const {
  incrementCounter,
  setGauge,
  recordHistogram,
  getMetrics,
  resetMetrics
} = require('../src/utils/metrics');

describe('Metrics Utility', () => {
  beforeEach(() => {
    resetMetrics();
  });

  describe('incrementCounter', () => {
    it('should increment a counter', () => {
      incrementCounter('test_counter');
      incrementCounter('test_counter');

      const metrics = getMetrics();
      const counter = metrics.counters.find(c => c.name === 'test_counter');

      expect(counter).toBeDefined();
      expect(counter.value).toBe(2);
    });

    it('should handle counters with labels', () => {
      incrementCounter('http_requests', { method: 'GET' });
      incrementCounter('http_requests', { method: 'POST' });
      incrementCounter('http_requests', { method: 'GET' });

      const metrics = getMetrics();
      const getCounter = metrics.counters.find(c =>
        c.name === 'http_requests' && c.labels.method === 'GET'
      );
      const postCounter = metrics.counters.find(c =>
        c.name === 'http_requests' && c.labels.method === 'POST'
      );

      expect(getCounter.value).toBe(2);
      expect(postCounter.value).toBe(1);
    });
  });

  describe('setGauge', () => {
    it('should set a gauge value', () => {
      setGauge('memory_usage', 85.5);

      const metrics = getMetrics();
      const gauge = metrics.gauges.find(g => g.name === 'memory_usage');

      expect(gauge).toBeDefined();
      expect(gauge.value).toBe(85.5);
    });

    it('should update existing gauge values', () => {
      setGauge('cpu_usage', 50);
      setGauge('cpu_usage', 75);

      const metrics = getMetrics();
      const gauge = metrics.gauges.find(g => g.name === 'cpu_usage');

      expect(gauge.value).toBe(75);
    });
  });

  describe('recordHistogram', () => {
    it('should record histogram values', () => {
      recordHistogram('response_time', 100);
      recordHistogram('response_time', 150);
      recordHistogram('response_time', 200);

      const metrics = getMetrics();
      const histogram = metrics.histograms.find(h => h.name === 'response_time');

      expect(histogram).toBeDefined();
      expect(histogram.count).toBe(3);
      expect(histogram.sum).toBe(450);
      expect(histogram.average).toBe(150);
      expect(histogram.min).toBe(100);
      expect(histogram.max).toBe(200);
    });
  });

  describe('getMetrics', () => {
    it('should return all metrics with runtime info', () => {
      incrementCounter('test_counter');
      setGauge('test_gauge', 42);
      recordHistogram('test_histogram', 100);

      const metrics = getMetrics();

      expect(metrics).toHaveProperty('counters');
      expect(metrics).toHaveProperty('gauges');
      expect(metrics).toHaveProperty('histograms');
      expect(metrics).toHaveProperty('runtime');
      expect(metrics).toHaveProperty('timestamp');

      expect(metrics.counters).toHaveLength(1);
      expect(metrics.gauges).toHaveLength(1);
      expect(metrics.histograms).toHaveLength(1);

      expect(metrics.runtime).toHaveProperty('uptime_seconds');
      expect(metrics.runtime).toHaveProperty('memory_usage_bytes');
    });
  });

  describe('resetMetrics', () => {
    it('should clear all metrics', () => {
      incrementCounter('test_counter');
      setGauge('test_gauge', 42);
      recordHistogram('test_histogram', 100);

      resetMetrics();

      const metrics = getMetrics();
      expect(metrics.counters).toHaveLength(0);
      expect(metrics.gauges).toHaveLength(0);
      expect(metrics.histograms).toHaveLength(0);
    });
  });
});