module Animate.Preview.Scene where

import qualified Animate
import qualified Data.Vector as V
import Control.Concurrent (readMVar, modifyMVar_)
import Control.Monad (when)
import Control.Monad.IO.Class (MonadIO(liftIO))
import Control.Monad.Reader (asks)
import Control.Monad.State (modify, gets)
import Data.Text.Conversions (toText, fromText)
import KeyState
import Linear

import Animate.Preview.Animation
import Animate.Preview.Config
import Animate.Preview.Renderer
import Animate.Preview.Input
import Animate.Preview.State
import Animate.Preview.ManagerInput
import Animate.Preview.Color
import Animate.Preview.Logger
import Animate.Preview.Scalar
import Animate.Preview.Mode
import Animate.Preview.Loader

class Monad m => Scene m where
  sceneStep :: m ()
  default sceneStep :: (R m, S m, Renderer m, HasInput m, Logger m, Loader m, MonadIO m) => m ()
  sceneStep = do
    updateMode
    updateReload
    toggleVisuals
    updateOrigin
    updateKeyFrame
    updateSpeed
    updateScale
    updateInfo
    updateAnimation
    drawScene

updateKeyFrame :: (R m, HasInput m, MonadIO m) => m ()
updateKeyFrame = do
  input <- getInput
  loaded' <- getLoaded 
  case loaded' of
    Nothing -> return ()
    Just loaded -> do
      let animations = (Animate.ssAnimations . lSpriteSheet) loaded
      when (isPressed $ iNextKeyFrame input) $ modifyCurrent' $ \c -> let
        key = unsafeNextKey (Animate.pKey $ cPos c) animations
        keyName = lIntToText loaded key
        in Current (Animate.initPosition key) keyName
      when (isPressed $ iPrevKeyFrame input) $ modifyCurrent' $ \c -> let
        key = unsafePrevKey (Animate.pKey $ cPos c) animations
        keyName = lIntToText loaded key
        in Current (Animate.initPosition key) keyName

unsafeNextKey :: Int -> Animate.Animations a b c -> Int
unsafeNextKey n (Animate.Animations a) = (1 + n) `mod` (V.length a)

unsafePrevKey :: Int -> Animate.Animations a b c -> Int
unsafePrevKey n (Animate.Animations a) = (n - 1) `mod` (V.length a)

updateMode :: (S m, HasInput m) => m ()
updateMode = do
  input <- getInput
  when (onceThenFire $ iMode input) $ modify $ \v -> v { vMode = if vMode v == Mode'Playback then Mode'Stepper else Mode'Playback }

updateReload :: (S m, R m, HasInput m, Loader m, MonadIO m) => m ()
updateReload = do
  input <- getInput
  mreload <- asks cReload
  watchReload <- liftIO $ readMVar mreload
  when watchReload $ do
    reload
    liftIO $ modifyMVar_ mreload $ \_ -> return False
  when (isPressed $ iReload input) reload

reload :: (R m, Loader m, MonadIO m) => m ()
reload = do
  _ <- load
  loaded' <- getLoaded
  case loaded' of
    Nothing -> return ()
    Just loaded -> do
      modifyCurrent $ \current ->
        case current of
          Nothing -> Just $ Current (Animate.initPosition 0) (lIntToText loaded 0)
          Just c -> Just $ reloadCurrent loaded c

reloadCurrent :: Loaded -> Current -> Current
reloadCurrent l c
  | lIntToText l (Animate.pKey . cPos $ c) == cKeyName c = case lTextToInt l (cKeyName c) of
      Nothing -> reset
      Just k -> c
        { cPos = (cPos c)
            { Animate.pKey = k
            , Animate.pFrameIndex = mod
                (Animate.pFrameIndex (cPos c))
                (V.length $ Animate.framesByAnimation (Animate.ssAnimations $ lSpriteSheet l) k)
            , Animate.pCounter = 0
            }
        }
  | otherwise = reset
  where
    reset = Current (Animate.initPosition 0) (lIntToText l 0)

updateAnimation :: (R m, S m, Renderer m, HasInput m, MonadIO m) => m ()
updateAnimation = do
  mode <- gets vMode
  loaded' <- getLoaded 
  frameDeltaSeconds <- asks cFrameDeltaSeconds
  case loaded' of
    Nothing -> return ()
    Just loaded -> do
      let animations = (Animate.ssAnimations . lSpriteSheet) loaded
      current' <- getCurrent
      case current' of
        Nothing -> return ()
        Just Current{cPos=pos} -> case mode of
          Mode'Stepper -> do
            input <- getInput
            when (onceThenFire $ iFaster input) $ modifyCurrent' $ \c -> c { cPos = forceNextFrameIndex animations pos }
            when (onceThenFire $ iSlower input) $ modifyCurrent' $ \c -> c { cPos = forcePrevFrameIndex animations pos }
          Mode'Playback -> do
            accel <- gets vAccel
            let accelScalar = scalarToSeconds accel
            let pos' = Animate.stepPosition animations pos (frameDeltaSeconds * (Seconds accelScalar))
            modifyCurrent' $ \c -> c { cPos = pos' }

unsafeForceNextFrameIndex :: V.Vector (Animate.Frame loc delay) -> Animate.FrameIndex -> Animate.FrameIndex
unsafeForceNextFrameIndex frames idx = if idx + 1 >= len then 0 else idx + 1
  where len = V.length frames

unsafeForcePrevFrameIndex :: V.Vector (Animate.Frame loc delay) -> Animate.FrameIndex -> Animate.FrameIndex
unsafeForcePrevFrameIndex frames idx = if idx <= 0 then len - 1 else idx - 1
  where len = V.length frames

forceNextFrameIndex :: Enum key => Animate.Animations key loc delay -> Animate.Position key delay -> Animate.Position key delay
forceNextFrameIndex a p = p { Animate.pFrameIndex = unsafeForceNextFrameIndex frames (Animate.pFrameIndex p) }
  where
    frames = Animate.framesByAnimation a (Animate.pKey p)

forcePrevFrameIndex :: Enum key => Animate.Animations key loc delay -> Animate.Position key delay -> Animate.Position key delay
forcePrevFrameIndex a p = p { Animate.pFrameIndex = unsafeForcePrevFrameIndex frames (Animate.pFrameIndex p) }
  where
    frames = Animate.framesByAnimation a (Animate.pKey p)

updateSpeed :: (S m, HasInput m) => m ()
updateSpeed = do
  input <- getInput
  mode <- gets vMode
  case mode of
    Mode'Stepper -> return ()
    Mode'Playback ->  do
      let up = onceThenFire (iFaster input) 
      let down = onceThenFire (iSlower input)
      let reset = isPressed (iAccelReset input)
      let change s
            | reset = Scalar'None
            | up && not down = incrementScalar 18 s
            | down && not up = decrementScalar 9 s
            | otherwise = s
      modify $ \v -> v { vAccel = change (vAccel v) }

onceThenFire :: KeyState Int -> Bool
onceThenFire ks = isPressed ks || (isHeld ks && counterGreater 20 ks)

counterGreater :: Int -> KeyState Int -> Bool  
counterGreater n ks = case ksCounter ks of
  Nothing -> False
  Just counter -> counter > n

updateInfo :: (S m, HasInput m) => m ()
updateInfo = do
  input <- getInput
  when (onceThenFire $ iInfo input) $ modify $ \v -> v { vInfoShown = not (vInfoShown v) }

updateScale :: (S m, HasInput m) => m ()
updateScale = do
  input <- getInput
  let up = onceThenFire (iScaleUp input) || iScaleMouseUp input > 0
  let down = onceThenFire (iScaleDown input) || iScaleMouseDown input > 0
  let reset = isPressed (iScaleReset input) || isPressed (iMouseMiddleClick input)
  let increment = replicate (max 1 (iScaleMouseUp input)) (incrementScalar 90)
  let decrement = replicate (max 1 (iScaleMouseDown input)) (decrementScalar 19)
  let change s
        | reset = Scalar'None
        | up && not down = fapply increment s
        | down && not up = fapply decrement s
        | otherwise = s
  modify $ \v -> v { vScale = change (vScale v) }

modifyCurrent' :: (R m, MonadIO m) => (Current -> Current) -> m ()
modifyCurrent' f = do
  m <- asks cCurrent
  liftIO $ modifyMVar_ m (\c -> return $ fmap f c)

modifyCurrent :: (R m, MonadIO m) => (Maybe Current -> Maybe Current) -> m ()
modifyCurrent f = do
  m <- asks cCurrent
  liftIO $ modifyMVar_ m (\c -> return $ f c)

setCurrent :: (R m, MonadIO m) => Maybe Current -> m ()
setCurrent c = do
  m <- asks cCurrent
  liftIO $ modifyMVar_ m (\_ -> return c)

getCurrent :: (R m, MonadIO m) => m (Maybe Current)
getCurrent = do
  m <- asks cCurrent
  liftIO $ readMVar m

fapply :: [a -> a] -> a -> a
fapply xs a = case xs of [] -> a; (y:ys) -> fapply ys (y a)

updateOrigin :: (R m, S m, HasInput m) => m ()
updateOrigin = do
  input <- getInput
  -- Move with keys
  let d = 5
  when (onceThenFire $ iUp input) $ modify $ \v -> v { vOrigin = vOrigin v + V2 0 (-d) }
  when (onceThenFire $ iDown input) $ modify $ \v -> v { vOrigin = vOrigin v + V2 0 d }
  when (onceThenFire $ iLeft input) $ modify $ \v -> v { vOrigin = vOrigin v + V2 (-d) 0 }
  when (onceThenFire $ iRight input) $ modify $ \v -> v { vOrigin = vOrigin v + V2 d 0 }
  -- Recenter origin
  when (isPressed $ iCenterOrigin input) $ do
    drawSize <- gets vDrawSize
    modify $ \v -> v { vOrigin = div <$> drawSize <*> 2 }
  -- Origin by mouse click
  when (isTouched $ iMouseClick input) $ modify $ \v -> v
   { vOrigin = iMousePos input }

toggleVisuals :: (S m, HasInput m) => m ()
toggleVisuals = do
  input <- getInput
  let toggleBackground = isPressed (iBackground input)
  let toggleOrigin = isPressed (iOrigin input)
  let toggleOutline = isPressed (iOutline input)
  modify $ (\v -> v
    { vBackground = (if toggleBackground then toggleMono else id) (vBackground v)
    , vOriginColor = (if toggleOrigin then toggleColors else id) (vOriginColor v)
    , vOutlineColor = (if toggleOutline then toggleColors else id) (vOutlineColor v)
    })

drawScene :: (R m, S m, Renderer m, HasInput m, MonadIO m) => m ()
drawScene = do
  V2 x y <- gets vOrigin
  current <- getCurrent
  originColor <- gets vOriginColor
  outlineColor <- gets vOutlineColor
  fps <- asks cFps
  accel <- gets vAccel
  mode <- gets vMode
  infoShown <- gets vInfoShown
  scale <- gets vScale
  let scalar = scalarToSpriteScale scale
  loaded' <- getLoaded 
  highDpi <- asks cHighDpi
  let lineSpacing = lineSpacing' highDpi
  case loaded' of
    Nothing -> when infoShown $ do
      drawText (ofsX, ofsY + lineSpacing * 5)  $ toText $ concat ["Anim:"]
      drawText (ofsX, ofsY + lineSpacing * 6)  $ toText $ concat ["  Key:"]
      drawText (ofsX, ofsY + lineSpacing * 7)  $ toText $ concat ["  Time:"]
      drawText (ofsX, ofsY + lineSpacing * 8)  $ toText $ concat ["Pos:"]
      drawText (ofsX, ofsY + lineSpacing * 9)  $ toText $ concat ["  Frame:"]
      drawText (ofsX, ofsY + lineSpacing * 10)  $ toText $ concat ["  Time:"]
      drawText (ofsX, ofsY + lineSpacing * 11) $ toText $ concat ["  Points:"]
      drawText (ofsX, ofsY + lineSpacing * 12) $ toText $ concat ["  Size:"]
      drawText (ofsX, ofsY + lineSpacing * 13) $ toText $ concat ["  Offset: "]
    Just loaded -> do
      case current of
        Nothing -> return ()
        Just c -> do
          let pos = cPos c
          let animations = (Animate.ssAnimations . lSpriteSheet) loaded
          let frames = Animate.framesByAnimation animations (Animate.pKey pos)
          let frame = frames V.! Animate.pFrameIndex pos
          let frameDelay = Animate.fDelay frame
          let frameClip = Animate.fLocation frame
          let (x0,y0) = (Animate.scX frameClip, Animate.scY frameClip)
          let (w,h) = (Animate.scW frameClip, Animate.scH frameClip)
          let (x1,y1) = (x0 + w, y0 + h)
          let framesLen = V.length frames
          let totalSeconds = sum $ map Animate.fDelay (V.toList frames)
          let loc = Animate.currentLocation animations pos
          drawAniSprite (lSpriteSheet loaded) outlineColor scalar loc (x, y)
          when infoShown $ do
            let keyName = cKeyName c
            drawText (ofsX, ofsY + lineSpacing * 5)  $ toText $ concat ["Anim:"]
            drawText (ofsX, ofsY + lineSpacing * 6)  $ toText $ concat ["  Key: \"", fromText keyName, "\" ", show $ Animate.pKey pos, " [", show $ lTotalKeys loaded - 1, "]"]
            drawText (ofsX, ofsY + lineSpacing * 7)  $ toText $ concat ["  Time: ", show totalSeconds]
            drawText (ofsX, ofsY + lineSpacing * 8)  $ toText $ concat ["Pos:"]
            drawText (ofsX, ofsY + lineSpacing * 9)  $ toText $ concat ["  Frame: ", show $ Animate.pFrameIndex pos,  " [", show $ framesLen - 1, "]"]
            drawText (ofsX, ofsY + lineSpacing * 10)  $ toText $ concat ["  Time: ", show $ Animate.pCounter pos, " [", show $ frameDelay, "]"]
            drawText (ofsX, ofsY + lineSpacing * 11) $ toText $ concat ["  Points: (", show x0, ",", show y0, ") (", show x1, ",", show y1, ")"]
            drawText (ofsX, ofsY + lineSpacing * 12) $ toText $ concat ["  Size: (", show w, ",", show h, ")"]
            drawText (ofsX, ofsY + lineSpacing * 13) $ toText $ concat $ ["  Offset: "] ++ case Animate.scOffset frameClip of
              Nothing -> []
              Just (ox,oy) -> ["(", show ox, ",", show oy, ")"]
  case originColor of
    Nothing -> return ()
    Just originColor' -> drawCrosshair (x,y) originColor'
  -- HUD
  when infoShown $ do
    settings <- asks cSettings
    drawText (ofsX, ofsY + lineSpacing * 0) ("Mode: " `mappend` if mode == Mode'Playback then "Playback" else "Stepper")
    drawText (ofsX, ofsY + lineSpacing * 1) ("File: " `mappend` toText (sTarget settings))
    drawText (ofsX, ofsY + lineSpacing * 2) ("FPS: " `mappend` toText (show fps))
    drawText (ofsX, ofsY + lineSpacing * 3) ("Scale: " `mappend` toText (asScaleString scale))
    drawText (ofsX, ofsY + lineSpacing * 4) ("Accel: " `mappend` toText (asSpeedString accel))
  where
    lineSpacing' x = if x then 26 else 13
    ofsX = 6
    ofsY = 6