/**
 * Performance Test: Queue Service Throughput
 *
 * Benchmarks the queue service's pure functions under load
 * to verify performance characteristics.
 *
 * Covers issue #229 (ORCH-128)
 */
import { describe, it, expect, beforeEach, vi } from "vitest";
import { QueueService } from "../../src/queue/queue.service";
import { ConfigService } from "@nestjs/config";

describe("Performance: Queue Service", () => {
  let service: QueueService;

  const mockValkeyService = {
    getConnection: vi.fn().mockReturnValue({
      host: "localhost",
      port: 6379,
    }),
    updateTaskStatus: vi.fn().mockResolvedValue(undefined),
    publishEvent: vi.fn().mockResolvedValue(undefined),
  };

  const mockConfigService = {
    get: vi.fn((key: string, defaultValue?: unknown) => {
      const config: Record<string, unknown> = {
        "orchestrator.queue.name": "perf-test-queue",
        "orchestrator.queue.maxRetries": 3,
        "orchestrator.queue.baseDelay": 1000,
        "orchestrator.queue.maxDelay": 60000,
      };
      return config[key] ?? defaultValue;
    }),
  };

  beforeEach(() => {
    vi.clearAllMocks();
    service = new QueueService(
      mockValkeyService as never,
      mockConfigService as unknown as ConfigService
    );
  });

  describe("Backoff calculation performance", () => {
    it("should calculate 10,000 backoff delays in under 10ms", () => {
      // Warmup
      for (let i = 0; i < 100; i++) {
        service.calculateBackoffDelay(i % 20, 1000, 60000);
      }

      const start = performance.now();

      for (let i = 0; i < 10000; i++) {
        service.calculateBackoffDelay(i % 20, 1000, 60000);
      }

      const duration = performance.now() - start;
      expect(duration).toBeLessThan(10);
    });

    it("should produce consistent results under rapid invocation", () => {
      const results: number[] = [];

      for (let attempt = 0; attempt <= 10; attempt++) {
        const delay = service.calculateBackoffDelay(attempt, 1000, 60000);
        results.push(delay);
      }

      // Verify expected exponential pattern
      expect(results[0]).toBe(1000); // 1000 * 2^0
      expect(results[1]).toBe(2000); // 1000 * 2^1
      expect(results[2]).toBe(4000); // 1000 * 2^2
      expect(results[3]).toBe(8000); // 1000 * 2^3

      // After attempt 6 (64000), should be capped at 60000
      expect(results[6]).toBe(60000);
      expect(results[10]).toBe(60000);
    });
  });

  describe("Backoff calculation at scale", () => {
    it("should handle all retry levels from 0 to 100 consistently", () => {
      // Warmup
      for (let i = 0; i < 50; i++) {
        service.calculateBackoffDelay(i, 1000, 60000);
      }

      const start = performance.now();
      const results = new Map<number, number>();

      for (let attempt = 0; attempt <= 100; attempt++) {
        const delay = service.calculateBackoffDelay(attempt, 1000, 60000);
        results.set(attempt, delay);
      }

      const duration = performance.now() - start;
      expect(duration).toBeLessThan(10);

      // Verify monotonic increase up to cap
      for (let attempt = 1; attempt <= 100; attempt++) {
        const current = results.get(attempt) ?? 0;
        const previous = results.get(attempt - 1) ?? 0;
        expect(current).toBeGreaterThanOrEqual(previous);
        expect(current).toBeLessThanOrEqual(60000);
      }
    });

    it("should calculate backoffs with varying base delays rapidly", () => {
      const baseDelays = [100, 500, 1000, 2000, 5000];
      const maxDelays = [10000, 30000, 60000, 120000];

      // Warmup
      service.calculateBackoffDelay(0, 1000, 60000);

      const start = performance.now();

      for (const base of baseDelays) {
        for (const max of maxDelays) {
          for (let attempt = 0; attempt < 20; attempt++) {
            const delay = service.calculateBackoffDelay(attempt, base, max);
            expect(delay).toBeLessThanOrEqual(max);
            expect(delay).toBeGreaterThanOrEqual(base);
          }
        }
      }

      const duration = performance.now() - start;
      // 5 * 4 * 20 = 400 calculations should complete quickly
      expect(duration).toBeLessThan(50);
    });
  });
});