\section{PrintText}

A \texttt{PrintTextObject} renders the text console at the bottom of the screen.

\begin{code}
module PrintText
    (newPrintTextObject,
     printText,
     PrintTextObject,
     renderText,
     PrintTextMode(..),
     TextType(..),
     getInputBuffer,
     setInputBuffer,
     setPrintTextMode,
     clearOutputBuffer,
     clearInputBuffer,
     keyCallback)
    where

import Data.IORef
import Graphics.UI.GLUT as GLUT
import PrintTextData
import Control.Monad
\end{code}

\begin{code}
data PrintTextData = PrintTextData {
    text_output_buffer :: [(TextType,String)],
    text_input_buffer :: String,
    text_output_mode :: PrintTextMode }

newtype PrintTextObject = PrintTextObject (IORef PrintTextData)

font_width_pixels :: Int
font_width_pixels = 9

font_height_pixels :: Int
font_height_pixels = 15

padding_pixels :: Int
padding_pixels = 10

font :: BitmapFont
font = Fixed9By15

newPrintTextObject :: IO PrintTextObject
newPrintTextObject = liftM PrintTextObject $ newIORef $ PrintTextData {
    text_output_buffer = [],
    text_input_buffer = [],
    text_output_mode = Unlimited } 

printText :: PrintTextObject -> TextType -> String -> IO ()
printText (PrintTextObject pto) text_type str =
    modifyIORef pto $ 
        \print_text -> print_text { text_output_buffer = text_output_buffer print_text ++ map (\l -> (text_type,l)) (lines str) } 

keyCallback :: PrintTextObject -> KeyboardMouseCallback
keyCallback _ _ Up _ _ = return ()
keyCallback _ (MouseButton {}) _ _ _ = return ()
keyCallback (PrintTextObject pto) (Char char) _ _ _ = modifyIORef pto $ 
    \ptd -> ptd { text_input_buffer = text_input_buffer ptd ++ [char] }
keyCallback (PrintTextObject pto) (SpecialKey special) _ _ _ = modifyIORef pto $
    \ptd -> ptd { text_input_buffer = text_input_buffer ptd ++ show special }

getInputBuffer :: PrintTextObject -> IO String
getInputBuffer (PrintTextObject pto) = liftM text_input_buffer $ readIORef pto

setInputBuffer :: PrintTextObject -> String -> IO ()
setInputBuffer (PrintTextObject pto) new_input_buffer = modifyIORef pto $
    \print_text -> print_text { text_input_buffer = new_input_buffer }

clearOutputBuffer :: PrintTextObject -> IO ()
clearOutputBuffer (PrintTextObject pto) = modifyIORef pto $ \ptd -> ptd { text_output_buffer = [] }

setPrintTextMode :: PrintTextObject -> PrintTextMode -> IO ()
setPrintTextMode (PrintTextObject pto) pt_mode =
    do modifyIORef pto $ \print_text -> print_text { text_output_mode = pt_mode }

clearInputBuffer :: PrintTextObject -> IO ()
clearInputBuffer (PrintTextObject pto) = modifyIORef pto $ \ptd -> ptd { text_input_buffer = [] }

renderText :: PrintTextObject -> IO ()
renderText (PrintTextObject pto) = 
    do ptd <- readIORef pto
       (Size width height) <- get windowSize
       save_depth_func <- get depthFunc
       save_depth_mask <- get depthMask
       save_blend <- get blend
       depthFunc $= Nothing
       depthMask $= GLUT.Disabled
       blend $= Enabled
       matrixMode $= Projection
       loadIdentity
       ortho2D 0 (fromIntegral width) 0 (fromIntegral height)
       matrixMode $= Modelview 0
       loadIdentity
       let max_characters_height = (fromIntegral height - 2 * fromIntegral padding_pixels) `div` (fromIntegral font_height_pixels)
       let max_characters_width = (fromIntegral width - 2 * fromIntegral padding_pixels) `div` (fromIntegral font_width_pixels)
       let lines_to_print = restrictLines max_characters_height max_characters_width $ 
			    (case (text_output_mode ptd) of
			        PrintTextData.Disabled -> []
			        Limited -> reverse $ take 3 $ reverse $ text_output_buffer ptd
	        		Unlimited -> (text_output_buffer ptd)) ++
                            (if length (text_input_buffer ptd) > 0 || (text_output_mode ptd) /= PrintTextData.Disabled 
			        then [(Query,"> " ++ (text_input_buffer ptd))] 
			        else [])
	   actual_width_pixels = font_width_pixels * (maximum $ map (length . snd) lines_to_print)
	   actual_height_pixels = font_height_pixels * (length lines_to_print)
	   in do color $ (Color4 0 0 0 0.92 :: Color4 GLfloat)
		 (rect :: Vertex2 GLfloat -> Vertex2 GLfloat -> IO ())
		     (Vertex2 (fromIntegral padding_pixels) (fromIntegral padding_pixels)) 
		     (Vertex2 (fromIntegral (actual_width_pixels + padding_pixels)) (fromIntegral (actual_height_pixels + padding_pixels)))
		 currentRasterPosition $= (Vertex4 (fromIntegral padding_pixels) (fromIntegral padding_pixels) 0 1)
		 mapM_ drawLine $ reverse lines_to_print
       blend $= save_blend
       depthMask $= save_depth_mask
       depthFunc $= save_depth_func

drawLine :: (TextType,String) -> IO ()
drawLine (textType,str) = do (Vertex4 x y _ _) <- get currentRasterPosition
			     color $ textTypeToColor textType
			     currentRasterPosition $= (Vertex4 x y 0 1)
			     renderString font str
			     currentRasterPosition $= (Vertex4 x (y + fromIntegral font_height_pixels) 0 1)

restrictLines :: Int -> Int -> [(TextType,String)] -> [(TextType,String)]
restrictLines height width text_lines = reverse $ take height $ reverse $ concatMap splitLongLines text_lines
    where splitLongLines (_,[]) = []
	  splitLongLines (textType,str) = (textType,take width str):(splitLongLines (textType,drop width str))

textTypeToColor :: TextType -> Color3 GLfloat
textTypeToColor UnexpectedEvent = Color3 1.0 0.5 0.0
textTypeToColor Event = Color3 0.5 0.75 1.0
textTypeToColor Input = Color3 0.5 1.0 0.5
textTypeToColor Query = Color3 1.0 1.0 1.0
\end{code}