2D6-Dungeon/src/rules/loot.ts

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,
  };
}