module Lib
    ( runBirch
    ) where

import           System.IO                      -- base
import qualified Network.Socket as N            -- network
import           Control.Monad.Trans.Reader     -- transformers
import           Data.List
import           System.Exit

data Bot = Bot { botSocket :: Handle }
type Net = ReaderT Bot IO

type Nick = String
type User = String
type Realname = String

-- Toplevel program
runBirch :: String -> N.PortNumber -> String -> [String] -> IO ()
runBirch myServer myPort myNick myChannels = do
    h <- connectTo myServer myPort
    register h myNick "tutorial bot"
    line <- hGetLine h
    putStrLn line
    let s = init line
    if isPing s then pong h s else eval h (clean s)
--    map (write h "JOIN") myChannels
    write h "JOIN" (head myChannels)
    listen h

-- Connect to a server given its name and port number
connectTo :: N.HostName -> N.PortNumber -> IO Handle
connectTo host port = do
    addr : _ <- N.getAddrInfo Nothing (Just host) (Just (show port))
    sock <- N.socket (N.addrFamily addr) (N.addrSocketType addr) (N.addrProtocol addr)
    N.connect sock (N.addrAddress addr)
    N.socketToHandle sock ReadWriteMode

-- Send a message to a handle
write :: Handle -> String -> String -> IO ()
write h cmd args = do
    let msg = cmd ++ " " ++ args ++ "\r\n"
    hPutStr h msg          -- Send message on the wire
    putStr ("> " ++ msg)   -- Show sent message on the command line

-- Process each line from the server
listen :: Handle -> IO ()
listen h = forever $ do
    line <- hGetLine h
    putStrLn line
    let s = init line
    if isPing s then pong h s else eval h (clean s)
  where
    forever :: IO () -> IO ()
    forever a = do a; forever a

clean :: String -> String
clean = drop 1 . dropWhile (/= ':') . drop 1

isPing :: String -> Bool
isPing x = "PING :" `isPrefixOf` x

pong :: Handle -> String -> IO ()
pong h x = write h "PONG" (':' : drop 6 x)

-- Dispatch a command
eval :: Handle -> String -> IO ()
eval h "!quit"                    = write h "QUIT" ":Exiting" >> exitSuccess
eval h x | "!id " `isPrefixOf` x  = privmsg h (drop 4 x)
eval _ _                          = return () -- ignore everything else

-- Send a privmsg to a channel
privmsg :: Handle -> String -> IO ()
privmsg h s = write h "PRIVMSG" ("#nais-testing" ++ " :" ++ s)

-- Register with the server
register :: Handle -> Nick -> Realname -> IO ()
register h nick realname = do
  sendNICK h nick
  sendUSER h nick realname

-- Send NICK command
sendNICK :: Handle -> Nick -> IO ()
sendNICK h nick = write h "NICK" nick

-- Send USER command
sendUSER :: Handle -> Nick -> Realname -> IO ()
sendUSER h nick realname = write h "USER" (nick ++ " 0 * :" ++ realname)