'use client'

import { useCallback, useEffect, useRef, useState } from 'react'
import type { GridResult, GridCell, WordEntry, WordGroundTruth } from '@/app/(admin)/ai/ocr-pipeline/types'

const KLAUSUR_API = '/klausur-api'

/** Render text with \n as line breaks */
function MultilineText({ text }: { text: string }) {
  if (!text) return <span className="text-gray-300 dark:text-gray-600">&mdash;</span>
  const lines = text.split('\n')
  if (lines.length === 1) return <>{text}</>
  return <>{lines.map((line, i) => (
    <span key={i}>{line}{i < lines.length - 1 && <br />}</span>
  ))}</>
}

/** Column type → human-readable header */
function colTypeLabel(colType: string): string {
  const labels: Record<string, string> = {
    column_en: 'English',
    column_de: 'Deutsch',
    column_example: 'Example',
    column_text: 'Text',
    column_marker: 'Marker',
    page_ref: 'Seite',
  }
  return labels[colType] || colType.replace('column_', '')
}

/** Column type → color class */
function colTypeColor(colType: string): string {
  const colors: Record<string, string> = {
    column_en: 'text-blue-600 dark:text-blue-400',
    column_de: 'text-green-600 dark:text-green-400',
    column_example: 'text-orange-600 dark:text-orange-400',
    column_text: 'text-purple-600 dark:text-purple-400',
    column_marker: 'text-gray-500 dark:text-gray-400',
  }
  return colors[colType] || 'text-gray-600 dark:text-gray-400'
}

interface StepWordRecognitionProps {
  sessionId: string | null
  onNext: () => void
  goToStep: (step: number) => void
}

export function StepWordRecognition({ sessionId, onNext, goToStep }: StepWordRecognitionProps) {
  const [gridResult, setGridResult] = useState<GridResult | null>(null)
  const [detecting, setDetecting] = useState(false)
  const [error, setError] = useState<string | null>(null)
  const [gtNotes, setGtNotes] = useState('')
  const [gtSaved, setGtSaved] = useState(false)

  // Step-through labeling state
  const [activeIndex, setActiveIndex] = useState(0)
  const [editedEntries, setEditedEntries] = useState<WordEntry[]>([])
  const [editedCells, setEditedCells] = useState<GridCell[]>([])
  const [mode, setMode] = useState<'overview' | 'labeling'>('overview')
  const [ocrEngine, setOcrEngine] = useState<'auto' | 'tesseract' | 'rapid'>('auto')
  const [usedEngine, setUsedEngine] = useState<string>('')
  const [pronunciation, setPronunciation] = useState<'british' | 'american'>('british')

  // Streaming progress state
  const [streamProgress, setStreamProgress] = useState<{ current: number; total: number } | null>(null)

  const enRef = useRef<HTMLInputElement>(null)
  const tableEndRef = useRef<HTMLDivElement>(null)

  const isVocab = gridResult?.layout === 'vocab'

  useEffect(() => {
    if (!sessionId) return
    // Always run fresh detection — word-lookup is fast (~0.03s)
    // and avoids stale cached results from previous pipeline versions.
    runAutoDetection()
  // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [sessionId])

  const applyGridResult = (data: GridResult) => {
    setGridResult(data)
    setUsedEngine(data.ocr_engine || '')
    if (data.layout === 'vocab' && data.entries) {
      initEntries(data.entries)
    }
    if (data.cells) {
      setEditedCells(data.cells.map(c => ({ ...c, status: c.status || 'pending' })))
    }
  }

  const initEntries = (entries: WordEntry[]) => {
    setEditedEntries(entries.map(e => ({ ...e, status: e.status || 'pending' })))
    setActiveIndex(0)
  }

  const runAutoDetection = useCallback(async (engine?: string) => {
    if (!sessionId) return
    const eng = engine || ocrEngine
    setDetecting(true)
    setError(null)
    setStreamProgress(null)
    setEditedCells([])
    setEditedEntries([])
    setGridResult(null)

    try {
      // Retry once if initial request fails (e.g. after container restart,
      // session cache may not be warm yet when navigating via wizard)
      let res: Response | null = null
      for (let attempt = 0; attempt < 2; attempt++) {
        res = await fetch(
          `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/words?stream=true&engine=${eng}&pronunciation=${pronunciation}`,
          { method: 'POST' },
        )
        if (res.ok) break
        if (attempt === 0 && (res.status === 400 || res.status === 404)) {
          // Wait briefly for cache to warm up, then retry
          await new Promise(r => setTimeout(r, 2000))
          continue
        }
        break
      }
      if (!res || !res.ok) {
        const err = await res?.json().catch(() => ({ detail: res?.statusText })) || { detail: 'Worterkennung fehlgeschlagen' }
        throw new Error(err.detail || 'Worterkennung fehlgeschlagen')
      }

      const reader = res.body!.getReader()
      const decoder = new TextDecoder()
      let buffer = ''
      let streamLayout: string | null = null
      let streamColumnsUsed: GridResult['columns_used'] = []
      let streamGridShape: GridResult['grid_shape'] | null = null
      let streamCells: GridCell[] = []

      while (true) {
        const { done, value } = await reader.read()
        if (done) break
        buffer += decoder.decode(value, { stream: true })

        // Parse SSE events (separated by \n\n)
        while (buffer.includes('\n\n')) {
          const idx = buffer.indexOf('\n\n')
          const chunk = buffer.slice(0, idx).trim()
          buffer = buffer.slice(idx + 2)

          if (!chunk.startsWith('data: ')) continue
          const dataStr = chunk.slice(6) // strip "data: "

          let event: any
          try {
            event = JSON.parse(dataStr)
          } catch {
            continue
          }

          if (event.type === 'meta') {
            streamLayout = event.layout || 'generic'
            streamGridShape = event.grid_shape || null
            // Show partial grid result so UI renders structure
            setGridResult(prev => ({
              ...prev,
              layout: event.layout || 'generic',
              grid_shape: event.grid_shape,
              columns_used: [],
              cells: [],
              summary: { total_cells: event.grid_shape?.total_cells || 0, non_empty_cells: 0, low_confidence: 0 },
              duration_seconds: 0,
              ocr_engine: '',
            } as GridResult))
          }

          if (event.type === 'columns') {
            streamColumnsUsed = event.columns_used || []
            setGridResult(prev => prev ? { ...prev, columns_used: streamColumnsUsed } : prev)
          }

          if (event.type === 'cell') {
            const cell: GridCell = { ...event.cell, status: 'pending' }
            streamCells = [...streamCells, cell]
            setEditedCells(streamCells)
            setStreamProgress(event.progress)
            // Auto-scroll table to bottom
            setTimeout(() => tableEndRef.current?.scrollIntoView({ behavior: 'smooth', block: 'nearest' }), 16)
          }

          if (event.type === 'complete') {
            // Build final GridResult
            const finalResult: GridResult = {
              cells: streamCells,
              grid_shape: streamGridShape || { rows: 0, cols: 0, total_cells: streamCells.length },
              columns_used: streamColumnsUsed,
              layout: streamLayout || 'generic',
              image_width: 0,
              image_height: 0,
              duration_seconds: event.duration_seconds || 0,
              ocr_engine: event.ocr_engine || '',
              summary: event.summary || {},
            }

            // If vocab: apply post-processed entries from complete event
            if (event.vocab_entries) {
              finalResult.entries = event.vocab_entries
              finalResult.vocab_entries = event.vocab_entries
              finalResult.entry_count = event.vocab_entries.length
            }

            applyGridResult(finalResult)
            setUsedEngine(event.ocr_engine || '')
            setStreamProgress(null)
          }
        }
      }
    } catch (e) {
      setError(e instanceof Error ? e.message : 'Unbekannter Fehler')
    } finally {
      setDetecting(false)
    }
  // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [sessionId, ocrEngine, pronunciation])

  const handleGroundTruth = useCallback(async (isCorrect: boolean) => {
    if (!sessionId) return
    const gt: WordGroundTruth = {
      is_correct: isCorrect,
      corrected_entries: isCorrect ? undefined : (isVocab ? editedEntries : undefined),
      notes: gtNotes || undefined,
    }
    try {
      await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/ground-truth/words`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(gt),
      })
      setGtSaved(true)
    } catch (e) {
      console.error('Ground truth save failed:', e)
    }
  }, [sessionId, gtNotes, editedEntries, isVocab])

  // Vocab mode: update entry field
  const updateEntry = (index: number, field: 'english' | 'german' | 'example', value: string) => {
    setEditedEntries(prev => prev.map((e, i) =>
      i === index ? { ...e, [field]: value, status: 'edited' as const } : e
    ))
  }

  // Generic mode: update cell text
  const updateCell = (cellId: string, value: string) => {
    setEditedCells(prev => prev.map(c =>
      c.cell_id === cellId ? { ...c, text: value, status: 'edited' as const } : c
    ))
  }

  // Step-through: confirm current row (always cell-based)
  const confirmEntry = () => {
    const rowCells = getRowCells(activeIndex)
    const cellIds = new Set(rowCells.map(c => c.cell_id))
    setEditedCells(prev => prev.map(c =>
      cellIds.has(c.cell_id) ? { ...c, status: c.status === 'edited' ? 'edited' : 'confirmed' } : c
    ))
    const maxIdx = getUniqueRowCount() - 1
    if (activeIndex < maxIdx) {
      setActiveIndex(activeIndex + 1)
    }
  }

  // Step-through: skip current row
  const skipEntry = () => {
    const rowCells = getRowCells(activeIndex)
    const cellIds = new Set(rowCells.map(c => c.cell_id))
    setEditedCells(prev => prev.map(c =>
      cellIds.has(c.cell_id) ? { ...c, status: 'skipped' as const } : c
    ))
    const maxIdx = getUniqueRowCount() - 1
    if (activeIndex < maxIdx) {
      setActiveIndex(activeIndex + 1)
    }
  }

  // Helper: get unique row indices from cells
  const getUniqueRowCount = () => {
    if (!editedCells.length) return 0
    return new Set(editedCells.map(c => c.row_index)).size
  }

  // Helper: get cells for a given row index (by position in sorted unique rows)
  const getRowCells = (rowPosition: number) => {
    const uniqueRows = [...new Set(editedCells.map(c => c.row_index))].sort((a, b) => a - b)
    const rowIdx = uniqueRows[rowPosition]
    return editedCells.filter(c => c.row_index === rowIdx)
  }

  // Focus english input when active entry changes in labeling mode
  useEffect(() => {
    if (mode === 'labeling' && enRef.current) {
      enRef.current.focus()
    }
  }, [activeIndex, mode])

  // Keyboard shortcuts in labeling mode
  useEffect(() => {
    if (mode !== 'labeling') return
    const handler = (e: KeyboardEvent) => {
      if (e.key === 'Enter' && !e.shiftKey) {
        e.preventDefault()
        confirmEntry()
      } else if (e.key === 'ArrowDown' && e.ctrlKey) {
        e.preventDefault()
        skipEntry()
      } else if (e.key === 'ArrowUp' && e.ctrlKey) {
        e.preventDefault()
        if (activeIndex > 0) setActiveIndex(activeIndex - 1)
      }
    }
    window.addEventListener('keydown', handler)
    return () => window.removeEventListener('keydown', handler)
  // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [mode, activeIndex, editedEntries, editedCells])

  if (!sessionId) {
    return (
      <div className="flex flex-col items-center justify-center py-16 text-center">
        <div className="text-5xl mb-4">🔤</div>
        <h3 className="text-lg font-medium text-gray-700 dark:text-gray-300 mb-2">
          Schritt 5: Worterkennung
        </h3>
        <p className="text-gray-500 dark:text-gray-400 max-w-md">
          Bitte zuerst Schritte 1-4 abschliessen.
        </p>
      </div>
    )
  }

  const overlayUrl = `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/image/words-overlay`
  const dewarpedUrl = `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/image/cropped`

  const confColor = (conf: number) => {
    if (conf >= 70) return 'text-green-600 dark:text-green-400'
    if (conf >= 50) return 'text-yellow-600 dark:text-yellow-400'
    return 'text-red-600 dark:text-red-400'
  }

  const statusBadge = (status?: string) => {
    const map: Record<string, string> = {
      pending: 'bg-gray-100 dark:bg-gray-700 text-gray-500',
      confirmed: 'bg-green-100 dark:bg-green-900/30 text-green-700 dark:text-green-400',
      edited: 'bg-blue-100 dark:bg-blue-900/30 text-blue-700 dark:text-blue-400',
      skipped: 'bg-orange-100 dark:bg-orange-900/30 text-orange-700 dark:text-orange-400',
    }
    return map[status || 'pending'] || map.pending
  }

  const summary = gridResult?.summary
  const columnsUsed = gridResult?.columns_used || []
  const gridShape = gridResult?.grid_shape

  // Counts for labeling progress (always cell-based)
  const confirmedRowIds = new Set(
    editedCells.filter(c => c.status === 'confirmed' || c.status === 'edited').map(c => c.row_index)
  )
  const confirmedCount = confirmedRowIds.size
  const totalCount = getUniqueRowCount()

  // Group cells by row for generic table display
  const cellsByRow: Map<number, GridCell[]> = new Map()
  for (const cell of editedCells) {
    const existing = cellsByRow.get(cell.row_index) || []
    existing.push(cell)
    cellsByRow.set(cell.row_index, existing)
  }
  const sortedRowIndices = [...cellsByRow.keys()].sort((a, b) => a - b)

  return (
    <div className="space-y-4">
      {/* Loading with streaming progress */}
      {detecting && (
        <div className="space-y-1">
          <div className="flex items-center gap-2 text-teal-600 dark:text-teal-400 text-sm">
            <div className="animate-spin w-4 h-4 border-2 border-teal-500 border-t-transparent rounded-full" />
            {streamProgress
              ? `Zelle ${streamProgress.current}/${streamProgress.total} erkannt...`
              : 'Worterkennung startet...'}
          </div>
          {streamProgress && streamProgress.total > 0 && (
            <div className="w-full bg-gray-200 dark:bg-gray-700 rounded-full h-1.5">
              <div
                className="bg-teal-500 h-1.5 rounded-full transition-all duration-150"
                style={{ width: `${(streamProgress.current / streamProgress.total) * 100}%` }}
              />
            </div>
          )}
        </div>
      )}

      {/* Layout badge + Mode toggle */}
      {gridResult && (
        <div className="flex items-center gap-2">
          {/* Layout badge */}
          <span className={`px-2 py-0.5 rounded text-[10px] uppercase font-semibold ${
            isVocab
              ? 'bg-indigo-100 dark:bg-indigo-900/30 text-indigo-700 dark:text-indigo-300'
              : 'bg-gray-100 dark:bg-gray-700 text-gray-600 dark:text-gray-400'
          }`}>
            {isVocab ? 'Vokabel-Layout' : 'Generisch'}
          </span>

          {gridShape && (
            <span className="text-[10px] text-gray-400">
              {gridShape.rows}×{gridShape.cols} = {gridShape.total_cells} Zellen
            </span>
          )}

          <div className="flex-1" />

          <button
            onClick={() => setMode('overview')}
            className={`px-3 py-1.5 text-xs rounded-lg font-medium transition-colors ${
              mode === 'overview'
                ? 'bg-teal-600 text-white'
                : 'bg-gray-100 dark:bg-gray-700 text-gray-600 dark:text-gray-300 hover:bg-gray-200 dark:hover:bg-gray-600'
            }`}
          >
            Uebersicht
          </button>
          <button
            onClick={() => setMode('labeling')}
            className={`px-3 py-1.5 text-xs rounded-lg font-medium transition-colors ${
              mode === 'labeling'
                ? 'bg-teal-600 text-white'
                : 'bg-gray-100 dark:bg-gray-700 text-gray-600 dark:text-gray-300 hover:bg-gray-200 dark:hover:bg-gray-600'
            }`}
          >
            Labeling ({confirmedCount}/{totalCount})
          </button>
        </div>
      )}

      {/* Overview mode */}
      {mode === 'overview' && (
        <>
          {/* Images: overlay vs clean */}
          <div className="grid grid-cols-2 gap-4">
            <div>
              <div className="text-xs font-medium text-gray-500 dark:text-gray-400 mb-1">
                Mit Grid-Overlay
              </div>
              <div className="border rounded-lg overflow-hidden dark:border-gray-700 bg-gray-50 dark:bg-gray-900">
                {gridResult ? (
                  // eslint-disable-next-line @next/next/no-img-element
                  <img
                    src={`${overlayUrl}?t=${Date.now()}`}
                    alt="Wort-Overlay"
                    className="w-full h-auto"
                  />
                ) : (
                  <div className="aspect-[3/4] flex items-center justify-center text-gray-400 text-sm">
                    {detecting ? 'Erkenne Woerter...' : 'Keine Daten'}
                  </div>
                )}
              </div>
            </div>
            <div>
              <div className="text-xs font-medium text-gray-500 dark:text-gray-400 mb-1">
                Entzerrtes Bild
              </div>
              <div className="border rounded-lg overflow-hidden dark:border-gray-700 bg-gray-50 dark:bg-gray-900">
                {/* eslint-disable-next-line @next/next/no-img-element */}
                <img
                  src={dewarpedUrl}
                  alt="Entzerrt"
                  className="w-full h-auto"
                />
              </div>
            </div>
          </div>

          {/* Result summary (only after streaming completes) */}
          {gridResult && summary && !detecting && (
            <div className="bg-white dark:bg-gray-800 rounded-xl border border-gray-200 dark:border-gray-700 p-4 space-y-3">
              <div className="flex items-center justify-between">
                <h4 className="text-sm font-medium text-gray-700 dark:text-gray-300">
                  Ergebnis: {summary.non_empty_cells}/{summary.total_cells} Zellen mit Text
                  ({sortedRowIndices.length} Zeilen, {columnsUsed.length} Spalten)
                </h4>
                <span className="text-xs text-gray-400">
                  {gridResult.duration_seconds}s
                </span>
              </div>

              {/* Summary badges */}
              <div className="flex gap-2 flex-wrap">
                <span className="px-2 py-0.5 rounded text-xs font-medium bg-blue-100 dark:bg-blue-900/30 text-blue-700 dark:text-blue-300">
                  Zellen: {summary.non_empty_cells}/{summary.total_cells}
                </span>
                {columnsUsed.map((col, i) => (
                  <span key={i} className={`px-2 py-0.5 rounded text-xs font-medium bg-gray-100 dark:bg-gray-700 ${colTypeColor(col.type)}`}>
                    C{col.index}: {colTypeLabel(col.type)}
                  </span>
                ))}
                {summary.low_confidence > 0 && (
                  <span className="px-2 py-0.5 rounded text-xs font-medium bg-red-100 dark:bg-red-900/30 text-red-700 dark:text-red-300">
                    Unsicher: {summary.low_confidence}
                  </span>
                )}
              </div>

              {/* Entry/Cell table */}
              <div className="max-h-80 overflow-y-auto">
                {/* Unified dynamic table — columns driven by columns_used */}
                <table className="w-full text-xs">
                  <thead className="sticky top-0 bg-white dark:bg-gray-800">
                    <tr className="text-left text-gray-500 dark:text-gray-400 border-b dark:border-gray-700">
                      <th className="py-1 pr-2 w-12">Zeile</th>
                      {columnsUsed.map((col, i) => (
                        <th key={i} className={`py-1 pr-2 ${colTypeColor(col.type)}`}>
                          {colTypeLabel(col.type)}
                        </th>
                      ))}
                      <th className="py-1 w-12 text-right">Conf</th>
                    </tr>
                  </thead>
                  <tbody>
                    {sortedRowIndices.map((rowIdx, posIdx) => {
                      const rowCells = cellsByRow.get(rowIdx) || []
                      const avgConf = rowCells.length
                        ? Math.round(rowCells.reduce((s, c) => s + c.confidence, 0) / rowCells.length)
                        : 0
                      return (
                        <tr
                          key={rowIdx}
                          className={`border-b dark:border-gray-700/50 ${
                            posIdx === activeIndex ? 'bg-teal-50 dark:bg-teal-900/20' : ''
                          }`}
                          onClick={() => { setActiveIndex(posIdx); setMode('labeling') }}
                        >
                          <td className="py-1 pr-2 text-gray-400 font-mono text-[10px]">
                            R{String(rowIdx).padStart(2, '0')}
                          </td>
                          {columnsUsed.map((col) => {
                            const cell = rowCells.find(c => c.col_index === col.index)
                            return (
                              <td key={col.index} className="py-1 pr-2 font-mono text-gray-700 dark:text-gray-300 cursor-pointer">
                                <MultilineText text={cell?.text || ''} />
                              </td>
                            )
                          })}
                          <td className={`py-1 text-right font-mono ${confColor(avgConf)}`}>
                            {avgConf}%
                          </td>
                        </tr>
                      )
                    })}
                  </tbody>
                </table>
                <div ref={tableEndRef} />
              </div>
            </div>
          )}

          {/* Streaming cell table (shown while detecting, before complete) */}
          {detecting && editedCells.length > 0 && !gridResult?.summary?.non_empty_cells && (
            <div className="bg-white dark:bg-gray-800 rounded-xl border border-gray-200 dark:border-gray-700 p-4 space-y-3">
              <h4 className="text-sm font-medium text-gray-700 dark:text-gray-300">
                Live: {editedCells.length} Zellen erkannt...
              </h4>
              <div className="max-h-80 overflow-y-auto">
                <table className="w-full text-xs">
                  <thead className="sticky top-0 bg-white dark:bg-gray-800">
                    <tr className="text-left text-gray-500 dark:text-gray-400 border-b dark:border-gray-700">
                      <th className="py-1 pr-2 w-12">Zelle</th>
                      {columnsUsed.map((col, i) => (
                        <th key={i} className={`py-1 pr-2 ${colTypeColor(col.type)}`}>
                          {colTypeLabel(col.type)}
                        </th>
                      ))}
                      <th className="py-1 w-12 text-right">Conf</th>
                    </tr>
                  </thead>
                  <tbody>
                    {(() => {
                      const liveByRow: Map<number, GridCell[]> = new Map()
                      for (const cell of editedCells) {
                        const existing = liveByRow.get(cell.row_index) || []
                        existing.push(cell)
                        liveByRow.set(cell.row_index, existing)
                      }
                      const liveSorted = [...liveByRow.keys()].sort((a, b) => a - b)
                      return liveSorted.map(rowIdx => {
                        const rowCells = liveByRow.get(rowIdx) || []
                        const avgConf = rowCells.length
                          ? Math.round(rowCells.reduce((s, c) => s + c.confidence, 0) / rowCells.length)
                          : 0
                        return (
                          <tr key={rowIdx} className="border-b dark:border-gray-700/50 animate-fade-in">
                            <td className="py-1 pr-2 text-gray-400 font-mono text-[10px]">
                              R{String(rowIdx).padStart(2, '0')}
                            </td>
                            {columnsUsed.map((col) => {
                              const cell = rowCells.find(c => c.col_index === col.index)
                              return (
                                <td key={col.index} className="py-1 pr-2 font-mono text-gray-700 dark:text-gray-300">
                                  <MultilineText text={cell?.text || ''} />
                                </td>
                              )
                            })}
                            <td className={`py-1 text-right font-mono ${confColor(avgConf)}`}>
                              {avgConf}%
                            </td>
                          </tr>
                        )
                      })
                    })()}
                  </tbody>
                </table>
                <div ref={tableEndRef} />
              </div>
            </div>
          )}
        </>
      )}

      {/* Labeling mode */}
      {mode === 'labeling' && editedCells.length > 0 && (
        <div className="grid grid-cols-3 gap-4">
          {/* Left 2/3: Image with highlighted active row */}
          <div className="col-span-2">
            <div className="text-xs font-medium text-gray-500 dark:text-gray-400 mb-1">
              Zeile {activeIndex + 1} von {getUniqueRowCount()}
            </div>
            <div className="border rounded-lg overflow-hidden dark:border-gray-700 bg-gray-50 dark:bg-gray-900 relative">
              {/* eslint-disable-next-line @next/next/no-img-element */}
              <img
                src={`${overlayUrl}?t=${Date.now()}`}
                alt="Wort-Overlay"
                className="w-full h-auto"
              />
              {/* Highlight overlay for active row */}
              {(() => {
                const rowCells = getRowCells(activeIndex)
                return rowCells.map(cell => (
                  <div
                    key={cell.cell_id}
                    className="absolute border-2 border-yellow-400 bg-yellow-400/10 pointer-events-none"
                    style={{
                      left: `${cell.bbox_pct.x}%`,
                      top: `${cell.bbox_pct.y}%`,
                      width: `${cell.bbox_pct.w}%`,
                      height: `${cell.bbox_pct.h}%`,
                    }}
                  />
                ))
              })()}
            </div>
          </div>

          {/* Right 1/3: Editable fields */}
          <div className="space-y-3">
            {/* Navigation */}
            <div className="flex items-center justify-between">
              <button
                onClick={() => setActiveIndex(Math.max(0, activeIndex - 1))}
                disabled={activeIndex === 0}
                className="px-2 py-1 text-xs border rounded hover:bg-gray-50 dark:hover:bg-gray-700 dark:border-gray-600 disabled:opacity-30"
              >
                Zurueck
              </button>
              <span className="text-xs text-gray-500">
                {activeIndex + 1} / {getUniqueRowCount()}
              </span>
              <button
                onClick={() => setActiveIndex(Math.min(
                  getUniqueRowCount() - 1,
                  activeIndex + 1
                ))}
                disabled={activeIndex >= getUniqueRowCount() - 1}
                className="px-2 py-1 text-xs border rounded hover:bg-gray-50 dark:hover:bg-gray-700 dark:border-gray-600 disabled:opacity-30"
              >
                Weiter
              </button>
            </div>

            {/* Status badge */}
            <div className="flex items-center gap-2">
              {(() => {
                const rowCells = getRowCells(activeIndex)
                const avgConf = rowCells.length
                  ? Math.round(rowCells.reduce((s, c) => s + c.confidence, 0) / rowCells.length)
                  : 0
                return (
                  <span className={`text-xs font-mono ${confColor(avgConf)}`}>
                    {avgConf}% Konfidenz
                  </span>
                )
              })()}
            </div>

            {/* Editable fields — one per column, driven by columns_used */}
            <div className="space-y-2">
              {(() => {
                const rowCells = getRowCells(activeIndex)
                return columnsUsed.map((col, colIdx) => {
                  const cell = rowCells.find(c => c.col_index === col.index)
                  if (!cell) return null
                  return (
                    <div key={col.index}>
                      <div className="flex items-center gap-1 mb-0.5">
                        <label className={`text-[10px] font-medium ${colTypeColor(col.type)}`}>
                          {colTypeLabel(col.type)}
                        </label>
                        <span className="text-[9px] text-gray-400">{cell.cell_id}</span>
                      </div>
                      {/* Cell crop */}
                      <div className="border rounded dark:border-gray-700 overflow-hidden bg-white dark:bg-gray-900 h-10 relative mb-1">
                        <CellCrop imageUrl={dewarpedUrl} bbox={cell.bbox_pct} />
                      </div>
                      <textarea
                        ref={colIdx === 0 ? enRef as any : undefined}
                        rows={Math.max(1, (cell.text || '').split('\n').length)}
                        value={cell.text || ''}
                        onChange={(e) => updateCell(cell.cell_id, e.target.value)}
                        className="w-full px-2 py-1.5 text-sm border rounded dark:bg-gray-700 dark:border-gray-600 font-mono resize-none"
                      />
                    </div>
                  )
                })
              })()}
            </div>

            {/* Action buttons */}
            <div className="flex gap-2">
              <button
                onClick={confirmEntry}
                className="flex-1 px-3 py-1.5 text-xs bg-green-600 text-white rounded-lg hover:bg-green-700 font-medium"
              >
                Bestaetigen (Enter)
              </button>
              <button
                onClick={skipEntry}
                className="px-3 py-1.5 text-xs border rounded-lg hover:bg-gray-50 dark:hover:bg-gray-700 dark:border-gray-600"
              >
                Skip
              </button>
            </div>

            {/* Shortcuts hint */}
            <div className="text-[10px] text-gray-400 space-y-0.5">
              <div>Enter = Bestaetigen & weiter</div>
              <div>Ctrl+Down = Ueberspringen</div>
              <div>Ctrl+Up = Zurueck</div>
            </div>

            {/* Row list (compact) */}
            <div className="border-t dark:border-gray-700 pt-2 mt-2">
              <div className="text-[10px] font-medium text-gray-500 dark:text-gray-400 mb-1">
                Alle Zeilen
              </div>
              <div className="max-h-48 overflow-y-auto space-y-0.5">
                {sortedRowIndices.map((rowIdx, posIdx) => {
                  const rowCells = cellsByRow.get(rowIdx) || []
                  const textParts = rowCells.filter(c => c.text).map(c => c.text.replace(/\n/g, ' '))
                  return (
                    <div
                      key={rowIdx}
                      onClick={() => setActiveIndex(posIdx)}
                      className={`flex items-center gap-1 px-2 py-1 rounded text-[10px] cursor-pointer transition-colors ${
                        posIdx === activeIndex
                          ? 'bg-teal-50 dark:bg-teal-900/30 border border-teal-200 dark:border-teal-700'
                          : 'hover:bg-gray-50 dark:hover:bg-gray-700/50'
                      }`}
                    >
                      <span className="w-6 text-right text-gray-400 font-mono">R{String(rowIdx).padStart(2, '0')}</span>
                      <span className="truncate text-gray-600 dark:text-gray-400 font-mono">
                        {textParts.join(' \u2192 ') || '\u2014'}
                      </span>
                    </div>
                  )
                })}
              </div>
            </div>
          </div>
        </div>
      )}

      {/* Controls */}
      {gridResult && (
        <div className="bg-white dark:bg-gray-800 rounded-xl border border-gray-200 dark:border-gray-700 p-4 space-y-3">
          <div className="flex items-center gap-3 flex-wrap">
            {/* OCR Engine selector */}
            <select
              value={ocrEngine}
              onChange={(e) => setOcrEngine(e.target.value as 'auto' | 'tesseract' | 'rapid')}
              className="px-2 py-1.5 text-xs border rounded-lg dark:bg-gray-700 dark:border-gray-600"
            >
              <option value="auto">Auto (RapidOCR wenn verfuegbar)</option>
              <option value="rapid">RapidOCR (ONNX)</option>
              <option value="tesseract">Tesseract</option>
            </select>

            {/* Pronunciation selector (only for vocab) */}
            {isVocab && (
              <select
                value={pronunciation}
                onChange={(e) => setPronunciation(e.target.value as 'british' | 'american')}
                className="px-2 py-1.5 text-xs border rounded-lg dark:bg-gray-700 dark:border-gray-600"
              >
                <option value="british">Britisch (RP)</option>
                <option value="american">Amerikanisch</option>
              </select>
            )}

            <button
              onClick={() => runAutoDetection()}
              disabled={detecting}
              className="px-3 py-1.5 text-xs border rounded-lg hover:bg-gray-50 dark:hover:bg-gray-700 dark:border-gray-600 disabled:opacity-50"
            >
              Erneut erkennen
            </button>

            {/* Show which engine was used */}
            {usedEngine && (
              <span className={`px-2 py-0.5 rounded text-[10px] uppercase font-semibold ${
                usedEngine === 'rapid'
                  ? 'bg-purple-100 dark:bg-purple-900/30 text-purple-700 dark:text-purple-300'
                  : 'bg-gray-100 dark:bg-gray-700 text-gray-600 dark:text-gray-400'
              }`}>
                {usedEngine}
              </span>
            )}

            <button
              onClick={() => goToStep(3)}
              className="px-3 py-1.5 text-xs border rounded-lg hover:bg-gray-50 dark:hover:bg-gray-700 dark:border-gray-600 text-orange-600 dark:text-orange-400 border-orange-300 dark:border-orange-700"
            >
              Zeilen korrigieren (Step 4)
            </button>

            <div className="flex-1" />

            {/* Ground truth */}
            {!gtSaved ? (
              <>
                <input
                  type="text"
                  placeholder="Notizen (optional)"
                  value={gtNotes}
                  onChange={(e) => setGtNotes(e.target.value)}
                  className="px-2 py-1 text-xs border rounded dark:bg-gray-700 dark:border-gray-600 w-48"
                />
                <button
                  onClick={() => handleGroundTruth(true)}
                  className="px-3 py-1.5 text-xs bg-green-600 text-white rounded-lg hover:bg-green-700"
                >
                  Korrekt
                </button>
                <button
                  onClick={() => handleGroundTruth(false)}
                  className="px-3 py-1.5 text-xs bg-red-600 text-white rounded-lg hover:bg-red-700"
                >
                  Fehlerhaft
                </button>
              </>
            ) : (
              <span className="text-xs text-green-600 dark:text-green-400">
                Ground Truth gespeichert
              </span>
            )}

            <button
              onClick={onNext}
              className="px-4 py-1.5 text-xs bg-teal-600 text-white rounded-lg hover:bg-teal-700 font-medium"
            >
              Weiter
            </button>
          </div>
        </div>
      )}

      {error && (
        <div className="p-3 bg-red-50 dark:bg-red-900/20 text-red-600 dark:text-red-400 rounded-lg text-sm">
          {error}
        </div>
      )}
    </div>
  )
}


/**
 * CellCrop: Shows a cropped portion of the dewarped image based on percent bbox.
 * Uses CSS background-image + background-position for efficient cropping.
 */
function CellCrop({ imageUrl, bbox }: { imageUrl: string; bbox: { x: number; y: number; w: number; h: number } }) {
  // Scale factor: how much to zoom into the cell
  const scaleX = 100 / bbox.w
  const scaleY = 100 / bbox.h
  const scale = Math.min(scaleX, scaleY, 8) // Cap zoom at 8x

  return (
    <div
      className="w-full h-full"
      style={{
        backgroundImage: `url(${imageUrl})`,
        backgroundSize: `${scale * 100}%`,
        backgroundPosition: `${-bbox.x * scale}% ${-bbox.y * scale}%`,
        backgroundRepeat: 'no-repeat',
      }}
    />
  )
}
