#4 Setup interaction

lib/RPGEngine/Input/ActionSelection.hs

@@ -0,0 +1,76 @@
+module RPGEngine.Input.ActionSelection
+( handleInputActionSelection
+) where
+
+import RPGEngine.Input.Core (InputHandler, handleKey, composeInputHandlers, ListSelector (selection))
+
+import RPGEngine.Data (Game (..), State (..), Direction (..), Action (..), ItemId, EntityId)
+import Graphics.Gloss.Interface.IO.Game (Key(SpecialKey), SpecialKey (KeyUp, KeyDown))
+import Graphics.Gloss.Interface.IO.Interact
+    ( SpecialKey(..), KeyState(..) )
+
+------------------------------ Exported ------------------------------
+
+handleInputActionSelection :: InputHandler Game
+handleInputActionSelection = composeInputHandlers [
+    handleKey (SpecialKey KeySpace) Down selectAction,
+
+    handleKey (SpecialKey KeyUp)    Down $ moveSelector North,
+    handleKey (SpecialKey KeyDown)  Down $ moveSelector South
+    ]
+
+----------------------------------------------------------------------
+
+selectAction :: Game -> Game
+selectAction game@Game{ state = ActionSelection list selection continue } = newGame
+    where newGame = game{ state = execute selectedAction continue }
+          selectedAction = Leave
+selectAction g = g
+
+-- TODO Lift this code from LevelSelection
+-- Move the selector either up or down
+moveSelector :: Direction -> Game -> Game
+moveSelector dir game@Game{ state = state@(ActionSelection list selector _) } = newGame
+    where newGame      = game{ state = newState }
+          newState     = state{ selector = newSelector }
+          newSelector  | constraint = selector{ selection = newSelection }
+                       | otherwise = selector
+          constraint   = 0 <= newSelection && newSelection < length list
+          newSelection = selection selector + diff
+          diff         | dir == North = -1
+                       | dir == South =  1
+                       | otherwise    =  0
+moveSelector _ g = g{ state = Error "Something went wrong while moving the selector up or down"}
+
+------------------------------ Actions -------------------------------
+
+execute :: Action -> State -> State
+execute (RetrieveItem id     ) s = pickUpItem id s
+execute (UseItem      id     ) s = useItem id s
+execute (DecreaseHp   eid iid) s = decreaseHp eid iid s
+execute (IncreasePlayerHp iid) s = increasePlayerHp iid s
+execute _ s = s
+
+-- Pick up the item with itemId and put it in the players inventory
+pickUpItem :: ItemId -> State -> State
+pickUpItem _ s = s -- TODO
+
+-- Use an item on the player
+useItem :: ItemId -> State -> State -- TODO
+useItem _ s = s -- TODO
+
+-- Attack an entity using an item
+decreaseHp :: EntityId -> ItemId -> State -> State
+decreaseHp _ _ s = s
+-- TODO DecreaseHp of monster
+-- TODO Check if monster is dead
+-- TODO Entity attack player
+-- TODO Decrease durability of item
+-- TODO Break item if durability below zero
+
+-- Heal a bit
+increasePlayerHp :: ItemId -> State -> State
+increasePlayerHp _ s = s
+-- TODO Increase playerHp
+-- TODO Decrease durability of item
+-- TODO Remove item if durability below zero