From be38a602675a22a5f121e9c19139b9d249d57d6f Mon Sep 17 00:00:00 2001
From: Kurt <kaphotics@gmail.com>
Date: Fri, 6 Dec 2019 18:16:11 -0800
Subject: [PATCH] Fix handling for get evolutions method

only used for Zukan7b, but add in handling so that it works for <=gen6
games, and supports form alterations too!

update style to match GetPreEvolutions

could probably update this to yield tuples (species, form) but LGPE/SWSH
only needs species. If there's the need for tuples later, should be ez
tweak.
---
 .../Legality/Evolutions/EvolutionTree.cs      | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/PKHeX.Core/Legality/Evolutions/EvolutionTree.cs b/PKHeX.Core/Legality/Evolutions/EvolutionTree.cs
index 30647f3b0..4f8e7fbb9 100644
--- a/PKHeX.Core/Legality/Evolutions/EvolutionTree.cs
+++ b/PKHeX.Core/Legality/Evolutions/EvolutionTree.cs
@@ -91,7 +91,7 @@ private EvolutionTree(IReadOnlyList<byte[]> data, GameVersion game, PersonalTabl
             Entries = GetEntries(data);
 
             // Starting in Generation 7, forms have separate evolution data.
-            int format = Game.GetGeneration();
+            int format = Game - Gen1 + 1;
             var oldStyle = format < 7;
             var connections = oldStyle ? CreateTreeOld() : CreateTree();
 
@@ -214,7 +214,7 @@ public List<EvoCriteria> GetValidPreEvolutions(PKM pkm, int maxLevel, int maxSpe
         }
 
         /// <summary>
-        /// Gets all species the <see cref="species"/>-<see cref="form"/> can evolve to &amp; from.
+        /// Gets all species the <see cref="species"/>-<see cref="form"/> can evolve to &amp; from, yielded in order of increasing evolution stage.
         /// </summary>
         /// <param name="species">Species ID</param>
         /// <param name="form">Form ID</param>
@@ -235,6 +235,8 @@ private IEnumerable<int> GetPreEvolutions(int species, int form)
             foreach (var method in node)
             {
                 var s = method.Species;
+                if (s == 0)
+                    continue;
                 var f = method.Form;
                 yield return s;
                 var preEvolutions = GetPreEvolutions(s, f);
@@ -245,13 +247,18 @@ private IEnumerable<int> GetPreEvolutions(int species, int form)
 
         private IEnumerable<int> GetEvolutions(int species, int form)
         {
-            int index = GetLookupKey(species, form);
-            var node = Lineage[index];
-            foreach (var method in node)
+            int format = Game - Gen1 + 1;
+            int index = format < 7 ? species : Personal.GetFormeIndex(species, form);
+            var evos = Entries[index];
+            foreach (var method in evos)
             {
                 var s = method.Species;
+                if (s == 0)
+                    continue;
+                var f = method.GetDestinationForm(form);
                 yield return s;
-                foreach (var next in GetEvolutions(s, form))
+                var nextEvolutions = GetEvolutions(s, f);
+                foreach (var next in nextEvolutions)
                     yield return next;
             }
         }