From 20737d63951a609dfcead89ab747adfa8810d623 Mon Sep 17 00:00:00 2001
From: Willem Van Onsem <vanonsem.willem@gmail.com>
Date: Fri, 28 Jul 2023 12:28:39 +0200
Subject: [PATCH] add orbital formatting

---
 chem-formula.cabal       |  1 +
 src/Chemistry/Element.hs | 21 ---------------------
 src/Chemistry/Orbit.hs   | 31 +++++++++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 21 deletions(-)
 create mode 100644 src/Chemistry/Orbit.hs

diff --git a/chem-formula.cabal b/chem-formula.cabal
index a2fe1ff..ed7f896 100644
--- a/chem-formula.cabal
+++ b/chem-formula.cabal
@@ -22,6 +22,7 @@ library
     , Chemistry.Element
     , Chemistry.Formula
     , Chemistry.Isotope
+    , Chemistry.Orbit
     , Chemistry.Parser
   build-depends:
       base >= 4.7 && < 5
diff --git a/src/Chemistry/Element.hs b/src/Chemistry/Element.hs
index 2382c1a..8046301 100644
--- a/src/Chemistry/Element.hs
+++ b/src/Chemistry/Element.hs
@@ -27,8 +27,6 @@ module Chemistry.Element (
   , elementName
   -- * Possible covalent bonds
   , covalentBonds
-  -- * Orbitals
-  , molecularOrbital, dd
   -- * Colors
   , withElementColorS, elementCPK, symbolColoured, symbolColouredS
   ) where
@@ -50,14 +48,6 @@ import Numeric.Units.Dimensional.NonSI (dalton)
 import Text.Blaze(ToMarkup(toMarkup), preEscapedString)
 import Test.QuickCheck.Arbitrary(Arbitrary(arbitrary), arbitraryBoundedEnum)
 
-data Orbital = OrbS | OrbP | OrbD | OrbF | OrbG
-
-maxElectronsPerOrbital :: Int -> Int
-maxElectronsPerOrbital n = 4*n + 2
-
-orbitalNames :: [Char]
-orbitalNames = "spdfgh"
-
 -- | A data type that defines the different chemical elements.
 data Element
   = H -- ^ The /hydrogen/ element.
@@ -255,17 +245,6 @@ pattern Uus = Ts
 pattern Uuo :: Element
 pattern Uuo = Og
 
-molecularOrbital :: Element -> [(Int, Char, Int)]
-molecularOrbital = fill 0 0 . atomNumber
-  where fill _ _ 0 = []
-        fill m 0 k = (m+1, 's', d) : fill (m - (m-1) `div` 2) ((m+1) `div` 2) (k-d)
-          where d = min 2 k
-        fill m n k = (m+1, "spdfg" !! n, d) : fill (m+1) (n-1) (k-d)
-          where d = min (maxElectronsPerOrbital n) k
-
--- electronsPerShell :: Element -> [Int]
--- electronsPerShell = map sum . molecularOrbital
-
 -- | Obtain the atomic number of the given 'Element'.
 atomNumber :: Element -- ^ The element for which we want to calculate the atomic number.
     -> Int -- ^ The atomic number of the given element.
diff --git a/src/Chemistry/Orbit.hs b/src/Chemistry/Orbit.hs
new file mode 100644
index 0000000..0be69a1
--- /dev/null
+++ b/src/Chemistry/Orbit.hs
@@ -0,0 +1,31 @@
+module Chemistry.Orbit where
+
+import Data.List.NonEmpty(NonEmpty)
+
+data Orbit = S | P | D | F | G deriving (Enum, Eq, Ord, Read, Show)
+newtype OrbitalConfig = OrbitalConfig (NonEmpty (NonEmpty Int)) deriving (Eq, Ord, Read, Show)
+
+totalElectrons :: OrbitalConfig -> Int
+totalElectrons (OrbitalConfig vs) = sum (fmap sum vs)
+
+toArrowText :: Int -> Int -> String
+toArrowText n k = concat (replicate f "\8645\8414" ++ [ "\8593\8414" | h == 1 ] ++ replicate ((maxElectronsForOrbit' n `div` 2) - f - h) " \8414")
+  where ~(f, h) = k `divMod` 2
+
+maxElectronsForOrbit' :: Int -> Int
+maxElectronsForOrbit' = (2+) . (4*)
+
+maxElectronsForOrbit :: Orbit -> Int
+maxElectronsForOrbit = maxElectronsForOrbit' . fromEnum
+
+electronsToOrbitals :: Int -> [(Int, Orbit, Int)]
+electronsToOrbitals = fill 0 0
+  where fill _ _ 0 = []
+        fill m 0 k = (m+1, S, d) : fill (m - (m-1) `div` 2) ((m+1) `div` 2) (k-d)
+          where d = min 2 k
+        fill m n k = (m+1, toEnum n, d) : fill (m+1) (n-1) (k-d)
+          where d = min (maxElectronsForOrbit' n) k
+
+-- electronsPerShell :: Element -> [Int]
+-- electronsPerShell = map sum . molecularOrbital
+