Use menus for combat and picking up items

Refactor a bunch of stuff around to allow for polymorphically surfacing
an EntityChar for all entities, and use this to write a generic
`entityMenu` function, which generates a menu from the chars of a list
of entities - and use that to fully implement (removing `undefined`)
menus for both attacking and picking things up when there are multiple
entities on the relevant tile.

1 files changed, 56 insertions, 0 deletions

diff --git a/src/Xanthous/Data/EntityChar.hs b/src/Xanthous/Data/EntityChar.hs
new file mode 100644
index 000000000000..7aeb5fdf86a0
--- /dev/null
+++ b/src/Xanthous/Data/EntityChar.hs
@@ -0,0 +1,56 @@
+{-# LANGUAGE RoleAnnotations      #-}
+{-# LANGUAGE RecordWildCards      #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# LANGUAGE GADTs                #-}
+{-# LANGUAGE AllowAmbiguousTypes  #-}
+{-# LANGUAGE TemplateHaskell      #-}
+--------------------------------------------------------------------------------
+module Xanthous.Data.EntityChar
+  ( EntityChar(..)
+  , HasChar(..)
+  , HasStyle(..)
+  ) where
+--------------------------------------------------------------------------------
+import           Xanthous.Prelude hiding ((.=))
+--------------------------------------------------------------------------------
+import qualified Graphics.Vty.Attributes as Vty
+import           Test.QuickCheck
+import           Data.Aeson
+--------------------------------------------------------------------------------
+import           Xanthous.Orphans ()
+import           Xanthous.Util.QuickCheck (GenericArbitrary(..))
+--------------------------------------------------------------------------------
+
+
+class HasChar s a | s -> a where
+  char :: Lens' s a
+  {-# MINIMAL char #-}
+
+data EntityChar = EntityChar
+  { _char :: Char
+  , _style :: Vty.Attr
+  }
+  deriving stock (Show, Eq, Generic)
+  deriving anyclass (NFData, CoArbitrary, Function)
+  deriving Arbitrary via GenericArbitrary EntityChar
+makeFieldsNoPrefix ''EntityChar
+
+instance FromJSON EntityChar where
+  parseJSON (String (chr :< Empty)) = pure $ EntityChar chr Vty.defAttr
+  parseJSON (Object o) = do
+    (EntityChar _char _) <- o .: "char"
+    _style <- o .:? "style" .!= Vty.defAttr
+    pure EntityChar {..}
+  parseJSON _ = fail "Invalid type, expected string or object"
+
+instance ToJSON EntityChar where
+  toJSON (EntityChar chr styl)
+    | styl == Vty.defAttr = String $ chr <| Empty
+    | otherwise = object
+      [ "char" .= chr
+      , "style" .= styl
+      ]
+
+instance IsString EntityChar where
+  fromString [ch] = EntityChar ch Vty.defAttr
+  fromString _ = error "Entity char must only be a single character"