{-# LANGUAGE ForeignFunctionInterface, TupleSections #-}

-- 
-- Copyright (C) 2004-5 Don Stewart - http://www.cse.unsw.edu.au/~dons
-- Copyright (c) 2019 Galen Huntington
-- 
-- This program is free software; you can redistribute it and/or
-- modify it under the terms of the GNU General Public License as
-- published by the Free Software Foundation; either version 2 of
-- the License, or (at your option) any later version.
-- 
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-- General Public License for more details.
-- 
-- You should have received a copy of the GNU General Public License
-- along with this program; if not, write to the Free Software
-- Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
-- 02111-1307, USA.
-- 
-- Derived from: riot/UI.hs
--      Copyright (c) Tuomo Valkonen 2004.
--
-- Released under the same license.
--

--
-- | This module defines a user interface implemented using ncurses. 
--
--

module UI (
        runDraw,

        -- * Construction, destruction
        start, end, suspend, screenSize, refresh, refreshClock, resetui,

        -- * Input
        getKey

  )   where

import Style
import Utils                    (isLightBg)
import FastIO                   (basenameP)
import Tree                     (File(fdir, fbase), Dir(dname))
import State
import Syntax
import Config
import qualified UI.HSCurses.Curses as Curses
import {-# SOURCE #-} Keymap    (extraTable, keyTable, unkey, charToKey)

import Data.List                (isPrefixOf)
import Data.Array               ((!), bounds, Array, listArray)
import Data.Array.Base          (unsafeAt)
import Control.Monad            (when, void)
import Control.Exception (catch, handle, SomeException)
import System.IO                (stderr, hFlush)
import System.Posix.Signals     (raiseSignal, sigTSTP, installHandler, Handler(..))
import System.Posix.Env         (getEnv, putEnv)
import Text.Printf

import Foreign.C.String
import Foreign.C.Types

import qualified Data.ByteString.Char8 as P
import qualified Data.ByteString as B
import qualified Data.ByteString.UTF8 as UTF8


newtype Draw = Draw (IO ())
instance Semigroup Draw where Draw x <> Draw y = Draw $ x >> y
instance Monoid Draw where mempty = Draw $ pure ()

runDraw :: Draw -> IO ()
runDraw (Draw d) = withDrawLock d

------------------------------------------------------------------------

--
-- | how to initialise the ui
--
start :: IO UIStyle
start = do
    Control.Exception.handle (\ (_ :: SomeException) -> return ()) $ do -- tweak for OpenBSD console
        thisterm <- getEnv "TERM"
        case thisterm of 
            Just "vt220" -> putEnv "TERM=xterm-color"
            Just t | "xterm" `isPrefixOf` t 
                   -> silentlyModifyST $ \st -> st { xterm = True }
            _ -> return ()

    Curses.initCurses
    case Curses.cursesSigWinch of
        Just wch -> void $ installHandler wch (Catch resetui) Nothing
        _        -> return () -- handled elsewhere

    colorify <- Curses.hasColors
    light    <- isLightBg

    let sty | colorify && light = lightBgStyle
            | colorify          = defaultStyle
            | otherwise         = bwStyle 

    initcolours sty
    Curses.keypad Curses.stdScr True    -- grab the keyboard
    runDraw nocursor

    return sty

-- | Reset
resetui :: IO ()
resetui = runDraw (resizeui <> nocursor) >> refresh

-- | And force invisible
nocursor :: Draw
nocursor = Draw $ do
    Control.Exception.catch (void $ Curses.cursSet Curses.CursorInvisible) 
                            (\ (_ :: SomeException) -> return ())

--
-- | Clean up and go home. Refresh is needed on linux. grr.
--
end :: Bool -> IO ()
end isXterm = do when isXterm $ setXtermTitle ["xterm"]
                 Curses.endWin

--
-- | Suspend the program
--
suspend :: IO ()
suspend = raiseSignal sigTSTP

--
-- | Find the current screen height and width.
--
screenSize :: IO (Int, Int)
screenSize = Curses.scrSize

--
-- | Read a key. UIs need to define a method for getting events.
-- We only need to refresh if we don't have no SIGWINCH support.
--
getKey :: IO Char
getKey = do
    k <- Curses.getCh
    if k == Curses.KeyResize 
        then do
              when (Curses.cursesSigWinch == Nothing) $
                  runDraw $ redraw <> resizeui
              getKey
        else return $ unkey k
 
-- | Resize the window
-- From "Writing Programs with NCURSES", by Eric S. Raymond and Zeyd M. Ben-Halim
--
resizeui :: Draw
resizeui = Draw $ void $ do
    Curses.endWin
    Curses.resetParams
    do
        -- not sure I need all these...
        Curses.nl True
        Curses.leaveOk True
        Curses.noDelay Curses.stdScr False
        Curses.cBreak True
        -- Curses.meta stdScr True -- not in module
        -- not sure about intrFlush, raw - set in hscurses
    Curses.refresh
    Curses.scrSize

refresh :: IO ()
refresh = runDraw $ redraw <> Draw Curses.refresh

refreshClock :: IO ()
refreshClock = runDraw $ redrawJustClock <> Draw Curses.refresh

------------------------------------------------------------------------

type Pos    = (Int{-H-}, Int{-W-})
type Size   = (Int{-H-}, Int{-W-})

--
-- | A class for renderable objects, given the application state, and
-- for printing the object as a list of strings
--
class Element a where
    draw  :: Size -> Pos -> HState -> Maybe Frame -> a

--
-- | The elements of the play mode widget
--
data PlayScreen = PlayScreen !PPlaying !ProgressBar !PTimes 

-- | How does this all work? Firstly, we mostly want to draw fast strings
-- directly to the screen. To break the drawing problem down, you need
-- to write an instance of Element for each element in the ui. Larger
-- and larger elements then combine these items together. 
--
-- Obviously to write the element instance, you need a new type for each
-- element, to disinguish them. As follows:

newtype PlayList = PlayList [StringA]

newtype PPlaying    = PPlaying    StringA
newtype PVersion    = PVersion    P.ByteString
newtype PMode       = PMode       P.ByteString
newtype PMode2      = PMode2      P.ByteString
newtype ProgressBar = ProgressBar StringA
newtype PTimes      = PTimes      StringA

newtype PInfo       = PInfo       P.ByteString
newtype PId3        = PId3        P.ByteString
newtype PTime       = PTime       P.ByteString

newtype PlayTitle = PlayTitle StringA
newtype PlayInfo  = PlayInfo  P.ByteString
newtype PlayModes = PlayModes P.ByteString
newtype HelpScreen = HelpScreen [StringA]

------------------------------------------------------------------------

instance Element PlayScreen where
    draw w x y z = PlayScreen a b c
        where
            a = draw w x y z :: PPlaying
            b = draw w x y z :: ProgressBar
            c = draw w x y z :: PTimes

-- | Decode the play screen
printPlayScreen :: PlayScreen -> [StringA]
printPlayScreen (PlayScreen (PPlaying a) 
                            (ProgressBar b) 
                            (PTimes c)) = [a , b , c]

------------------------------------------------------------------------

instance (Element a, Element b) => Element (a,b) where
    draw a b c d = (draw a b c d, draw a b c d)

------------------------------------------------------------------------

-- Info about the current track
instance Element PPlaying where
    draw w@(_,x') x st z = PPlaying . FancyS $ 
            map (, defaultSty) $ spc2 : alignLR (x'-4) (UTF8.toString a) b
        where
            PId3 a  = draw w x st z
            PInfo b = draw w x st z

-- | Id3 Info
instance Element PId3 where
    draw _ _ st _ = case id3 st of
        Just i  -> PId3 $ id3str i
        Nothing -> PId3 $ case size st of
                                0 -> emptyVal
                                _ -> fbase $ (music st) ! (current st)

-- | mp3 information
instance Element PInfo where
    draw _ _ st _ = PInfo $ case info st of
        Nothing  -> emptyVal
        Just i   -> userinfo i

emptyVal :: P.ByteString
emptyVal = "(empty)"

spc2 :: AmbiString
spc2 = B $ spaces 2

------------------------------------------------------------------------

instance Element HelpScreen where
    draw (_,w) _ st _ = HelpScreen $ 
        [ Fast (f cs h) sty | (h,cs,_) <- keyTable ] ++
        [ Fast (f cs h) sty | (h,cs) <- extraTable ]
        where
            sty  = helpscreen . config $ st

            f :: [Char] -> P.ByteString -> P.ByteString
            f cs ps = 
                let p = str `P.append` ps
                    s = P.pack (take (tot - P.length p) (repeat ' '))
                in p `P.append` s
                where
                    tot = round $! fromIntegral w *   (0.8::Float)
                    len = round $! fromIntegral tot * (0.2::Float)

                    str = P.take len $ P.intercalate " "
                        ([""] ++ map pprIt cs ++ [P.replicate len ' '])

                    pprIt c = case c of
                          '\n'            -> "Enter"
                          '\f'            -> "^L"
                          '\\'            -> "'\\'"
                          _ -> case charToKey c of
                            Curses.KeyUp    -> "Up"
                            Curses.KeyDown  -> "Down"
                            Curses.KeyPPage -> "PgUp"
                            Curses.KeyNPage -> "PgDn"
                            Curses.KeyLeft  -> "Left"
                            Curses.KeyRight -> "Right"
                            Curses.KeyEnd   -> "End"
                            Curses.KeyHome  -> "Home"
                            Curses.KeyBackspace -> "Backspace"
                            _ -> P.pack $ show c

------------------------------------------------------------------------

-- | The time used and time left
instance Element PTimes where
    draw _ _ _ Nothing       = PTimes $ Fast (spaces 5) defaultSty
    draw (_,x) _ _ (Just fr) = PTimes $ FancyS $
                                [(spc2,     defaultSty)
                                ,(B elapsed,  defaultSty)
                                ,(B gap,      defaultSty)
                                ,(B remaining,defaultSty)]
      where
        elapsed   = P.pack $ printf "%d:%02d" lm lm'
        remaining = P.pack $ printf "-%d:%02d" rm rm'
        (lm,lm')  = quotRem (fst . currentTime $ fr) 60
        (rm,rm')  = quotRem (fst . timeLeft    $ fr) 60
        gap       = spaces distance
        distance  = x - 4 - P.length elapsed - P.length remaining

------------------------------------------------------------------------

-- | A progress bar
instance Element ProgressBar where
    draw (_,w) _ st Nothing = ProgressBar . FancyS $
          [(spc2,defaultSty) ,(B $ spaces (w-4), bgs)]
        where 
          (Style _ bg) = progress (config st)
          bgs          = Style bg bg

    draw (_,w) _ st (Just fr) = ProgressBar . FancyS $
          [(spc2,defaultSty)
          ,((B $ spaces distance),fgs)
          ,((B $ spaces (width - distance)),bgs)]
        where 
          width    = w - 4
          total    = curr + left
          distance = round ((curr / total) * fromIntegral width)
          curr     = toFloat (currentTime fr)
          left     = toFloat (timeLeft fr)
          (Style fg bg) = progress (config st)
          bgs           = Style bg bg
          fgs           = Style fg fg

          toFloat (x,y) | x `seq` y `seq` False = undefined
          toFloat (x,y) = (fromIntegral x :: Float) + (fromIntegral y / 100)

------------------------------------------------------------------------

-- | Version info
instance Element PVersion where
    draw _ _ _ _ = PVersion $ P.pack versinfo

-- | Uptime
instance Element PTime where
    draw _ _ st _ = PTime . uptime $ st

-- | Play mode
instance Element PMode where
    draw _ _ st _ = PMode $! case status st of 
                        Stopped -> a
                        Paused  -> b
                        Playing -> c

        where a = "stop"
              b = "pause"
              c = "play"

-- | Loop, normal or random
instance Element PMode2 where
    draw _ _ st _ = PMode2 $ case mode st of 
                        Random  -> a
                        Loop    -> b
                        Normal  -> c

        where a = "random"
              b = "loop"
              c = ""

------------------------------------------------------------------------

instance Element PlayModes where
    draw a b c d = PlayModes $  
        m `P.append` if m' == P.empty then P.empty else ' ' `P.cons` m'
        where
            (PMode  m ) = draw a b c d :: PMode
            (PMode2 m') = draw a b c d :: PMode2

instance Element PlayInfo where
    draw _ _ st _ = PlayInfo $ P.concat
         [percent
         , " ("
         ,P.pack (show (1 + ( snd . bounds . folders $ st)))
         , " dir"
         ,if (snd . bounds $ folders st) == 1 then P.empty else plural
         , ", "
         ,P.pack (show . size $ st)
         , " file"
         ,if size st == 1 then P.empty else plural
         , ")"]
      where
        plural = "s"   -- expose to inlining
        pct    = "%"
        curr   = cursor  st

        percent | percent' == 0  && curr == 0 = "top"
                | percent' == 100             = "all"
                | otherwise = if P.length s == 2 then ' ' `P.cons` s else s
            where 
                s = P.pack (show percent') `P.append` pct

                percent' :: Int 
                percent' = round $ ((fromIntegral curr) / 
                                   ((fromIntegral . size $ st) - 1) * 100.0 :: Float)

instance Element PlayTitle where
    draw a@(_,x) b c d =
        PlayTitle $ flip Fast hl $ P.concat 
              [space
              ,inf
              ,spaces gapl
              ,modes
              ,spaces gapr
              ,time
              ,space
              ,ver
              ,space]
      where
        (PlayInfo inf)    = draw a b c d :: PlayInfo
        (PTime time)      = draw a b c d :: PTime
        (PlayModes modes) = draw a b c d :: PlayModes
        (PVersion ver)    = draw a b c d :: PVersion

        gap     = x - padding - P.length inf - modlen - P.length time - P.length ver
        gapl    = gap `div` 2
        gapr    = gap - gapl
        padding = 3
        modlen  = P.length modes
        space   = spaces 1
        hl      = titlebar . config $ c

-- | Playlist
instance Element PlayList where
    draw p@(y,x) q@(o,_) st z =
        PlayList $! title 
                 : list 
                 ++ (replicate (height - length list - 2) (Fast P.empty defaultSty))
                 ++ [minibuffer st]
        where
            (PlayTitle title)       = draw p q st z :: PlayTitle

            songs  = music st
            this   = current st
            curr   = cursor  st
            height = y - o

            -- number of screens down, and then offset
            buflen    = height - 2
            (screens,select) = quotRem curr buflen -- keep cursor in screen

            playing  = let top = screens * buflen
                           bot = (screens + 1) * buflen
                       in if this >= top && this < bot
                            then this - top -- playing song is visible
                            else (-1)

            -- visible slice of the playlist
            visible = slice off (off + buflen) songs
                where off = screens * buflen

            -- TODO rewrite as fold
            visible' :: [(Maybe Int, String)]
            visible' = loop (-1) visible where
                loop _ []     = []
                loop n (v:vs) =
                    let r = if fdir v > n then Just (fdir v) else Nothing
                    in (r, ellipsize (x - indent - 1) $ UTF8.toString $ fbase v)
                            : loop (fdir v) vs

            list   = [ drawIt . color $ n | n <- zip visible' [0..] ]

            indent = (round $ (0.334 :: Float) * fromIntegral x) :: Int
                
            color :: ((Maybe Int, String), Int)
                        -> (Maybe Int, Style, [AmbiString])
            color ((m,s),i) 
                | i == select && i == playing = f sty3
                | i == select                 = f sty2
                | i == playing                = f sty1
                | otherwise                   = (m, defaultSty, [U s])
                where
                    f sty = (m, sty, [
                        U s,
                        B $ spaces (x - indent - 1 - displayWidth s)])
            
            sty1 = selected . config $ st
            sty2 = cursors  . config $ st
            sty3 = combined . config $ st

            drawIt :: (Maybe Int, Style, [AmbiString]) -> StringA
            drawIt (Nothing, sty, v) =
                FancyS $ map (, sty) $ (B $ spaces (1 + indent)) : v

            drawIt (Just i, sty, v) = FancyS
                $ (U d, sty')
                : (B $ spaces (indent + 1 - displayWidth d), sty')
                : map (, sty) v
              where
                sty' = if sty == sty2 || sty == sty3 then sty2 else sty1
                d = ellipsize (indent - 1) $ UTF8.toString $ basenameP
                        $ case size st of
                            0 -> "(empty)"
                            _ -> dname $ folders st ! i

--
-- | Decode the list of current tracks
--
printPlayList :: PlayList -> [StringA]
printPlayList (PlayList s) = s
{-# INLINE printPlayList #-}
                
------------------------------------------------------------------------

-- | Take two strings, and pad them in the middle
alignLR :: Int -> String -> P.ByteString -> [AmbiString]
alignLR w l r 
    | padding >  0 = [U l, B gap, B r]
    -- | otherwise    = [U P.take (w - P.length r - 4 - 1) l, ellipsis, spaces 1, r]
    | otherwise    = [U $ ellipsize (w - P.length r - 1) l, B " ", B r]

    where padding = w - displayWidth l - P.length r
          gap     = spaces padding

-- | Calculate whitespaces, very common, so precompute likely values
spaces :: Int -> P.ByteString
spaces n
    | n <= 0    = ""
    | n > 100   = P.replicate n ' ' -- unlikely
    | otherwise = arr ! n
  where
    arr :: Array Int P.ByteString   -- precompute some whitespace strs
    arr = listArray (0,100) [ P.take i s100 | i <- [0..100] ]

    s100 :: P.ByteString
    s100 = P.replicate 100 ' '  -- seems reasonable

------------------------------------------------------------------------
--
-- | Now write out just the clock line
-- Speed things up a bit, just use read State.
--
redrawJustClock :: Draw
redrawJustClock = Draw $ do
   Control.Exception.handle (\ (_ :: SomeException) -> return ()) $ do

   st      <- getsST id
   let fr = clock st
   s@(_,w) <- screenSize
   let (ProgressBar bar) = draw s undefined st fr :: ProgressBar
       (PTimes times)    = {-# SCC "redrawJustClock.times" #-} draw s undefined st fr :: PTimes
   Curses.wMove Curses.stdScr 1 0   -- hardcoded!
   drawLine w bar
   Curses.wMove Curses.stdScr 2 0   -- hardcoded!
   drawLine w times
   drawHelp st fr s

------------------------------------------------------------------------
--
-- work for drawing help. draw the help screen if it is up
--
drawHelp :: HState -> Maybe Frame -> (Int,Int) -> IO ()
drawHelp st fr s@(h,w) =
   when (helpVisible st) $ do
       let (HelpScreen help') = draw s (0,0) st fr :: HelpScreen
           (Fast fps _)      = head help'
           offset            = (w - (P.length fps)) `div` 2
           height            = (h - length help') `div` 2
       when (height > 0) $ do
            Curses.wMove Curses.stdScr ((h - length help') `div` 2) offset
            mapM_ (\t -> do drawLine w t
                            (y',_) <- Curses.getYX Curses.stdScr
                            Curses.wMove Curses.stdScr (y'+1) offset) help'

------------------------------------------------------------------------
--
-- | Draw the screen
--
redraw :: Draw
redraw = Draw $
   -- linux ncurses, in particular, seems to complain a lot. this is an easy solution
   Control.Exception.handle (\ (_ :: SomeException) -> return ()) $ do

   s <- getsST id    -- another refresh could be triggered?
   let f = clock s
   sz@(h,w) <- screenSize

   let x = printPlayScreen (draw sz (0,0) s f :: PlayScreen)
       y = printPlayList   (draw sz (length x,0) s f :: PlayList)
       a = x ++ y

   when (xterm s) $ setXterm s sz f
   
   gotoTop
   mapM_ (\t -> do drawLine w t
                   (y',x') <- Curses.getYX Curses.stdScr
                   fillLine
                   maybeLineDown t h y' x' )
         (take (h-1) (init a))
   drawHelp s f sz

   -- minibuffer
   Curses.wMove Curses.stdScr (h-1) 0
   fillLine 
   Curses.wMove Curses.stdScr (h-1) 0
   drawLine (w-1) (last a)
   when (miniFocused s) $ do -- a fake cursor
        drawLine 1 (Fast (spaces 1) (blockcursor . config $ s ))
        -- todo rendering bug here when deleting backwards in minibuffer

------------------------------------------------------------------------
--
-- | Draw a coloured (or not) string to the screen
--
drawLine :: Int -> StringA -> IO ()
drawLine _ (Fast ps sty) = drawAmbiString (B ps) sty
drawLine _ (FancyS ls) = sequence_ $ map (uncurry drawAmbiString) ls

drawAmbiString :: AmbiString -> Style -> IO ()
drawAmbiString as sty = withStyle sty $ case as of
    B ps -> void $ B.useAsCString ps \cstr ->
                waddnstr Curses.stdScr cstr (fromIntegral $ P.length ps)
    U s  -> Curses.wAddStr Curses.stdScr s
{-# INLINE drawAmbiString #-}


------------------------------------------------------------------------

maybeLineDown :: StringA -> Int -> Int -> Int -> IO ()
maybeLineDown (Fast s _) h y _ | s == P.empty = lineDown h y
maybeLineDown _ h y x
    | x == 0    = return ()     -- already moved down
    | otherwise = lineDown h y

------------------------------------------------------------------------

lineDown :: Int -> Int -> IO ()
lineDown h y = Curses.wMove Curses.stdScr (min h (y+1)) 0

--
-- | Fill to end of line spaces
--
fillLine :: IO ()
fillLine = Control.Exception.catch (Curses.clrToEol) (\ (_ :: SomeException) -> return ()) -- harmless?

--
-- | move cursor to origin of stdScr.
--
gotoTop :: IO ()
gotoTop = Curses.wMove Curses.stdScr 0 0
{-# INLINE gotoTop #-}

-- | Take a slice of an array efficiently
slice :: Int -> Int -> Array Int e -> [e]
slice i j arr = 
    let (a,b) = bounds arr
    in [unsafeAt arr n | n <- [max a i .. min b j] ]
{-# INLINE slice #-}

-- isAscii :: P.ByteString -> Bool
-- isAscii = P.all (<'\128')

------------------------------------------------------------------------

--
-- | magics for setting xterm titles using ansi escape sequences
--
setXtermTitle :: [P.ByteString] -> IO ()
setXtermTitle strs = do
    mapM_ (P.hPut stderr) (before : strs ++ [after])
    hFlush stderr 
  where
    before = "\ESC]0;"
    after  = "\007"

------------------------------------------------------------------------

-- set xterm title (should have an instance Element)
-- Don't need to do this on each refresh...
setXterm :: HState -> (Int,Int) -> Maybe Frame -> IO ()
setXterm s sz f = setXtermTitle $ 
    if status s == Playing
      then case id3 s of
            Nothing -> case size s of
                            0 -> ["hmp3"]
                            _ -> [(fbase $ music s ! current s)]
            Just ti -> id3artist ti :
                       if P.null (id3title ti) 
                            then [] 
                            else [": ", id3title ti]
      else let (PMode pm) = draw sz (0,0) s f :: PMode in [pm]

displayWidth :: String -> Int
displayWidth = sum . map charWidth

ellipsize :: Int -> String -> String
ellipsize w s
  | displayWidth s <= w = s
  | w <= 3 = replicate w '.'
  | True = go 0 0 s where
    go !i !l (c:s') =
        if l' > w-3
            then take i s ++ replicate (w-3-l) ' ' ++ "..."
            else go (i+1) l' s'
      where l' = l + charWidth c
    go _  _ _ = error "Should've been in first case!"

charWidth :: Char -> Int
charWidth = fromIntegral . wcwidth . toEnum . fromEnum

foreign import ccall safe
    wcwidth :: CWchar -> CInt

--  Not exported by hscurses.
foreign import ccall safe
    waddnstr :: Curses.Window -> CString -> CInt -> IO CInt