All files / src/components/TimelineSliderV2 layout.ts

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import type {
  BuildLayoutParams,
  ColorWeight,
  LayoutMark,
  PositionedMark,
  TimelineCluster,
  TimelineLayout,
  TimelineNode,
} from './types';
 
export const DOT_SIZE_PX = 12;
export const CLUSTER_DOT_SIZE_PX = 18;
export const EXPANDED_SPACING_PX = 20;
export const MIN_SQUEEZE_PITCH_PX = DOT_SIZE_PX;
export const BAND_PADDING_PX = 8;
export const SQUEEZE_GAP_PX = 12;
export const MAX_BAND_RATIO = 0.8;
export const DEFAULT_CLUSTER_THRESHOLD_PX = 16;
export const DIMMED_OPACITY = 0.35;
 
export const normalizePositions = (marks: LayoutMark[], containerWidth: number): PositionedMark[] => {
  if (marks.length === 0) {
    return [];
  }
 
  const values = marks.map((mark) => mark.value);
  const minValue = Math.min(...values);
  const maxValue = Math.max(...values);
  const range = maxValue - minValue;
 
  // Mirrors TimelineSlider's behavior: when every mark shares one value, they all land at the right edge.
  return marks
    .map((mark) => ({
      color: mark.color,
      id: mark.id,
      positionPx: (range === 0 ? 1 : (mark.value - minValue) / range) * containerWidth,
    }))
    .sort((a, b) => a.positionPx - b.positionPx);
};
 
export const toColorWeights = (colors: string[]): ColorWeight[] => {
  const weights = new Map<string, number>();
 
  colors.forEach((color) => {
    weights.set(color, (weights.get(color) ?? 0) + 1);
  });
 
  return [...weights.entries()].map(([color, weight]) => ({ color, weight }));
};
 
export const buildClusters = (marks: LayoutMark[], containerWidth: number, thresholdPx: number): TimelineCluster[] => {
  const positioned = normalizePositions(marks, containerWidth);
  const clusters: TimelineCluster[] = [];
  let current: PositionedMark[] = [];
 
  const flush = () => {
    if (current.length === 0) {
      return;
    }
 
    const total = current.reduce((sum, member) => sum + member.positionPx, 0);
 
    clusters.push({
      anchorPx: total / current.length,
      id: `cluster-${current[0].id}`,
      members: current,
    });
 
    current = [];
  };
 
  positioned.forEach((mark) => {
    const previous = current[current.length - 1];
 
    if (previous !== undefined && mark.positionPx - previous.positionPx >= thresholdPx) {
      flush();
    }
 
    current.push(mark);
  });
 
  flush();
 
  return clusters;
};
 
export const toConicGradient = (colorWeights: ColorWeight[]): string => {
  if (colorWeights.length <= 1) {
    return colorWeights[0]?.color ?? 'transparent';
  }
 
  const total = colorWeights.reduce((sum, { weight }) => sum + weight, 0);
  let consumed = 0;
 
  const stops = colorWeights.map(({ color, weight }) => {
    const startDeg = (consumed / total) * 360;
    consumed += weight;
    const endDeg = (consumed / total) * 360;
 
    return `${color} ${startDeg}deg ${endDeg}deg`;
  });
 
  return `conic-gradient(${stops.join(', ')})`;
};
 
const toCollapsedNode = (cluster: TimelineCluster, dimmed: boolean): TimelineNode => ({
  colorWeights: toColorWeights(cluster.members.map((member) => member.color)),
  dimmed,
  id: cluster.id,
  leftPx: cluster.anchorPx,
  markIds: cluster.members.map((member) => member.id),
  sizePx: cluster.members.length > 1 ? CLUSTER_DOT_SIZE_PX : DOT_SIZE_PX,
});
 
const clamp = (value: number, min: number, max: number): number => Math.min(Math.max(value, min), max);
 
const expandedSpacing = (memberCount: number, containerWidth: number, maxBandWidth: number): number => {
  Iif (memberCount <= 1) {
    return EXPANDED_SPACING_PX;
  }
 
  const cap = Math.min(containerWidth * MAX_BAND_RATIO, maxBandWidth);
  const fitted = (cap - DOT_SIZE_PX - 2 * BAND_PADDING_PX) / (memberCount - 1);
 
  return Math.max(0, Math.min(EXPANDED_SPACING_PX, fitted));
};
 
const rescale = (value: number, fromStart: number, fromEnd: number, toStart: number, toEnd: number): number => {
  const fromSpan = fromEnd - fromStart;
 
  Iif (fromSpan <= 0) {
    return toStart;
  }
 
  return toStart + ((value - fromStart) / fromSpan) * (toEnd - toStart);
};
 
export const buildLayout = ({
  containerWidth,
  expandedClusterId,
  marks,
  thresholdPx = DEFAULT_CLUSTER_THRESHOLD_PX,
}: BuildLayoutParams): TimelineLayout => {
  if (containerWidth <= 0 || marks.length === 0) {
    return { nodes: [] };
  }
 
  const clusters = buildClusters(marks, containerWidth, thresholdPx);
  const expanded = clusters.find((cluster) => cluster.id === expandedClusterId && cluster.members.length > 1);
 
  if (expanded === undefined) {
    return { nodes: clusters.map((cluster) => toCollapsedNode(cluster, false)) };
  }
 
  const sideClusters = clusters.filter((cluster) => cluster.id !== expanded.id);
  const leftCount = sideClusters.filter((cluster) => cluster.anchorPx < expanded.anchorPx).length;
  const rightCount = sideClusters.length - leftCount;
 
  const reserve = (count: number) => (count === 0 ? 0 : SQUEEZE_GAP_PX + (count - 1) * MIN_SQUEEZE_PITCH_PX);
  const leftReserve = reserve(leftCount);
  const rightReserve = reserve(rightCount);
 
  const minBandWidth = DOT_SIZE_PX + 2 * BAND_PADDING_PX;
  const maxBandWidth = Math.max(minBandWidth, containerWidth - leftReserve - rightReserve);
 
  const spacing = expandedSpacing(expanded.members.length, containerWidth, maxBandWidth);
  const widthPx = Math.min(maxBandWidth, (expanded.members.length - 1) * spacing + minBandWidth);
  const leftPx = clamp(
    expanded.anchorPx - widthPx / 2,
    leftReserve,
    Math.max(leftReserve, containerWidth - widthPx - rightReserve)
  );
  const band = { leftPx, memberCount: expanded.members.length, widthPx };
 
  const leftLimit = Math.max(0, leftPx - SQUEEZE_GAP_PX);
  const rightLimit = Math.min(containerWidth, leftPx + widthPx + SQUEEZE_GAP_PX);
 
  const nodes = clusters.flatMap((cluster): TimelineNode[] => {
    if (cluster.id === expanded.id) {
      return cluster.members.map((member, index) => ({
        colorWeights: [{ color: member.color, weight: 1 }],
        dimmed: false,
        id: member.id,
        leftPx: leftPx + BAND_PADDING_PX + DOT_SIZE_PX / 2 + index * spacing,
        markIds: [member.id],
        sizePx: DOT_SIZE_PX,
      }));
    }
 
    const collapsed = toCollapsedNode(cluster, true);
    const squeezed =
      cluster.anchorPx < expanded.anchorPx
        ? rescale(cluster.anchorPx, 0, expanded.anchorPx, 0, leftLimit)
        : rescale(cluster.anchorPx, expanded.anchorPx, containerWidth, rightLimit, containerWidth);
 
    return [{ ...collapsed, leftPx: squeezed }];
  });
 
  return { band, nodes };
};