import threading
from random import randint
import time
import socket
import threading
import ssl
from collections import defaultdict
import hashlib
from copy import deepcopy

from log import log
import world
import utils

### Exceptions

class ProtocolError(Exception):
    pass

### Internal classes (users, servers, channels)

class Irc():
    def initVars(self):
        self.connected.clear()
        self.aborted.clear()
        self.pseudoclient = None
        self.lastping = time.time()

        # Internal variable to set the place the last command was called (in PM
        # or in a channel), used by fantasy command support.
        self.called_by = None

        # Server, channel, and user indexes to be populated by our protocol module
        self.servers = {self.sid: IrcServer(None, self.serverdata['hostname'],
                        internal=True, desc=self.serverdata.get('serverdesc')
                        or self.botdata['serverdesc'])}
        self.users = {}
        self.channels = defaultdict(IrcChannel)
        # Sets flags such as whether to use halfops, etc. The default RFC1459
        # modes are implied.
        self.cmodes = {'op': 'o', 'secret': 's', 'private': 'p',
                       'noextmsg': 'n', 'moderated': 'm', 'inviteonly': 'i',
                       'topiclock': 't', 'limit': 'l', 'ban': 'b',
                       'voice': 'v', 'key': 'k',
                       # Type A, B, and C modes
                       '*A': 'b',
                       '*B': 'k',
                       '*C': 'l',
                       '*D': 'imnpstr'}
        self.umodes = {'invisible': 'i', 'snomask': 's', 'wallops': 'w',
                       'oper': 'o',
                       '*A': '', '*B': '', '*C': 's', '*D': 'iow'}

        # This max nick length starts off as the config value, but may be
        # overwritten later by the protocol module if such information is
        # received. Note that only some IRCds (InspIRCd) give us nick length
        # during link, so it is still required that the config value be set!
        self.maxnicklen = self.serverdata['maxnicklen']
        self.prefixmodes = {'o': '@', 'v': '+'}

        # Uplink SID (filled in by protocol module)
        self.uplink = None
        self.start_ts = int(time.time())

    def __init__(self, netname, proto, conf):
        # Initialize some variables
        self.name = netname.lower()
        self.conf = conf
        self.serverdata = conf['servers'][netname]
        self.sid = self.serverdata["sid"]
        self.botdata = conf['bot']
        self.protoname = proto.__name__
        self.proto = proto.Class(self)
        self.pingfreq = self.serverdata.get('pingfreq') or 30
        self.pingtimeout = self.pingfreq * 2

        self.connected = threading.Event()
        self.aborted = threading.Event()

        self.initVars()

        if world.testing:
            # HACK: Don't thread if we're running tests.
            self.connect()
        else:
            self.connection_thread = threading.Thread(target = self.connect)
            self.connection_thread.start()
        self.pingTimer = None

    def connect(self):
        ip = self.serverdata["ip"]
        port = self.serverdata["port"]
        while True:
            self.initVars()
            checks_ok = True
            try:
                self.socket = socket.socket()
                self.socket.setblocking(0)
                # Initial connection timeout is a lot smaller than the timeout after
                # we've connected; this is intentional.
                self.socket.settimeout(self.pingfreq)
                self.ssl = self.serverdata.get('ssl')
                if self.ssl:
                    log.info('(%s) Attempting SSL for this connection...', self.name)
                    certfile = self.serverdata.get('ssl_certfile')
                    keyfile = self.serverdata.get('ssl_keyfile')
                    if certfile and keyfile:
                        try:
                            self.socket = ssl.wrap_socket(self.socket,
                                                          certfile=certfile,
                                                          keyfile=keyfile)
                        except OSError:
                             log.exception('(%s) Caught OSError trying to '
                                           'initialize the SSL connection; '
                                           'are "ssl_certfile" and '
                                           '"ssl_keyfile" set correctly?',
                                           self.name)
                             checks_ok = False
                    else:
                        log.error('(%s) SSL certfile/keyfile was not set '
                                  'correctly, aborting... ', self.name)
                        checks_ok = False
                log.info("Connecting to network %r on %s:%s", self.name, ip, port)
                self.socket.connect((ip, port))
                self.socket.settimeout(self.pingtimeout)

                if self.ssl and checks_ok:
                    peercert = self.socket.getpeercert(binary_form=True)
                    sha1fp = hashlib.sha1(peercert).hexdigest()
                    expected_fp = self.serverdata.get('ssl_fingerprint')
                    if expected_fp:
                        if sha1fp != expected_fp:
                            log.error('(%s) Uplink\'s SSL certificate '
                                      'fingerprint (SHA1) does not match the '
                                      'one configured: expected %r, got %r; '
                                      'disconnecting...', self.name,
                                      expected_fp, sha1fp)
                            checks_ok = False
                        else:
                            log.info('(%s) Uplink SSL certificate fingerprint '
                                     '(SHA1) verified: %r', self.name, sha1fp)
                    else:
                        log.info('(%s) Uplink\'s SSL certificate fingerprint '
                                 'is %r. You can enhance the security of your '
                                 'link by specifying this in a "ssl_fingerprint"'
                                 ' option in your server block.', self.name,
                                 sha1fp)

                if checks_ok:
                    self.proto.connect()
                    self.spawnMain()
                    log.info('(%s) Starting ping schedulers....', self.name)
                    self.schedulePing()
                    log.info('(%s) Server ready; listening for data.', self.name)
                    self.run()
                else:
                    log.error('(%s) A configuration error was encountered '
                              'trying to set up this connection. Please check'
                              ' your configuration file and try again.',
                              self.name)
            except (socket.error, ProtocolError, ConnectionError) as e:
                log.warning('(%s) Disconnected from IRC: %s: %s',
                            self.name, type(e).__name__, str(e))
            self._disconnect()
            autoconnect = self.serverdata.get('autoconnect')
            log.debug('(%s) Autoconnect delay set to %s seconds.', self.name, autoconnect)
            if autoconnect is not None and autoconnect >= 0:
                log.info('(%s) Going to auto-reconnect in %s seconds.', self.name, autoconnect)
                time.sleep(autoconnect)
            else:
                return

    def callCommand(self, source, text):
        cmd_args = text.strip().split(' ')
        cmd = cmd_args[0].lower()
        cmd_args = cmd_args[1:]
        if cmd not in world.commands:
            self.msg(self.called_by or source, 'Error: Unknown command %r.' % cmd)
            return
        log.info('(%s) Calling command %r for %s', self.name, cmd, utils.getHostmask(self, source))
        for func in world.commands[cmd]:
            try:
                func(self, source, cmd_args)
            except utils.NotAuthenticatedError:
                self.msg(self.called_by or source, 'Error: You are not authorized to perform this operation.')
            except Exception as e:
                log.exception('Unhandled exception caught in command %r', cmd)
                self.msg(self.called_by or source, 'Uncaught exception in command %r: %s: %s' % (cmd, type(e).__name__, str(e)))

    def msg(self, target, text, notice=False, source=None):
        """Handy function to send messages/notices to clients. Source
        is optional, and defaults to the main PyLink client if not specified."""
        source = source or self.pseudoclient.uid
        if notice:
            self.proto.noticeClient(source, target, text)
            cmd = 'PYLINK_SELF_NOTICE'
        else:
            self.proto.messageClient(source, target, text)
            cmd = 'PYLINK_SELF_PRIVMSG'
        self.callHooks([source, cmd, {'target': target, 'text': text}])

    def _disconnect(self):
        log.debug('(%s) Canceling pingTimer at %s due to _disconnect() call', self.name, time.time())
        self.connected.clear()
        try:
            self.socket.close()
            self.pingTimer.cancel()
        except:  # Socket timed out during creation; ignore
            pass
        # Internal hook signifying that a network has disconnected.
        self.callHooks([None, 'PYLINK_DISCONNECT', {}])

    def disconnect(self):
        """Closes the IRC connection."""
        self.aborted.set()

    def run(self):
        buf = b""
        data = b""
        while not self.aborted.is_set():
            data = self.socket.recv(2048)
            buf += data
            if self.connected.is_set() and not data:
                log.warning('(%s) No data received and self.connected is set; disconnecting!', self.name)
                return
            elif (time.time() - self.lastping) > self.pingtimeout:
                log.warning('(%s) Connection timed out.', self.name)
                return
            while b'\n' in buf:
                line, buf = buf.split(b'\n', 1)
                line = line.strip(b'\r')
                # FIXME: respect other encodings?
                line = line.decode("utf-8", "replace")
                self.runline(line)

    def runline(self, line):
        """Sends a command to the protocol module."""
        log.debug("(%s) <- %s", self.name, line)
        try:
            hook_args = self.proto.handle_events(line)
        except Exception:
            log.exception('(%s) Caught error in handle_events, disconnecting!', self.name)
            log.error('(%s) The offending line was: <- %s', self.name, line)
            return
        # Only call our hooks if there's data to process. Handlers that support
        # hooks will return a dict of parsed arguments, which can be passed on
        # to plugins and the like. For example, the JOIN handler will return
        # something like: {'channel': '#whatever', 'users': ['UID1', 'UID2',
        # 'UID3']}, etc.
        if hook_args is not None:
            self.callHooks(hook_args)

    def callHooks(self, hook_args):
        numeric, command, parsed_args = hook_args
        # Always make sure TS is sent.
        if 'ts' not in parsed_args:
            parsed_args['ts'] = int(time.time())
        hook_cmd = command
        hook_map = self.proto.hook_map
        # Handlers can return a 'parse_as' key to send their payload to a
        # different hook. An example of this is "/join 0" being interpreted
        # as leaving all channels (PART).
        if command in hook_map:
            hook_cmd = hook_map[command]
        hook_cmd = parsed_args.get('parse_as') or hook_cmd
        log.debug('(%s) Parsed args %r received from %s handler (calling hook %s)',
                  self.name, parsed_args, command, hook_cmd)
        # Iterate over hooked functions, catching errors accordingly
        for hook_func in world.hooks[hook_cmd]:
            try:
                log.debug('(%s) Calling hook function %s from plugin "%s"', self.name,
                          hook_func, hook_func.__module__)
                hook_func(self, numeric, command, parsed_args)
            except Exception:
                # We don't want plugins to crash our servers...
                log.exception('(%s) Unhandled exception caught in %r',
                              self.name, hook_func)
                continue

    def send(self, data):
        # Safeguard against newlines in input!! Otherwise, each line gets
        # treated as a separate command, which is particularly nasty.
        data = data.replace('\n', ' ')
        data = data.encode("utf-8") + b"\n"
        stripped_data = data.decode("utf-8").strip("\n")
        log.debug("(%s) -> %s", self.name, stripped_data)
        try:
            self.socket.send(data)
        except (OSError, AttributeError):
            log.debug("(%s) Dropping message %r; network isn't connected!", self.name, stripped_data)

    def schedulePing(self):
        self.proto.pingServer()
        self.pingTimer = threading.Timer(self.pingfreq, self.schedulePing)
        self.pingTimer.daemon = True
        self.pingTimer.start()
        log.debug('(%s) Ping scheduled at %s', self.name, time.time())

    def spawnMain(self):
        nick = self.botdata.get('nick') or 'PyLink'
        ident = self.botdata.get('ident') or 'pylink'
        host = self.serverdata["hostname"]
        log.info('(%s) Connected! Spawning main client %s.', self.name, nick)
        olduserobj = self.pseudoclient
        self.pseudoclient = self.proto.spawnClient(nick, ident, host,
                                                   modes={("+o", None)},
                                                   manipulatable=True)
        for chan in self.serverdata['channels']:
            self.proto.joinClient(self.pseudoclient.uid, chan)
        # PyLink internal hook called when spawnMain is called and the
        # contents of Irc().pseudoclient change.
        self.callHooks([self.sid, 'PYLINK_SPAWNMAIN', {'olduser': olduserobj}])

class IrcUser():
    def __init__(self, nick, ts, uid, ident='null', host='null',
                 realname='PyLink dummy client', realhost='null',
                 ip='0.0.0.0', manipulatable=False):
        self.nick = nick
        self.ts = ts
        self.uid = uid
        self.ident = ident
        self.host = host
        self.realhost = realhost
        self.ip = ip
        self.realname = realname
        self.modes = set()

        self.identified = False
        self.channels = set()
        self.away = ''

        # Whether the client should be marked as manipulatable
        # (i.e. we are allowed to play with it using bots.py's commands).
        # For internal services clients, this should always be False.
        self.manipulatable = manipulatable

    def __repr__(self):
        return repr(self.__dict__)

class IrcServer():
    """PyLink IRC Server class.

    uplink: The SID of this IrcServer instance's uplink. This is set to None
            for the main PyLink PseudoServer!
    name: The name of the server.
    internal: Whether the server is an internal PyLink PseudoServer.
    """
    def __init__(self, uplink, name, internal=False, desc="(None given)"):
        self.uplink = uplink
        self.users = set()
        self.internal = internal
        self.name = name.lower()
        self.desc = desc
    def __repr__(self):
        return repr(self.__dict__)

class IrcChannel():
    def __init__(self):
        self.users = set()
        self.modes = {('n', None), ('t', None)}
        self.topic = ''
        self.ts = int(time.time())
        self.topicset = False
        self.prefixmodes = {'ops': set(), 'halfops': set(), 'voices': set(),
                            'owners': set(), 'admins': set()}

    def __repr__(self):
        return repr(self.__dict__)

    def removeuser(self, target):
        for s in self.prefixmodes.values():
            s.discard(target)
        self.users.discard(target)

    def deepcopy(self):
        return deepcopy(self)

### FakeIRC classes, used for test cases

class FakeIRC(Irc):
    def connect(self):
        self.messages = []
        self.hookargs = []
        self.hookmsgs = []
        self.socket = None
        self.initVars()
        self.spawnMain()
        self.connected = threading.Event()
        self.connected.set()

    def run(self, data):
        """Queues a message to the fake IRC server."""
        log.debug('<- ' + data)
        hook_args = self.proto.handle_events(data)
        if hook_args is not None:
            self.hookmsgs.append(hook_args)
            self.callHooks(hook_args)

    def send(self, data):
        self.messages.append(data)
        log.debug('-> ' + data)

    def takeMsgs(self):
        """Returns a list of messages sent by the protocol module since
        the last takeMsgs() call, so we can track what has been sent."""
        msgs = self.messages
        self.messages = []
        return msgs

    def takeCommands(self, msgs):
        """Returns a list of commands parsed from the output of takeMsgs()."""
        sidprefix = ':' + self.sid
        commands = []
        for m in msgs:
            args = m.split()
            if m.startswith(sidprefix):
                commands.append(args[1])
            else:
                commands.append(args[0])
        return commands

    def takeHooks(self):
        """Returns a list of hook arguments sent by the protocol module since
        the last takeHooks() call."""
        hookmsgs = self.hookmsgs
        self.hookmsgs = []
        return hookmsgs

class Protocol():
    # TODO: Future state-keeping things will go here
    def __init__(self, irc):
        self.irc = irc
        self.casemapping = 'rfc1459'
        self.hook_map = {}

    def parseArgs(self, args):
        """Parses a string of RFC1459-style arguments split into a list, where ":" may
        be used for multi-word arguments that last until the end of a line.
        """
        real_args = []
        for idx, arg in enumerate(args):
            real_args.append(arg)
            # If the argument starts with ':' and ISN'T the first argument.
            # The first argument is used for denoting the source UID/SID.
            if arg.startswith(':') and idx != 0:
                # : is used for multi-word arguments that last until the end
                # of the message. We can use list splicing here to turn them all
                # into one argument.
                # Set the last arg to a joined version of the remaining args
                arg = args[idx:]
                arg = ' '.join(arg)[1:]
                # Cut the original argument list right before the multi-word arg,
                # and then append the multi-word arg.
                real_args = args[:idx]
                real_args.append(arg)
                break
        return real_args

    def removeClient(self, numeric):
        """Internal function to remove a client from our internal state."""
        for c, v in self.irc.channels.copy().items():
            v.removeuser(numeric)
            # Clear empty non-permanent channels.
            if not (self.irc.channels[c].users or ((self.irc.cmodes.get('permanent'), None) in self.irc.channels[c].modes)):
                del self.irc.channels[c]
            assert numeric not in v.users, "IrcChannel's removeuser() is broken!"

        sid = numeric[:3]
        log.debug('Removing client %s from self.irc.users', numeric)
        del self.irc.users[numeric]
        log.debug('Removing client %s from self.irc.servers[%s].users', numeric, sid)
        self.irc.servers[sid].users.discard(numeric)

class FakeProto(Protocol):
    """Dummy protocol module for testing purposes."""
    def handle_events(self, data):
        pass

    def connect(self):
        pass

    def spawnClient(self, nick, *args, **kwargs):
        uid = str(randint(1, 10000000000))
        ts = int(time.time())
        self.irc.users[uid] = user = IrcUser(nick, ts, uid)
        return user

    def joinClient(self, client, channel):
        self.irc.channels[channel].users.add(client)
        self.irc.users[client].channels.add(channel)

FakeProto.Class = FakeProto