/**
 * Tests for PerformanceCollector with mocked page.evaluate.
 */

import { PerformanceCollector, DEFAULT_PERF_CONFIG } from '../../src/plugins/collectors/PerformanceCollector';
import type { IAction } from '../../src/core/interfaces';

// ─── Helpers ──────────────────────────────────────────────────────────────────

function makeAction(): IAction {
  return { id: 'a1', type: 'click', timestamp: Date.now(), seed: 42, stateId: 'state1' };
}

function makePage(timing = { ttfb: 100, domContentLoaded: 500, loadComplete: 1000 }, vitals = { lcp: null as number | null, cls: null as number | null, inp: null as number | null }) {
  return {
    url: () => 'http://localhost:3000/page',
    evaluate: jest.fn()
      .mockResolvedValueOnce(timing)
      .mockResolvedValueOnce(vitals),
  };
}

// ─── Tests ────────────────────────────────────────────────────────────────────

describe('PerformanceCollector — disabled', () => {
  it('returns zeroed metrics and no anomalies when disabled', async () => {
    const collector = new PerformanceCollector({ enabled: false });
    const page = makePage();
    const { metrics, anomalies } = await collector.collect(page as never, 'state1', 'sess1', []);

    expect(anomalies).toHaveLength(0);
    expect(metrics.ttfb).toBe(0);
    expect(metrics.lcp).toBeNull();
    expect(page.evaluate).not.toHaveBeenCalled();
  });
});

describe('PerformanceCollector — enabled', () => {
  it('captures timing metrics correctly', async () => {
    const collector = new PerformanceCollector({ enabled: true });
    const page = makePage(
      { ttfb: 200, domContentLoaded: 800, loadComplete: 1500 },
      { lcp: null, cls: null, inp: null }
    );

    const { metrics } = await collector.collect(page as never, 'state1', 'sess1', [makeAction()]);

    expect(metrics.ttfb).toBe(200);
    expect(metrics.domContentLoaded).toBe(800);
    expect(metrics.loadComplete).toBe(1500);
    expect(metrics.sessionId).toBe('sess1');
    expect(metrics.stateId).toBe('state1');
    expect(metrics.url).toBe('http://localhost:3000/page');
  });

  it('captures Core Web Vitals when available', async () => {
    const collector = new PerformanceCollector({ enabled: true });
    const page = makePage(
      { ttfb: 100, domContentLoaded: 400, loadComplete: 900 },
      { lcp: 1800, cls: 0.05, inp: 120 }
    );

    const { metrics } = await collector.collect(page as never, 'state1', 'sess1', []);
    expect(metrics.lcp).toBe(1800);
    expect(metrics.cls).toBe(0.05);
    expect(metrics.inp).toBe(120);
  });

  it('returns no anomalies when all metrics are within thresholds', async () => {
    const collector = new PerformanceCollector({
      enabled: true,
      lcpThresholdMs: 4000,
      clsThreshold: 0.25,
      inpThresholdMs: 500,
      ttfbThresholdMs: 1800,
    });
    const page = makePage(
      { ttfb: 200, domContentLoaded: 500, loadComplete: 1000 },
      { lcp: 1500, cls: 0.05, inp: 100 }
    );

    const { anomalies } = await collector.collect(page as never, 'state1', 'sess1', []);
    expect(anomalies).toHaveLength(0);
  });

  it('detects LCP violation above threshold', async () => {
    const collector = new PerformanceCollector({
      enabled: true,
      lcpThresholdMs: 2500,
      clsThreshold: 0.25,
      inpThresholdMs: 500,
      ttfbThresholdMs: 1800,
    });
    const page = makePage(
      { ttfb: 200, domContentLoaded: 600, loadComplete: 1200 },
      { lcp: 5000, cls: 0.01, inp: 50 }
    );

    const { anomalies } = await collector.collect(page as never, 'state1', 'sess1', [makeAction()]);
    expect(anomalies).toHaveLength(1);
    expect(anomalies[0]!.type).toBe('performance_degradation');
    expect(anomalies[0]!.severity).toBe('high');
    expect(anomalies[0]!.description).toContain('LCP');
    expect(anomalies[0]!.evidence.rawErrors).toEqual(
      expect.arrayContaining([expect.stringContaining('LCP')])
    );
  });

  it('detects TTFB violation above threshold', async () => {
    const collector = new PerformanceCollector({
      enabled: true,
      lcpThresholdMs: 4000,
      clsThreshold: 0.25,
      inpThresholdMs: 500,
      ttfbThresholdMs: 800,
    });
    const page = makePage(
      { ttfb: 2000, domContentLoaded: 2500, loadComplete: 4000 },
      { lcp: null, cls: null, inp: null }
    );

    const { anomalies } = await collector.collect(page as never, 'state1', 'sess1', []);
    expect(anomalies).toHaveLength(1);
    expect(anomalies[0]!.type).toBe('performance_degradation');
    expect(anomalies[0]!.evidence.rawErrors).toEqual(
      expect.arrayContaining([expect.stringContaining('TTFB')])
    );
  });

  it('detects CLS violation', async () => {
    const collector = new PerformanceCollector({
      enabled: true,
      lcpThresholdMs: 4000,
      clsThreshold: 0.1,
      inpThresholdMs: 500,
      ttfbThresholdMs: 1800,
    });
    const page = makePage(
      { ttfb: 200, domContentLoaded: 500, loadComplete: 1000 },
      { lcp: null, cls: 0.35, inp: null }
    );

    const { anomalies } = await collector.collect(page as never, 'state1', 'sess1', []);
    expect(anomalies).toHaveLength(1);
    const rawErrors = anomalies[0]!.evidence.rawErrors ?? [];
    expect(rawErrors.some((e) => e.includes('CLS'))).toBe(true);
  });

  it('accumulates metrics in getMetrics()', async () => {
    const collector = new PerformanceCollector({ enabled: true });
    const page = makePage(
      { ttfb: 100, domContentLoaded: 400, loadComplete: 800 },
      { lcp: null, cls: null, inp: null }
    );

    await collector.collect(page as never, 'state1', 'sess1', []);

    const page2 = makePage(
      { ttfb: 150, domContentLoaded: 450, loadComplete: 900 },
      { lcp: 2000, cls: null, inp: null }
    );
    await collector.collect(page2 as never, 'state2', 'sess1', []);

    expect(collector.getMetrics()).toHaveLength(2);
  });

  it('handles page.evaluate failure gracefully', async () => {
    const collector = new PerformanceCollector({ enabled: true });
    const page = {
      url: () => 'http://localhost',
      evaluate: jest.fn().mockRejectedValue(new Error('page disconnected')),
    };

    const { metrics, anomalies } = await collector.collect(page as never, 's1', 'sess1', []);
    expect(metrics.ttfb).toBe(0);
    expect(anomalies).toHaveLength(0);
  });

  it('uses default thresholds matching DEFAULT_PERF_CONFIG', () => {
    expect(DEFAULT_PERF_CONFIG.lcpThresholdMs).toBe(4000);
    expect(DEFAULT_PERF_CONFIG.clsThreshold).toBe(0.25);
    expect(DEFAULT_PERF_CONFIG.inpThresholdMs).toBe(500);
    expect(DEFAULT_PERF_CONFIG.ttfbThresholdMs).toBe(1800);
  });
});