From 314d8f6b58e9475422e44d9a2c0b5d1bcaae50b9 Mon Sep 17 00:00:00 2001
From: Kurt <kaphotics@gmail.com>
Date: Fri, 6 Dec 2019 17:36:36 -0800
Subject: [PATCH] Update form destination handling

espurr-F evolves to form-1 from form0, even tho the form arg is -1 (gen7
consideration)
gen8 has 0/1 for the two evolutions, dictating the destination form
---
 .../Legality/Evolutions/EvolutionMethod.cs    |  6 ++-
 .../Legality/Evolutions/EvolutionTree.cs      | 41 +++++++++++++++++--
 2 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/PKHeX.Core/Legality/Evolutions/EvolutionMethod.cs b/PKHeX.Core/Legality/Evolutions/EvolutionMethod.cs
index be3754aee..9708f6bbb 100644
--- a/PKHeX.Core/Legality/Evolutions/EvolutionMethod.cs
+++ b/PKHeX.Core/Legality/Evolutions/EvolutionMethod.cs
@@ -10,12 +10,16 @@ public sealed class EvolutionMethod
         public int Method;
         public int Species;
         public int Argument;
-        public int Form = -1;
+        public int Form = AnyForm;
         public int Level;
 
+        public const int AnyForm = -1;
+
         // Not stored in binary data
         public bool RequiresLevelUp; // tracks if this method requires a Level Up, lazily set
 
+        public int GetDestinationForm(int form) => Form == AnyForm ? form : Method == (int)LevelUpFormFemale1 ? 1 : Form;
+
         /// <summary>
         /// Checks the <see cref="EvolutionMethod"/> for validity by comparing against the <see cref="PKM"/> data.
         /// </summary>
diff --git a/PKHeX.Core/Legality/Evolutions/EvolutionTree.cs b/PKHeX.Core/Legality/Evolutions/EvolutionTree.cs
index 0d3b03b01..30647f3b0 100644
--- a/PKHeX.Core/Legality/Evolutions/EvolutionTree.cs
+++ b/PKHeX.Core/Legality/Evolutions/EvolutionTree.cs
@@ -89,10 +89,40 @@ private EvolutionTree(IReadOnlyList<byte[]> data, GameVersion game, PersonalTabl
             Personal = personal;
             MaxSpeciesTree = maxSpeciesTree;
             Entries = GetEntries(data);
-            var connections = CreateTree();
+
+            // Starting in Generation 7, forms have separate evolution data.
+            int format = Game.GetGeneration();
+            var oldStyle = format < 7;
+            var connections = oldStyle ? CreateTreeOld() : CreateTree();
+
             Lineage = connections.ToLookup(obj => obj.Key, obj => obj.Value);
         }
 
+        private IEnumerable<KeyValuePair<int, EvolutionLink>> CreateTreeOld()
+        {
+            for (int sSpecies = 1; sSpecies <= MaxSpeciesTree; sSpecies++)
+            {
+                var fc = Personal[sSpecies].FormeCount;
+                for (int sForm = 0; sForm < fc; sForm++)
+                {
+                    var index = sSpecies;
+                    var evos = Entries[index];
+                    foreach (var evo in evos)
+                    {
+                        var dSpecies = evo.Species;
+                        if (dSpecies == 0)
+                            continue;
+
+                        var dForm = sForm;
+                        var key = GetLookupKey(dSpecies, dForm);
+
+                        var link = new EvolutionLink(sSpecies, sForm, evo);
+                        yield return new KeyValuePair<int, EvolutionLink>(key, link);
+                    }
+                }
+            }
+        }
+
         private IEnumerable<KeyValuePair<int, EvolutionLink>> CreateTree()
         {
             for (int sSpecies = 1; sSpecies <= MaxSpeciesTree; sSpecies++)
@@ -107,7 +137,12 @@ private EvolutionTree(IReadOnlyList<byte[]> data, GameVersion game, PersonalTabl
                         var dSpecies = evo.Species;
                         if (dSpecies == 0)
                             continue;
-                        var dForm = evo.Form < 0 ? sForm : evo.Form;
+
+                        bool any = evo.Form == EvolutionMethod.AnyForm;
+                        if (!any && evo.Form != sForm)
+                            continue;
+
+                        var dForm = evo.GetDestinationForm(sForm);
                         var key = GetLookupKey(dSpecies, dForm);
 
                         var link = new EvolutionLink(sSpecies, sForm, evo);
@@ -210,7 +245,7 @@ private IEnumerable<int> GetPreEvolutions(int species, int form)
 
         private IEnumerable<int> GetEvolutions(int species, int form)
         {
-            int index = Personal.GetFormeIndex(species, form);
+            int index = GetLookupKey(species, form);
             var node = Lineage[index];
             foreach (var method in node)
             {