocabulary)))) / \
               (math.sqrt(sum(v1**2 for v1 in vec1)) * math.sqrt(sum(v2**2 for v2 in vec2)))
    except ZeroDivisionError:
        # can happen if empty-string cmdnames appear for some reason.
        # This is a no-match.
        return 0


def string_suggestions(string, vocabulary, cutoff=0.6, maxnum=3):
    """
    Given a string and a vocabulary, return a match or a list of suggestsion
    based on string similarity.

    Args:
        string (str)- a string to search for
        vocabulary (iterable) - a list of available strings
        cutoff (int, 0-1) - limit the similarity matches (higher, the more
                            exact is required)
        maxnum (int) - maximum number of suggestions to return
    Returns:
        list of suggestions from vocabulary (could be empty if there are
        no matches)
    """
    return [tup[1] for tup in sorted([(string_similarity(string, sugg), sugg)
                                       for sugg in vocabulary],
                                           key=lambda tup: tup[0], reverse=True)
                                           if tup[0] >= cutoff][:maxnum]


def string_partial_matching(alternatives, inp, ret_index=True):
    """
    Partially matches a string based on a list of alternatives. Matching
    is made from the start of each subword in each alternative. Case is not
    important. So e.g. "bi sh sw" or just "big" or "shiny" or "sw" will match
    "Big shiny sword". Scoring is done to allow to separate by most common
    demoninator. You will get multiple matches returned if appropriate.

    Input:
        alternatives (list of str) - list of possible strings to match
        inp (str) - search criterion
        ret_index (bool) - return list of indices (from alternatives
                           array) or strings
    Returns:
        list of matching indices or strings, or an empty list

    """
    if not alternatives or not inp:
        return []

    matches = defaultdict(list)
    inp_words = inp.lower().split()
    for altindex, alt in enumerate(alternatives):
        alt_words = alt.lower().split()
        last_index = 0
        score = 0
        for inp_word in inp_words:
            # loop over parts, making sure only to visit each part once
            # (this will invalidate input in the wrong word order)
            submatch = [last_index + alt_num for alt_num, alt_word
                        in enumerate(alt_words[last_index:])
                                     if alt_word.startswith(inp_word)]
            if submatch:
                last_index = min(submatch) + 1
                score += 1
            else:
                score = 0
                break
        if score:
            if ret_index:
                matches[score].append(altindex)
            else:
                matches[score].append(alt)
    if matches:
        return matches[max(matches)]
    return []


def format_table(table, extra_space=1):
    """
    Note: src.utils.prettytable is more powerful than this, but this
    function can be useful when the number of columns and rows are
    unknown and must be calculated on the fly.

    Takes a table of collumns: [[val,val,val,...], [val,val,val,...], ...]
    where each val will be placed on a separate row in the column. All
    collumns must have the same number of rows (some positions may be
    empty though).

    The function formats the columns to be as wide as the widest member
    of each column.

    extra_space defines how much extra padding should minimum be left between
    collumns.

    print the resulting list e.g. with

    for ir, row in enumarate(ftable):
        if ir == 0:
            # make first row white
            string += "\n{w" + ""join(row) + "{n"
        else:
            string += "\n" + "".join(row)
    print string

    """
    if not table:
        return [[]]

    max_widths = [max([len(str(val)) for val in col]) for col in table]
    ftable = []
    for irow in range(len(table[0])):
        ftable.append([str(col[irow]).ljust(max_widths[icol]) + " " * extra_space
                       for icol, col in enumerate(table)])
    return ftable


def get_evennia_pids():
    """
    Get the currently valids PIDs (Process IDs) of the Portal and Server
    by trying to access an PID file. This can be used to determine if we
    are in a subprocess by something like

     self_pid = os.getpid()
     server_pid, portal_pid = get_evennia_pids()
     is_subprocess = self_pid not in (server_pid, portal_pid)

    """
    server_pidfile = os.path.join(settings.GAME_DIR, 'server.pid')
    portal_pidfile = os.path.join(settings.GAME_DIR, 'portal.pid')
    server_pid, portal_pid = None, None
    if os.path.exists(server_pidfile):
        f = open(server_pidfile, 'r')
        server_pid = f.read()
        f.close()
    if os.path.exists(portal_pidfile):
        f = open(portal_pidfile, 'r')
        portal_pid = f.read()
        f.close()
    if server_pid and portal_pid:
        return int(server_pid), int(portal_pid)
    return None, None