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Bastian Wagner
243
apps/api/src/shops/shop.service.ts
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243
apps/api/src/shops/shop.service.ts
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import { Injectable } from '@nestjs/common';
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import { DataSource } from 'typeorm';
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import { Character } from '../characters/entities/character.entity';
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import { GameConditionService } from '../conditions/game-condition.service';
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import { CharacterItem } from '../items/entities/character-item.entity';
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import { NpcService } from '../npcs/npc.service';
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import { NpcShop } from './entities/npc-shop.entity';
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import { ShopOffer } from './entities/shop-offer.entity';
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import {
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characterNotFound,
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shopDisabled,
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shopInsufficientSilver,
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shopInvalidQuantity,
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shopNotFound,
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shopOfferLocked,
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shopOfferNotFound,
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} from './shop.errors';
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export const SILVER_CURRENCY = 'SILVER';
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export interface ShopOfferDto {
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itemKey: string;
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itemName: string;
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itemDescription: string;
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iconPath: string;
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currencyType: string;
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price: number;
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quantity: number;
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/** False when the offer's conditions are not met (Slice 0.8.5 content). */
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unlocked: boolean;
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/** True when the character simply cannot afford an otherwise open offer. */
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affordable: boolean;
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}
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export interface ShopViewDto {
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shopKey: string;
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shopName: string;
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npcKey: string;
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silver: number;
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offers: ShopOfferDto[];
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}
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export interface ShopPurchaseResultDto {
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shopKey: string;
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itemKey: string;
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itemName: string;
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quantity: number;
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silverSpent: number;
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silverBalance: number;
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}
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/**
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* Sells goods for Silver (NPC spec §15, §30).
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*
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* Prices and availability are read from content on every call. The request
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* names an item and a count and nothing else, so a client cannot set its own
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* price or open a locked offer (spec §37.9, §33).
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*/
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@Injectable()
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export class ShopService {
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constructor(
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private readonly dataSource: DataSource,
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private readonly conditions: GameConditionService,
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private readonly npcs: NpcService,
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) {}
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async getShopView(
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characterId: string,
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merchantKey: string,
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): Promise<ShopViewDto> {
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const { shop, npcId } = await this.requireShop(characterId, merchantKey);
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const character = await this.dataSource
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.getRepository(Character)
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.findOneBy({ id: characterId });
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if (!character) {
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throw characterNotFound();
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}
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const offers = await this.dataSource.getRepository(ShopOffer).find({
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where: { shopId: shop.id, enabled: true },
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relations: { itemDefinition: true },
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order: { sortOrder: 'ASC' },
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});
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const view: ShopOfferDto[] = [];
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for (const offer of offers) {
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const unlocked = await this.conditions.evaluate(
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{ characterId, npcId },
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offer.conditions,
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);
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view.push({
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itemKey: offer.itemDefinition.key,
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itemName: offer.itemDefinition.name,
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itemDescription: offer.itemDefinition.description,
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iconPath: offer.itemDefinition.iconPath,
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currencyType: offer.currencyType,
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price: offer.price,
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quantity: offer.quantity,
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unlocked,
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affordable: character.silver >= offer.price,
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});
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}
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return {
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shopKey: shop.key,
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shopName: shop.name,
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npcKey: merchantKey,
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silver: character.silver,
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offers: view,
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};
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}
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/**
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* Buys `quantity` lots of one offer, atomically (spec §31).
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*
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* Silver is debited and the item granted in the same transaction, so a
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* failure cannot leave the character paid-up and empty-handed.
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*/
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async purchase(
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characterId: string,
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merchantKey: string,
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itemKey: string,
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quantity: number,
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): Promise<ShopPurchaseResultDto> {
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if (!Number.isInteger(quantity) || quantity <= 0) {
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throw shopInvalidQuantity();
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}
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const { shop, npcId } = await this.requireShop(characterId, merchantKey);
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return this.dataSource.transaction(async (manager) => {
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const characters = manager.getRepository(Character);
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const character = await characters.findOne({
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where: { id: characterId },
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lock: { mode: 'pessimistic_write' },
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});
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if (!character) {
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throw characterNotFound();
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}
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// Matched on the joined definition's business key: the offer table is
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// keyed by item definition id, while the request carries the stable key.
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const offers = await manager.getRepository(ShopOffer).find({
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where: { shopId: shop.id, enabled: true },
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relations: { itemDefinition: true },
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});
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const match = offers.find(
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(candidate) => candidate.itemDefinition.key === itemKey,
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);
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if (!match) {
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throw shopOfferNotFound();
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}
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const unlocked = await this.conditions.evaluate(
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{ characterId, npcId },
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match.conditions,
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manager,
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);
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if (!unlocked) {
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throw shopOfferLocked();
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}
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if (!match.repeatable && quantity > 1) {
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throw shopInvalidQuantity();
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}
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const silverSpent = match.price * quantity;
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if (character.silver < silverSpent) {
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throw shopInsufficientSilver();
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}
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character.silver -= silverSpent;
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await characters.save(character);
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await this.grantItem(
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manager,
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characterId,
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match.itemDefinitionId,
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match.quantity * quantity,
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);
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return {
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shopKey: shop.key,
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itemKey,
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itemName: match.itemDefinition.name,
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quantity: match.quantity * quantity,
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silverSpent,
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silverBalance: character.silver,
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};
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});
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}
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/**
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* Adds to an existing stack or starts a new one.
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*
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* Purchases deliberately ignore loot-bag capacity: bags limit trade goods
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* carried out of a hunt, and equipment and consumables are unaffected by
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* them (Slice 0.7.5 §8).
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*/
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private async grantItem(
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manager: { getRepository: DataSource['getRepository'] },
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characterId: string,
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itemDefinitionId: string,
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quantity: number,
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): Promise<void> {
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const characterItems = manager.getRepository(CharacterItem);
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const existing = await characterItems.findOne({
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where: { characterId, itemDefinitionId },
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});
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if (existing) {
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existing.quantity += quantity;
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await characterItems.save(existing);
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return;
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}
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await characterItems.save(
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characterItems.create({ characterId, itemDefinitionId, quantity }),
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);
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}
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private async requireShop(
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characterId: string,
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merchantKey: string,
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): Promise<{ shop: NpcShop; npcId: string }> {
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const npc = await this.npcs.requireReachableNpc(characterId, merchantKey);
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const shop = await this.dataSource
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.getRepository(NpcShop)
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.findOneBy({ npcId: npc.id });
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if (!shop) {
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throw shopNotFound();
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}
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if (!shop.enabled) {
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throw shopDisabled();
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}
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return { shop, npcId: npc.id };
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}
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}
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