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2025-09-14 15:15:03 +03:30
commit be82059172
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+import { EventEmitter } from "events";
+
+import { HydratedDocument, Types } from "mongoose";
+
+import { ColorModel } from "../modules/category/models/color.model";
+import { MeterageModel } from "../modules/category/models/meterage.model";
+import { SizeModel } from "../modules/category/models/size.model";
+import { IPriceHistory } from "../modules/product/models/Abstraction/IPriceHistory";
+import { PriceHistoryModel } from "../modules/product/models/priceHistory.model";
+import { ProductObserveModel } from "../modules/product/models/productObserve.model";
+import { IUser } from "../modules/user/models/Abstraction/IUser";
+import { EmailService } from "../utils/email.service";
+import { TimeService } from "../utils/time.service"; // Use DI to inject TimeService for better testability
+
+enum PriceChangeEventType {
+  PRICE_CHANGE = "priceChange",
+  OBSERVER_NOTIFICATION = "observerNotification",
+}
+
+type PriceDetails = {
+  product: number;
+  shop: string;
+  selling_price: number;
+  retail_price: number;
+  variantId: string;
+  isSpecial?: boolean;
+  colorId?: number;
+  sizeId?: number;
+  meterageId?: number;
+};
+
+type historyDetail = { shop: string; selling_price: number; retail_price: number };
+
+class PriceChangeEventService extends EventEmitter {
+  private static instance: PriceChangeEventService;
+
+  private constructor() {
+    super();
+    this.subscribeToEvents();
+  }
+  //**** */
+  public static getInstance(): PriceChangeEventService {
+    if (!PriceChangeEventService.instance) {
+      PriceChangeEventService.instance = new PriceChangeEventService();
+    }
+    return PriceChangeEventService.instance;
+  }
+  //**** */
+  public emitPriceChange(priceDetails: PriceDetails): void {
+    this.emit(PriceChangeEventType.PRICE_CHANGE, priceDetails);
+    if (priceDetails.isSpecial) {
+      this.emitObserverNotification(priceDetails);
+    }
+  }
+  //**** */
+  private emitObserverNotification(priceDetails: PriceDetails): void {
+    this.emit(PriceChangeEventType.OBSERVER_NOTIFICATION, priceDetails);
+  }
+  //**** */
+  private subscribeToEvents(): void {
+    this.on(PriceChangeEventType.PRICE_CHANGE, this.handlePriceChange);
+    this.on(PriceChangeEventType.OBSERVER_NOTIFICATION, this.handleObserverNotification);
+  }
+  //**** */
+  private async handlePriceChange(priceDetails: PriceDetails): Promise<void> {
+    try {
+      const title = await this.findVariantTitle(priceDetails);
+      const now = TimeService.getCurrentPersianDate();
+      const { colorId, sizeId, meterageId, product, ...history } = priceDetails;
+
+      const existingHistory = await PriceHistoryModel.findOne({ title, product });
+
+      if (existingHistory) {
+        await this.appendPriceHistory(existingHistory, history, now);
+        console.log(`Updated price history for product ${product} with price: ${history.selling_price}`);
+      } else {
+        await this.createPriceHistory(title, product, history, now);
+        console.log(`Created new price history for product ${product} with price: ${history.selling_price}`);
+      }
+    } catch (error) {
+      console.error("Failed to record price change:", error);
+    }
+  }
+  //**** */
+  private async handleObserverNotification(priceDetails: PriceDetails): Promise<void> {
+    try {
+      const observers = await this.findObserversForProduct(priceDetails.product, priceDetails.variantId);
+
+      for (const observer of observers) {
+        const user = observer.user as unknown as IUser;
+        const emailContent = this.generateEmailContent(user.fullName, observer.registeredPrice, priceDetails);
+        await EmailService.sendEmail({
+          subject: "تخفیف ویژه",
+          to: user.email,
+          text: emailContent,
+        });
+        console.log(`Sent notification to observer: ${user.email}`);
+      }
+    } catch (error) {
+      console.error("Failed to send observer notifications:", error);
+    }
+  }
+
+  //**** */
+  private async findObserversForProduct(productId: number, variantId: string) {
+    return await ProductObserveModel.find({ product: productId, variant: variantId }).populate("user").lean();
+  }
+  //**** */
+  private generateEmailContent(userName: string, observerPrice: number, priceDetails: PriceDetails): string {
+    const priceDiff = observerPrice - priceDetails.selling_price;
+    const message = `کاربر گرامی ${userName},\n\nقیمت محصولی که شما برای آن منتظر شده‌اید، به ${priceDetails.selling_price} تغییر کرده است.`;
+
+    if (priceDiff > 0) {
+      return message + `\n\nاین قیمت ${priceDiff} تومان کمتر از قیمت هدف شما است. این فرصت را از دست ندهید!`;
+    } else {
+      return message + `\n\nاین یک پیشنهاد ویژه است که ممکن است برای شما جذاب باشد!`;
+    }
+  }
+  //**** */
+  private async appendPriceHistory(existHistory: HydratedDocument<IPriceHistory>, history: historyDetail, now: string) {
+    existHistory.history.push({
+      ...history,
+      date: now,
+      shop: new Types.ObjectId(history.shop),
+    });
+    await existHistory.save();
+  }
+  //**** */
+  private async createPriceHistory(title: string, product: number, history: historyDetail, now: string): Promise<void> {
+    const priceHistory = new PriceHistoryModel({ title, product });
+    priceHistory.history.push({
+      ...history,
+      date: now,
+      shop: new Types.ObjectId(history.shop),
+    });
+    await priceHistory.save();
+  }
+  //**** */
+  private async findVariantTitle(priceDetails: PriceDetails): Promise<string> {
+    if (priceDetails.colorId) {
+      const color = await ColorModel.findById(priceDetails.colorId).lean();
+      return color?.name || "Unknown color";
+    } else if (priceDetails.sizeId) {
+      const size = await SizeModel.findById(priceDetails.sizeId).lean();
+      return size?.value || "Unknown size";
+    } else if (priceDetails.meterageId) {
+      const meterage = await MeterageModel.findById(priceDetails.meterageId).lean();
+      return meterage?.value || "Unknown meterage";
+    }
+    return "";
+  }
+}
+
+const instance = PriceChangeEventService.getInstance();
+
+export { instance as PriceChangeEvent, PriceChangeEventService, PriceChangeEventType };