initial commit
This commit is contained in:
chungyeong
443
src/priceWatcher.js
Normal file
443
src/priceWatcher.js
Normal file
@@ -0,0 +1,443 @@
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"use strict";
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const crypto = require("node:crypto");
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function cloneJson(value) {
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if (value === undefined) return undefined;
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return JSON.parse(JSON.stringify(value));
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}
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function newWatchId() {
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if (typeof crypto.randomUUID === "function") {
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return crypto.randomUUID();
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}
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return `watch-${Date.now()}-${Math.floor(Math.random() * 1000000)}`;
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}
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function normalizeAlertRules(alertRules = {}) {
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const targetPrice =
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alertRules.targetPrice === null || alertRules.targetPrice === undefined
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? null
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: Number(alertRules.targetPrice);
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return {
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targetPrice:
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targetPrice !== null && Number.isFinite(targetPrice) && targetPrice > 0
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? Math.round(targetPrice)
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: null,
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notifyOnPriceChange: alertRules.notifyOnPriceChange !== false,
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notifyOnFirstResult: alertRules.notifyOnFirstResult === true,
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};
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}
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function normalizeToggle(value, defaultValue = true) {
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if (value === undefined) return defaultValue;
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return value !== false;
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}
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function normalizeOffers(offers) {
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if (!Array.isArray(offers)) return [];
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return offers
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.map((offer) => {
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if (!offer || typeof offer !== "object") return null;
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const price = Number(offer.price);
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if (!Number.isFinite(price) || price <= 0) return null;
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const currency =
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typeof offer.currency === "string" && offer.currency.trim()
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? offer.currency.trim().toUpperCase()
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: "KRW";
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const provider =
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typeof offer.provider === "string" && offer.provider.trim()
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? offer.provider.trim()
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: "unknown-provider";
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return {
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...offer,
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provider,
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currency,
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price: Math.round(price),
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};
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})
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.filter(Boolean)
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.sort((a, b) => a.price - b.price);
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}
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function buildAlertEvent(watch, previousSnapshot, currentSnapshot) {
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const reasons = [];
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const { targetPrice, notifyOnPriceChange, notifyOnFirstResult } = watch.alertRules;
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if (targetPrice !== null && currentSnapshot.bestPrice <= targetPrice) {
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const crossedThreshold = !previousSnapshot || previousSnapshot.bestPrice > targetPrice;
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const betterPriceBelowThreshold =
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previousSnapshot &&
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previousSnapshot.bestPrice <= targetPrice &&
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currentSnapshot.bestPrice < previousSnapshot.bestPrice;
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if (crossedThreshold || betterPriceBelowThreshold) {
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reasons.push("target_price");
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}
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}
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if (
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notifyOnPriceChange &&
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previousSnapshot &&
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previousSnapshot.bestPrice !== currentSnapshot.bestPrice
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) {
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reasons.push("price_changed");
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}
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if (notifyOnFirstResult && !previousSnapshot) {
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reasons.push("first_result");
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}
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if (reasons.length === 0) return null;
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const uniqueReasons = [...new Set(reasons)];
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return {
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watchId: watch.id,
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rawInput: watch.rawInput,
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eventType: uniqueReasons.includes("target_price") ? "target_price" : uniqueReasons[0],
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reasons: uniqueReasons,
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threshold: targetPrice,
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previousBestPrice: previousSnapshot ? previousSnapshot.bestPrice : null,
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currentBestPrice: currentSnapshot.bestPrice,
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currency: currentSnapshot.currency,
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bestOffer: currentSnapshot.bestOffer,
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observedAt: currentSnapshot.polledAt,
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};
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}
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function createWatchError({ message, at, phase }) {
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return {
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message: typeof message === "string" && message ? message : "Unknown error",
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at,
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phase: phase || "crawl",
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};
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}
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class PriceWatcher {
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constructor(options = {}) {
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this.crawler = options.crawler;
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this.notifier = options.notifier;
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this.pollIntervalMs =
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Number.isFinite(Number(options.pollIntervalMs)) && Number(options.pollIntervalMs) > 0
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? Number(options.pollIntervalMs)
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: 60000;
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this.logger = options.logger || console;
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this.now = options.now || (() => new Date());
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this.onWatchPolled =
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typeof options.onWatchPolled === "function" ? options.onWatchPolled : null;
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if (!this.crawler || typeof this.crawler.getQuotes !== "function") {
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throw new Error("crawler.getQuotes function is required");
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}
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if (!this.notifier || typeof this.notifier.notify !== "function") {
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throw new Error("notifier.notify function is required");
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}
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this.watches = new Map();
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this.timer = null;
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this.globalControls = {
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crawlingEnabled: true,
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alertsEnabled: true,
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};
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}
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toPublicWatch(watch) {
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return {
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id: watch.id,
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rawInput: watch.rawInput,
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searchParams: cloneJson(watch.searchParams),
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alertRules: cloneJson(watch.alertRules),
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pollingEnabled: watch.pollingEnabled,
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alertsEnabled: watch.alertsEnabled,
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createdAt: watch.createdAt,
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updatedAt: watch.updatedAt,
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lastSnapshot: cloneJson(watch.lastSnapshot),
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lastError: cloneJson(watch.lastError),
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};
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}
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getWatch(watchId) {
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const watch = this.watches.get(watchId);
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return watch ? this.toPublicWatch(watch) : null;
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}
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listWatches() {
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return Array.from(this.watches.values())
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.map((watch) => this.toPublicWatch(watch))
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.sort((a, b) => String(b.createdAt).localeCompare(String(a.createdAt)));
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}
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setGlobalControls(patch = {}) {
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if (Object.prototype.hasOwnProperty.call(patch, "crawlingEnabled")) {
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this.globalControls.crawlingEnabled = normalizeToggle(
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patch.crawlingEnabled,
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this.globalControls.crawlingEnabled
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);
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}
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if (Object.prototype.hasOwnProperty.call(patch, "alertsEnabled")) {
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this.globalControls.alertsEnabled = normalizeToggle(
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patch.alertsEnabled,
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this.globalControls.alertsEnabled
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);
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}
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return { ...this.globalControls };
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}
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getGlobalControls() {
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return { ...this.globalControls };
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}
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updateWatch(watchId, patch = {}) {
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const watch = this.watches.get(watchId);
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if (!watch) {
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throw new Error(`Unknown watchId: ${watchId}`);
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}
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if (Object.prototype.hasOwnProperty.call(patch, "rawInput")) {
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watch.rawInput = typeof patch.rawInput === "string" ? patch.rawInput : watch.rawInput;
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}
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if (Object.prototype.hasOwnProperty.call(patch, "searchParams")) {
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if (!patch.searchParams || typeof patch.searchParams !== "object") {
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throw new Error("searchParams must be an object");
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}
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watch.searchParams = patch.searchParams;
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}
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if (Object.prototype.hasOwnProperty.call(patch, "alertRules")) {
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watch.alertRules = normalizeAlertRules(patch.alertRules);
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}
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if (Object.prototype.hasOwnProperty.call(patch, "pollingEnabled")) {
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watch.pollingEnabled = normalizeToggle(patch.pollingEnabled, watch.pollingEnabled);
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}
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if (Object.prototype.hasOwnProperty.call(patch, "alertsEnabled")) {
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watch.alertsEnabled = normalizeToggle(patch.alertsEnabled, watch.alertsEnabled);
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}
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if (Object.prototype.hasOwnProperty.call(patch, "lastSnapshot")) {
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watch.lastSnapshot = patch.lastSnapshot || null;
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}
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if (Object.prototype.hasOwnProperty.call(patch, "lastError")) {
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watch.lastError = patch.lastError || null;
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}
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watch.updatedAt = new Date(this.now()).toISOString();
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return this.toPublicWatch(watch);
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}
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async emitPolled(watch, result) {
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if (!this.onWatchPolled) return;
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try {
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await this.onWatchPolled({
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watch: this.toPublicWatch(watch),
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result: cloneJson(result),
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});
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} catch (error) {
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this.logger.error(`[watch:${watch.id}] post-poll hook failed: ${error.message}`);
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}
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}
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addWatch({
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id,
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rawInput,
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searchParams,
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alertRules,
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pollingEnabled = true,
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alertsEnabled = true,
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lastSnapshot = null,
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lastError = null,
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createdAt,
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updatedAt,
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}) {
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if (!searchParams || typeof searchParams !== "object") {
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throw new Error("searchParams is required");
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}
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const watchId = id || newWatchId();
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if (this.watches.has(watchId)) {
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throw new Error(`watchId already exists: ${watchId}`);
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}
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const nowIso = new Date(this.now()).toISOString();
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this.watches.set(watchId, {
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id: watchId,
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rawInput: typeof rawInput === "string" ? rawInput : "",
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searchParams,
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alertRules: normalizeAlertRules(alertRules),
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pollingEnabled: normalizeToggle(pollingEnabled, true),
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alertsEnabled: normalizeToggle(alertsEnabled, true),
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createdAt: typeof createdAt === "string" ? createdAt : nowIso,
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updatedAt: typeof updatedAt === "string" ? updatedAt : nowIso,
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lastSnapshot: lastSnapshot || null,
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lastError: lastError || null,
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});
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return watchId;
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}
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removeWatch(watchId) {
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return this.watches.delete(watchId);
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}
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listWatchIds() {
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return Array.from(this.watches.keys());
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}
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async start() {
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if (this.timer) return;
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await this.pollAll();
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this.timer = setInterval(() => {
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void this.pollAll();
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}, this.pollIntervalMs);
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}
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stop() {
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if (!this.timer) return;
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clearInterval(this.timer);
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this.timer = null;
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}
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async pollAll() {
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if (!this.globalControls.crawlingEnabled) {
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const skipped = [];
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for (const watch of this.watches.values()) {
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const result = {
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watchId: watch.id,
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skipped: {
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reason: "global_crawling_disabled",
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},
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};
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skipped.push(result);
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await this.emitPolled(watch, result);
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}
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return skipped;
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}
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const results = [];
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for (const watch of this.watches.values()) {
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if (!watch.pollingEnabled) {
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const result = {
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watchId: watch.id,
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skipped: {
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reason: "watch_polling_disabled",
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},
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};
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results.push(result);
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await this.emitPolled(watch, result);
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continue;
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}
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// Poll sequentially to keep provider-side rate limits predictable.
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results.push(await this.pollWatch(watch.id));
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}
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return results;
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}
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async pollWatch(watchId) {
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const watch = this.watches.get(watchId);
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if (!watch) {
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throw new Error(`Unknown watchId: ${watchId}`);
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}
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if (!this.globalControls.crawlingEnabled) {
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const result = {
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watchId: watch.id,
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skipped: { reason: "global_crawling_disabled" },
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};
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await this.emitPolled(watch, result);
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return result;
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}
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if (!watch.pollingEnabled) {
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const result = {
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watchId: watch.id,
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skipped: { reason: "watch_polling_disabled" },
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};
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await this.emitPolled(watch, result);
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return result;
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}
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try {
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const offers = await this.crawler.getQuotes({
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watchId: watch.id,
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rawInput: watch.rawInput,
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searchParams: watch.searchParams,
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});
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const normalizedOffers = normalizeOffers(offers);
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if (normalizedOffers.length === 0) {
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throw new Error("Crawler returned no valid offers");
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}
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const bestOffer = normalizedOffers[0];
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const currentSnapshot = {
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polledAt: new Date(this.now()).toISOString(),
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bestPrice: bestOffer.price,
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currency: bestOffer.currency,
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bestOffer,
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offers: normalizedOffers,
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};
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const alert = buildAlertEvent(watch, watch.lastSnapshot, currentSnapshot);
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watch.lastSnapshot = currentSnapshot;
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watch.updatedAt = currentSnapshot.polledAt;
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let notificationSent = false;
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let notificationError = null;
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if (alert) {
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if (this.globalControls.alertsEnabled && watch.alertsEnabled) {
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try {
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await this.notifier.notify(alert);
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notificationSent = true;
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} catch (error) {
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const at = new Date(this.now()).toISOString();
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notificationError = createWatchError({
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message: `Notifier failed: ${error.message}`,
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at,
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phase: "notify",
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});
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this.logger.error(`[watch:${watch.id}] notify failed: ${error.message}`);
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}
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} else {
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alert.notificationSuppressed = true;
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}
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}
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watch.lastError = notificationError;
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if (notificationError) {
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watch.updatedAt = notificationError.at;
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}
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const result = {
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watchId: watch.id,
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snapshot: currentSnapshot,
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alert,
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notificationSent,
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};
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if (notificationError) {
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result.error = notificationError;
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}
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await this.emitPolled(watch, result);
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return result;
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} catch (error) {
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watch.lastError = createWatchError({
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message: error.message,
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at: new Date(this.now()).toISOString(),
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phase: "crawl",
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});
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watch.updatedAt = watch.lastError.at;
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this.logger.error(`[watch:${watch.id}] poll failed: ${error.message}`);
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const result = {
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watchId: watch.id,
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error: watch.lastError,
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};
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await this.emitPolled(watch, result);
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return result;
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}
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}
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}
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module.exports = {
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PriceWatcher,
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};
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Reference in New Issue
Block a user