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Main.hs
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{-# LANGUAGE LambdaCase, RecordWildCards, ViewPatterns #-}
module Main where
import Data.Set (Set)
import qualified Data.Set as Set
import ImperativeVty
import PureFramework.TUI
textBlock :: [String] -> TextPicture
textBlock ss
= mconcat [ Translated (0, y) (Text s)
| (y, s) <- zip [0..] ss
]
centeredTextBlock :: [String] -> (Int, Int) -> TextPicture
centeredTextBlock ss (ww, hh)
= Translated (x, y) (textBlock ss)
where
w = maximum (0 : fmap length ss)
h = length ss
x = (ww - w) `div` 2
y = (hh - h) `div` 2
-- (x1,y1)-----------+
-- | |
-- | |
-- +-----------(x2,y2)
border :: (Int, Int) -> (Int, Int) -> TextPicture
border (x1,y1) (x2,y2)
= Translated (x1, y1) fullRow
<> mconcat [ Translated (x1, y) emptyRow
| y <- [y1+1..y2-1]
]
<> Translated (x1, y2) fullRow
where
fullRow = Text ("+" ++ replicate (x2-x1-1) '-' ++ "+")
emptyRow = Text "|" <> Translated (x2-x1, 0) (Text "|")
type Username = String
type Message = (Username, String)
data Chat = Chat
{ chatEditbox :: String
}
initialChat :: Chat
initialChat = Chat ""
readEditbox :: Chat -> String
readEditbox = chatEditbox
modifyEditbox :: (String -> String) -> Chat -> Chat
modifyEditbox f chat@(Chat {..}) = chat
{ chatEditbox = f chatEditbox
}
wrapText :: Int -> String -> [String]
wrapText w s
| length s <= w
= [s]
| otherwise
= take w s : wrapText w (drop w s)
-- take as much space as needed for the edit box, then fill as much of
-- the recent history as will fit.
renderChat :: Chat -> [Message] -> (Int, Int) -> TextPicture
renderChat chat msgs (ww, hh)
= border (0, 0) (maxX, dividerY)
<> border (0, dividerY) (maxX, maxY)
<> Translated (2, dividerY+1) (textBlock wrappedEditbox)
<> Translated (2, 1) (renderMessages msgs (w, dividerY-1))
where
maxX = ww-1
maxY = hh-1
w = ww - 4 -- leave space for the a bit of padding
wrappedEditbox = wrapText w ("> " ++ readEditbox chat ++ "_")
editboxHeight = length wrappedEditbox
dividerY = maxY - editboxHeight - 1
renderMessages :: [Message] -> (Int, Int) -> TextPicture
renderMessages msgs (w, h)
= textBlock block
where
renderMessage (username, msg) = username ++ ": " ++ msg
blocks = fmap (wrapText w . renderMessage) msgs
block = reverse . take h . concatMap reverse $ blocks
-- we don't really need this layer of indirection, but it makes the signature
-- of handleUsernameFormKey easier to understand in the blog post.
data UsernameForm = UsernameForm
{ formUsername :: Username
}
initialUsernameForm :: UsernameForm
initialUsernameForm = UsernameForm "user"
readUsername :: UsernameForm -> Username
readUsername (UsernameForm username) = username
modifyUsername :: (Username -> Username) -> UsernameForm -> UsernameForm
modifyUsername f (UsernameForm username) = UsernameForm (f username)
renderUsernameForm :: UsernameForm -> (Int, Int) -> TextPicture
renderUsernameForm (UsernameForm username)
= centeredTextBlock [ "Please pick a username."
, ""
, "> " ++ username ++ "_"
]
handleEditboxKey :: Key -> Maybe (String -> String)
handleEditboxKey = \case
KBS
-- backspace; erase the last character
-> Just $ \s -> take (length s - 1) s
KChar c
-- add a character
-> Just (++ [c])
_ -- unrecognized, let the event bubble up
-> Nothing
data Screen = Screen
{ render :: [Message] -> (Int, Int) -> TextPicture
, handleKey :: Key -> Maybe ([Message], Screen)
}
initialScreen :: Screen
initialScreen = usernameScreen initialUsernameForm
usernameScreen :: UsernameForm -> Screen
usernameScreen usernameForm = Screen
{ render = \_ -> renderUsernameForm usernameForm
, handleKey = \case
KEsc
-- quit
-> Nothing
KEnter
-- the user picked a username; proceed to the chat loop
-> pure
$ pure
$ chatLoopScreen (readUsername usernameForm) initialChat
(handleEditboxKey -> Just f)
-- edit the username
-> pure
$ pure
$ usernameScreen
$ modifyUsername f usernameForm
_ -> pure
$ pure
$ usernameScreen usernameForm
}
chatLoopScreen :: Username -> Chat -> Screen
chatLoopScreen username chat = Screen
{ render = renderChat chat
, handleKey = \case
KEsc
-- quit
-> Nothing
KEnter
-- send the edit box's message, clear the edit box
-> Just ( [(username, readEditbox chat)]
, chatLoopScreen username
$ modifyEditbox (const "")
$ chat
)
(handleEditboxKey -> Just f)
-- delegate to the edit box
-> pure
$ pure
$ chatLoopScreen username
$ modifyEditbox f
$ chat
_ -> pure
$ pure
$ chatLoopScreen username chat
}
data ClientModel = ClientModel
{ clientMessages :: [Message] -- most recent first
, clientScreen :: Screen
}
data ServerModel = ServerModel
{ serverClients :: Set ClientNumber
, serverMessages :: [Message] -- most recent first
, serverScreen :: Screen
}
sendMessageToAll
:: ServerModel
-> Message
-> ([SendToClient Message], ServerModel)
sendMessageToAll serverModel@(ServerModel {..}) msg
= ( [ SendToClient clientNumber msg
| clientNumber <- Set.toList serverClients
]
, serverModel { serverMessages = msg : serverMessages }
)
sendMessagesToAll
:: ServerModel
-> [Message]
-> ([SendToClient Message], ServerModel)
sendMessagesToAll serverModel = \case
[]
-> ([], serverModel)
msg : msgs
-> let (out1, serverModel') = sendMessageToAll serverModel msg
(out2, serverModel'') = sendMessagesToAll serverModel' msgs
in (out1 ++ out2, serverModel'')
main :: IO ()
main = clientServerTUI (pure clientInit) clientRender
clientHandleKey clientHandleToClient
serverInit serverRender
serverHandleKey serverHandleToServer
where
clientInit :: ClientModel
clientInit = ClientModel
{ clientMessages = []
, clientScreen = initialScreen
}
serverInit :: ServerModel
serverInit = ServerModel
{ serverClients = Set.empty
, serverMessages = []
, serverScreen = initialScreen
}
clientRender :: ClientModel -> (Int, Int) -> TextPicture
clientRender (ClientModel {..})
= render clientScreen clientMessages
serverRender :: ServerModel -> (Int, Int) -> TextPicture
serverRender (ServerModel {..})
= render serverScreen serverMessages
clientHandleKey
:: ClientModel
-> Key
-> Maybe ([Message], ClientModel)
clientHandleKey clientModel key = do
let screen = clientScreen clientModel
(out, screen') <- handleKey screen key
let clientModel' = clientModel { clientScreen = screen' }
pure (out, clientModel')
serverHandleKey
:: ServerModel
-> Key
-> Maybe ([SendToClient Message], ServerModel)
serverHandleKey serverModel@(ServerModel {..}) key = do
(msgs, screen') <- handleKey serverScreen key
let serverModel' = serverModel { serverScreen = screen' }
pure $ sendMessagesToAll serverModel' msgs
clientHandleToClient
:: ClientModel
-> Maybe Message
-> Maybe ([Message], ClientModel)
clientHandleToClient clientModel maybeMessage = do
let messages = clientMessages clientModel
message <- maybeMessage
let messages' = message : messages
let clientModel' = clientModel { clientMessages = messages' }
Just ([], clientModel')
serverHandleToServer
:: ServerModel
-> ServerEvent Message
-> Maybe ([SendToClient Message], ServerModel)
serverHandleToServer serverModel = \case
ClientConnected clientNumber -> do
let clients = serverClients serverModel
let clients' = Set.insert clientNumber clients
let serverModel' = serverModel { serverClients = clients' }
pure ([], serverModel')
ClientDisconnected clientNumber -> do
let clients = serverClients serverModel
let clients' = Set.delete clientNumber clients
let serverModel' = serverModel { serverClients = clients' }
pure ([], serverModel')
MessageFromClient _ msg -> do
pure $ sendMessageToAll serverModel msg