feat: New features (research, invest, gambling, new game+, trophies)

public/js/engine/legacy.js

@@ -0,0 +1,52 @@
+// Legacy (prestige): restart the run for permanent points. Points are spent on
+// repeatable perks, and every point ever earned also gives a small passive bonus.
+// What survives a restart: see META_KEYS in state.js.
+
+import { modifiersFor } from './modifiers.js';
+import { createState, META_KEYS } from './state.js';
+
+/** Points a restart would grant right now (0 until the run is big enough). */
+export function legacyGain(state, ctx, mods) {
+  const { threshold } = ctx.rules.legacy;
+  if (state.totalProduced < threshold) return 0;
+  return Math.floor(Math.sqrt(state.totalProduced / threshold) * mods.legacyGain);
+}
+
+export function perkLevel(state, perk) {
+  return state.legacy.perks[perk.id] ?? 0;
+}
+
+export function perkCost(perk, level) {
+  return Math.ceil(perk.baseCost * perk.costGrowth ** level);
+}
+
+export function buyPerk(state, ctx, id) {
+  const perk = ctx.perksById.get(id);
+  if (!perk) return false;
+  const level = perkLevel(state, perk);
+  const cost = perkCost(perk, level);
+  if (level >= perk.maxLevel || state.legacy.points < cost) return false;
+  state.legacy.points -= cost;
+  state.legacy.perks[id] = level + 1;
+  return true;
+}
+
+/** Restart the run in place. Returns the points gained, or 0 if not allowed. */
+export function prestige(state, ctx, now = Date.now()) {
+  const gain = legacyGain(state, ctx, modifiersFor(state, ctx));
+  if (gain < 1) return 0;
+
+  const fresh = createState(ctx, now);
+  const kept = Object.fromEntries(META_KEYS.map((key) => [key, state[key]]));
+  kept.legacy = {
+    ...state.legacy,
+    points: state.legacy.points + gain,
+    earned: state.legacy.earned + gain,
+    prestiges: state.legacy.prestiges + 1,
+  };
+  Object.assign(state, fresh, kept);
+
+  // Perks like "head start" shape the new run.
+  state.funds += modifiersFor(state, ctx).startFunds;
+  return gain;
+}