From 163fadbd6271dfbb7a8ec243e8f211bf5debd20c Mon Sep 17 00:00:00 2001
From: MokaStitcher <54149968+MokaStitcher@users.noreply.github.com>
Date: Sun, 25 Aug 2024 17:25:40 +0200
Subject: [PATCH] [Bug] Prevent being able to start with a hidden ability
 that's not unlocked for some Pokemon (#3663)

* prevent being able to start with a hidden ability that's not unlocked for some Pokemon

* fix starter ui for pokemon with a single ability and only ability 2 unlocked
---
 src/ui/starter-select-ui-handler.ts | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/ui/starter-select-ui-handler.ts b/src/ui/starter-select-ui-handler.ts
index 250f097c2fc..99191bbcd15 100644
--- a/src/ui/starter-select-ui-handler.ts
+++ b/src/ui/starter-select-ui-handler.ts
@@ -1795,15 +1795,17 @@ export default class StarterSelectUiHandler extends MessageUiHandler {
           if (this.canCycleAbility) {
             const abilityCount = this.lastSpecies.getAbilityCount();
             const abilityAttr = this.scene.gameData.starterData[this.lastSpecies.speciesId].abilityAttr;
+            const hasAbility1 = abilityAttr & AbilityAttr.ABILITY_1;
             let newAbilityIndex = this.abilityCursor;
             do {
               newAbilityIndex = (newAbilityIndex + 1) % abilityCount;
-              if (!newAbilityIndex) {
-                if (abilityAttr & AbilityAttr.ABILITY_1) {
+              if (newAbilityIndex === 0) {
+                if (hasAbility1) {
                   break;
                 }
               } else if (newAbilityIndex === 1) {
-                if (this.lastSpecies.ability1 === this.lastSpecies.ability2) {
+                // If ability 1 and 2 are the same and ability 1 is unlocked, skip over ability 2
+                if (this.lastSpecies.ability1 === this.lastSpecies.ability2 && hasAbility1) {
                   newAbilityIndex = (newAbilityIndex + 1) % abilityCount;
                 }
                 break;
@@ -3045,7 +3047,20 @@ export default class StarterSelectUiHandler extends MessageUiHandler {
 
         this.canCycleShiny = isVariantCaught || isVariant2Caught || isVariant3Caught;
         this.canCycleGender = isMaleCaught && isFemaleCaught;
-        this.canCycleAbility = [ abilityAttr & AbilityAttr.ABILITY_1, (abilityAttr & AbilityAttr.ABILITY_2) && species.ability2, abilityAttr & AbilityAttr.ABILITY_HIDDEN ].filter(a => a).length > 1;
+        const hasAbility1 = abilityAttr & AbilityAttr.ABILITY_1;
+        let hasAbility2 = abilityAttr & AbilityAttr.ABILITY_2;
+        const hasHiddenAbility = abilityAttr & AbilityAttr.ABILITY_HIDDEN;
+
+        /*
+         * Check for Pokemon with a single ability (at some point it was possible to catch them with their ability 2 attribute)
+         * This prevents cycling between ability 1 and 2 if they are both unlocked and the same
+         * but we still need to account for the possibility ability 1 was never unlocked and fallback on ability 2 in this case
+         */
+        if (hasAbility1 && hasAbility2 && species.ability1 === species.ability2) {
+          hasAbility2 = 0;
+        }
+
+        this.canCycleAbility = [ hasAbility1, hasAbility2, hasHiddenAbility ].filter(a => a).length > 1;
         this.canCycleForm = species.forms.filter(f => f.isStarterSelectable || !pokemonFormChanges[species.speciesId]?.find(fc => fc.formKey))
           .map((_, f) => dexEntry.caughtAttr & this.scene.gameData.getFormAttr(f)).filter(f => f).length > 1;
         this.canCycleNature = this.scene.gameData.getNaturesForAttr(dexEntry.natureAttr).length > 1;