module Snakey.TwoSnakes where
import Graphics.Gloss.Interface.Pure.Game
import Scratchy.Syntax

-- Helper functions
moveSnake :: SpritePtr -> [SpritePtr] -> Dir -> SProg ()
moveSnake h tailSeg dir =
    OnTargetReached h (\pos ->
        let newPos = nextCell dir pos in
        InspectCell newPos
        (\case
            HasBarrier -> SetBackgroundColor red $ Pure ()
            HasSprite  -> SetBackgroundColor black $ Pure ()
            IsFree     ->
                    SetTarget h newPos $
                    moveTail pos tailSeg $
                    SetBackgroundColor white $
                    Pure ()
        )
    ) $ Pure ()

moveTail :: (Int,Int) -> [SpritePtr] -> SProg () -> SProg ()
moveTail _ [] cont = cont
moveTail prevPos (t:ts) cont =
    GetTarget t (\curPos ->
        SetTarget t prevPos $
            moveTail curPos ts cont
   )

-- Green snake
greenSnake :: SProg ()
greenSnake = 
    -- Create head
    NewSprite (5, 5) (Color green $ circleSolid (cellSize * 0.6)) $ \h ->
    -- Create 7 tail segments
    NewSprite (4, 5) (Color green $ rectangleSolid cellSize cellSize) $ \t1 ->
    NewSprite (3, 5) (Color green $ rectangleSolid cellSize cellSize) $ \t2 ->
    NewSprite (2, 5) (Color green $ rectangleSolid cellSize cellSize) $ \t3 ->
    NewSprite (1, 5) (Color green $ rectangleSolid cellSize cellSize) $ \t4 ->
    NewSprite (0, 5) (Color green $ rectangleSolid cellSize cellSize) $ \t5 ->
    NewSprite (0, 4) (Color green $ rectangleSolid cellSize cellSize) $ \t6 ->
    NewSprite (0, 3) (Color green $ rectangleSolid cellSize cellSize) $ \t7 ->
    
    -- Movement
    OnKeyEvent (Char 'w') (moveSnake h [t1,t2,t3,t4,t5,t6,t7] U) $
    OnKeyEvent (Char 's') (moveSnake h [t1,t2,t3,t4,t5,t6,t7] D) $
    OnKeyEvent (Char 'a') (moveSnake h [t1,t2,t3,t4,t5,t6,t7] L) $
    OnKeyEvent (Char 'd') (moveSnake h [t1,t2,t3,t4,t5,t6,t7] R) $

    Pure ()

-- Blue snake
blueSnake :: SProg ()
blueSnake = 
    -- Create head
    NewSprite (15, 15) (Color blue $ circleSolid (cellSize * 0.6)) $ \h ->
    -- Create 7 tail segments
    NewSprite (16, 15) (Color blue $ rectangleSolid cellSize cellSize) $ \t1 ->
    NewSprite (17, 15) (Color blue $ rectangleSolid cellSize cellSize) $ \t2 ->
    NewSprite (18, 15) (Color blue $ rectangleSolid cellSize cellSize) $ \t3 ->
    NewSprite (19, 15) (Color blue $ rectangleSolid cellSize cellSize) $ \t4 ->
    NewSprite (19, 16) (Color blue $ rectangleSolid cellSize cellSize) $ \t5 ->
    NewSprite (19, 17) (Color blue $ rectangleSolid cellSize cellSize) $ \t6 ->
    NewSprite (19, 18) (Color blue $ rectangleSolid cellSize cellSize) $ \t7 ->
    
    -- Movement
    OnKeyEvent (Char 'i') (moveSnake h [t1,t2,t3,t4,t5,t6,t7] U) $
    OnKeyEvent (Char 'k') (moveSnake h [t1,t2,t3,t4,t5,t6,t7] D) $
    OnKeyEvent (Char 'j') (moveSnake h [t1,t2,t3,t4,t5,t6,t7] L) $
    OnKeyEvent (Char 'l') (moveSnake h [t1,t2,t3,t4,t5,t6,t7] R) $

    Pure ()

-- Combine game
twoSnakes :: SProg ()
twoSnakes = combine greenSnake blueSnake