module4_backend_project/tests/integration/duplicate-prevention.test.js

const request = require("supertest");
const app = require("../../server");
const redisClient = require("../../src/utils/redis-client");
const fallbackStore = require("../../src/utils/fallback-store");

describe("Duplicate Ticket Prevention - Integration Tests", () => {
  let server;
  let testEventId = "999"; // Use a unique event ID for testing

  beforeAll(async () => {
    // Start the server
    server = app.listen(0); // Use random port

    // Wait for server to be ready
    await new Promise((resolve) => setTimeout(resolve, 1000));

    // Ensure Redis is connected
    if (!redisClient.isConnected) {
      await redisClient.connect();
    }
  });

  afterAll(async () => {
    // Clean up test data
    try {
      if (redisClient.isConnected) {
        const testEventKey = `event:${testEventId}:meta`;
        const testTicketsKey = `event:${testEventId}:tickets`;
        await redisClient.client.del(testEventKey);
        await redisClient.client.del(testTicketsKey);
      }
    } catch (error) {
      console.warn("Failed to cleanup test data:", error.message);
    }

    // Close server
    if (server) {
      await new Promise((resolve) => server.close(resolve));
    }

    // Disconnect Redis
    if (redisClient.isConnected) {
      await redisClient.disconnect();
    }
  });

  beforeEach(async () => {
    // Reset fallback store
    fallbackStore.deactivate();
    fallbackStore.events.clear();
    fallbackStore.globalStats = {
      totalEvents: 0,
      totalTickets: 0,
      totalSold: 0,
      lastSeeded: null,
    };

    // Create test event with 10 tickets in Redis
    if (redisClient.isConnected) {
      const testEventKey = `event:${testEventId}:meta`;
      const testTicketsKey = `event:${testEventId}:tickets`;

      // Create event metadata
      await redisClient.client.hSet(testEventKey, {
        eventId: testEventId,
        name: "Test Event for Duplicate Prevention",
        description: "Test event to verify no duplicate tickets",
        totalTickets: "10",
        soldTickets: "0",
        createdAt: new Date().toISOString(),
        lastSoldAt: "never",
      });

      // Create 10 test tickets
      const testTickets = Array.from(
        { length: 10 },
        (_, i) => `test-ticket-${i + 1}`
      );
      await redisClient.client.lPush(testTicketsKey, testTickets);

      // Update global stats
      await redisClient.client.hSet("global:stats", {
        totalEvents: "1",
        totalTickets: "10",
        totalSold: "0",
        lastSeeded: new Date().toISOString(),
      });
    }
  });

  describe("Redis Ticket Purchase - Duplicate Prevention", () => {
    test("should prevent duplicate ticket sales under normal conditions", async () => {
      if (!redisClient.isConnected) {
        console.warn("Skipping Redis test - Redis not connected");
        return;
      }

      const purchaseIds = [];
      const soldTickets = new Set();
      let successCount = 0;
      let failureCount = 0;

      // Attempt to purchase 15 tickets (more than available)
      for (let i = 0; i < 15; i++) {
        const purchaseId = `test-purchase-${Date.now()}-${i}`;
        purchaseIds.push(purchaseId);

        try {
          const response = await request(server)
            .post(`/buy/${testEventId}`)
            .set("Content-Type", "application/json");

          if (response.status === 200 && response.body.success) {
            successCount++;
            const ticket = response.body.ticket;

            // Verify ticket is unique
            expect(soldTickets.has(ticket)).toBe(false);
            soldTickets.add(ticket);

            expect(response.body.usingFallback).toBe(false);
          } else {
            failureCount++;
            expect(response.status).toBe(409); // No tickets available
            expect(response.body.message).toContain("No tickets available");
          }
        } catch (error) {
          failureCount++;
        }
      }

      // Should have sold exactly 10 tickets (no duplicates)
      expect(successCount).toBe(10);
      expect(failureCount).toBe(5);
      expect(soldTickets.size).toBe(10);

      // Verify no tickets remain
      const remainingTickets = await redisClient.client.lLen(
        `event:${testEventId}:tickets`
      );
      expect(remainingTickets).toBe(0);
    });

    test("should prevent duplicate tickets under concurrent load", async () => {
      if (!redisClient.isConnected) {
        console.warn("Skipping Redis test - Redis not connected");
        return;
      }

      // Reset test event with 5 tickets
      const testTicketsKey = `event:${testEventId}:tickets`;
      await redisClient.client.del(testTicketsKey);
      const testTickets = Array.from(
        { length: 5 },
        (_, i) => `concurrent-ticket-${i + 1}`
      );
      await redisClient.client.lPush(testTicketsKey, testTickets);

      const soldTickets = new Set();
      const purchasePromises = [];

      // Create 10 concurrent purchase requests
      for (let i = 0; i < 10; i++) {
        const purchaseId = `concurrent-purchase-${Date.now()}-${i}`;

        const promise = request(server)
          .post(`/buy/${testEventId}`)
          .set("Content-Type", "application/json")
          .then((response) => ({ success: true, response, purchaseId }))
          .catch((error) => ({ success: false, error, purchaseId }));

        purchasePromises.push(promise);
      }

      // Wait for all requests to complete
      const results = await Promise.all(purchasePromises);

      let successCount = 0;
      let failureCount = 0;

      results.forEach((result) => {
        if (
          result.success &&
          result.response.status === 200 &&
          result.response.body.success
        ) {
          successCount++;
          const ticket = result.response.body.ticket;

          // Verify ticket is unique
          expect(soldTickets.has(ticket)).toBe(false);
          soldTickets.add(ticket);
        } else {
          failureCount++;
        }
      });

      // Should have sold exactly 5 tickets (no duplicates)
      expect(successCount).toBe(5);
      expect(failureCount).toBe(5);
      expect(soldTickets.size).toBe(5);

      // Verify no tickets remain
      const remainingTickets = await redisClient.client.lLen(testTicketsKey);
      expect(remainingTickets).toBe(0);
    });
  });

  describe("Fallback Store - Duplicate Prevention", () => {
    test("should prevent duplicate tickets in fallback mode", async () => {
      // Seed fallback store with test event
      const metadata = {
        eventId: testEventId,
        name: "Test Event for Duplicate Prevention",
        description: "Test event to verify no duplicate tickets",
        totalTickets: 5,
        soldTickets: 0,
        createdAt: new Date().toISOString(),
        lastSoldAt: "never",
      };

      const testTickets = Array.from(
        { length: 5 },
        (_, i) => `fallback-ticket-${i + 1}`
      );
      fallbackStore.seedEvent(testEventId, testTickets, metadata);
      fallbackStore.activate("Test activation");

      const soldTickets = new Set();
      let successCount = 0;
      let failureCount = 0;

      // Attempt to purchase 8 tickets (more than available)
      for (let i = 0; i < 8; i++) {
        const purchaseId = `fallback-purchase-${Date.now()}-${i}`;

        try {
          const response = await request(server)
            .post(`/buy/${testEventId}`)
            .set("Content-Type", "application/json");

          if (response.status === 200 && response.body.success) {
            successCount++;
            const ticket = response.body.ticket;

            // Verify ticket is unique
            expect(soldTickets.has(ticket)).toBe(false);
            soldTickets.add(ticket);

            expect(response.body.usingFallback).toBe(true);
          } else {
            failureCount++;
            expect(response.status).toBe(409); // No tickets available
            expect(response.body.message).toContain("No tickets available");
          }
        } catch (error) {
          failureCount++;
        }
      }

      // Should have sold exactly 5 tickets (no duplicates)
      expect(successCount).toBe(5);
      expect(failureCount).toBe(3);
      expect(soldTickets.size).toBe(5);

      // Verify no tickets remain in fallback store
      const event = fallbackStore.events.get(testEventId);
      expect(event.tickets).toHaveLength(0);
    });
  });

  describe("Mixed Mode - Redis + Fallback", () => {
    test("should prevent duplicates when switching between Redis and fallback", async () => {
      if (!redisClient.isConnected) {
        console.warn("Skipping Redis test - Redis not connected");
        return;
      }

      // Start with Redis
      const soldTickets = new Set();

      // Purchase 3 tickets from Redis
      for (let i = 0; i < 3; i++) {
        const purchaseId = `mixed-purchase-redis-${Date.now()}-${i}`;

        const response = await request(server)
          .post(`/buy/${testEventId}`)
          .set("Content-Type", "application/json");

        expect(response.status).toBe(200);
        expect(response.body.success).toBe(true);
        expect(response.body.usingFallback).toBe(false);

        const ticket = response.body.ticket;
        expect(soldTickets.has(ticket)).toBe(false);
        soldTickets.add(ticket);
      }

      // Simulate Redis failure by disconnecting
      await redisClient.disconnect();

      // Purchase remaining tickets from fallback
      for (let i = 0; i < 7; i++) {
        const purchaseId = `mixed-purchase-fallback-${Date.now()}-${i}`;

        const response = await request(server)
          .post(`/buy/${testEventId}`)
          .set("Content-Type", "application/json");

        expect(response.status).toBe(200);
        expect(response.body.success).toBe(true);
        expect(response.body.usingFallback).toBe(true);

        const ticket = response.body.ticket;
        expect(soldTickets.has(ticket)).toBe(false);
        soldTickets.add(ticket);
      }

      // Verify total unique tickets sold
      expect(soldTickets.size).toBe(10);

      // Try to purchase one more (should fail)
      const response = await request(server)
        .post(`/buy/${testEventId}`)
        .set("Content-Type", "application/json");

      expect(response.status).toBe(409);
      expect(response.body.success).toBe(false);
      expect(response.body.message).toContain("No tickets available");
    });
  });

  describe("Data Integrity Verification", () => {
    test("should maintain consistent ticket counts across Redis and fallback", async () => {
      if (!redisClient.isConnected) {
        console.warn("Skipping Redis test - Redis not connected");
        return;
      }

      // Purchase 3 tickets
      for (let i = 0; i < 3; i++) {
        const purchaseId = `integrity-purchase-${Date.now()}-${i}`;

        const response = await request(server)
          .post(`/buy/${testEventId}`)
          .set("Content-Type", "application/json");

        expect(response.status).toBe(200);
        expect(response.body.success).toBe(true);
      }

      // Check Redis stats
      const redisStats = await redisClient.getEventStats(testEventId);
      expect(redisStats.remainingTickets).toBe(7);
      expect(redisStats.soldTickets).toBe(3);

      // Check fallback store stats (should be synced)
      fallbackStore.activate("Test activation");
      const fallbackStats = fallbackStore.getEventStats(testEventId);
      expect(fallbackStats.remainingTickets).toBe(7);
      expect(fallbackStats.soldTickets).toBe(3);

      // Verify global stats
      const globalStats = await redisClient.getGlobalStats();
      expect(globalStats.totalSold).toBe(3);
    });
  });
});