From 7361289f325ffd05db83f4c304b6df17b6e04f3a Mon Sep 17 00:00:00 2001
From: siers <wimuan@gmail.com>
Date: Sat, 16 Sep 2023 01:09:10 +0300
Subject: [PATCH] Add counterclockwise rotation
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The default rotation is now clockwise¹. In the help widget, it now says: RotateR with k/↑, RotateL with g.

1 - both tetris.com and [tetris.fandom.com/wiki/Tetris_Guideline](https://tetris.fandom.com/wiki/Tetris_Guideline) use cw rotation for up
---
 src/Tetris.hs  | 32 ++++++++++++++++++--------------
 src/UI/Game.hs |  8 +++++---
 2 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/src/Tetris.hs b/src/Tetris.hs
index cc04ee9..a513d46 100644
--- a/src/Tetris.hs
+++ b/src/Tetris.hs
@@ -21,6 +21,7 @@ module Tetris
   , Block(..)
   , Coord
   , Direction(..)
+  , RotationalDirection(..)
   , Game(..)
   , Tetrimino(..)
   , Tetris
@@ -65,6 +66,9 @@ makeLenses ''Block
 data Direction = Left | Right | Down
   deriving (Eq, Show)
 
+data RotationalDirection = Clockwise | Counterclockwise
+  deriving (Eq, Show)
+
 -- | Board
 --
 -- If coordinate not present in map, yet in bounds, then it is empty,
@@ -132,19 +136,20 @@ boardHeight = 20
 startOrigin :: Coord
 startOrigin = V2 6 22
 
--- | Rotate block counter clockwise about origin
+-- | Rotate the block clockwise (or counter-) around origin
 -- *Note*: Strict unsafe rotation not respecting boundaries
 -- Safety can only be assured within Game context
-rotateRaw :: Block -> Block
-rotateRaw b@(Block s o@(V2 xo yo) cs)
+rotateRaw :: RotationalDirection -> Block -> Block
+rotateRaw rd b@(Block s o@(V2 xo yo) cs)
   | -- O doesn't need rotation
     s == O                             = b
   | -- I only has two orientations
-    s == I && V2 xo (yo + 1) `elem` cs = rotateWith clockwise
-  | otherwise                          = rotateWith counterclockwise
+    s == I && V2 xo (yo + 1) `elem` cs = rotateWith (direction Counterclockwise)
+  | s == I                             = rotateWith (direction Clockwise)
+  | otherwise                          = rotateWith (direction rd)
  where
-  clockwise        = (+ o) . cwperp . subtract o
-  counterclockwise = (+ o) . LV.perp . subtract o
+  direction Clockwise = (+ o) . cwperp . subtract o
+  direction Counterclockwise = (+ o) . LV.perp . subtract o
   rotateWith dir = b & extra %~ fmap dir
   cwperp (V2 x y) = V2 y (-x)
 
@@ -238,19 +243,18 @@ updateScore = do
     latestOrZero Empty     = 0
     latestOrZero (_ :|> n) = n
 
--- | Handle counterclockwise block rotation (if possible)
--- Allows wallkicks: http://tetris.wikia.com/wiki/TGM_rotation
-rotate :: Tetris ()
-rotate = do
+-- | Allows wallkicks: http://tetris.wikia.com/wiki/TGM_rotation
+rotate :: RotationalDirection -> Tetris ()
+rotate rd = do
   blk <- use block
   brd <- use board
   let mblk = foldr (<|>) Nothing
         $   mfilter (isValidBlockPosition brd)
         .   pure
         .   ($ blk)
-        <$> [ rotateRaw
-            , rotateRaw . translate Left
-            , rotateRaw . translate Right
+        <$> [ rotateRaw rd
+            , rotateRaw rd . translate Left
+            , rotateRaw rd . translate Right
             ]
   forM_ mblk $ assign block
 
diff --git a/src/UI/Game.hs b/src/UI/Game.hs
index c4c5214..c836fe6 100644
--- a/src/UI/Game.hs
+++ b/src/UI/Game.hs
@@ -89,8 +89,9 @@ handleEvent (VtyEvent (V.EvKey V.KDown       [])) = exec (shift Down)
 handleEvent (VtyEvent (V.EvKey (V.KChar 'l') [])) = exec (shift Right)
 handleEvent (VtyEvent (V.EvKey (V.KChar 'h') [])) = exec (shift Left)
 handleEvent (VtyEvent (V.EvKey (V.KChar 'j') [])) = exec (shift Down)
-handleEvent (VtyEvent (V.EvKey V.KUp         [])) = exec rotate
-handleEvent (VtyEvent (V.EvKey (V.KChar 'k') [])) = exec rotate
+handleEvent (VtyEvent (V.EvKey V.KUp         [])) = exec (rotate Clockwise)
+handleEvent (VtyEvent (V.EvKey (V.KChar 'k') [])) = exec (rotate Clockwise)
+handleEvent (VtyEvent (V.EvKey (V.KChar 'g') [])) = exec (rotate Counterclockwise)
 handleEvent (VtyEvent (V.EvKey (V.KChar ' ') [])) =
   guarded
     (not . view paused)
@@ -262,7 +263,8 @@ drawHelp =
       [ ("Left"   , "h, ←")
       , ("Right"  , "l, →")
       , ("Down"   , "j, ↓")
-      , ("Rotate" , "k, ↑")
+      , ("RotateR", "k, ↑")
+      , ("RotateL", "g")
       , ("Drop"   , "space")
       , ("Restart", "r")
       , ("Pause"  , "p")