'''
Automated Python IRC bot structure.

This is a threaded bot class designed to make simple the creation of IRC
bots with Python. It is inspired by the cmd standard library module and
is very similar to it in many respects, including its setup.

Various security features are implemented, including a levels system,
which allows individual commands to restrict access to groups of users,
and an access system, which allows groups of commands to provide access
to individual users.

An extension system allows new commands to be added. Extensions may be
loaded with the bot or dynamically. Preprocessors and postprocessors can
also be created.

'''

from __future__ import unicode_literals, print_function
import sys
import os
# The threading module is not available on all platforms.
try:
    import threading
except ImportError:
    import dummy_threading as threading
import socket
import time
import re
import itertools
# Compatibility stuff to make Python 2 behave more like py3k.
if sys.version_info.major == 3:
    import queue
    import configparser
    deutf = lambda s: str(s, 'utf-8')
    basestring = (str, bytes)
else:
    import Queue as queue
    import ConfigParser as configparser
    deutf = lambda s: unicode(s, 'utf-8')

__all__ = ['Bot', 'User', 'Channel', 'deutf']
__version__ = '0.0.0a1'


class User(object):

    '''User object for IRC bots.

    This helps keep track of user information.
    '''

    def __init__(self, nick, user, real, host, mode, channels):
        '''Frobnicate the bizbang.

        nick, user, real, and host correspond to the nickname, username,
        realname, and hostmask of the user, respectively.
        mode is the user's mode, including op/voice/ban/&c status.
        channels is a list of Channel objects for each channel in which
        both the user and this bot are.
        '''
        # target is the target of Bot.send() calls.
        self.target = self.nick = nick
        self.user = user
        self.real = real
        self.host = host
        self.mode = mode
        self.channels = channels

    __slots__ = ('target', 'nick', 'user', 'real', 'host', 'mode', 'channels')

class Channel(object):

    '''Channel object for IRC bots.

    This helps keep track of users, modes, and topics of channels.
    '''

    def __init__(self, name, users, mode, topic):
        '''Catenifrob the bangbiz.

        name is the channel's name, including the initial # (or &).
        users is a list of User objects for each user in the channel.
        mode is the channel's mode, not including modes applying
        specifically to individual users (op, voice, ban, &c).
        topic is the channel's topic.
        '''
        # target is the target of Bot.send() calls.
        self.target = self.name = name
        self.users = users
        self.mode = mode
        self.topic = topic

    __slots__ = ('target', 'name', 'users', 'mode', 'topic')

class Bot(object):

    '''IRC bot class.

    New bots may subclass this or use only extension modules. The
    default implementation provides the commands join, to have the bot
    join a channel; part, to have it leave a channel; quit, to have it
    disconnect from the server; load, to load an extension; unload, to
    disable an extension; levels, to set a user's security level;
    access, to modify a command's access list; identify, to give a user
    owner-level priveleges; raw, to have the bot send a raw string to
    the server (not run through any postprocessors); and eval, to have
    the bot execute an arbitrary Python expression.

    To define a new command named, for example, `spam', define a method
    named `do_spam(self, channel, sender, line, time)'. channel will be
    a Channel object representing the originating channel or the sending
    user if it was sent in a personal message; the sender argument will
    be a User object corresponding to the user who sent the message;
    line will be a string containing the line accompanying the command
    call; and time will be the struct_time for the time when the
    message was sent as returned by time.localtime(). For example, if a
    user with nick `spam' attempts to call a command called `say' in
    #foobar as follows:

        <spam> !say Ni.

    the bot will call
    do_say(<Channel '#foobar'>, <User 'spam'>, 'Ni.', time.localtime()).

    The return value for a command must be a string which will be sent
    to the server, unless it is empty. It will be run through any
    postprocessors which have been defined.

    To specify security levels for a command named, for example, `eggs',
    create an attribute named `level_eggs' with the numeric level. If
    the level is None, only identified users will be allowed to use it;
    if it is not defined, it will be treated as 0.
    '''

    def __init__(self, nick, user=None, realname=None, server=None, port=None,
                 pass_=None, channel=None, idpass=None, debug=None,
                 eval_allowed=None, raw_allowed=None, configfile=None):
        '''Spawn more overlords.

        nick, user, and realname are the bot's nickname, username, and
        realname.
        server is the server to which the bot should connect.
        If port is not given, 6667 will be used.
        pass_ is the password with which to connect. If not given, none
        will be sent.
        channel may be a single channel name or a sequence of them.
        idpass should be a string used as a password for giving users
        owner privileges via the identify command.
        If debug is True, a lot of information you probably don't need
        to know will be printed. self.debug will be set to True, too.
        Setting eval_allowed to False will disable the eval command. Use
        this to prevent the crazy people to whom you have given your
        idpass from rm -rf /ing you.
        raw_allowed is the same as eval_allowed but for raw instead of
        eval.
        configfile may be the path to a file containing these options in
        the format used by the configfile standard library module. The
        option names are the same, with the nick specifying the section
        name. Options specified both here and in the config file use the
        former. If the config file does not specify an option, the same
        default is used as here.

        This method calls pre_init_hook() before doing anything and
        post_init_hook() after it has finished. The former does nothing
        by default; the latter calls self.check_init().
        '''
        self.pre_init_hook()
        if configfile is not None:
            # Note to self: Bo Burnham is an excellent comedian.
            # Note to self: Sources are not the best places for notes to self.
            cfg = configparser.SafeConfigParser(
                {
                    'user': None, 'realname': None, 'server': None,
                    'port': 6667, 'pass_': None, 'channel': None,
                    'idpass': None, 'debug': False, 'eval_allowed': True,
                    'raw_allowed': True
                }, dict)
            with open(configfile) as f:
                cfg.readfp(f)
            self.user = cfg.get(nick, 'user')
            self.realname = cfg.get(nick, 'realname')
            self.server = cfg.get(nick, 'server')
            self.port = cfg.getint(nick, 'port')
            self.pass_ = cfg.get(nick, 'pass')
            c = cfg.get(nick, 'channel')
            if c and ',' in c:
                self.channels = dict(zip(eval(c, {}, {}),
                                         itertools.repeat(None)))
            else:
                self.channels = c
            self.idpass = cfg.get(nick, 'idpass')
            self.debug = cfg.getboolean(nick, 'debug')
            self.eval_allowed = cfg.getboolean(nick, 'eval_allowed')
            self.raw_allowed = cfg.getboolean(nick, 'raw_allowed')
        if user is not None:
            self.user = user
        if realname is not None:
            self.realname = realname
        if server is not None:
            self.server = server
        if port is not None:
            self.port = port
        if pass_ is not None:
            self.pass_ = pass_
        if channel is not None:
            if isinstance(channel, basestring):
                self.channels = {channel: None}
            else:
                self.channels = dict(zip(channel, itertools.repeat(None)))
        if idpass is not None:
            self.idpass = idpass
        if debug is not None:
            self.debug = debug
        if eval_allowed is not None:
            self.eval_allowed = eval_allowed
        self.preprocessors = {'builtins': []}
        self.commands = {'builtins': ['join', 'part', 'quit', 'load', 'unload',
                                      'levels', 'access', 'raw', 'eval']}
        self.postprocessors = {'builtins': []}
        self.post_init_hook()

    def connect(self):
        '''Connect to the server and begin processing.

        Once this is called, the bot becomes autonomous.
        '''
        self.pre_connect_hook()
        if not getattr(self, 'params_checked', False):
            raise AttributeError('parameters not checked')
        # The send thread manages all messages to the server.
        self.send_thread = threading.Thread(target=self.send_mgr, args=(self,))
        # The recv thread delegates (or responds to) messages from the server.
        self.recv_thread = threading.Thread(target=self.recv_mgr, args=(self,))
        self.recv_thread.daemon = True #TODO: remember why this was a bad idea
        # The work thread runs commands.
        self.work_thread = threading.Thread(target=self.work_mgr, args=(self,))
        self.work_thread.daemon = True
        # The send queue is used by the send thread for unknown purposes.
        self.send_queue = queue.Queue()
        # The send timer is used by the send thread to prevent flooding.
        self.send_timer = time.time()
        # The work queue is used by the work thread for well-known purposes.
        self.work_queue = queue.Queue()
        # Initialize the send queue.
        if self.pass_ is not None:
            self.rawmsg('PASS ' + self.pass_)
        self.rawmsg('NICK ' + self.nick)
        self.rawmsg('USER ' + self.user + ' * * :' + self.realname)
        # More hooks, please.
        self.pre_connect_start_hook()
        self.running = True # I'll just leave this here.
        # Connection begins with YOU!!
        self.socket = socket.create_connection((self.server, self.port), 180)
        # Start the threads.
        self.send_thread.start()
        self.recv_thread.start()
        self.work_thread.start()
        self.post_connect_hook()
        # Optionally block.
        if getattr(self, 'join_send_thread', True):
            self.send_thread.join()
        return self.exit_hook()

    def reconnect(self):
        '''Reconnect to the server.

        This is chiefly aimed at reconnecting after a ping timeout or
        some other unexpected disconnection.
        '''
        self.pre_reconnect_hook()
        # Close the connection in case it really is still active.
        self.socket.close()
        self.socket = socket.create_connect((self.server, self.port), 180)
        if self.pass_ is not None:
            self.rawmsg('PASS ' + self.pass_)
        self.rawmsg('NICK ' + self.nick)
        self.rawmsg('USER ' + self.user + ' * * :' + self.realname)
        self.post_reconnect_hook()

    def send_wait(self):
        '''Block until it is safe to send the next message.'''
        if time.time() > self.send_timer:
            self.send_timer = time.time()
        elif time.time() < self.send_timer - 7.0:
            time.sleep(2)

    def send_mgr(self):
        '''Manage messages sent to the server.

        This should prevent the bot from flooding.
        '''
        while True:
            m = self.send_queue.get().rstrip('\r\n\0')
            if m:
                # If the message is too long, it must be split.
                if len(m) > 510: # This is the maximum in RFC 1459.
                    # PRIVMSGs and NOTICEs need to be split such that they all
                    # go where they are intended to go.
                    s = m.split(' ', 2)
                    # It is assumed that no message will contain no spaces yet
                    # still be over the limit.
                    if len(s) == 2:
                        t, r = s
                    else:
                        t = ' '.join(s[:2])
                        r = s[2]
                    if r.startswith(':'):
                        t += ' :'
                        r = r[1:]
                    else:
                        t += ' '
                    while len(r) > 510 - len(t):
                        self.send_wait()
                        #TODO: prevent any chance of paramaters being split
                        n = self.socket.send(t + r[:511] + '\r\n')
                        if not n:
                            # The connection has been broken by this point.
                            self.reconnect()
                            continue
                        #TODO: I don't think this is right.
                        r = r[n:]
                    self.send_wait()
                    n = self.socket.send(t + r + '\r\n')
                    while not n:
                        self.reconnect()
                        self.send_wait()
                        n = self.socket.send(t + r + '\r\n')
                else:
                    # The message may be sent in its entirety.
                    while True:
                        self.send_wait()
                        n = self.socket.send(t + r + '\r\n')
                        if n > 0:
                            break
                        self.reconnect()
                if m.startswith('QUIT'):
                    # The bot has quit; end this thread.
                    self.running = False
                    self.socket.close()
                    return