import { type HeartRateSample } from '../src/training/trainingTypes';
import {
  applyPan,
  applyZoomIn,
  applyZoomOut,
  buildChartViewport,
  formatTickLabel,
  granularityForSpan,
  isLiveTailSnap,
  pickSampleAtTimestamp,
  xFromTimestampMs,
  timestampMsFromX,
  type Viewport,
} from '../src/training/chartViewport';

const MIN_SPAN = 1_000;
const MAX_SPAN = 24 * 60 * 60 * 1_000;

function sample(timestamp: number, bpm: number): HeartRateSample {
  return {
    timestamp,
    bpm,
    contactDetected: null,
    rrIntervalsMs: [],
    deviceName: 'Magene H003',
  };
}

function viewport(startMs: number, endMs: number, liveTail = true): Viewport {
  return { startMs, endMs, liveTail };
}

describe('granularityForSpan', () => {
  test('returns minute granularity for spans >= 5 minutes', () => {
    const g = granularityForSpan(5 * 60 * 1_000);
    expect(g.kind).toBe('minute');
    expect(g.stepMs).toBe(60_000);
  });

  test('returns halfMinute granularity for spans >= 1 minute and < 5 minutes', () => {
    expect(granularityForSpan(60 * 1_000).kind).toBe('halfMinute');
    expect(granularityForSpan(4 * 60 * 1_000).kind).toBe('halfMinute');
    expect(granularityForSpan(5 * 60 * 1_000).kind).toBe('minute');
  });

  test('returns quarterMinute granularity for spans >= 30s and < 1 minute', () => {
    expect(granularityForSpan(30 * 1_000).kind).toBe('quarterMinute');
    expect(granularityForSpan(59 * 1_000).kind).toBe('quarterMinute');
  });

  test('returns tenSeconds granularity for spans >= 10s and < 30s', () => {
    expect(granularityForSpan(10 * 1_000).kind).toBe('tenSeconds');
    expect(granularityForSpan(29 * 1_000).kind).toBe('tenSeconds');
  });

  test('returns second granularity for spans >= 2s and < 10s', () => {
    expect(granularityForSpan(2 * 1_000).kind).toBe('second');
    expect(granularityForSpan(9 * 1_000).kind).toBe('second');
  });

  test('returns halfSecond granularity for spans < 2s', () => {
    expect(granularityForSpan(1_999).kind).toBe('halfSecond');
    expect(granularityForSpan(0).kind).toBe('halfSecond');
  });
});

describe('formatTickLabel', () => {
  const T = new Date('2026-06-14T09:30:45.500Z').getTime();

  test('minute granularity formats HH:mm in local time', () => {
    const g = granularityForSpan(5 * 60 * 1_000);
    const label = formatTickLabel(T, g);
    expect(label).toMatch(/^\d{2}:\d{2}$/);
  });

  test('second granularity formats HH:mm:ss', () => {
    const g = granularityForSpan(2 * 1_000);
    const label = formatTickLabel(T, g);
    expect(label).toMatch(/^\d{2}:\d{2}:\d{2}$/);
  });

  test('halfSecond granularity formats HH:mm:ss.S', () => {
    const g = granularityForSpan(500);
    const label = formatTickLabel(T, g);
    expect(label).toMatch(/^\d{2}:\d{2}:\d{2}\.\d$/);
  });
});

describe('buildChartViewport', () => {
  test('returns null for fewer than 2 samples', () => {
    expect(buildChartViewport([], { defaultSpanMs: 60_000 })).toBeNull();
    expect(
      buildChartViewport([sample(1_000, 90)], { defaultSpanMs: 60_000 }),
    ).toBeNull();
  });

  test('initial viewport fits the dataset when total span is smaller than defaultSpan', () => {
    const samples = [
      sample(1_000, 90),
      sample(11_000, 100),
      sample(21_000, 110),
    ];
    const vp = buildChartViewport(samples, { defaultSpanMs: 60_000 });
    expect(vp).not.toBeNull();
    expect(vp!.startMs).toBe(1_000);
    expect(vp!.endMs).toBe(21_000);
    expect(vp!.liveTail).toBe(true);
  });

  test('initial viewport keeps defaultSpan ending at the last sample when dataset is larger', () => {
    const samples = [
      sample(0, 90),
      sample(10_000, 100),
      sample(20_000, 110),
      sample(30_000, 120),
      sample(40_000, 130),
    ];
    const vp = buildChartViewport(samples, { defaultSpanMs: 30_000 });
    expect(vp).not.toBeNull();
    expect(vp!.endMs).toBe(40_000);
    expect(vp!.endMs - vp!.startMs).toBe(30_000);
    expect(vp!.liveTail).toBe(true);
  });

  test('initial viewport is non-live when liveTail: false is passed', () => {
    const samples = [sample(0, 90), sample(10_000, 100)];
    const vp = buildChartViewport(samples, {
      defaultSpanMs: 60_000,
      liveTail: false,
    });
    expect(vp!.liveTail).toBe(false);
  });

  test('sorts samples defensively before computing viewport', () => {
    const samples = [sample(30_000, 130), sample(0, 90), sample(15_000, 110)];
    const vp = buildChartViewport(samples, { defaultSpanMs: 60_000 });
    expect(vp!.startMs).toBe(0);
    expect(vp!.endMs).toBe(30_000);
  });
});

describe('applyZoomIn', () => {
  test('halves the span around the focus point', () => {
    const start = viewport(0, 60_000);
    const z = applyZoomIn(start, 30_000, {
      minSpanMs: MIN_SPAN,
      maxSpanMs: MAX_SPAN,
    });
    expect(z.endMs - z.startMs).toBe(30_000);
    expect(z.startMs + (z.endMs - z.startMs) / 2).toBeCloseTo(30_000, 0);
    expect(z.liveTail).toBe(false);
  });

  test('never goes below minSpanMs', () => {
    const start = viewport(0, 2_000);
    const z = applyZoomIn(start, 1_000, {
      minSpanMs: MIN_SPAN,
      maxSpanMs: MAX_SPAN,
    });
    expect(z.endMs - z.startMs).toBe(MIN_SPAN);
  });

  test('preserves focus when minSpan is hit', () => {
    const start = viewport(0, 2_000);
    const z = applyZoomIn(start, 1_000, {
      minSpanMs: MIN_SPAN,
      maxSpanMs: MAX_SPAN,
    });
    expect(z.startMs).toBeLessThanOrEqual(1_000);
    expect(z.endMs).toBeGreaterThanOrEqual(1_000);
  });

  test('forces liveTail=false (zoom is always a user interaction)', () => {
    const start = viewport(0, 60_000, true);
    expect(applyZoomIn(start, 30_000).liveTail).toBe(false);
  });
});

describe('applyZoomOut', () => {
  test('doubles the span around the focus point', () => {
    const start = viewport(0, 30_000, false);
    const z = applyZoomOut(start, 15_000, {
      minSpanMs: MIN_SPAN,
      maxSpanMs: MAX_SPAN,
    });
    expect(z.endMs - z.startMs).toBe(60_000);
    expect(z.startMs + (z.endMs - z.startMs) / 2).toBeCloseTo(15_000, 0);
  });

  test('never goes above maxSpanMs', () => {
    const start = viewport(0, 12 * 60 * 60 * 1_000, false);
    const z = applyZoomOut(start, 6 * 60 * 60 * 1_000, {
      minSpanMs: MIN_SPAN,
      maxSpanMs: MAX_SPAN,
    });
    expect(z.endMs - z.startMs).toBe(MAX_SPAN);
  });

  test('forces liveTail=false', () => {
    expect(applyZoomOut(viewport(0, 30_000, true), 15_000).liveTail).toBe(
      false,
    );
  });
});

describe('applyPan', () => {
  test('dx > 0 shifts the viewport forward in time and disables liveTail', () => {
    const start = viewport(0, 60_000, true);
    const p = applyPan(start, 100, 1); // 1 pixel per ms
    expect(p.startMs).toBe(100);
    expect(p.endMs).toBe(60_100);
    expect(p.liveTail).toBe(false);
  });

  test('dx < 0 shifts the viewport backward in time', () => {
    const start = viewport(0, 60_000, true);
    const p = applyPan(start, -50, 1);
    expect(p.startMs).toBe(-50);
    expect(p.endMs).toBe(59_950);
    expect(p.liveTail).toBe(false);
  });

  test('keeps liveTail false even if input was live (any pan detaches)', () => {
    const start = viewport(0, 60_000, true);
    expect(applyPan(start, 0.5, 1).liveTail).toBe(false);
  });
});

describe('isLiveTailSnap', () => {
  test('returns true when endMs is within 5% of last sample timestamp', () => {
    const vp = viewport(0, 100_000, false);
    expect(isLiveTailSnap(vp, 104_000)).toBe(true);
    expect(isLiveTailSnap(vp, 105_000, 0.05)).toBe(true);
  });

  test('returns false when endMs is more than 5% behind last sample timestamp', () => {
    const vp = viewport(0, 100_000, false);
    expect(isLiveTailSnap(vp, 110_000, 0.05)).toBe(false);
  });

  test('uses a custom snap fraction', () => {
    const vp = viewport(0, 100_000, false);
    expect(isLiveTailSnap(vp, 150_000, 0.5)).toBe(true);
    expect(isLiveTailSnap(vp, 250_000, 0.5)).toBe(false);
  });
});

describe('pickSampleAtTimestamp', () => {
  const samples = [
    sample(0, 80),
    sample(1_000, 90),
    sample(2_500, 100),
    sample(4_000, 110),
    sample(5_000, 120),
  ];

  test('returns the closest sample within tolerance', () => {
    expect(pickSampleAtTimestamp(samples, 2_400, 500)).toEqual(samples[2]);
    expect(pickSampleAtTimestamp(samples, 600, 500)).toEqual(samples[1]);
  });

  test('returns null when no sample is within tolerance', () => {
    expect(pickSampleAtTimestamp(samples, 3_500, 100)).toBeNull();
  });

  test('tolerates unsorted samples by considering the global closest', () => {
    const shuffled = [
      samples[3],
      samples[0],
      samples[2],
      samples[4],
      samples[1],
    ];
    expect(pickSampleAtTimestamp(shuffled, 2_400, 500)).toEqual(samples[2]);
  });

  test('returns null for empty input', () => {
    expect(pickSampleAtTimestamp([], 0, 1_000)).toBeNull();
  });
});

describe('xFromTimestampMs and timestampMsFromX', () => {
  const vp = viewport(0, 100_000, false);
  const chartWidth = 320;
  const padX = 14;

  test('xFromTimestampMs maps edge timestamps to padX and chartWidth-padX', () => {
    expect(xFromTimestampMs(0, vp, chartWidth, padX)).toBeCloseTo(padX, 5);
    expect(xFromTimestampMs(100_000, vp, chartWidth, padX)).toBeCloseTo(
      chartWidth - padX,
      5,
    );
    expect(xFromTimestampMs(50_000, vp, chartWidth, padX)).toBeCloseTo(
      chartWidth / 2,
      5,
    );
  });

  test('timestampMsFromX is the inverse of xFromTimestampMs', () => {
    const ts = 73_421;
    const x = xFromTimestampMs(ts, vp, chartWidth, padX);
    const back = timestampMsFromX(x, vp, chartWidth, padX);
    expect(back).toBeCloseTo(ts, 0);
  });

  test('timestampMsFromX clamps to viewport bounds', () => {
    const before = timestampMsFromX(-100, vp, chartWidth, padX);
    expect(before).toBeLessThanOrEqual(vp.startMs);
    const after = timestampMsFromX(500, vp, chartWidth, padX);
    expect(after).toBeGreaterThanOrEqual(vp.endMs);
  });
});