Multi-Signal Line

"use client"import * as React from "react"import {  ResponsiveContainer,  LineChart,  Line,  XAxis,  YAxis,  Tooltip,  CartesianGrid,  ReferenceLine,} from "recharts"import { HugeiconsIcon } from "@hugeicons/react"import { LockKeyIcon, ViewIcon, ViewOffSlashIcon } from "@hugeicons/core-free-icons"import { useChartReducedMotion } from "../shared/use-chart-reduced-motion"import { ChartContainer } from "../shared/chart-container"import {  ChartLoadingState,  ChartEmptyState,  ChartErrorState,  ChartUnavailableState,} from "../shared/chart-state"import { cn } from "@/lib/utils"/* -------------------------------------------------------------------------- *//*  Type Definitions                                                          *//* -------------------------------------------------------------------------- *//** * Filter keys of TData that correspond to number or null/undefined values. */export type NumericKeyOf<TData> = [keyof TData] extends [never]  ? string  : {      [K in keyof TData]: TData[K] extends number | null | undefined ? K : never    }[keyof TData] extends never  ? string  : {      [K in keyof TData]: TData[K] extends number | null | undefined ? K : never    }[keyof TData] & string/** * Configuration descriptor for an individual series within the multi-signal chart. */export interface MultiSignalSeries<TData extends Record<string, unknown> = Record<string, unknown>> {  /** Property key on the data row containing this series' numeric metrics */  key: NumericKeyOf<TData>  /** Human-readable display label for legend, tooltips, and screen readers */  label: string  /** Explicit stroke and indicator color. If omitted, resolves from deterministic palette */  color?: string  /** Stroke dash style for multi-modal and monochrome differentiation */  strokeStyle?: "solid" | "dashed" | "dotted"  /** Custom numeric metric formatter for tooltip and scale values */  valueFormatter?: (value: number) => string}/** * Resolved internal representation of a series with deterministic palette tokens. */export interface ResolvedMultiSignalSeries<TData extends Record<string, unknown> = Record<string, unknown>> {  key: NumericKeyOf<TData>  label: string  color: string  strokeDasharray?: string  strokeStyle: "solid" | "dashed" | "dotted"  valueFormatter?: (value: number) => string  originalIndex: number}/** * Inspection datum structure passed to active observation callbacks. */export interface MultiSignalActiveDatum<  TData extends Record<string, unknown> = Record<string, unknown>,  XVal extends string | number = string | number> {  index: number  x: XVal  raw: TData  values: Record<string, number | null>  isLocked: boolean}export interface MultiSignalLineProps<  TData extends Record<string, unknown> = Record<string, unknown>,  XVal extends string | number = string | number> {  /** Readonly array of observation records. Caller data is never mutated. */  data: readonly TData[]  /** Key for the horizontal domain coordinate (e.g. month, date, timestamp, sprint). */  xKey: keyof TData & string  /** Readonly array of series definitions to render as peer signals. */  series: readonly MultiSignalSeries<TData>[]  /** Container height in pixels or CSS dimension string. (default: 320) */  height?: number | string  /** Curve interpolation: "monotone" | "linear" | "step". (default: "monotone") */  curve?: "linear" | "monotone" | "step"  /** Explicit Y-axis numeric domain, or "auto" calculation across visible series. */  domain?: [number, number] | ["auto", "auto"] | "auto"  /** Whether to render subtle horizontal background reference gridlines. (default: true) */  showGrid?: boolean  /** Whether to render the horizontal category scale. (default: true) */  showXAxis?: boolean  /** Whether to render the vertical numeric scale. (default: true) */  showYAxis?: boolean  /** Whether to render the series identity legend. (default: true) */  showLegend?: boolean  /** Whether legend items can be clicked/keyboard-activated to toggle series visibility. (default: true) */  interactiveLegend?: boolean  /** Whether clicking or pressing Enter/Space pins the currently inspected X datum. (default: true) */  lockableTooltip?: boolean  /** Default observation index to pin/lock on initial mount. (default: null) */  defaultLockedIndex?: number | null  /** Default set of series keys that should be initially visible. (defaults to all series) */  defaultVisibleSeries?: readonly string[]  /** Callback fired whenever the set of visible series changes. */  onVisibleSeriesChange?: (visibleKeys: readonly string[]) => void  /** Accent color for locked crosshair and selection markers. (default: var(--chart-selection)) */  selectionColor?: string  /** Custom formatter for Y-axis scale numbers and default tooltip metric values. */  valueFormatter?: (value: number) => string  /** Custom formatter for X-axis coordinate labels. */  xFormatter?: (value: string | number) => string  /** Visual policy for missing (null/undefined) observations: 'gap' leaves breaks, 'carry' forward-fills. (default: "gap") */  missingValuePolicy?: "gap" | "carry"  /** Animation style: "draw" | "fade" | "none". (default: "draw") */  animation?: "draw" | "fade" | "none"  /** Motion toggle or configuration object. Respects prefers-reduced-motion. */  motion?: boolean | { duration?: number }  /** Callback fired whenever the active inspected observation changes. */  onActiveDatumChange?: (datum: MultiSignalActiveDatum<TData, XVal> | null) => void  /** Optional heading announced to assistive technologies. */  title?: string  /** Optional descriptive summary announced to assistive technologies. */  description?: string  /** Optional CSS class name passed to the root figure element. */  className?: string  /** Display neutral skeleton loading state. */  loading?: boolean  /** Display actionable error banner. */  error?: Error | string | null  /** Display metric unavailability notice. */  unavailable?: boolean | string | null}/* -------------------------------------------------------------------------- *//*  Deterministic Palette & Series Resolver                                   *//* -------------------------------------------------------------------------- */const PALETTE_TOKENS = [  "var(--chart-1, #3b82f6)",  "var(--chart-2, #10b981)",  "var(--chart-3, #f59e0b)",  "var(--chart-4, #ef4444)",  "var(--chart-5, #8b5cf6)",  "var(--chart-6, #06b6d4)",  "var(--chart-7, #ec4899)",  "var(--chart-8, #84cc16)",]export function isFiniteNumber(val: unknown): val is number {  return typeof val === "number" && Number.isFinite(val)}/** * Resolves each series configuration into a deterministic identity. * Rule: Palette tokens map strictly by original canonical series index. * Hiding a series will NEVER shift or re-assign the colors of remaining series. */export function resolveMultiSignalSeries<TData extends Record<string, unknown>>(  seriesList: readonly MultiSignalSeries<TData>[]): ResolvedMultiSignalSeries<TData>[] {  if (!Array.isArray(seriesList)) return []  return seriesList.map((s, idx) => {    const fallbackColor = PALETTE_TOKENS[idx % PALETTE_TOKENS.length]    const resolvedColor = s.color && s.color.trim() !== "" ? s.color : fallbackColor    let dashArray: string | undefined = undefined    if (s.strokeStyle === "dashed") dashArray = "5 5"    if (s.strokeStyle === "dotted") dashArray = "2 3"    return {      key: s.key,      label: s.label || String(s.key),      color: resolvedColor,      strokeDasharray: dashArray,      strokeStyle: s.strokeStyle || "solid",      valueFormatter: s.valueFormatter,      originalIndex: idx,    }  })}/** * Safely normalizes observation rows: * 1. Missing values remain null (truthful gaps per series). * 2. Non-finite values (NaN, Infinity) are treated as null. * 3. Never mutates input objects or arrays. */export function normalizeMultiSignalData<TData extends Record<string, unknown>>(  data: readonly TData[],  xKey: keyof TData & string,  seriesList: readonly ResolvedMultiSignalSeries<TData>[] | readonly MultiSignalSeries<TData>[],  policy: "gap" | "carry" = "gap"): Record<string, any>[] {  if (!Array.isArray(data) || data.length === 0) return []  const lastKnown: Record<string, number | null> = {}  return data.map((d, idx) => {    const rawX = d[xKey]    const xVal = typeof rawX === "string" || typeof rawX === "number" ? rawX : String(rawX ?? "")    const row: Record<string, any> = {      __x: xVal,      __index: idx,      __raw: d,    }    for (const s of seriesList) {      const keyStr = String(s.key)      const val = d[s.key]      if (isFiniteNumber(val)) {        row[keyStr] = val        lastKnown[keyStr] = val      } else if (policy === "carry" && typeof lastKnown[keyStr] === "number") {        row[keyStr] = lastKnown[keyStr]      } else {        row[keyStr] = null      }    }    return row  })}/** * Calculates a Cartesian Y-domain covering all valid values of CURRENTLY VISIBLE series. * Excludes hidden series from domain to optimize analytical readability for remaining signals. */export function calculateMultiSignalDomain(  normalized: readonly Record<string, any>[],  visibleSeries: readonly ResolvedMultiSignalSeries<any>[],  explicitDomain?: [number, number] | ["auto", "auto"] | "auto"): [number, number] {  if (    Array.isArray(explicitDomain) &&    typeof explicitDomain[0] === "number" &&    typeof explicitDomain[1] === "number" &&    Number.isFinite(explicitDomain[0]) &&    Number.isFinite(explicitDomain[1])  ) {    return explicitDomain  }  const values: number[] = []  for (const row of normalized) {    for (const s of visibleSeries) {      const val = row[s.key]      if (val !== null && Number.isFinite(val)) {        values.push(val)      }    }  }  if (values.length === 0) {    return [0, 100]  }  const min = Math.min(...values)  const max = Math.max(...values)  if (min === max) {    if (min === 0) return [-10, 10]    const delta = Math.abs(min) * 0.15 || 10    return [Math.floor(min - delta), Math.ceil(max + delta)]  }  const span = max - min  const pad = span * 0.08  return [Math.floor(min - pad), Math.ceil(max + pad)]}/* -------------------------------------------------------------------------- *//*  Synchronized Shared Multi-Series Tooltip                                  *//* -------------------------------------------------------------------------- */interface MultiSignalTooltipContentProps {  active?: boolean  payload?: readonly any[]  label?: React.ReactNode  activeX: string | number | null  activeDatum: MultiSignalActiveDatum | null  visibleSeries: readonly ResolvedMultiSignalSeries<any>[]  allSeries: readonly ResolvedMultiSignalSeries<any>[]  valueFormatter?: (value: number) => string  xFormatter?: (value: string | number) => string  lockableTooltip?: boolean  isLocked?: boolean  selectionColor?: string}function MultiSignalTooltipContent({  active,  payload,  label: _label,  activeX,  activeDatum,  visibleSeries,  allSeries: _allSeries,  valueFormatter,  xFormatter,  lockableTooltip,  isLocked = false,  selectionColor = "var(--chart-selection, #8b5cf6)",}: MultiSignalTooltipContentProps) {  const payloadRow = payload?.[0]?.payload as Record<string, any> | undefined  const hasPayload = Boolean(payloadRow)  if (!activeDatum && (!active || !hasPayload)) {    return null  }  const rawX = activeDatum ? activeDatum.x : (payloadRow?.__x ?? activeX ?? "")  const xDisplay = xFormatter ? xFormatter(rawX) : String(rawX)  const lockedState = activeDatum ? activeDatum.isLocked : isLocked  const defaultValueFmt = valueFormatter ?? ((n: number) => n.toLocaleString())  const isCustomHex = typeof selectionColor === "string" && selectionColor.startsWith("#")  return (    <div      className={cn(        "rounded-xl border bg-zinc-950/95 p-3.5 shadow-2xl backdrop-blur-md min-w-[200px] max-w-[290px] text-left transition-all duration-150 pointer-events-none select-none z-50",        lockedState          ? "border-violet-500/40 shadow-[0_12px_32px_-4px_rgba(0,0,0,0.6),0_0_16px_rgba(139,92,246,0.15)] ring-1 ring-violet-500/25"          : "border-white/[0.12] ring-1 ring-white/[0.04]"      )}      style={        lockedState && isCustomHex          ? {              borderColor: `${selectionColor}66`,              boxShadow: `0 12px 32px -4px rgba(0,0,0,0.6), 0 0 16px ${selectionColor}26, 0 0 0 1px ${selectionColor}40`,            }          : undefined      }    >      {/* Header: X-Domain Coordinate + Optional Lock Badge */}      <div className="flex items-center justify-between gap-2 border-b border-white/[0.08] pb-2 mb-2.5">        <span className="font-mono text-xs font-semibold text-zinc-200 tracking-wide truncate">          {xDisplay}        </span>        {lockedState && (          <span            className="inline-flex items-center gap-1 rounded-md px-1.5 py-0.5 text-[10px] font-mono font-semibold tracking-tight border bg-violet-500/15 border-violet-500/40 text-violet-300 dark:bg-violet-400/15 dark:border-violet-400/40 dark:text-violet-200 shadow-2xs"            style={              isCustomHex                ? {                    backgroundColor: `${selectionColor}20`,                    borderColor: `${selectionColor}55`,                    color: selectionColor,                  }                : undefined            }          >            <HugeiconsIcon icon={LockKeyIcon} size={11} strokeWidth={2.2} className="shrink-0" />            Locked          </span>        )}      </div>      {/* Peer Series Values in Canonical Order */}      <div className="space-y-1.5">        {visibleSeries.map((s) => {          const val = activeDatum            ? activeDatum.values[s.key]            : (payloadRow ? payloadRow[s.key] : null)          const isMissing = val === null || val === undefined          const fmt = s.valueFormatter || defaultValueFmt          return (            <div key={s.key} className="flex items-center justify-between gap-3 text-xs">              <div className="flex items-center gap-2 min-w-0">                <span                  className="size-2 rounded-full shrink-0 ring-1 ring-white/20 shadow-xs"                  style={{ backgroundColor: s.color }}                />                <span className="text-zinc-300 font-sans truncate text-xs font-medium">                  {s.label}                </span>              </div>              <span className="font-mono text-xs font-bold text-white shrink-0 tabular-nums">                {isMissing ? "—" : fmt(val)}              </span>            </div>          )        })}      </div>      {/* Lock Interaction Hint */}      {lockableTooltip && (        <div className="mt-2.5 pt-2 border-t border-white/[0.08] flex items-center justify-between text-[10px] font-mono text-zinc-400">          {lockedState ? (            <span className="flex items-center gap-1.5">              <kbd className="inline-flex items-center justify-center px-1.5 py-0.5 rounded bg-zinc-800/90 border border-white/15 text-[9px] font-mono font-semibold text-zinc-200 shadow-2xs">                Esc              </kbd>              <span className="text-zinc-400">or click to release</span>            </span>          ) : (            <span className="flex items-center gap-1.5 text-zinc-500">              <kbd className="inline-flex items-center justify-center px-1.5 py-0.5 rounded bg-zinc-800/60 border border-white/10 text-[9px] font-mono font-medium text-zinc-400">                Click              </kbd>              <span>to lock</span>            </span>          )}        </div>      )}    </div>  )}/* -------------------------------------------------------------------------- *//*  Main MultiSignalLine Component                                            *//* -------------------------------------------------------------------------- */export function MultiSignalLine<  TData extends Record<string, unknown> = Record<string, unknown>,  XVal extends string | number = string | number>({  data,  xKey,  series,  height = 320,  curve = "monotone",  domain = "auto",  showGrid = true,  showXAxis = true,  showYAxis = true,  showLegend = true,  interactiveLegend = true,  lockableTooltip = true,  defaultLockedIndex = null,  defaultVisibleSeries,  onVisibleSeriesChange,  selectionColor = "var(--chart-selection, #8b5cf6)",  missingValuePolicy = "gap",  animation = "draw",  valueFormatter,  xFormatter,  motion = true,  onActiveDatumChange,  title,  description,  className,  loading = false,  error = null,  unavailable = false,}: MultiSignalLineProps<TData, XVal>) {  // Accessibility and container hooks  const reducedMotion = useChartReducedMotion()  const uid = React.useId()  const titleId = `plotcn-multisignal-title-${uid}`  const descId = `plotcn-multisignal-desc-${uid}`  // 1. Resolve deterministic series identities  const resolvedSeries = React.useMemo(    () => resolveMultiSignalSeries(series),    [series]  )  // 2. Normalize dataset  const normalizedData = React.useMemo(    () => normalizeMultiSignalData(data, xKey, resolvedSeries, missingValuePolicy),    [data, xKey, resolvedSeries, missingValuePolicy]  )  // 3. Interactive Series Visibility State (keyed by stable series.key)  const [hiddenSeries, setHiddenSeries] = React.useState<Set<string>>(() => {    if (defaultVisibleSeries && Array.isArray(defaultVisibleSeries)) {      const visibleSet = new Set(defaultVisibleSeries)      const initialHidden = new Set<string>()      for (const s of resolvedSeries) {        if (!visibleSet.has(s.key)) {          initialHidden.add(s.key)        }      }      return initialHidden    }    return new Set<string>()  })  // Clean stale keys if series list changes  React.useEffect(() => {    const validKeys = new Set<string>(resolvedSeries.map((s) => String(s.key)))    setHiddenSeries((prev) => {      let changed = false      const next = new Set<string>()      for (const k of prev) {        if (validKeys.has(k)) {          next.add(k)        } else {          changed = true        }      }      return changed ? next : prev    })  }, [resolvedSeries])  // Toggle single series visibility  const toggleSeriesVisibility = React.useCallback(    (key: string) => {      if (!interactiveLegend) return      setHiddenSeries((prev) => {        const next = new Set(prev)        if (next.has(key)) {          next.delete(key)        } else {          next.add(key)        }        if (onVisibleSeriesChange) {          const visible = resolvedSeries.filter((s) => !next.has(String(s.key))).map((s) => String(s.key))          onVisibleSeriesChange(visible)        }        return next      })    },    [interactiveLegend, onVisibleSeriesChange, resolvedSeries]  )  // Show all series recovery action  const showAllSeries = React.useCallback(() => {    setHiddenSeries(new Set<string>())    if (onVisibleSeriesChange) {      onVisibleSeriesChange(resolvedSeries.map((s) => String(s.key)))    }  }, [onVisibleSeriesChange, resolvedSeries])  // Derive visible series list in canonical order  const visibleSeries = React.useMemo(    () => resolvedSeries.filter((s) => !hiddenSeries.has(s.key)),    [resolvedSeries, hiddenSeries]  )  // Safe Y-axis domain covering all visible series  const safeDomain = React.useMemo(    () => calculateMultiSignalDomain(normalizedData, visibleSeries, domain),    [normalizedData, visibleSeries, domain]  )  // 4. Inspection State: active hover vs locked persistent datum  const [lockedIndex, setLockedIndex] = React.useState<number | null>(() => {    if (      typeof defaultLockedIndex === "number" &&      defaultLockedIndex >= 0 &&      defaultLockedIndex < normalizedData.length    ) {      return defaultLockedIndex    }    return null  })  const [activeIndex, setActiveIndex] = React.useState<number | null>(() => {    if (      typeof defaultLockedIndex === "number" &&      defaultLockedIndex >= 0 &&      defaultLockedIndex < normalizedData.length    ) {      return defaultLockedIndex    }    return null  })  const [isChartFocused, setIsChartFocused] = React.useState(false)  // Clear locked index if data shrinks  React.useEffect(() => {    if (lockedIndex !== null && (lockedIndex >= normalizedData.length || normalizedData.length === 0)) {      setLockedIndex(null)    }  }, [normalizedData.length, lockedIndex])  const effectiveIndex = lockedIndex !== null ? lockedIndex : activeIndex  // Construct active datum for consumers and tooltips  const activeDatum = React.useMemo<MultiSignalActiveDatum<TData, XVal> | null>(() => {    if (effectiveIndex === null || effectiveIndex < 0 || effectiveIndex >= normalizedData.length) {      return null    }    const row = normalizedData[effectiveIndex]    const values: Record<string, number | null> = {}    for (const s of resolvedSeries) {      values[s.key] = row[s.key]    }    return {      index: effectiveIndex,      x: row.__x as XVal,      raw: row.__raw as TData,      values,      isLocked: lockedIndex !== null && lockedIndex === effectiveIndex,    }  }, [effectiveIndex, lockedIndex, normalizedData, resolvedSeries])  // Notify consumer callback  React.useEffect(() => {    if (onActiveDatumChange) {      onActiveDatumChange(activeDatum)    }  }, [activeDatum, onActiveDatumChange])  /* -------------------------------------------------------------------------- */  /*  Keyboard & Pointer Scrubbing Handlers                                     */  /* -------------------------------------------------------------------------- */  const handleKeyDown = (e: React.KeyboardEvent<HTMLElement>) => {    if (normalizedData.length === 0) return    switch (e.key) {      case "ArrowRight": {        e.preventDefault()        const nextIdx = activeIndex === null ? 0 : Math.min(activeIndex + 1, normalizedData.length - 1)        setActiveIndex(nextIdx)        break      }      case "ArrowLeft": {        e.preventDefault()        const prevIdx =          activeIndex === null            ? normalizedData.length - 1            : Math.max(activeIndex - 1, 0)        setActiveIndex(prevIdx)        break      }      case "Home": {        e.preventDefault()        setActiveIndex(0)        break      }      case "End": {        e.preventDefault()        setActiveIndex(normalizedData.length - 1)        break      }      case "Enter":      case " ": {        if (!lockableTooltip) return        e.preventDefault()        const targetIndex = activeIndex !== null ? activeIndex : 0        if (lockedIndex === targetIndex) {          setLockedIndex(null)        } else {          setLockedIndex(targetIndex)          setActiveIndex(targetIndex)        }        break      }      case "Escape": {        e.preventDefault()        setLockedIndex(null)        setActiveIndex(null)        break      }    }  }  const handleChartMouseMove = (state: any) => {    if (!state || typeof state.activeTooltipIndex !== "number") return    const idx = state.activeTooltipIndex    if (idx < 0 || idx >= normalizedData.length) return    if (lockedIndex === null) {      if (activeIndex !== idx) {        setActiveIndex(idx)      }    }  }  const handleChartMouseLeave = () => {    if (lockedIndex === null) {      setActiveIndex(null)    }  }  const handleChartClick = (state: any) => {    if (!lockableTooltip || normalizedData.length === 0) return    const clickedIdx = typeof state?.activeTooltipIndex === "number" ? state.activeTooltipIndex : activeIndex    if (clickedIdx === null || clickedIdx < 0 || clickedIdx >= normalizedData.length) return    if (lockedIndex === clickedIdx) {      setLockedIndex(null)    } else {      setLockedIndex(clickedIdx)      setActiveIndex(clickedIdx)    }  }  // Animation settings  const isAnimated = motion !== false && !reducedMotion  const animationDuration =    typeof motion === "object" && motion?.duration !== undefined ? motion.duration * 1000 : 350  // Factual screen reader summary  const factualSummary = React.useMemo(() => {    if (normalizedData.length === 0) return "No observations recorded."    const visibleCount = visibleSeries.length    const totalCount = resolvedSeries.length    const obsCount = normalizedData.length    const activeInfo = activeDatum      ? ` Currently ${activeDatum.isLocked ? "locked on" : "inspecting"} observation ${activeDatum.index + 1} of ${obsCount} at ${String(activeDatum.x)}.`      : " Use Left and Right Arrow keys to inspect observations across all visible signals."    return `Multi-series line chart with ${visibleCount} visible of ${totalCount} series across ${obsCount} observations.${activeInfo}`  }, [normalizedData.length, visibleSeries.length, resolvedSeries.length, activeDatum])  /* -------------------------------------------------------------------------- */  /*  Early Return Error / Loading States                                       */  /* -------------------------------------------------------------------------- */  if (error) {    return (      <figure        role="region"        aria-label={title || "Multi-signal chart error state"}        className={cn("plotcn-multi-signal relative w-full overflow-hidden rounded-xl border border-white/10 bg-zinc-950 p-4", className)}        style={{ height, minHeight: typeof height === "number" ? height : 320 }}      >        <ChartErrorState          title="Unable to render multi-signal series"          description={typeof error === "string" ? error : error?.message || "An unexpected error occurred while loading series data."}        />      </figure>    )  }  if (loading) {    return (      <figure        role="region"        aria-label={title || "Multi-signal chart loading state"}        className={cn("plotcn-multi-signal relative w-full overflow-hidden rounded-xl border border-white/10 bg-zinc-950 p-4", className)}        style={{ height, minHeight: typeof height === "number" ? height : 320 }}      >        <ChartLoadingState          title="Loading multi-signal series…"          description="Preparing time-series trends and series comparison data"        />      </figure>    )  }  if (unavailable) {    return (      <figure        role="region"        aria-label={title || "Multi-signal chart unavailable state"}        className={cn("plotcn-multi-signal relative w-full overflow-hidden rounded-xl border border-white/10 bg-zinc-950 p-4", className)}        style={{ height, minHeight: typeof height === "number" ? height : 320 }}      >        <ChartUnavailableState          title="Multi-signal metrics unavailable"          description={typeof unavailable === "string" ? unavailable : "Comparative series data is currently unavailable."}        />      </figure>    )  }  if (normalizedData.length === 0) {    return (      <figure        role="region"        aria-label={title || "Multi-signal chart empty state"}        className={cn("plotcn-multi-signal relative w-full overflow-hidden rounded-xl border border-white/10 bg-zinc-950 p-4", className)}        style={{ height, minHeight: typeof height === "number" ? height : 320 }}      >        <ChartEmptyState          title="No data available"          description="Provide ordered observations and series keys to display comparative signals."        />      </figure>    )  }  const activeXCoordinate = effectiveIndex !== null ? normalizedData[effectiveIndex].__x : null  const isCurrentlyLocked = lockedIndex !== null  return (    <figure      role="region"      aria-labelledby={titleId}      aria-describedby={descId}      tabIndex={0}      onKeyDown={handleKeyDown}      onFocus={() => setIsChartFocused(true)}      onBlur={() => setIsChartFocused(false)}      className={cn(        "plotcn-multi-signal relative flex flex-col w-full outline-none select-none transition-all duration-150 rounded-xl",        "focus-visible:ring-2 focus-visible:ring-[var(--chart-focus,#38bdf8)] focus-visible:ring-offset-2 focus-visible:ring-offset-zinc-950",        className      )}      style={{        height,        minHeight: typeof height === "number" ? height : 320,        touchAction: "pan-y",      }}    >      {/* Screen Reader Semantic Announcement */}      <div className="sr-only">        <h3 id={titleId}>{title || "Multi-Signal Comparison Line Chart"}</h3>        <p id={descId}>{description ? `${description} ${factualSummary}` : factualSummary}</p>      </div>      {/* Chart Canvas Area */}      <ChartContainer className="w-full flex-1 min-w-0 min-h-0 max-w-full overflow-hidden relative">        {/* All-Series Hidden Truthful Recovery Overlay */}        {visibleSeries.length === 0 ? (          <div className="flex flex-col items-center justify-center h-full w-full py-12 px-4 text-center space-y-3 z-20">            <div className="size-10 rounded-full bg-zinc-900/80 border border-white/10 flex items-center justify-center text-zinc-400">              <HugeiconsIcon icon={ViewOffSlashIcon} size={20} />            </div>            <div className="space-y-1">              <p className="text-sm font-semibold text-zinc-200">No visible series</p>              <p className="text-xs text-zinc-400 max-w-xs">                Select a series in the legend below to display its trend on the chart.              </p>            </div>            {interactiveLegend && (              <button                type="button"                onClick={showAllSeries}                className="inline-flex items-center gap-1.5 px-3 py-1 rounded-lg bg-white/[0.08] hover:bg-white/[0.14] border border-white/[0.12] text-xs font-mono font-medium text-white transition-all cursor-pointer"              >                <HugeiconsIcon icon={ViewIcon} size={14} />                <span>Show all series</span>              </button>            )}          </div>        ) : (          <ResponsiveContainer            width="100%"            height="100%"            minWidth={0}            minHeight={0}            initialDimension={{ width: 320, height: typeof height === "number" ? height : 320 }}          >            <LineChart              data={normalizedData}              margin={{ top: 12, right: 16, bottom: 8, left: 8 }}              onMouseMove={handleChartMouseMove}              onMouseLeave={handleChartMouseLeave}              onClick={handleChartClick}            >              {/* Reference Grid */}              {showGrid && (                <CartesianGrid                  stroke="var(--chart-grid, rgba(255, 255, 255, 0.08))"                  strokeDasharray="3 3"                  vertical={false}                />              )}              {/* Horizontal Category Scale */}              <XAxis                hide={!showXAxis}                dataKey="__x"                tickLine={false}                axisLine={false}                tick={{ fontSize: 11, fill: "var(--chart-axis, #71717a)" }}                tickFormatter={xFormatter as any}                dy={6}              />              {/* Vertical Numeric Scale */}              <YAxis                hide={!showYAxis}                domain={safeDomain as any}                tickLine={false}                axisLine={false}                tick={{ fontSize: 11, fill: "var(--chart-axis, #71717a)" }}                tickFormatter={valueFormatter ? (v) => valueFormatter(Number(v)) : undefined}                dx={-4}              />              {/* Persistent Vertical Inspection Crosshair */}              {activeXCoordinate !== null && isCurrentlyLocked && (                <ReferenceLine                  x={activeXCoordinate}                  stroke={selectionColor}                  strokeDasharray="3 3"                  strokeWidth={1.5}                />              )}              {/* Synchronized Shared Tooltip */}              <Tooltip                active={isCurrentlyLocked || (isChartFocused && activeIndex !== null) ? true : undefined}                defaultIndex={typeof defaultLockedIndex === "number" ? defaultLockedIndex : undefined}                content={                  <MultiSignalTooltipContent                    activeX={activeXCoordinate}                    activeDatum={activeDatum}                    visibleSeries={visibleSeries}                    allSeries={resolvedSeries}                    valueFormatter={valueFormatter}                    xFormatter={xFormatter}                    lockableTooltip={lockableTooltip}                    isLocked={isCurrentlyLocked}                    selectionColor={selectionColor}                  />                }                cursor={{                  stroke: isCurrentlyLocked ? selectionColor : "var(--chart-crosshair, rgba(255, 255, 255, 0.28))",                  strokeDasharray: "3 3",                  strokeWidth: isCurrentlyLocked ? 1.5 : 1.2,                }}              />              {/* Peer Continuous Lines for all VISIBLE series */}              {visibleSeries.map((s) => (                <Line                  key={s.key}                  type={curve === "step" ? "stepAfter" : curve}                  dataKey={s.key}                  name={s.label}                  stroke={s.color}                  strokeWidth={2}                  strokeDasharray={s.strokeDasharray}                  connectNulls={false}                  isAnimationActive={isAnimated}                  animationDuration={animationDuration}                  dot={(dotProps: any) => {                    const { cx, cy, index, payload } = dotProps                    if (typeof cx !== "number" || typeof cy !== "number" || payload[s.key] === null) {                      return <React.Fragment key={`dot-${s.key}-${index}`} />                    }                    // Special active/locked marker for active observation                    if (index === effectiveIndex) {                      if (index === lockedIndex) {                        return (                          <g key={`locked-marker-${s.key}-${index}`} className="pointer-events-none">                            <circle cx={cx} cy={cy} r={7} fill="none" stroke={s.color} strokeWidth={2} />                            <circle cx={cx} cy={cy} r={3.5} fill={s.color} stroke="var(--chart-background, #09090b)" strokeWidth={1.5} />                          </g>                        )                      }                      return (                        <circle                          key={`active-marker-${s.key}-${index}`}                          cx={cx}                          cy={cy}                          r={5}                          fill={s.color}                          stroke="var(--chart-background, #09090b)"                          strokeWidth={2}                          className="pointer-events-none"                        />                      )                    }                    return <React.Fragment key={`dot-${s.key}-${index}`} />                  }}                  activeDot={(activeProps: any) => {                    const { cx, cy, index, payload } = activeProps                    if (typeof cx !== "number" || typeof cy !== "number" || payload?.[s.key] === null) {                      return <React.Fragment key={`act-dot-${s.key}-${index}`} />                    }                    if (index === lockedIndex) {                      return (                        <g key={`locked-act-${s.key}-${index}`} className="pointer-events-none">                          <circle cx={cx} cy={cy} r={7} fill="none" stroke={s.color} strokeWidth={2} />                          <circle cx={cx} cy={cy} r={3.5} fill={s.color} stroke="var(--chart-background, #09090b)" strokeWidth={1.5} />                        </g>                      )                    }                    return (                      <circle                        key={`hover-dot-${s.key}-${index}`}                        cx={cx}                        cy={cy}                        r={5}                        fill={s.color}                        stroke="var(--chart-background, #09090b)"                        strokeWidth={2}                        className="pointer-events-none"                      />                    )                  }}                />              ))}            </LineChart>          </ResponsiveContainer>        )}      </ChartContainer>      {/* Interactive Responsive Series Legend */}      {showLegend && (        <div          role="group"          aria-label="Chart series visibility toggles"          className="flex flex-wrap items-center justify-center gap-x-4 gap-y-2 pt-3 px-2 text-xs font-mono select-none"        >          {resolvedSeries.map((s) => {            const isHidden = hiddenSeries.has(s.key)            return (              <button                key={s.key}                type="button"                role="switch"                aria-checked={!isHidden}                aria-label={`${s.label} series: ${isHidden ? "hidden, click to show" : "visible, click to hide"}`}                disabled={!interactiveLegend}                onClick={() => toggleSeriesVisibility(s.key)}                className={cn(                  "inline-flex items-center gap-2 px-2.5 py-1 rounded-md transition-all",                  interactiveLegend                    ? "cursor-pointer hover:bg-white/[0.06] focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-white/30"                    : "cursor-default",                  isHidden ? "opacity-35 line-through text-zinc-500" : "opacity-100 text-zinc-300 font-medium"                )}              >                {/* Structural Line Stroke Sample */}                <svg width={16} height={6} className="shrink-0 overflow-visible" aria-hidden="true">                  <line                    x1={0}                    y1={3}                    x2={16}                    y2={3}                    stroke={isHidden ? "currentColor" : s.color}                    strokeWidth={2}                    strokeDasharray={s.strokeDasharray}                  />                </svg>                <span className="truncate">{s.label}</span>              </button>            )          })}        </div>      )}    </figure>  )}