[Balance] The cost of buying same-species eggs can be reduced (#6837)

* [Balance] The cost of buying same-species eggs can be reduced

After hatching a certain number of eggs for a starter,
the cost of buying same-species eggs
for that starter will be reduced (up to 50%)

* Add test to validate array lengths for egg costs

src/data/balance/starters.ts

@@ -7,10 +7,11 @@ export const CLASSIC_CANDY_FRIENDSHIP_MULTIPLIER = 3;
 export const FRIENDSHIP_GAIN_FROM_BATTLE = 3;
 export const FRIENDSHIP_GAIN_FROM_RARE_CANDY = 6;
 export const FRIENDSHIP_LOSS_FROM_FAINT = 5;
+// #endregion
 
 /**
  * Function to get the cumulative friendship threshold at which a candy is earned
- * @param starterCost The cost of the starter, found in {@linkcode speciesStarterCosts}
+ * @param starterCost - The cost of the starter, found in {@linkcode speciesStarterCosts}
  * @returns aforementioned threshold
  */
 export function getStarterValueFriendshipCap(starterCost: number): number {
@@ -618,43 +619,72 @@ export const speciesStarterCosts = {
   [SpeciesId.BLOODMOON_URSALUNA]: 5,
 };
 
-const starterCandyCosts: { passive: number; costReduction: [number, number]; egg: number; }[] = [
+interface StarterCandyCosts {
-  { passive: 40, costReduction: [ 25, 60 ], egg: 30 }, // 1 Cost
+  /** The candy cost to unlock the starter's passive ability */
-  { passive: 40, costReduction: [ 25, 60 ], egg: 30 }, // 2 Cost
+  readonly passive: number;
-  { passive: 35, costReduction: [ 20, 50 ], egg: 25 }, // 3 Cost
+  /** The candy costs to reduce the starter's point cost */
-  { passive: 30, costReduction: [ 15, 40 ], egg: 20 }, // 4 Cost
+  readonly costReduction: readonly [number, number];
-  { passive: 25, costReduction: [ 12, 35 ], egg: 18 }, // 5 Cost
+  /** The costs to buy a same-species egg */
-  { passive: 20, costReduction: [ 10, 30 ], egg: 15 }, // 6 Cost
+  readonly eggCosts: readonly [number, ...number[]];
-  { passive: 15, costReduction: [ 8, 20 ], egg: 12 }, // 7 Cost
+  /** The number of eggs required to hatch to reduce the cost for buying more eggs */
-  { passive: 10, costReduction: [ 5, 15 ], egg: 10 }, // 8 Cost
+  readonly eggCostReductionThresholds: readonly number[];
-  { passive: 10, costReduction: [ 5, 15 ], egg: 10 }, // 9 Cost
+}
-  { passive: 10, costReduction: [ 5, 15 ], egg: 10 }, // 10 Cost
+
+const allStarterCandyCosts: readonly StarterCandyCosts[] = [
+  { passive: 40, costReduction: [25, 60], eggCosts: [30, 27, 22, 15], eggCostReductionThresholds: [20, 40, 80] }, // 1 Cost
+  { passive: 40, costReduction: [25, 60], eggCosts: [30, 27, 22, 15], eggCostReductionThresholds: [20, 40, 80] }, // 2 Cost
+  { passive: 35, costReduction: [20, 50], eggCosts: [25, 22, 18, 12], eggCostReductionThresholds: [20, 40, 80] }, // 3 Cost
+  { passive: 30, costReduction: [15, 40], eggCosts: [20, 18, 15, 10], eggCostReductionThresholds: [15, 30, 60] }, // 4 Cost
+  { passive: 25, costReduction: [12, 35], eggCosts: [18, 16, 13, 9], eggCostReductionThresholds: [15, 30, 60] }, // 5 Cost
+  { passive: 20, costReduction: [10, 30], eggCosts: [15, 13, 11, 7], eggCostReductionThresholds: [15, 30, 60] }, // 6 Cost
+  { passive: 15, costReduction: [8, 20], eggCosts: [12, 10, 9, 6], eggCostReductionThresholds: [10, 20, 40] }, // 7 Cost
+  { passive: 10, costReduction: [5, 15], eggCosts: [10, 9, 7, 5], eggCostReductionThresholds: [10, 20, 40] }, // 8 Cost
+  { passive: 10, costReduction: [5, 15], eggCosts: [10, 9, 7, 5], eggCostReductionThresholds: [10, 20, 40] }, // 9 Cost
+  { passive: 10, costReduction: [5, 15], eggCosts: [10, 9, 7, 5], eggCostReductionThresholds: [8, 16, 32] }, // 10 Cost
 ];
 
 /**
- * Getter for {@linkcode starterCandyCosts} for passive unlock candy cost based on initial point cost
+ * Getter for {@linkcode allStarterCandyCosts} for passive unlock candy cost based on initial point cost
- * @param starterCost the default point cost of the starter found in {@linkcode speciesStarterCosts}
+ * @param starterCost - The default point cost of the starter found in {@linkcode speciesStarterCosts}
  * @returns the candy cost for passive unlock
  */
 export function getPassiveCandyCount(starterCost: number): number {
-  return starterCandyCosts[starterCost - 1].passive;
+  return allStarterCandyCosts[starterCost - 1].passive;
 }
 
 /**
- * Getter for {@linkcode starterCandyCosts} for value reduction unlock candy cost based on initial point cost
+ * Getter for {@linkcode allStarterCandyCosts} for value reduction unlock candy cost based on initial point cost
- * @param starterCost the default point cost of the starter found in {@linkcode speciesStarterCosts}
+ * @param starterCost - The default point cost of the starter found in {@linkcode speciesStarterCosts}
  * @returns respective candy cost for the two cost reductions as an array 2 numbers
  */
-export function getValueReductionCandyCounts(starterCost: number): [number, number] {
+export function getValueReductionCandyCounts(starterCost: number): readonly [number, number] {
-  return starterCandyCosts[starterCost - 1].costReduction;
+  return allStarterCandyCosts[starterCost - 1].costReduction;
 }
 
 /**
- * Getter for {@linkcode starterCandyCosts} for egg purchase candy cost based on initial point cost
+ * Getter for {@linkcode allStarterCandyCosts} for egg purchase candy cost based on initial point cost
- * @param starterCost the default point cost of the starter found in {@linkcode speciesStarterCosts}
+ * @param starterCost - The default point cost of the starter found in {@linkcode speciesStarterCosts}
+ * @param hatchCount - The number of eggs hatched of the starter
  * @returns the candy cost for the purchasable egg
  */
-export function getSameSpeciesEggCandyCounts(starterCost: number): number {
+export function getSameSpeciesEggCandyCounts(starterCost: number, hatchCount: number): number {
-  return starterCandyCosts[starterCost - 1].egg;
+  const starterCandyCosts = allStarterCandyCosts[starterCost - 1];
+  let eggCostIndex = 0;
+  while (hatchCount >= starterCandyCosts.eggCostReductionThresholds[eggCostIndex]) {
+    eggCostIndex++;
+  }
+  return starterCandyCosts.eggCosts[eggCostIndex];
 }
 
+/**
+ * ⚠️ This is used for internal testing purposes only and will not be populated outside of the test environment.
+ * @internal
+ */
+export const __TEST_allStarterCandyCosts: readonly StarterCandyCosts[] = [];
+
+if (import.meta.env.NODE_ENV === "test") {
+  for (const starterCandyCosts of allStarterCandyCosts) {
+    // @ts-expect-error: done this way to keep it `readonly`
+    __TEST_allStarterCandyCosts.push(starterCandyCosts);
+  }
+}

src/ui/handlers/pokedex-page-ui-handler.ts

@@ -2020,7 +2020,8 @@ export class PokedexPageUiHandler extends MessageUiHandler {
               }
 
               // Same species egg menu option.
-              const sameSpeciesEggCost = getSameSpeciesEggCandyCounts(speciesStarterCosts[this.starterId]);
+              const hatchCount = globalScene.gameData.dexData[this.starterId].hatchedCount;
+              const sameSpeciesEggCost = getSameSpeciesEggCandyCounts(speciesStarterCosts[this.starterId], hatchCount);
               options.push({
                 label: `×${sameSpeciesEggCost} ${i18next.t("pokedexUiHandler:sameSpeciesEgg")}`,
                 handler: () => {
@@ -2367,8 +2368,9 @@ export class PokedexPageUiHandler extends MessageUiHandler {
   isSameSpeciesEggAvailable(): boolean {
     // Get this species ID's starter data
     const starterData = globalScene.gameData.starterData[this.starterId];
+    const hatchCount = globalScene.gameData.dexData[this.starterId].hatchedCount;
 
-    return starterData.candyCount >= getSameSpeciesEggCandyCounts(speciesStarterCosts[this.starterId]);
+    return starterData.candyCount >= getSameSpeciesEggCandyCounts(speciesStarterCosts[this.starterId], hatchCount);
   }
 
   setSpecies() {

src/ui/handlers/pokedex-ui-handler.ts

@@ -893,11 +893,12 @@ export class PokedexUiHandler extends MessageUiHandler {
    */
   isSameSpeciesEggAvailable(speciesId: number): boolean {
     // Get this species ID's starter data
-    const starterData = this.gameData.starterData[this.getStarterSpeciesId(speciesId)];
+    const { gameData } = this;
+    const starterId = this.getStarterSpeciesId(speciesId);
+    const candyCount = gameData.starterData[starterId].candyCount;
+    const hatchCount = gameData.dexData[starterId].hatchedCount;
 
-    return (
+    return candyCount >= getSameSpeciesEggCandyCounts(speciesStarterCosts[starterId], hatchCount);
-      starterData.candyCount >= getSameSpeciesEggCandyCounts(speciesStarterCosts[this.getStarterSpeciesId(speciesId)])
-    );
   }
 
   /**

src/ui/handlers/starter-select-ui-handler.ts

@@ -1417,8 +1417,9 @@ export class StarterSelectUiHandler extends MessageUiHandler {
   isSameSpeciesEggAvailable(speciesId: number): boolean {
     // Get this species ID's starter data
     const starterData = globalScene.gameData.starterData[speciesId];
+    const hatchedCount = globalScene.gameData.dexData[speciesId].hatchedCount;
 
-    return starterData.candyCount >= getSameSpeciesEggCandyCounts(speciesStarterCosts[speciesId]);
+    return starterData.candyCount >= getSameSpeciesEggCandyCounts(speciesStarterCosts[speciesId], hatchedCount);
   }
 
   /**
@@ -2265,7 +2266,9 @@ export class StarterSelectUiHandler extends MessageUiHandler {
             }
 
             // Same species egg menu option.
-            const sameSpeciesEggCost = getSameSpeciesEggCandyCounts(speciesStarterCosts[this.lastSpecies.speciesId]);
+            const lastSpeciesId = this.lastSpecies.speciesId;
+            const hatchedCount = globalScene.gameData.dexData[lastSpeciesId].hatchedCount;
+            const sameSpeciesEggCost = getSameSpeciesEggCandyCounts(speciesStarterCosts[lastSpeciesId], hatchedCount);
             options.push({
               label: `×${sameSpeciesEggCost} ${i18next.t("starterSelectUiHandler:sameSpeciesEgg")}`,
               handler: () => {

test/data/balance/starter-candy-costs.test.ts

@@ -0,0 +1,10 @@
+import { __TEST_allStarterCandyCosts } from "#balance/starters";
+import { describe, expect, it } from "vitest";
+
+describe("Starter Candy Costs", () => {
+  it("should have the proper length of arrays in `allStarterCandyCosts`", () => {
+    for (const starterCandyCosts of __TEST_allStarterCandyCosts) {
+      expect(starterCandyCosts.eggCosts).toHaveLength(starterCandyCosts.eggCostReductionThresholds.length + 1);
+    }
+  });
+});