'use client'

/**
 * StepAnsicht — Unified Grid View.
 *
 * Left:  Original scan with OCR word overlay
 * Right: Unified grid (single zone, boxes integrated) rendered via GridTable
 */

import { useCallback, useEffect, useRef, useState } from 'react'
import dynamic from 'next/dynamic'
import { useGridEditor } from '@/components/grid-editor/useGridEditor'
import { GridTable } from '@/components/grid-editor/GridTable'
import type { GridZone } from '@/components/grid-editor/types'

// Lazy-load SpreadsheetView (Fortune Sheet, SSR-incompatible)
const SpreadsheetView = dynamic(
  () => import('./SpreadsheetView').then((m) => m.SpreadsheetView),
  { ssr: false, loading: () => <div className="py-8 text-center text-sm text-gray-400">Spreadsheet wird geladen...</div> },
)

const KLAUSUR_API = '/klausur-api'

interface StepAnsichtProps {
  sessionId: string | null
  onNext: () => void
}

export function StepAnsicht({ sessionId, onNext }: StepAnsichtProps) {
  const gridEditor = useGridEditor(sessionId)
  const {
    loading, error, selectedCell, setSelectedCell,
    updateCellText, toggleColumnBold, toggleRowHeader,
    getAdjacentCell, deleteColumn, addColumn, deleteRow, addRow,
    commitUndoPoint, selectedCells, toggleCellSelection,
    clearCellSelection, toggleSelectedBold, setCellColor,
    saveGrid, saving, dirty, undo, redo, canUndo, canRedo,
  } = gridEditor

  const [unifiedGrid, setUnifiedGrid] = useState<any>(null)
  const [building, setBuilding] = useState(false)
  const [buildError, setBuildError] = useState<string | null>(null)
  const leftRef = useRef<HTMLDivElement>(null)
  const [leftHeight, setLeftHeight] = useState(600)
  const [viewMode, setViewMode] = useState<'spreadsheet' | 'grid'>('spreadsheet')

  // Build unified grid
  const buildUnified = useCallback(async () => {
    if (!sessionId) return
    setBuilding(true)
    setBuildError(null)
    try {
      const res = await fetch(
        `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/build-unified-grid`,
        { method: 'POST' },
      )
      if (!res.ok) {
        const d = await res.json().catch(() => ({}))
        throw new Error(d.detail || `HTTP ${res.status}`)
      }
      const data = await res.json()
      setUnifiedGrid(data)
    } catch (e) {
      setBuildError(e instanceof Error ? e.message : String(e))
    } finally {
      setBuilding(false)
    }
  }, [sessionId])

  // Load both grids on mount
  useEffect(() => {
    if (!sessionId) return
    // Load multi-zone grid (for spreadsheet mode)
    gridEditor.loadGrid()
    // Load unified grid (for grid mode)
    ;(async () => {
      try {
        const res = await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/unified-grid`)
        if (res.ok) {
          setUnifiedGrid(await res.json())
        } else {
          buildUnified()
        }
      } catch {
        buildUnified()
      }
    })()
  }, [sessionId]) // eslint-disable-line react-hooks/exhaustive-deps

  // Track left panel height for sync
  useEffect(() => {
    if (!leftRef.current) return
    const ro = new ResizeObserver(([e]) => setLeftHeight(e.contentRect.height))
    ro.observe(leftRef.current)
    return () => ro.disconnect()
  }, [])

  const unifiedZone: GridZone | null = unifiedGrid?.zones?.[0] ?? null

  if (loading || building) {
    return (
      <div className="flex items-center justify-center py-16">
        <div className="w-8 h-8 border-4 border-teal-500 border-t-transparent rounded-full animate-spin" />
        <span className="ml-3 text-gray-500">{building ? 'Baue Unified Grid...' : 'Lade...'}</span>
      </div>
    )
  }

  return (
    <div className="space-y-3">
      {/* Header */}
      <div className="flex items-center justify-between">
        <div>
          <h3 className="text-lg font-semibold text-gray-900 dark:text-white">Ansicht — Unified Grid</h3>
          <p className="text-sm text-gray-500 dark:text-gray-400">
            Alle Inhalte in einem Grid. Boxen sind integriert (farbig markiert).
            {unifiedGrid && (
              <span className="ml-2 font-mono text-xs">
                {unifiedGrid.summary?.total_rows} Zeilen × {unifiedGrid.summary?.total_columns} Spalten
                {unifiedGrid.dominant_row_h && ` · Zeilenhöhe: ${Math.round(unifiedGrid.dominant_row_h)}px`}
              </span>
            )}
          </p>
        </div>
        <div className="flex items-center gap-2">
          <div className="flex rounded-lg overflow-hidden border border-gray-300 dark:border-gray-600">
            <button
              onClick={() => setViewMode('spreadsheet')}
              className={`px-3 py-1.5 text-xs font-medium ${viewMode === 'spreadsheet' ? 'bg-teal-600 text-white' : 'bg-white dark:bg-gray-700 text-gray-600 dark:text-gray-300'}`}
            >
              Spreadsheet
            </button>
            <button
              onClick={() => setViewMode('grid')}
              className={`px-3 py-1.5 text-xs font-medium ${viewMode === 'grid' ? 'bg-teal-600 text-white' : 'bg-white dark:bg-gray-700 text-gray-600 dark:text-gray-300'}`}
            >
              Grid
            </button>
          </div>
          <button
            onClick={buildUnified}
            disabled={building}
            className="px-3 py-1.5 bg-amber-600 text-white rounded-lg hover:bg-amber-700 text-xs font-medium disabled:opacity-50"
          >
            {building ? 'Baut...' : 'Neu aufbauen'}
          </button>
          <button onClick={onNext} className="px-5 py-2 bg-teal-600 text-white rounded-lg hover:bg-teal-700 text-sm font-medium">
            Weiter →
          </button>
        </div>
      </div>

      {(error || buildError) && (
        <div className="p-3 bg-red-50 dark:bg-red-900/30 border border-red-200 dark:border-red-800 rounded-lg text-red-700 dark:text-red-300 text-sm">
          {error || buildError}
        </div>
      )}

      {/* Split view */}
      <div className="flex gap-2">
        {/* LEFT: Original + OCR overlay */}
        <div ref={leftRef} className="w-1/3 border border-gray-300 dark:border-gray-600 rounded-lg overflow-hidden bg-white dark:bg-gray-900 flex-shrink-0">
          <div className="px-2 py-1 bg-black/60 text-white text-[10px] font-medium">Original + OCR</div>
          {sessionId && (
            <img
              src={`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/image/words-overlay`}
              alt="Original + OCR"
              className="w-full h-auto"
            />
          )}
        </div>

        {/* RIGHT: Spreadsheet or Grid view */}
        <div className="flex-1 border border-gray-300 dark:border-gray-600 rounded-lg overflow-hidden bg-white dark:bg-gray-900" style={{ maxHeight: `${Math.max(700, leftHeight)}px` }}>
          {viewMode === 'spreadsheet' && (unifiedGrid || gridEditor.grid) ? (
            <SpreadsheetView gridData={gridEditor.grid} height={Math.max(650, leftHeight - 10)} />
          ) : viewMode === 'grid' && unifiedZone ? (
            <div className="overflow-auto h-full">
              <div className="px-2 py-1 bg-teal-600/80 text-white text-[10px] font-medium sticky top-0 z-20">
                Grid View ({unifiedGrid?.summary?.total_rows}×{unifiedGrid?.summary?.total_columns})
              </div>
              <GridTable
                zone={unifiedZone}
                selectedCell={selectedCell}
                selectedCells={selectedCells}
                onSelectCell={setSelectedCell}
                onCellTextChange={updateCellText}
                onToggleColumnBold={toggleColumnBold}
                onToggleRowHeader={toggleRowHeader}
                onNavigate={(cellId, dir) => {
                  const next = getAdjacentCell(cellId, dir)
                  if (next) setSelectedCell(next)
                }}
                onDeleteColumn={deleteColumn}
                onAddColumn={addColumn}
                onDeleteRow={deleteRow}
                onAddRow={addRow}
                onToggleCellSelection={toggleCellSelection}
                onSetCellColor={setCellColor}
              />
            </div>
          ) : (
            <div className="p-8 text-center text-gray-400">
              <p>Kein Unified Grid verfügbar.</p>
              <button onClick={buildUnified} className="mt-2 text-teal-600 text-sm">Jetzt aufbauen</button>
            </div>
          )}
        </div>
      </div>
    </div>
  )
}