#!/usr/bin/env python
#
# Claire Cavanaugh, 2016
# Written in Python 3. Follows RFC 2812

# The purpose of this project is to create a bot that connects to an IRC server
# and joins a channel to perform various tasks, including:
#
#     * Providing the titles of pages linked to through URLs

import re

class Message:
    """Represents an IRC Message, allowing access to the components of it."""
    def __init__(self, message=b''):
        self.message = message
        self.items = {"servername" : None,
                       "nickname" : None,
                       "user" : None,
                       "hostname" : None,
                       "hostaddr" : None,
                       "command" : None,
                       "params" : None,
                       "middle" : None,
                       "trailing" : None }

    def lex(self):
        """Lex self.message into its components."""
        shortname = rb"(?: [a-zA-Z0-9] (?: [a-zA-Z0-9-]* [a-zA-Z0-9])?)"
        ip4addr = rb"(?: [0-9]{1,3} (?: \. [0-9]{1,3}){3})"
        ip6addr = (rb"(?: (?: [0-9a-fA-F]+ (?: :[0-9a-fA-F]+){7})|"
                   rb"(?: (?: 0:){5} (?: 0|FFFF):%s))" % ip4addr )
        servername = rb"(?P<servername> %s (?: \.%s*)*)" % (shortname, shortname)
        hostaddr = rb"(?P<hostaddr> %s | %s )" % (ip4addr, ip6addr)
        hostname = rb"(?P<hostname> %s (?: \.%s*)*)" % (shortname, shortname)
        nickname = rb"(?P<nickname> []a-zA-Z[\\`_^{|}] []a-zA-Z0-9[\\`_^{|}-]*)"
        user = rb"(?P<user> [^\x00\n\r @]+)"
        host = rb"(?P<host> %s|%s )" % (hostname, hostaddr)
        clientname = rb"(?: %s (?: (?: !%s)? @%s)?)" % (nickname, user, host)
        middle = rb"(?: [^ \x00\r\n:] [^ \x00\r\n]*)"
        params = (rb"(?P<params>(?: (?P<middle>(?: \ %s){,14})(?P<trailing> \ :[^\x00\r\n]*)?)|"
                  rb"(?:(?P<m2>(?: \  %s){14}) (?P<t2> \ :? [^\x00\r\n]*)?))?" % (middle, middle))
        prefix = rb"(?P<prefix> : (?:%s|%s) \ )?" % (servername, clientname)
        prefix2 = rb"(?: "
        command = rb"(?P<command> [a-zA-Z]+ | [0-9]{3})"
        msg_re = re.compile(prefix + command + params + rb"[\r\n]+", re.X)
        matched = msg_re.match(self.message)
        items = matched.groupdict()
        if items["middle"] is None:
            items["middle"] = items.pop("m2")
        if items["trailing"] is None:
            items["trailing"] = items.pop("t2")
        del items["m2"]; del items["t2"]
        self.items = items