✨Feature: implement loot resolution system with gold and item tracking from defeated creatures

src/rules/loot.ts

@@ -0,0 +1,172 @@
+import { findCreatureById, findItemById, findTableByCode } from "@/data/contentHelpers";
+import type { ContentPack } from "@/types/content";
+import type { CombatState, InventoryEntry, InventoryState } from "@/types/state";
+import type { LogEntry } from "@/types/rules";
+
+import type { DiceRoller } from "./dice";
+import { lookupTable } from "./tables";
+
+export type ResolveCombatLootOptions = {
+  content: ContentPack;
+  combat: CombatState;
+  inventory: InventoryState;
+  roller?: DiceRoller;
+  at: string;
+};
+
+export type ResolveCombatLootResult = {
+  inventory: InventoryState;
+  itemsAwarded: InventoryEntry[];
+  goldAwarded: number;
+  logEntries: LogEntry[];
+};
+
+function cloneInventory(inventory: InventoryState): InventoryState {
+  return {
+    ...inventory,
+    carried: inventory.carried.map((entry) => ({ ...entry })),
+    equipped: inventory.equipped.map((entry) => ({ ...entry })),
+    stored: inventory.stored.map((entry) => ({ ...entry })),
+    currency: { ...inventory.currency },
+    lightSources: inventory.lightSources.map((entry) => ({ ...entry })),
+  };
+}
+
+function createInventoryEntry(definitionId: string, quantity = 1): InventoryEntry {
+  return {
+    definitionId,
+    quantity,
+  };
+}
+
+function mergeInventoryEntry(
+  content: ContentPack,
+  entries: InventoryEntry[],
+  definitionId: string,
+  quantity: number,
+) {
+  const item = findItemById(content, definitionId);
+
+  if (item.stackable) {
+    const existing = entries.find((entry) => entry.definitionId === definitionId);
+
+    if (existing) {
+      existing.quantity += quantity;
+      return;
+    }
+  }
+
+  entries.push(createInventoryEntry(definitionId, quantity));
+}
+
+function createLootLog(
+  id: string,
+  at: string,
+  text: string,
+  relatedIds: string[],
+): LogEntry {
+  return {
+    id,
+    at,
+    type: "loot",
+    text,
+    relatedIds,
+  };
+}
+
+function summarizeLoot(
+  goldAwarded: number,
+  itemsAwarded: InventoryEntry[],
+  content: ContentPack,
+) {
+  const parts: string[] = [];
+
+  if (goldAwarded > 0) {
+    parts.push(`${goldAwarded} gold`);
+  }
+
+  for (const item of itemsAwarded) {
+    const itemName = findItemById(content, item.definitionId).name;
+    parts.push(item.quantity > 1 ? `${item.quantity}x ${itemName}` : itemName);
+  }
+
+  return parts.length > 0 ? parts.join(", ") : "nothing useful";
+}
+
+export function resolveCombatLoot(
+  options: ResolveCombatLootOptions,
+): ResolveCombatLootResult {
+  const inventory = cloneInventory(options.inventory);
+  const itemsAwarded: InventoryEntry[] = [];
+  const logEntries: LogEntry[] = [];
+  let goldAwarded = 0;
+
+  const defeatedCreatures = options.combat.enemies.filter(
+    (enemy) => enemy.hpCurrent === 0 && enemy.sourceDefinitionId,
+  );
+
+  for (const enemy of defeatedCreatures) {
+    const creature = findCreatureById(options.content, enemy.sourceDefinitionId!);
+    const lootTableCodes = creature.lootTableCodes ?? [];
+
+    for (const tableCode of lootTableCodes) {
+      const table = findTableByCode(options.content, tableCode);
+      const lookup = lookupTable(table, { roller: options.roller });
+      const rollTotal = lookup.roll.modifiedTotal ?? lookup.roll.total;
+
+      logEntries.push({
+        id: `${options.combat.id}.${creature.id}.${tableCode}.roll`,
+        at: options.at,
+        type: "roll",
+        text: `Rolled loot ${lookup.roll.diceKind} [${lookup.roll.rolls.join(", ")}] on ${tableCode} for ${rollTotal}: ${lookup.entry.label}.`,
+        relatedIds: [options.combat.id, creature.id, tableCode],
+      });
+
+      let creatureGold = 0;
+      const creatureItems: InventoryEntry[] = [];
+
+      for (const effect of lookup.entry.effects ?? []) {
+        if (effect.type === "gain-gold" && effect.amount) {
+          creatureGold += effect.amount;
+        }
+
+        if (effect.type === "add-item" && effect.referenceId) {
+          mergeInventoryEntry(options.content, inventory.carried, effect.referenceId, effect.amount ?? 1);
+          mergeInventoryEntry(options.content, itemsAwarded, effect.referenceId, effect.amount ?? 1);
+          mergeInventoryEntry(options.content, creatureItems, effect.referenceId, effect.amount ?? 1);
+        }
+      }
+
+      for (const reference of lookup.entry.references ?? []) {
+        if (reference.type !== "item") {
+          continue;
+        }
+
+        mergeInventoryEntry(options.content, inventory.carried, reference.id, 1);
+        mergeInventoryEntry(options.content, itemsAwarded, reference.id, 1);
+        mergeInventoryEntry(options.content, creatureItems, reference.id, 1);
+      }
+
+      if (creatureGold > 0) {
+        inventory.currency.gold += creatureGold;
+        goldAwarded += creatureGold;
+      }
+
+      logEntries.push(
+        createLootLog(
+          `${options.combat.id}.${creature.id}.${tableCode}.loot`,
+          options.at,
+          `${creature.name} yielded ${summarizeLoot(creatureGold, creatureItems, options.content)}.`,
+          [options.combat.id, creature.id, tableCode],
+        ),
+      );
+    }
+  }
+
+  return {
+    inventory,
+    itemsAwarded,
+    goldAwarded,
+    logEntries,
+  };
+}