From cdd0c3989cb1c6475b075c75ee17f1fbb9e43d4c Mon Sep 17 00:00:00 2001
From: Tibo De Peuter <tibo.depeuter@ugent.be>
Date: Wed, 14 Dec 2022 22:20:44 +0100
Subject: [PATCH] #15 Basic input handling

---
 lib/RPGEngine.hs             | 12 +++++------
 lib/control/Input.hs         | 23 ++++++++++++++++++++
 lib/control/InputHandling.hs | 41 ++++++++++++++++++++++++++++++++++++
 rpg-engine.cabal             |  1 +
 4 files changed, 70 insertions(+), 7 deletions(-)
 create mode 100644 lib/control/Input.hs
 create mode 100644 lib/control/InputHandling.hs

diff --git a/lib/RPGEngine.hs b/lib/RPGEngine.hs
index 44047fb..d5ea2e7 100644
--- a/lib/RPGEngine.hs
+++ b/lib/RPGEngine.hs
@@ -7,6 +7,8 @@ module RPGEngine
 
 import Game
 import Render
+import Input
+
 import Graphics.Gloss (
     Color(..)
     , white
@@ -23,10 +25,6 @@ winDimensions = (1280, 720)
 winOffsets :: (Int, Int)
 winOffsets = (0, 0)
 
--- Game background color
-bgColor :: Color
-bgColor = white
-
 ----------------------------------------------------------------------
 
 -- This is the gameloop.
@@ -34,6 +32,6 @@ bgColor = white
 playRPGEngine :: String -> Int -> IO()
 playRPGEngine title fps = do 
     play window bgColor fps initGame render handleInputs step
-    where window           = initWindow title winDimensions winOffsets
-          step         _ g = g -- TODO Do something with step?
-          handleInputs _ g = g -- TODO Implement inputHanlders
+    where window       = initWindow title winDimensions winOffsets
+          step _ g     = g -- TODO Do something with step?
+          handleInputs = handleAllInput
diff --git a/lib/control/Input.hs b/lib/control/Input.hs
new file mode 100644
index 0000000..e13b523
--- /dev/null
+++ b/lib/control/Input.hs
@@ -0,0 +1,23 @@
+module Input
+(
+-- Handle all input for RPG-Engine
+handleAllInput
+) where
+
+import Game
+import State
+import InputHandling
+
+import Graphics.Gloss.Interface.IO.Game
+
+----------------------------------------------------------------------
+
+handleAllInput :: InputHandler Game
+handleAllInput = composeInputHandlers [
+    handleSpecialKey KeySpace setNextState
+    ]
+
+-- Go to the next stage of the Game
+setNextState :: Game -> Game
+setNextState game = game{ state = newState }
+    where newState = nextState $ state game
diff --git a/lib/control/InputHandling.hs b/lib/control/InputHandling.hs
new file mode 100644
index 0000000..86704e4
--- /dev/null
+++ b/lib/control/InputHandling.hs
@@ -0,0 +1,41 @@
+-- Allows to create a massive inputHandler that can handle anything
+-- after you specify what you want it to do.
+
+module InputHandling
+( InputHandler(..),
+-- Compose multiple InputHandlers into one InputHandler that handles
+-- all of them.
+composeInputHandlers,
+
+handle, 
+handleSpecialKey
+) where
+
+import Graphics.Gloss.Interface.IO.Game
+
+----------------------------- Constants ------------------------------
+
+type InputHandler a = Event -> (a -> a)
+
+----------------------------------------------------------------------
+
+composeInputHandlers :: [InputHandler a] -> InputHandler a
+composeInputHandlers []       ev a = a
+composeInputHandlers (ih:ihs) ev a = composeInputHandlers ihs ev (ih ev a)
+
+handle :: Event -> (a -> a) -> Event -> (a -> a)
+handle (EventKey key _ _ _) = handleKey key
+-- handle (EventMotion _)      = undefined
+-- handle (EventResize _)      = undefined
+handle _                    = (\_ -> (\_ -> id))
+
+handleKey :: Key -> (a -> a) -> Event -> (a -> a)
+handleKey (SpecialKey  key) = handleSpecialKey key
+handleKey (Char        _  ) = (\_ -> (\_ -> id))
+handleKey (MouseButton _  ) = (\_ -> (\_ -> id))
+
+handleSpecialKey :: SpecialKey -> (a -> a) -> Event -> (a -> a)
+handleSpecialKey sk1 f (EventKey (SpecialKey sk2) Down _ _)
+    | sk1 == sk2 = f
+    | otherwise  = id
+handleSpecialKey _   _ _ = id
diff --git a/rpg-engine.cabal b/rpg-engine.cabal
index 754ec51..28aea68 100644
--- a/rpg-engine.cabal
+++ b/rpg-engine.cabal
@@ -11,6 +11,7 @@ library
     gloss >= 1.11 && < 1.14, gloss-juicy >= 0.2.3
   exposed-modules:
     RPGEngine,
+    Input, InputHandling,
     Game, State,
     Render