-- Copyright © 2015 Benjamin Barenblat
--
-- Licensed under the Apache License, Version 2.0 (the "License"); you may not
-- use this file except in compliance with the License.  You may obtain a copy
-- of the License at
--
--     http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-- WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
-- License for the specific language governing permissions and limitations under
-- the License.

module Main (main) where

import Prelude hiding (lines, log)

import Control.Concurrent (forkIO, threadDelay)
import Control.Concurrent.MSampleVar
import Control.Monad (forever, void)
import Data.Default.Class (def)
import Data.IORef
import Graphics.Vty (Vty)
import qualified Graphics.Vty as Vty

main :: IO ()
main = do
  terminal <- Vty.mkVty def
  initialize terminal
  jarvis terminal
  Vty.shutdown terminal

initialize :: Vty -> IO ()
initialize _ = return ()

jarvis :: Vty -> IO ()
jarvis terminal = do
  log <- newIORef Vty.emptyImage
  prompt <- newIORef Vty.emptyImage
  ready <- newEmptySV
  void $ forkIO $ redrawer ready log prompt terminal
  void $ forkIO $ prompter prompt ready
  void $ forkIO $ logger log ready
  void $ Vty.nextEvent terminal

prompter :: IORef Vty.Image -> MSampleVar () -> IO ()
prompter output redraw = prompt' 0
  where prompt' :: Integer -> IO ()
        prompt' n = do
          writeIORef output $ Vty.string def ("jarvis " ++ show n ++ " >")
          writeSV redraw ()
          threadDelay 1000000
          prompt' (n + 1)

logger :: IORef Vty.Image -> MSampleVar () -> IO ()
logger output redraw = log 0 []
  where log :: Integer -> [String] -> IO ()
        log n lines = do
          let lines' = lines ++ ["<" ++ show n ++ ">"]
          writeIORef output $ Vty.vertCat $ map (Vty.string def) lines'
          writeSV redraw ()
          threadDelay 200000
          log (n + 1) lines'

redrawer :: MSampleVar () -> IORef Vty.Image -> IORef Vty.Image -> Vty -> IO ()
redrawer ready log prompt terminal = forever $ do
  void $ readSV ready
  (_maxX, maxY) <- Vty.displayBounds $ Vty.outputIface terminal
  images <- sequence $ map readIORef [log, prompt]
  let stack = resizeHeight' maxY $ Vty.vertCat images
  Vty.update terminal $ Vty.picForImage stack
  Vty.refresh terminal

resizeHeight' :: Int -> Vty.Image -> Vty.Image
resizeHeight' h i = case h `compare` Vty.imageHeight i of
    LT -> Vty.cropTop h i
    EQ -> i
    GT -> Vty.translateY (h - Vty.imageHeight i) i