import socket
import yaml
from sys import exit
from time import sleep


class IRC:
    """Methods for basic IRC communication."""

    def config(self, conf):
        """Load runtime settings from a YAML config file, and returns a
        dictionary of config values."""
        yml = open(conf, "r")
        cfg = yaml.safe_load(yml)
        yml.close()
        self.server = (cfg["server"]["host"], cfg["server"]["port"])
        self.channels = cfg["channels"]
        self.bot_nick = cfg["bot_nick"]
        self.req_prefix = cfg["req_prefix"]
        self.admin_user = cfg["admin"]["user"]
        self.admin_code = cfg["admin"]["code"]
        self.debug = cfg["debug"]
        return cfg

    def run(self, listen_hook):
        """A routine that connects to a server, joins channels, and attaches
        the request listener hook to a loop."""
        self.connect(self.server, self.bot_nick)
        self.join_channels(self.channels)
        while 1:
            sleep(2)
            data = self.receive()
            self.keepalive(data)
            self.msg = self.parse(data, self.req_prefix)
            for c in self.channels:
                # Pass in a context dict for handlers
                listen_hook({"msg": self.msg, "listen_chan": c})

    def connect(self, server, bot_nick):
        """Connect to the server and sends user/nick information."""
        try:
            self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            self.sock.connect(server)
        except ConnectionError as err:
            exit("[debug] " + str(err))   
        self.send("USER", bot_nick + " " + bot_nick + " " + \
            bot_nick + " " + bot_nick)
        self.send("NICK", bot_nick)

    def disconnect(self, resp_msg, quit_msg):
        """Notify the admin user and disconnect from the server."""
        self.send("PRIVMSG", resp_msg, recvr=self.admin_user)
        self.send("QUIT", ":" + quit_msg)
        # Currently only one server per app instance is supported, so
        # disconnect also exits the app
        exit("Shutting down ...")
    
    def keepalive(self, line):
        """Stay connected to a server by responding to server pings."""
        if "PING" in line:
            self.send("PONG", ":" + line.split(":", 2)[1].split(" ", 1)[0])

    def join_channels(self, channels):
        """Join channels given a list of channel names."""
        for c in channels:
            if c.strip() != "" or c.strip() != "#":
                self.send("JOIN", c)

    def send(self, command, text, *args, **kwargs):
        """Send messages given the IRC command and text. Optionally specify a 
        message recipient with `recvr=user`."""
        recvr = kwargs.get("recvr", "")
        if recvr != "":
            recvr += " :"
        if self.debug:
            print("[debug][send] " + command + " " + recvr + text)
        bs = bytes(command + " " + recvr + text + "\r\n", "utf-8")
        try:
            self.sock.sendall(bs)
        except BrokenPipeError as err:
            if self.debug:
                print("[debug] " + str(err) + " at `" + \
                    bs.decode("utf-8").strip() + "`")
            pass

    def receive(self):
        """Get messages from the connected socket."""
        data = self.sock.recv(2040).decode("utf-8").strip("\r\n")
        if self.debug:
            print("[debug][recv] " + data)
        return data

    def parse(self, line, req_prefix):
        """Using received data from a socket, extract the request, the nick and
        username of the requester, the channel where the request originated and
        return a dictionary of values."""
        data = {"req": "", "req_chan": "", "nick": "", "user": ""}
        if (":" + req_prefix) in line:
            data["req"] = line.split("PRIVMSG", 1)[1].split(":" + \
                req_prefix, 1)[1].strip()
            data["req_chan"] = line.split("PRIVMSG ", \
                1)[1].split(" :", 1)[0]
            data["nick"] = line.split("!~", 1)[0][1:]
            data["user"] = line.split("!~", 2)[1][0:].split("@", 1)[0]
        return data

    def listen(self, context, trigger, handler, *args, **kwargs):
        """Listen for a trigger and call the handler. It takes a context
        dictionary (to determine the channel and recipient), trigger string and
        corresponding handler function. Optional flags (chan, query, admin) can
        be used to specify whether a trigger is active in channels or by
        /msg. e.g. `chan=False, query=True` to make a trigger query-only. By
        default, it will listen in both channels and private messages."""
        in_chan = kwargs.get("chan", True)
        in_query = kwargs.get("query", True)
        in_admin = kwargs.get("admin", False)
        # Admin requests are query/pm only
        if in_admin:
            in_chan = False
        msg = context["msg"]
        channel = context["listen_chan"]
        # Responses are sent via pm to the user by default, while requests made
        # in a channel are sent to the channel. While it's possible to override
        # the recvr, it usually easier to enable a trigger in the same location
        # where the response will be sent.
        context["recvr"] = msg["user"]

        if msg["req"] == trigger:
            # Respond only in the channel where the request was made
            if in_chan and channel == msg["req_chan"]:
                context["recvr"] = msg["req_chan"]
                handler(context)
            # Respond to query/pm
            elif in_query and msg["req_chan"] == self.bot_nick:
                handler(context)
            # Respond only to the admin user
            elif in_admin and msg["user"].lower() == \
                self.admin_user.lower() and self.admin_code in msg["req"]:
                    handler(context)

    def reply(self, cxt, text):
        """Alias of send() with PRIVMSG command preset."""
        self.send("PRIVMSG", text, recvr=cxt["recvr"])