All files / web/src/components/decomposition DecompositionDisplay.tsx

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'use client'
 
import type React from 'react'
import { createContext, useContext, useEffect, useMemo, useRef, useState } from 'react'
import { useDecomposition } from '@/contexts/DecompositionContext'
import type { PedagogicalSegment, UnifiedStepData } from '@/utils/unifiedStepGenerator'
import { ReasonTooltip } from './ReasonTooltip'
import './decomposition.css'
 
// ============================================================================
// Internal Context for term hover coordination
// ============================================================================
 
interface InternalDecompositionContextType {
  activeTerms: Set<number>
  activeSegmentId: string | null
  addActiveTerm: (termIndex: number, segmentId?: string) => void
  removeActiveTerm: (termIndex: number, segmentId?: string) => void
}
 
const InternalDecompositionContext = createContext<InternalDecompositionContextType>({
  activeTerms: new Set(),
  activeSegmentId: null,
  addActiveTerm: () => {},
  removeActiveTerm: () => {},
})
 
// ============================================================================
// TermSpan Component
// ============================================================================
 
interface TermSpanProps {
  termIndex: number
  text: string
  segment?: PedagogicalSegment
  isCurrentStep?: boolean
}
 
function TermSpan({ termIndex, text, segment, isCurrentStep = false }: TermSpanProps) {
  const { addActiveTerm, removeActiveTerm } = useContext(InternalDecompositionContext)
  const rule = segment?.plan[0]?.rule
 
  // Only show styling for terms that have pedagogical reasoning
  if (!rule) {
    return <span className="term term--plain">{text}</span>
  }
 
  // Determine CSS classes based on current step only
  const cssClasses = ['term', isCurrentStep && 'term--current'].filter(Boolean).join(' ')
 
  // Individual term hover handlers for two-level highlighting
  const handleTermHover = (isHovering: boolean) => {
    if (isHovering) {
      addActiveTerm(termIndex, segment?.id)
    } else {
      removeActiveTerm(termIndex, segment?.id)
    }
  }
 
  return (
    <span
      data-element="decomposition-term"
      data-term-index={termIndex}
      className={cssClasses}
      onMouseEnter={() => handleTermHover(true)}
      onMouseLeave={() => handleTermHover(false)}
      style={{ cursor: 'pointer' }}
    >
      {text}
    </span>
  )
}
 
// ============================================================================
// SegmentGroup Component
// ============================================================================
 
interface SegmentGroupProps {
  segment: PedagogicalSegment
  steps: UnifiedStepData[]
  children: React.ReactNode
}
 
function SegmentGroup({ segment, steps, children }: SegmentGroupProps) {
  const { addActiveTerm, removeActiveTerm } = useContext(InternalDecompositionContext)
 
  // Calculate the original term that was expanded
  // digit * 10^place gives us the original value (e.g., digit=5, place=1 -> 50)
  const originalValue = (segment.digit * 10 ** segment.place).toString()
 
  // Get provenance from the first step in this segment
  const firstStepIndex = segment.termIndices[0]
  const firstStep = steps[firstStepIndex]
  const provenance = firstStep?.provenance
 
  const handleHighlightChange = (active: boolean) => {
    // Only handle highlighting, let HoverCard manage its own open/close timing
    if (active) {
      segment.termIndices.forEach((termIndex) => addActiveTerm(termIndex, segment.id))
    } else {
      segment.termIndices.forEach((termIndex) => removeActiveTerm(termIndex, segment.id))
    }
  }
 
  return (
    <ReasonTooltip
      termIndex={segment.termIndices[0]} // Use first term for tooltip ID
      segment={segment}
      originalValue={originalValue}
      steps={steps}
      provenance={provenance}
    >
      <span
        data-element="segment-group"
        data-segment-id={segment.id}
        className="segment-group"
        onMouseEnter={() => handleHighlightChange(true)}
        onMouseLeave={() => handleHighlightChange(false)}
      >
        {children}
      </span>
    </ReasonTooltip>
  )
}
 
// ============================================================================
// DecompositionDisplay Component
// ============================================================================
 
/**
 * Renders the decomposition string with interactive terms and tooltips.
 *
 * Must be used inside a DecompositionProvider.
 *
 * @example
 * ```tsx
 * <DecompositionProvider startValue={0} targetValue={45}>
 *   <DecompositionDisplay />
 * </DecompositionProvider>
 * ```
 */
export function DecompositionDisplay() {
  const {
    fullDecomposition,
    termPositions,
    segments,
    steps,
    currentStepIndex,
    activeTermIndices,
    setActiveTermIndices,
    setActiveIndividualTermIndex,
    getGroupTermIndicesFromTermIndex,
    isMeaningfulDecomposition,
  } = useDecomposition()
 
  // Don't render if decomposition is not meaningful (e.g., "5 = 5")
  if (!isMeaningfulDecomposition) {
    return null
  }
 
  // Refs for overflow detection
  const containerRef = useRef<HTMLDivElement>(null)
  const measureRef = useRef<HTMLDivElement>(null)
  const [needsMultiLine, setNeedsMultiLine] = useState(false)
 
  // Build a quick lookup: termIndex -> segment
  const termIndexToSegment = useMemo(() => {
    const map = new Map<number, PedagogicalSegment>()
    segments?.forEach((seg) => seg.termIndices.forEach((i) => map.set(i, seg)))
    return map
  }, [segments])
 
  // Determine which segment should be highlighted based on active terms
  const activeSegmentId = useMemo(() => {
    if (activeTermIndices.size === 0) return null

    // Find the segment that contains any of the active terms
    for (const termIndex of activeTermIndices) {
      const segment = termIndexToSegment.get(termIndex)
      if (segment) {
        return segment.id
      }
    }
    return null
  }, [activeTermIndices, termIndexToSegment])
 
  // Detect overflow and enable multi-line mode if needed
  // Uses a hidden measurement element that always renders in single-line mode
  useEffect(() => {
    const container = containerRef.current
    const measure = measureRef.current
    if (!container || !measure) return
 
    const checkOverflow = () => {
      // measureRef always contains the single-line version, so we can
      // reliably compare its width to the container width
      const singleLineWidth = measure.scrollWidth
      const containerWidth = container.clientWidth
 
      // Add a small buffer (2px) to avoid edge cases
      setNeedsMultiLine(singleLineWidth > containerWidth + 2)
    }
 
    // Check on mount and content changes
    checkOverflow()
 
    // Use ResizeObserver to detect container size changes
    const resizeObserver = new ResizeObserver(checkOverflow)
    resizeObserver.observe(container)
 
    return () => resizeObserver.disconnect()
  }, [fullDecomposition])
 
  // Term hover handlers
  const addActiveTerm = (termIndex: number, _segmentId?: string) => {
    // Set individual term highlight (orange glow)
    setActiveIndividualTermIndex(termIndex)

    // Set group term highlights (blue glow) - for complement groups, highlight only the target column
    const groupTermIndices = getGroupTermIndicesFromTermIndex(termIndex)

    if (groupTermIndices.length > 0) {
      // For complement groups, highlight only the target column (rhsPlace, not individual termPlaces)
      // Use any term from the group since they all share the same rhsPlace (target column)
      setActiveTermIndices(new Set([termIndex]))
    } else {
      // This is a standalone term, just highlight it
      setActiveTermIndices(new Set([termIndex]))
    }
  }
 
  const removeActiveTerm = (_termIndex: number, _segmentId?: string) => {
    // Clear individual term highlight
    setActiveIndividualTermIndex(null)

    // Clear group term highlights
    setActiveTermIndices(new Set())
  }
 
  // Find positions of '=' signs in fullDecomposition for line breaking
  const equalSignPositions = useMemo(() => {
    const positions: number[] = []
    for (let i = 0; i < fullDecomposition.length; i++) {
      if (fullDecomposition[i] === '=') {
        positions.push(i)
      }
    }
    return positions
  }, [fullDecomposition])
 
  // Render elements for a given range of the decomposition string
  const renderElementsForRange = (rangeStart: number, rangeEnd: number, keyPrefix: string) => {
    const elements: React.ReactNode[] = []
    let cursor = rangeStart
 
    for (let termIndex = 0; termIndex < termPositions.length; termIndex++) {
      const { startIndex, endIndex } = termPositions[termIndex]
 
      // Skip terms outside our range
      if (endIndex <= rangeStart || startIndex >= rangeEnd) continue
 
      const segment = termIndexToSegment.get(termIndex)
 
      // Add connector text before this term (within range)
      const connectorStart = Math.max(cursor, rangeStart)
      const connectorEnd = Math.min(startIndex, rangeEnd)
      if (connectorStart < connectorEnd) {
        elements.push(
          <span key={`${keyPrefix}-connector-${connectorStart}`}>
            {fullDecomposition.slice(connectorStart, connectorEnd)}
          </span>
        )
      }
 
      // Check if this term starts a new segment
      if (segment && segment.termIndices[0] === termIndex) {
        // This is the first term of a segment - wrap all segment terms
        const segmentElements: React.ReactNode[] = []
        let segmentCursor = Math.max(startIndex, rangeStart)
 
        for (const segTermIndex of segment.termIndices) {
          const segPos = termPositions[segTermIndex]
          if (!segPos) continue
 
          // Skip segment terms outside our range
          if (segPos.endIndex <= rangeStart || segPos.startIndex >= rangeEnd) continue
 
          // Add connector within segment (within range)
          const segConnectorStart = Math.max(segmentCursor, rangeStart)
          const segConnectorEnd = Math.min(segPos.startIndex, rangeEnd)
          if (segConnectorStart < segConnectorEnd) {
            segmentElements.push(
              <span key={`${keyPrefix}-seg-connector-${segConnectorStart}`}>
                {fullDecomposition.slice(segConnectorStart, segConnectorEnd)}
              </span>
            )
          }
 
          const termStart = Math.max(segPos.startIndex, rangeStart)
          const termEnd = Math.min(segPos.endIndex, rangeEnd)
          const segText = fullDecomposition.slice(termStart, termEnd)
 
          if (segText) {
            segmentElements.push(
              <TermSpan
                key={`${keyPrefix}-seg-term-${segTermIndex}`}
                termIndex={segTermIndex}
                text={segText}
                segment={segment}
                isCurrentStep={segTermIndex === currentStepIndex}
              />
            )
          }
 
          segmentCursor = segPos.endIndex
        }
 
        if (segmentElements.length > 0) {
          elements.push(
            <SegmentGroup
              key={`${keyPrefix}-segment-${segment.id}`}
              segment={segment}
              steps={steps}
            >
              {segmentElements}
            </SegmentGroup>
          )
        }
 
        // Skip ahead past all terms in this segment
        const lastSegTermIndex = segment.termIndices[segment.termIndices.length - 1]
        const lastSegPos = termPositions[lastSegTermIndex]
        cursor = Math.min(lastSegPos?.endIndex ?? endIndex, rangeEnd)
        termIndex = lastSegTermIndex // Will be incremented by for loop
      } else if (!segment) {
        // Regular term not in a segment
        const termStart = Math.max(startIndex, rangeStart)
        const termEnd = Math.min(endIndex, rangeEnd)
        const termText = fullDecomposition.slice(termStart, termEnd)

        if (termText) {
          elements.push(
            <TermSpan
              key={`${keyPrefix}-term-${termIndex}`}
              termIndex={termIndex}
              text={termText}
              segment={segment}
              isCurrentStep={termIndex === currentStepIndex}
            />
          )
        }
        cursor = termEnd
      }
      // If this term is part of a segment but not the first, it was already handled above
    }
 
    // Add trailing text within range
    if (cursor < rangeEnd) {
      elements.push(
        <span key={`${keyPrefix}-trailing`}>{fullDecomposition.slice(cursor, rangeEnd)}</span>
      )
    }
 
    return elements
  }
 
  // Render elements - either single line or multi-line split on '='
  const renderElements = () => {
    if (!needsMultiLine || equalSignPositions.length === 0) {
      // Single line mode
      return renderElementsForRange(0, fullDecomposition.length, 'single')
    }

    // Multi-line mode: split on '=' signs
    // First line: everything before first '='
    // Subsequent lines: start with '=' and go to next '=' (or end)
    const lines: React.ReactNode[] = []

    // First line: from start to first '='
    const firstEqualPos = equalSignPositions[0]
    if (firstEqualPos > 0) {
      lines.push(
        <div key="line-0" className="decomposition-line">
          {renderElementsForRange(0, firstEqualPos, 'line-0')}
        </div>
      )
    }

    // Subsequent lines: each starts with '=' and goes to next '=' or end
    for (let i = 0; i < equalSignPositions.length; i++) {
      const lineStart = equalSignPositions[i]
      const lineEnd = equalSignPositions[i + 1] ?? fullDecomposition.length

      lines.push(
        <div key={`line-${i + 1}`} className="decomposition-line">
          {renderElementsForRange(lineStart, lineEnd, `line-${i + 1}`)}
        </div>
      )
    }

    return lines
  }
 
  return (
    <InternalDecompositionContext.Provider
      value={{
        activeTerms: activeTermIndices,
        activeSegmentId,
        addActiveTerm,
        removeActiveTerm,
      }}
    >
      <div
        ref={containerRef}
        data-element="decomposition-display"
        className={`decomposition ${needsMultiLine ? 'decomposition--multiline' : ''}`}
      >
        {/* Hidden measurement element - always renders single-line to measure true width */}
        <div ref={measureRef} className="decomposition-measure" aria-hidden="true">
          {renderElementsForRange(0, fullDecomposition.length, 'measure')}
        </div>
        {/* Visible content - may be multi-line if overflow detected */}
        <div className="decomposition-content">{renderElements()}</div>
      </div>
    </InternalDecompositionContext.Provider>
  )
}
 
/**
 * DecompositionSection - A self-contained section with label that hides when decomposition is not meaningful
 *
 * Use this when you want the entire section (including "Step-by-Step" label) to disappear
 * when the decomposition is trivial (e.g., "5 = 5").
 *
 * Must be used inside a DecompositionProvider.
 */
export function DecompositionSection({
  label = 'Step-by-Step',
  className,
  labelClassName,
  contentClassName,
}: {
  label?: string
  className?: string
  labelClassName?: string
  contentClassName?: string
}) {
  const { isMeaningfulDecomposition } = useDecomposition()

  if (!isMeaningfulDecomposition) {
    return null
  }

  return (
    <div data-element="decomposition-section" className={className}>
      <div data-element="decomposition-label" className={labelClassName}>
        {label}
      </div>
      <div data-element="decomposition-content" className={contentClassName}>
        <DecompositionDisplay />
      </div>
    </div>
  )
}