import { describe, expect, it } from "vite-plus/test";import {  getAnchoredTurnMetrics,  getRowBottom,  timelineContentOverflowsViewport,} from "./timelineScrollAnchoring"; function buildState({  positions,  sizes,  scroll = 0,  scrollLength = 700,}: {  readonly positions: readonly number[];  readonly sizes: readonly number[];  readonly scroll?: number;  readonly scrollLength?: number;}) {  return {    data: positions.map((_, index) => index),    scroll,    scrollLength,    positionAtIndex: (index: number) => positions[index],    sizeAtIndex: (index: number) => sizes[index],  };} describe("timelineContentOverflowsViewport", () => {  const inset = { composerInset: 100, anchorOffset: 24 };   it("reports overflow from the last row, not the inset spacer", () => {    const fits = buildState({ positions: [0, 200], sizes: [200, 300], scrollLength: 700 });    expect(timelineContentOverflowsViewport(fits, inset)).toBe(false);     const overflows = buildState({ positions: [0, 200], sizes: [200, 400], scrollLength: 700 });    expect(timelineContentOverflowsViewport(overflows, inset)).toBe(true);  });   it("treats an empty or unmeasured list as fitting", () => {    expect(timelineContentOverflowsViewport(undefined, inset)).toBe(false);    expect(      timelineContentOverflowsViewport(        buildState({ positions: [0, 200], sizes: [200, 400], scrollLength: 0 }),        inset,      ),    ).toBe(false);    expect(timelineContentOverflowsViewport(buildState({ positions: [], sizes: [] }), inset)).toBe(      false,    );    expect(      timelineContentOverflowsViewport(        buildState({ positions: [0, 200], sizes: [200, Number.NaN] }),        inset,      ),    ).toBe(false);  });}); describe("timeline scroll anchoring", () => {  it("measures row bottoms from LegendList row position and size", () => {    const state = buildState({      positions: [0, 120],      sizes: [80, 40],    });     expect(getRowBottom(state, 1)).toBe(160);  });   it("treats the active turn as fitting when it fits above the composer", () => {    const state = buildState({      positions: [0, 300, 460],      sizes: [240, 80, 140],      scrollLength: 760,    });     const metrics = getAnchoredTurnMetrics({      state,      anchorIndex: 1,      composerOverlayHeight: 180,      anchorOffset: 16,    });     expect(metrics?.turnHeight).toBe(300);    expect(metrics?.usableViewportHeight).toBe(564);    expect(metrics?.overflowsUsableViewport).toBe(false);    expect(metrics?.targetScrollToRevealEnd).toBe(36);    expect(metrics?.scrollDeltaToRevealEnd).toBe(36);  });   it("targets the real row end instead of any temporary reserved tail", () => {    const state = buildState({      positions: [0, 1720, 1880],      sizes: [1600, 80, 120],      scroll: 1900,      scrollLength: 760,    });     const metrics = getAnchoredTurnMetrics({      state,      anchorIndex: 1,      composerOverlayHeight: 180,      anchorOffset: 16,    });     expect(metrics?.lastBottom).toBe(2000);    expect(metrics?.targetScrollToRevealEnd).toBe(1436);    expect(metrics?.scrollDeltaToRevealEnd).toBe(0);  });   it("reports overflow only for the current anchored turn", () => {    const state = buildState({      positions: [0, 900, 1180],      sizes: [800, 220, 300],      scroll: 900,      scrollLength: 760,    });     const metrics = getAnchoredTurnMetrics({      state,      anchorIndex: 1,      composerOverlayHeight: 180,      anchorOffset: 16,    });     expect(metrics?.turnHeight).toBe(580);    expect(metrics?.usableViewportHeight).toBe(564);    expect(metrics?.overflowsUsableViewport).toBe(true);  });   it("returns the minimal positive scroll delta needed to reveal the turn end", () => {    const state = buildState({      positions: [0, 900, 1180],      sizes: [800, 220, 360],      scroll: 900,      scrollLength: 760,    });     const metrics = getAnchoredTurnMetrics({      state,      anchorIndex: 1,      composerOverlayHeight: 180,      anchorOffset: 16,    });     expect(metrics?.lastBottom).toBe(1540);    expect(metrics?.visibleUsableBottom).toBe(1464);    expect(metrics?.scrollDeltaToRevealEnd).toBe(76);  });   it("subtracts composer height from usable viewport height", () => {    const state = buildState({      positions: [0, 300],      sizes: [120, 470],      scrollLength: 700,    });     const withoutComposer = getAnchoredTurnMetrics({      state,      anchorIndex: 1,      composerOverlayHeight: 0,      anchorOffset: 16,    });    const withComposer = getAnchoredTurnMetrics({      state,      anchorIndex: 1,      composerOverlayHeight: 220,      anchorOffset: 16,    });     expect(withoutComposer?.overflowsUsableViewport).toBe(false);    expect(withComposer?.overflowsUsableViewport).toBe(true);  });});