Observed monthly AAPL brush selection

import type { AaplRow } from '@charts-poc/demo-data/aapl'

export interface BrushRange {
  start: Date
  end: Date
}

export function monthlyAaplRows(rows: readonly AaplRow[]): readonly AaplRow[] {
  const byMonth = new Map<number, AaplRow>()
  for (const row of rows) {
    if (row.Date.getUTCFullYear() === 2017) {
      byMonth.set(row.Date.getUTCMonth(), row)
    }
  }
  return [...byMonth.values()]
}

export function observedBrushDates(rows: readonly AaplRow[]) {
  return rows.map((row) => row.Date)
}

export function brushDomain(dates: readonly Date[]): readonly [Date, Date] {
  const first = dates[0]
  const last = dates.at(-1)
  if (!first || !last) throw new Error('Brush selection requires dates.')
  return [first, last]
}

export function initialBrushRange(dates: readonly Date[]): BrushRange {
  const start = dates[3]
  const end = dates[5]
  if (!start || !end) throw new Error('Brush selection requires six dates.')
  return { start, end }
}

export function brushDateKey(date: Date) {
  return date.toISOString().slice(0, 10)
}

export function brushShortDate(date: Date) {
  return date.toLocaleDateString('en-US', {
    month: 'short',
    day: 'numeric',
    timeZone: 'UTC',
  })
}

export function brushDateFromAnchor(dates: readonly Date[], anchor: string) {
  const key = anchor.startsWith('date:') ? anchor.slice(5) : ''
  return dates.find((date) => brushDateKey(date) === key) ?? null
}

export function clampBrushDate(dates: readonly Date[], date: Date) {
  const first = dates[0]
  if (!first) throw new Error('Brush selection requires dates.')
  return dates.reduce((nearest, candidate) =>
    Math.abs(candidate.getTime() - date.getTime()) <
    Math.abs(nearest.getTime() - date.getTime())
      ? candidate
      : nearest,
  )
}

export function normalizedBrushRange(a: Date, b: Date): BrushRange {
  return a.getTime() <= b.getTime()
    ? { start: a, end: b }
    : { start: b, end: a }
}

export function brushRowsInRange(rows: readonly AaplRow[], range: BrushRange) {
  const start = range.start.getTime()
  const end = range.end.getTime()
  return rows.filter((row) => {
    const timestamp = row.Date.getTime()
    return timestamp >= start && timestamp <= end
  })
}

export function brushRangeSummary(rows: readonly AaplRow[], range: BrushRange) {
  const selected = brushRowsInRange(rows, range)
  const total = selected.reduce((sum, row) => sum + row.Close, 0)
  const first = selected[0]
  const last = selected.at(-1)
  return {
    count: selected.length,
    average: selected.length ? total / selected.length : 0,
    change: first && last ? last.Close - first.Close : 0,
  }
}

export const brushSelectionFill = 'rgba(147, 197, 253, 0.4)'

export function normalizedElementFill(element: Element) {
  const view = element.ownerDocument.defaultView
  if (!view) return null
  const style = view.getComputedStyle(element)
  return normalizedRenderedFill(style.fill, style.fillOpacity, style.opacity)
}

export function normalizedRenderedFill(
  fill: string,
  fillOpacity: string | number | undefined,
  opacity: string | number | undefined,
) {
  const color = parseColor(fill)
  if (!color) return null
  const alpha =
    color.alpha * numericOpacity(fillOpacity) * numericOpacity(opacity)
  return `rgba(${color.red}, ${color.green}, ${color.blue}, ${formatAlpha(alpha)})`
}

interface ParsedColor {
  red: number
  green: number
  blue: number
  alpha: number
}

function parseColor(value: string): ParsedColor | null {
  const normalized = value.trim().toLowerCase()
  if (normalized === 'transparent') {
    return { red: 0, green: 0, blue: 0, alpha: 0 }
  }

  const hex = /^#([\da-f]{6})([\da-f]{2})?$/.exec(normalized)
  if (hex) {
    const channels = hex[1]
    if (!channels) return null
    return {
      red: Number.parseInt(channels.slice(0, 2), 16),
      green: Number.parseInt(channels.slice(2, 4), 16),
      blue: Number.parseInt(channels.slice(4, 6), 16),
      alpha: hex[2] ? Number.parseInt(hex[2], 16) / 255 : 1,
    }
  }

  const functional = /^rgba?\((.*)\)$/.exec(normalized)
  if (!functional?.[1]) return null
  const [channelText, slashAlpha] = functional[1]
    .split('/')
    .map((part) => part.trim())
  if (!channelText) return null
  const commaParts = channelText.split(',').map((part) => part.trim())
  const parts =
    commaParts.length > 1
      ? commaParts
      : channelText.split(/\s+/).filter(Boolean)
  if (parts.length < 3) return null
  const red = colorChannel(parts[0])
  const green = colorChannel(parts[1])
  const blue = colorChannel(parts[2])
  const inlineAlpha = commaParts.length > 3 ? commaParts[3] : undefined
  const alpha = alphaChannel(slashAlpha ?? inlineAlpha ?? '1')
  if (red === null || green === null || blue === null || alpha === null) {
    return null
  }
  return { red, green, blue, alpha }
}

function colorChannel(value: string | undefined) {
  if (!value) return null
  const numeric = Number.parseFloat(value)
  if (!Number.isFinite(numeric)) return null
  return Math.round(
    Math.min(255, Math.max(0, value.endsWith('%') ? numeric * 2.55 : numeric)),
  )
}

function alphaChannel(value: string) {
  const numeric = Number.parseFloat(value)
  if (!Number.isFinite(numeric)) return null
  return Math.min(1, Math.max(0, value.endsWith('%') ? numeric / 100 : numeric))
}

function numericOpacity(value: string | number | undefined) {
  const numeric = Number(value ?? 1)
  return Number.isFinite(numeric) ? numeric : 1
}

function formatAlpha(value: number) {
  return String(Math.round(Math.min(1, Math.max(0, value)) * 10_000) / 10_000)
}

import { aapl } from '@charts-poc/demo-data/aapl'
import { defineChart, dot, lineY, mountChart } from '@tanstack/charts'
import { brushX } from '@tanstack/charts/interaction/brush'
import { controlledSignal } from '@tanstack/charts/interaction/signal'
import { decorative } from '@tanstack/charts/mark/decorative'
import { scaleLinear, scaleUtc } from 'd3-scale'
import {
  clientPointBounds,
  scenePointToClient,
} from '../../shared/driver-geometry'
import { tanstackCase } from '../../shared/mount'
import {
  brushDateFromAnchor,
  brushDateKey,
  brushDomain,
  brushRangeSummary,
  brushShortDate,
  initialBrushRange,
  monthlyAaplRows,
  observedBrushDates,
} from './model'
import { brushSelectionFill, normalizedElementFill } from './paint'
import type { AaplRow } from '@charts-poc/demo-data/aapl'
import type {
  BrushRange,
  BrushXChange,
} from '@tanstack/charts/interaction/brush'
import type { ChartHost, ChartHostOptions, ChartScene } from '@tanstack/charts'
import type {
  ConformanceGeometryQuery,
  ConformanceGeometrySample,
  ConformanceInput,
  ConformanceJsonObject,
  ConformanceMount,
  ConformanceTarget,
  ConformanceTestDriver,
} from '../../types'

interface BrushState {
  range: BrushRange<Date>
  dragging: boolean
}

const color = '#2563eb'
const brushRows = monthlyAaplRows(aapl)
const brushDates = observedBrushDates(brushRows)
const fullDomain = brushDomain(brushDates)
const brushMonthFormatter = new Intl.DateTimeFormat('en-US', {
  month: 'short',
  timeZone: 'UTC',
})

export function brushRangeDefinition(
  range: BrushRange<Date>,
  onChange: (range: BrushRange<Date>, reason: BrushXChange<Date>) => void,
) {
  return defineChart({
    marks: [
      decorative(
        lineY(brushRows, {
          id: 'brush-series-line',
          x: 'Date',
          y: 'Close',
          stroke: color,
          strokeWidth: 2.5,
        }),
      ),
      dot(brushRows, {
        id: 'brush-series-points',
        x: 'Date',
        y: 'Close',
        fill: color,
        r: 3.5,
        stroke: '#ffffff',
        strokeWidth: 1,
      }),
    ],
    x: {
      scale: scaleUtc().domain(fullDomain),
      axis: {
        ticks: { format: (value) => brushMonthFormatter.format(value) },
        label: 'Month',
      },
    },
    y: {
      scale: scaleLinear,
      grid: true,
      axis: { ticks: { count: 4 }, label: 'AAPL close ($)' },
    },
    controls: [
      brushX({
        id: 'monthly-range',
        range: controlledSignal<BrushRange<Date>, BrushXChange<Date>>(
          range,
          (next, { reason }) => onChange(next, reason),
        ),
        values: brushDates,
        ariaLabel:
          'Monthly range brush. Drag to select; focus either handle and use arrow keys, Home, or End to adjust.',
        startAriaLabel: 'Range start',
        endAriaLabel: 'Range end',
        format: brushDateKey,
        handleSize: 16,
        selectionStyle: {
          fill: brushSelectionFill,
          fillOpacity: 1,
          stroke: color,
          strokeWidth: 1,
        },
        handleStyle: {
          fill: 'Canvas',
          fillOpacity: 1,
          stroke: color,
          strokeWidth: 2,
        },
      }),
    ],
    svgAnimation: false,
    keyboard: false,
    focusRing: false,
    margin: { top: 52, right: 24, bottom: 44, left: 58 },
  })
}

export const catalogCase = tanstackCase(
  () => brushRangeDefinition(initialBrushRange(brushDates), () => {}),
  'Time series with a draggable horizontal range brush',
)

export const mount: ConformanceMount = (container, input) => {
  let currentInput = input
  let accepted = copyRange(initialBrushRange(brushDates))
  let state: BrushState = { range: copyRange(accepted), dragging: false }
  let host: ChartHost<AaplRow, Date, number> | undefined

  const shell = container.ownerDocument.createElement('div')
  const chartFrame = container.ownerDocument.createElement('div')
  const status = createRangeStatus(container.ownerDocument)
  shell.dataset.conformanceView = 'main'
  shell.setAttribute('role', 'application')
  shell.setAttribute(
    'aria-label',
    'Monthly time range brush with two adjustable handles',
  )
  shell.style.position = 'relative'
  chartFrame.style.position = 'relative'
  shell.append(chartFrame, status)
  container.append(shell)
  sizeShell(shell, chartFrame, input)

  const handleBrushChange = (
    next: BrushRange<Date>,
    reason: BrushXChange<Date>,
  ) => {
    state = {
      range: copyRange(next),
      dragging: reason.type === 'preview',
    }
    updateRangeStatus(status, state.range)
    if (reason.type === 'preview') return
    accepted = copyRange(next)
    host?.update(options())
  }

  const options = (): ChartHostOptions<AaplRow, Date, number> => ({
    definition: brushRangeDefinition(accepted, handleBrushChange),
    width: currentInput.width,
    height: currentInput.height,
    ariaLabel: 'Time series with a draggable horizontal range brush',
  })

  host = mountChart(chartFrame, options())
  updateRangeStatus(status, state.range)

  const driver = createDriver(
    shell,
    chartFrame,
    () => host!.getScene(),
    () => state,
  )

  return {
    driver,
    update(nextInput) {
      currentInput = nextInput
      sizeShell(shell, chartFrame, nextInput)
      host!.update(options())
      updateRangeStatus(status, state.range)
    },
    destroy() {
      host!.destroy()
      shell.remove()
    },
  }
}

function createDriver(
  shell: HTMLElement,
  surface: HTMLElement,
  getScene: () => ChartScene<AaplRow, Date, number>,
  getState: () => BrushState,
): ConformanceTestDriver {
  return {
    resolveTarget(target) {
      return resolveTarget(surface, getScene(), target)
    },
    readState() {
      return interactionState(getState())
    },
    geometry(query) {
      return brushGeometry(surface, getScene(), getState().range, query)
    },
    viewBounds(view) {
      if (view && view !== 'main') return null
      const bounds = shell.getBoundingClientRect()
      return {
        x: bounds.left,
        y: bounds.top,
        width: bounds.width,
        height: bounds.height,
      }
    },
  }
}

function resolveTarget(
  surface: HTMLElement,
  scene: ChartScene<AaplRow, Date, number>,
  target: ConformanceTarget,
) {
  if (target.view !== undefined && target.view !== 'main') return null
  if (target.anchor === 'handle:start' || target.anchor === 'handle:end') {
    const handle = surface.querySelector<SVGRectElement>(
      `[data-chart-brush-handle="${target.anchor === 'handle:start' ? 'start' : 'end'}"]`,
    )
    return handle ? center(handle) : null
  }
  const date = brushDateFromAnchor(brushDates, target.anchor)
  const row = date
    ? brushRows.find((datum) => datum.Date.getTime() === date.getTime())
    : null
  return date && row
    ? scenePointToClient(
        surface,
        scene,
        scene.scales.x.map(date),
        scene.scales.y.map(row.Close),
      )
    : null
}

function interactionState(state: BrushState): ConformanceJsonObject {
  const summary = brushRangeSummary(brushRows, state.range)
  return {
    selection: {
      start: brushDateKey(state.range.start),
      end: brushDateKey(state.range.end),
      pointCount: summary.count,
      closeAverage: summary.average,
      closeChange: summary.change,
      dragging: state.dragging,
    },
  }
}

function brushGeometry(
  surface: HTMLElement,
  scene: ChartScene<AaplRow, Date, number>,
  range: BrushRange<Date>,
  query: ConformanceGeometryQuery,
): readonly ConformanceGeometrySample[] {
  if (query.view !== undefined && query.view !== 'main') return []
  const svg = surface.querySelector<SVGSVGElement>('svg.ts-chart')
  if (!svg) return []
  const bounds = svg.getBoundingClientRect()
  const scaleX = bounds.width / scene.width
  const scaleY = bounds.height / scene.height
  const points = brushRows.map(
    (row) =>
      [scene.scales.x.map(row.Date), scene.scales.y.map(row.Close)] as const,
  )

  if (query.role === 'dot') {
    return points.map(([x, y]) => ({
      x: bounds.left + (x - 3.5) * scaleX,
      y: bounds.top + (y - 3.5) * scaleY,
      width: 7 * scaleX,
      height: 7 * scaleY,
      paint: color,
    }))
  }
  if (query.role === 'line') {
    const sample = clientPointBounds(points, bounds, {
      scaleX,
      scaleY,
      paint: color,
    })
    return sample ? [sample] : []
  }
  if (query.role !== 'rect') return []
  const band = surface.querySelector<SVGRectElement>(
    '[data-chart-brush-selection]',
  )
  if (band) {
    const bandBounds = band.getBoundingClientRect()
    return [
      {
        x: bandBounds.x,
        y: bandBounds.y,
        width: bandBounds.width,
        height: bandBounds.height,
        paint:
          normalizedElementFill(band) ?? 'invalid-tanstack-rendered-brush-fill',
      },
    ]
  }
  const start = scene.scales.x.map(range.start)
  const end = scene.scales.x.map(range.end)
  return [
    {
      x: bounds.left + Math.min(start, end) * scaleX,
      y: bounds.top + scene.chart.y * scaleY,
      width: Math.max(1, Math.abs(end - start) * scaleX),
      height: scene.chart.height * scaleY,
      paint: 'missing-tanstack-rendered-brush-fill',
    },
  ]
}

function createRangeStatus(document: Document) {
  const status = document.createElement('output')
  status.setAttribute('role', 'status')
  status.setAttribute('aria-live', 'polite')
  Object.assign(status.style, {
    position: 'absolute',
    right: '24px',
    top: '10px',
    zIndex: '4',
    padding: '4px 8px',
    border: '1px solid color-mix(in srgb, CanvasText 24%, transparent)',
    borderRadius: '999px',
    background: 'Canvas',
    color: 'CanvasText',
    font: '600 12px/1.2 system-ui, sans-serif',
    pointerEvents: 'none',
  })
  return status
}

function updateRangeStatus(status: HTMLOutputElement, range: BrushRange<Date>) {
  const summary = brushRangeSummary(brushRows, range)
  const label = `${brushShortDate(range.start)} → ${brushShortDate(range.end)} · ${summary.count} AAPL closes · avg $${summary.average.toFixed(1)}`
  status.value = label
  status.textContent = label
  status.setAttribute(
    'aria-label',
    `${brushDateKey(range.start)} through ${brushDateKey(range.end)}, ${summary.count} AAPL closing prices, average $${summary.average.toFixed(1)}`,
  )
}

function copyRange(range: BrushRange<Date>): BrushRange<Date> {
  return {
    start: new Date(range.start.getTime()),
    end: new Date(range.end.getTime()),
  }
}

function center(element: HTMLElement | SVGElement) {
  const bounds = element.getBoundingClientRect()
  return {
    x: bounds.left + bounds.width / 2,
    y: bounds.top + bounds.height / 2,
    focusElement: element,
  }
}

function sizeShell(
  shell: HTMLDivElement,
  chartFrame: HTMLDivElement,
  input: ConformanceInput,
) {
  shell.style.width = `${input.width}px`
  shell.style.height = `${input.height}px`
  chartFrame.style.width = `${input.width}px`
  chartFrame.style.height = `${input.height}px`
}

import type {
  ConformanceGeometrySample,
  ConformanceResolvedTarget,
} from '../types'

export interface ClientPointBoundsOptions {
  paint: string
  scaleX?: number
  scaleY?: number
}

/**
 * Bounds local chart points in viewport-relative client coordinates.
 * Degenerate point clouds retain a one-pixel geometry sample for comparison.
 */
export function clientPointBounds(
  points: readonly (readonly [number, number])[],
  origin: Pick<DOMRectReadOnly, 'left' | 'top'>,
  options: ClientPointBoundsOptions,
): ConformanceGeometrySample | null {
  if (!points.length) return null

  let left = Number.POSITIVE_INFINITY
  let right = Number.NEGATIVE_INFINITY
  let top = Number.POSITIVE_INFINITY
  let bottom = Number.NEGATIVE_INFINITY
  for (const [x, y] of points) {
    left = Math.min(left, x)
    right = Math.max(right, x)
    top = Math.min(top, y)
    bottom = Math.max(bottom, y)
  }

  const scaleX = options.scaleX ?? 1
  const scaleY = options.scaleY ?? 1
  return {
    x: origin.left + left * scaleX,
    y: origin.top + top * scaleY,
    width: Math.max(1, (right - left) * scaleX),
    height: Math.max(1, (bottom - top) * scaleY),
    paint: options.paint,
  }
}

/** Maps one outer-scene coordinate through the mounted SVG viewport. */
export function scenePointToClient(
  surface: ParentNode,
  scene: { readonly width: number; readonly height: number },
  x: number,
  y: number,
): ConformanceResolvedTarget | null {
  const svg = surface.querySelector<SVGSVGElement>('svg.ts-chart')
  if (
    !svg ||
    !Number.isFinite(scene.width) ||
    !Number.isFinite(scene.height) ||
    scene.width <= 0 ||
    scene.height <= 0 ||
    !Number.isFinite(x) ||
    !Number.isFinite(y)
  ) {
    return null
  }
  const bounds = svg.getBoundingClientRect()
  return {
    x: bounds.left + (x / scene.width) * bounds.width,
    y: bounds.top + (y / scene.height) * bounds.height,
    focusElement: svg,
  }
}

import {
  defineChart,
  isResponsiveChartDefinition,
  mountChart,
} from '@tanstack/charts'
import { tooltip } from '@tanstack/charts/tooltip'
import type {
  DomChartDefinition,
  ChartDefinitionOptions,
  ChartValue,
  ChartTooltipOptions,
} from '@tanstack/charts'
import type {
  ConformanceHandle,
  ConformanceInput,
  ConformanceMount,
} from '../types'
import { catalogPreviewDefinition, type CatalogPreviewOptions } from './preview'

export function mountObservablePlot(
  container: HTMLElement,
  input: ConformanceInput,
  render: (input: ConformanceInput) => HTMLElement | SVGSVGElement,
): ConformanceHandle {
  let element = render(input)
  container.append(element)

  return {
    update(nextInput) {
      const nextElement = render(nextInput)
      element.replaceWith(nextElement)
      element = nextElement
    },
    destroy() {
      element.remove()
    },
  }
}

export function tanstackMount<
  TDatum,
  TXValue extends ChartValue = ChartValue,
  TYValue extends ChartValue = ChartValue,
>(
  createDefinition: (
    input: ConformanceInput,
  ) => DomChartDefinition<TDatum, TXValue, TYValue>,
  ariaLabel: string,
  interactiveTooltip: true | ChartTooltipOptions<TDatum> = true,
  previewOptions: CatalogPreviewOptions<TDatum, TXValue, TYValue> = {},
): TanStackConformanceCase<TDatum, TXValue, TYValue> {
  const mount: ConformanceMount = (container, input) => {
    const options = {
      definition: withConformanceBehavior(
        createDefinition(input),
        input,
        interactiveTooltip,
        previewOptions,
      ),
      width: input.width,
      height: input.height,
      ariaLabel,
    } as const
    const host = mountChart(container, options)
    applyCatalogPreviewFocus(host, input, previewOptions)

    return {
      update(nextInput) {
        host.update({
          ...options,
          definition: withConformanceBehavior(
            createDefinition(nextInput),
            nextInput,
            interactiveTooltip,
            previewOptions,
          ),
          width: nextInput.width,
          height: nextInput.height,
        })
        applyCatalogPreviewFocus(host, nextInput, previewOptions)
      },
      destroy() {
        host.destroy()
      },
    }
  }

  const catalogCase = Object.assign(mount, {
    createDefinition,
    ariaLabel,
    interactiveTooltip,
  })

  return Object.assign(catalogCase, { mount: catalogCase })
}

export interface TanStackConformanceCase<
  TDatum,
  TXValue extends ChartValue = ChartValue,
  TYValue extends ChartValue = ChartValue,
> {
  (container: HTMLElement, input: ConformanceInput): ConformanceHandle
  createDefinition: (
    input: ConformanceInput,
  ) => DomChartDefinition<TDatum, TXValue, TYValue>
  ariaLabel: string
  interactiveTooltip: true | ChartTooltipOptions<TDatum>
  mount: ConformanceMount
}

export function tanstackCase<
  TDatum,
  TXValue extends ChartValue = ChartValue,
  TYValue extends ChartValue = ChartValue,
>(
  createDefinition: (
    input: ConformanceInput,
  ) => DomChartDefinition<TDatum, TXValue, TYValue>,
  ariaLabel: string,
  interactiveTooltip: true | ChartTooltipOptions<TDatum> = true,
  previewOptions: CatalogPreviewOptions<TDatum, TXValue, TYValue> = {},
): TanStackConformanceCase<TDatum, TXValue, TYValue> {
  return tanstackMount(
    createDefinition,
    ariaLabel,
    interactiveTooltip,
    previewOptions,
  )
}

export function withConformanceBehavior<
  TDatum,
  TXValue extends ChartValue,
  TYValue extends ChartValue,
>(
  definition: DomChartDefinition<TDatum, TXValue, TYValue>,
  input: ConformanceInput,
  interactiveTooltip: true | ChartTooltipOptions<TDatum>,
  previewOptions: CatalogPreviewOptions<TDatum, TXValue, TYValue> = {},
): DomChartDefinition<TDatum, TXValue, TYValue> {
  const presentation =
    input.preview === true
      ? catalogPreviewDefinition(definition, previewOptions)
      : definition
  const behavior: ChartDefinitionOptions<TDatum, TXValue, TYValue, 'dom'> = {
    svgAnimation: false,
    ...(input.interactive === true ||
    (input.preview === true && previewOptions.focus)
      ? {}
      : { focus: false }),
    keyboard: input.interactive === true,
    tooltip:
      input.interactive !== true
        ? false
        : interactiveTooltip === true
          ? tooltip
          : { use: tooltip, ...interactiveTooltip },
  }

  if (isResponsiveChartDefinition(presentation)) {
    return defineChart(presentation, behavior)
  }
  return defineChart(presentation, behavior)
}

function applyCatalogPreviewFocus<
  TDatum,
  TXValue extends ChartValue,
  TYValue extends ChartValue,
>(
  host: ReturnType<typeof mountChart<TDatum, TXValue, TYValue>>,
  input: ConformanceInput,
  options: CatalogPreviewOptions<TDatum, TXValue, TYValue>,
) {
  if (input.preview !== true || !options.focus) return
  host.interaction.setControlledFocus(options.focus(host.getScene(), input), {
    source: 'programmatic',
  })
}

import { isResponsiveChartDefinition } from '@tanstack/charts'
import type {
  ChartPoint,
  ChartScene,
  ChartValue,
  DomChartDefinition,
} from '@tanstack/charts'
import type { ConformanceInput } from '../types'

export interface CatalogPreviewOptions<
  TDatum = unknown,
  TXValue extends ChartValue = ChartValue,
  TYValue extends ChartValue = ChartValue,
> {
  /** Keep the source definition's Cartesian axes and grid. */
  guides?: boolean
  /** Keep the source definition's color legend. */
  legend?: boolean
  /** Keep the source definition's authored or automatic margins. */
  margin?: boolean
  /** Paint one deterministic source point through the chart's focus strategy. */
  focus?: (
    scene: ChartScene<TDatum, TXValue, TYValue>,
    input: ConformanceInput,
  ) => ChartPoint<TDatum, TXValue, TYValue> | null
}

export function catalogPreviewDefinition<
  TDatum,
  TXValue extends ChartValue,
  TYValue extends ChartValue,
>(
  definition: DomChartDefinition<TDatum, TXValue, TYValue>,
  options: CatalogPreviewOptions<TDatum, TXValue, TYValue> = {},
): DomChartDefinition<TDatum, TXValue, TYValue> {
  if (isResponsiveChartDefinition(definition)) {
    return {
      ...definition,
      chart(context) {
        const spec = definition.chart(context)
        const color = previewColor(spec.color, options.legend === true)
        return {
          ...spec,
          ...(options.guides === true ? {} : { guides: false }),
          ...(options.margin === true ? {} : { margin: 0 }),
          ...(color ? { color } : {}),
        }
      },
    }
  }

  const color = previewColor(definition.color, options.legend === true)
  return {
    ...definition,
    ...(options.guides === true ? {} : { guides: false }),
    ...(options.margin === true ? {} : { margin: 0 }),
    ...(color ? { color } : {}),
  }
}

function previewColor<TColor extends { legend?: unknown }>(
  color: TColor | undefined,
  keepLegend: boolean,
): Omit<TColor, 'legend'> | TColor | undefined {
  if (!color || keepLegend) return color
  const { legend: _legend, ...withoutLegend } = color
  return withoutLegend
}

export function samplePreviewData<TDatum>(
  data: readonly TDatum[],
  input: ConformanceInput,
  limit: number,
  accessors: readonly ((datum: TDatum) => number | null | undefined)[] = [],
): readonly TDatum[] {
  if (input.preview !== true || data.length <= limit) return data

  const selected = new Set<number>()
  const slots = Math.max(2, limit - accessors.length * 2)
  for (let slot = 0; slot < slots; slot += 1) {
    selected.add(Math.round((slot / (slots - 1)) * (data.length - 1)))
  }

  for (const accessor of accessors) {
    let minimumIndex = -1
    let minimum = Number.POSITIVE_INFINITY
    let maximumIndex = -1
    let maximum = Number.NEGATIVE_INFINITY

    data.forEach((datum, index) => {
      const value = accessor(datum)
      if (value === null || value === undefined || !Number.isFinite(value)) {
        return
      }
      if (value < minimum) {
        minimum = value
        minimumIndex = index
      }
      if (value > maximum) {
        maximum = value
        maximumIndex = index
      }
    })

    if (minimumIndex >= 0) selected.add(minimumIndex)
    if (maximumIndex >= 0) selected.add(maximumIndex)
  }

  return data.filter((_datum, index) => selected.has(index))
}

export function samplePreviewSeries<TDatum, TSeries>(
  data: readonly TDatum[],
  input: ConformanceInput,
  limitPerSeries: number,
  series: (datum: TDatum) => TSeries,
): readonly TDatum[] {
  if (input.preview !== true) return data

  const indicesBySeries = new Map<TSeries, number[]>()
  data.forEach((datum, index) => {
    const key = series(datum)
    const indices = indicesBySeries.get(key) ?? []
    indices.push(index)
    indicesBySeries.set(key, indices)
  })

  const selected = new Set<number>()
  for (const indices of indicesBySeries.values()) {
    if (indices.length <= limitPerSeries) {
      indices.forEach((index) => selected.add(index))
      continue
    }
    for (let slot = 0; slot < limitPerSeries; slot += 1) {
      const index =
        indices[
          Math.round((slot / (limitPerSeries - 1)) * (indices.length - 1))
        ]
      if (index !== undefined) selected.add(index)
    }
  }

  return data.filter((_datum, index) => selected.has(index))
}

export type ConformanceReferenceRenderer =
  'observable-plot' | 'recharts' | 'echarts'

export type ConformanceRenderer = ConformanceReferenceRenderer | 'tanstack'

export type ConformanceSupport = 'native' | 'composed' | 'gap' | 'deferred'

export type ConformanceGeometryRole =
  | 'arc'
  | 'area'
  | 'arrow'
  | 'bar'
  | 'cell'
  | 'contour'
  | 'delaunay'
  | 'density'
  | 'dot'
  | 'frame'
  | 'geo'
  | 'hexagon'
  | 'line'
  | 'link'
  | 'rect'
  | 'radar'
  | 'regression'
  | 'rule'
  | 'text'
  | 'tick'
  | 'vector'
  | 'voronoi'
  | 'waffle'

export interface ConformanceInput {
  width: number
  height: number
  revision: number
  interactive?: boolean
  /** Use lower-detail geometry suited to compact catalog cards. */
  preview?: boolean
  /** True only for semantic browser scenarios, not catalog or visual mounts. */
  behavior?: boolean
}

export interface ConformanceHandle {
  update: (input: ConformanceInput) => void
  driver?: ConformanceTestDriver
  destroy: () => void
}

export type ConformanceMount = (
  container: HTMLElement,
  input: ConformanceInput,
) => ConformanceHandle

export interface ConformanceGeometryExpectation {
  id?: string
  view?: string
  role: ConformanceGeometryRole
  count: number
  maxCount?: number
  rendererRoles?: Partial<Record<ConformanceRenderer, ConformanceGeometryRole>>
}

export type ConformanceAxis = 'x' | 'y' | 'fx' | 'fy'

export interface ConformanceGuideExpectation {
  id: string
  axis:
    | ConformanceAxis
    | (Record<'tanstack', ConformanceAxis> &
        Partial<Record<ConformanceReferenceRenderer, ConformanceAxis>>)
  sequence?: readonly string[]
  maxRepeat?: number
}

export type ConformanceJsonValue =
  | null
  | boolean
  | number
  | string
  | readonly ConformanceJsonValue[]
  | ConformanceJsonObject

export interface ConformanceJsonObject {
  readonly [key: string]: ConformanceJsonValue
}

export interface ConformanceTarget {
  view?: string
  anchor: string
}

export type ConformanceRenderedTarget =
  | {
      selector: string
      index?: number
      role?: never
      name?: never
      exact?: never
      root?: never
      page?: never
    }
  | {
      role: string
      name?: string
      exact?: boolean
      index?: number
      selector?: never
      root?: never
      page?: never
    }
  | {
      root: true
      selector?: never
      role?: never
      name?: never
      exact?: never
      index?: never
      page?: never
    }
  | {
      page: true
      selector?: never
      role?: never
      name?: never
      exact?: never
      index?: never
      root?: never
    }

export interface ConformanceResolvedTarget {
  /** Viewport-relative client coordinate used by Playwright mouse input. */
  x: number
  /** Viewport-relative client coordinate used by Playwright mouse input. */
  y: number
  /** Optional element to focus before a real Playwright keyboard action. */
  focusElement?: HTMLElement | SVGElement
}

export interface ConformanceGeometryQuery {
  view?: string
  role: ConformanceGeometryRole
}

export interface ConformanceGeometrySample {
  /** Viewport-relative client box, matching getBoundingClientRect coordinates. */
  x: number
  y: number
  width: number
  height: number
  paint?: string
}

export interface ConformanceTestDriver {
  /**
   * Benchmark-only semantic bridge. Case metadata names anchors; each renderer
   * resolves those anchors without exposing renderer-specific selectors.
   */
  resolveTarget: (target: ConformanceTarget) => ConformanceResolvedTarget | null
  readState: () => ConformanceJsonObject
  geometry?: (
    query: ConformanceGeometryQuery,
  ) => readonly ConformanceGeometrySample[]
  /**
   * Viewport-relative logical view bounds. Multi-grid renderers may expose
   * independent views without separate DOM roots.
   */
  viewBounds?: (view?: string) => ConformanceGeometrySample | null
  settle?: () => void | Promise<void>
}

export type ConformanceStateAssertion =
  | {
      path: string
      equals: ConformanceJsonValue
    }
  | {
      path: string
      includes: ConformanceJsonValue
    }
  | {
      path: string
      approx: number
      tolerance: number
    }

type ConformanceRenderedStringMatcher =
  | {
      equals: string | null
      includes?: never
    }
  | {
      includes: string
      equals?: never
    }

type ConformanceRenderedNumberMatcher =
  | {
      equals: number
      approx?: never
      tolerance?: never
      atLeast?: never
      atMost?: never
    }
  | {
      approx: number
      tolerance: number
      equals?: never
      atLeast?: never
      atMost?: never
    }
  | {
      atLeast: number
      equals?: never
      approx?: never
      tolerance?: never
      atMost?: never
    }
  | {
      atMost: number
      equals?: never
      approx?: never
      tolerance?: never
      atLeast?: never
    }

export type ConformanceRenderedAssertion =
  | ({
      target: ConformanceRenderedTarget
      property: 'count'
    } & ConformanceRenderedNumberMatcher)
  | ({
      target: ConformanceRenderedTarget
      property: 'text'
    } & ConformanceRenderedStringMatcher)
  | ({
      target: ConformanceRenderedTarget
      property: 'attribute'
      attribute: string
    } & ConformanceRenderedStringMatcher)
  | {
      target: ConformanceRenderedTarget
      property: 'visible' | 'focused'
      equals: boolean
    }
  | ({
      target: ConformanceRenderedTarget
      property:
        | 'scrollLeft'
        | 'scrollTop'
        | 'scrollWidth'
        | 'scrollHeight'
        | 'clientWidth'
        | 'clientHeight'
        | 'width'
        | 'height'
    } & ConformanceRenderedNumberMatcher)
  | {
      target: ConformanceRenderedTarget
      property: 'contained'
      within?: ConformanceRenderedTarget
      tolerance?: number
      equals: true
    }

export type ConformanceInteractionStep =
  | {
      type: 'pointerMove'
      target: ConformanceTarget
      steps?: number
    }
  | {
      type: 'pointerDown'
      target: ConformanceTarget
    }
  | {
      type: 'pointerUp'
      target: ConformanceTarget
    }
  | {
      type: 'pointerCancel'
    }
  | {
      type: 'pointerLeave'
      view?: string
    }
  | {
      type: 'update'
      revision: number
    }
  | {
      type: 'click'
      target: ConformanceTarget
    }
  | {
      type: 'key'
      key: string
      target?: ConformanceTarget
    }
  | {
      type: 'drag'
      from: ConformanceTarget
      to: ConformanceTarget
      steps?: number
    }
  | {
      type: 'wheel'
      target: ConformanceTarget
      deltaX?: number
      deltaY?: number
      steps?: number
      deltaMode?: 'pixel' | 'line' | 'page'
    }
  | {
      type: 'touchTap'
      target: ConformanceTarget
    }
  | {
      type: 'touchDrag'
      from: ConformanceTarget
      to: ConformanceTarget
      steps?: number
      cancel?: boolean
    }
  | {
      type: 'wait'
      durationMs: number
    }
  | {
      type: 'assert'
      assertions: readonly ConformanceStateAssertion[]
    }
  | {
      type: 'assertRendered'
      assertions: readonly ConformanceRenderedAssertion[]
    }
  | {
      type: 'screenshot'
      name: string
      view?: string
    }

export interface ConformanceInteractionScenario {
  id: string
  steps: readonly ConformanceInteractionStep[]
}

export interface ConformanceCaseMeta {
  schemaVersion: 1
  referenceRenderer?: ConformanceReferenceRenderer
  order: number
  id: string
  title: string
  family: string
  intent: string
  support: ConformanceSupport
  features: readonly string[]
  geometry: readonly ConformanceGeometryExpectation[]
  minimumGeometrySimilarity?: number
  guideAssertions?: readonly ConformanceGuideExpectation[]
  interactionScenarios?: readonly ConformanceInteractionScenario[]
  source: {
    title: string
    url: string
  }
  ai: {
    create: string
    maintain: string
  }
}

export interface ConformanceImplementationModule {
  mount: ConformanceMount
  /** Definition-only mount used by compact generated catalog previews. */
  catalogCase?: { mount: ConformanceMount }
}