'use client'

import { useCallback, useEffect, useRef, useState } from 'react'
import type { ColumnTypeKey, PageRegion } from '@/app/(admin)/ai/ocr-pipeline/types'

const COLUMN_TYPES: { value: ColumnTypeKey; label: string }[] = [
  { value: 'column_en', label: 'EN' },
  { value: 'column_de', label: 'DE' },
  { value: 'column_example', label: 'Beispiel' },
  { value: 'column_text', label: 'Text' },
  { value: 'page_ref', label: 'Seite' },
  { value: 'column_marker', label: 'Marker' },
  { value: 'column_ignore', label: 'Ignorieren' },
]

const TYPE_OVERLAY_COLORS: Record<string, string> = {
  column_en: 'rgba(59, 130, 246, 0.12)',
  column_de: 'rgba(34, 197, 94, 0.12)',
  column_example: 'rgba(249, 115, 22, 0.12)',
  column_text: 'rgba(6, 182, 212, 0.12)',
  page_ref: 'rgba(168, 85, 247, 0.12)',
  column_marker: 'rgba(239, 68, 68, 0.12)',
  column_ignore: 'rgba(128, 128, 128, 0.06)',
}

const TYPE_BADGE_COLORS: Record<string, string> = {
  column_en: 'bg-blue-100 text-blue-700 dark:bg-blue-900/30 dark:text-blue-400',
  column_de: 'bg-green-100 text-green-700 dark:bg-green-900/30 dark:text-green-400',
  column_example: 'bg-orange-100 text-orange-700 dark:bg-orange-900/30 dark:text-orange-400',
  column_text: 'bg-cyan-100 text-cyan-700 dark:bg-cyan-900/30 dark:text-cyan-400',
  page_ref: 'bg-purple-100 text-purple-700 dark:bg-purple-900/30 dark:text-purple-400',
  column_marker: 'bg-red-100 text-red-700 dark:bg-red-900/30 dark:text-red-400',
  column_ignore: 'bg-gray-100 text-gray-500 dark:bg-gray-700/30 dark:text-gray-500',
}

// Default column type sequence for newly created columns
const DEFAULT_TYPE_SEQUENCE: ColumnTypeKey[] = [
  'page_ref', 'column_en', 'column_de', 'column_example', 'column_text',
]

const MIN_DIVIDER_DISTANCE_PERCENT = 2 // Minimum 2% apart

interface ManualColumnEditorProps {
  imageUrl: string
  imageWidth: number
  imageHeight: number
  onApply: (columns: PageRegion[]) => void
  onCancel: () => void
  applying: boolean
  mode?: 'manual' | 'ground-truth'
  layout?: 'two-column' | 'stacked'
  initialDividers?: number[]
  initialColumnTypes?: ColumnTypeKey[]
}

export function ManualColumnEditor({
  imageUrl,
  imageWidth,
  imageHeight,
  onApply,
  onCancel,
  applying,
  mode = 'manual',
  layout = 'two-column',
  initialDividers,
  initialColumnTypes,
}: ManualColumnEditorProps) {
  const containerRef = useRef<HTMLDivElement>(null)
  const [dividers, setDividers] = useState<number[]>(initialDividers ?? [])
  const [columnTypes, setColumnTypes] = useState<ColumnTypeKey[]>(initialColumnTypes ?? [])
  const [dragging, setDragging] = useState<number | null>(null)
  const [imageLoaded, setImageLoaded] = useState(false)

  const isGT = mode === 'ground-truth'

  // Sync columnTypes length when dividers change
  useEffect(() => {
    const numColumns = dividers.length + 1
    setColumnTypes(prev => {
      if (prev.length === numColumns) return prev
      const next = [...prev]
      while (next.length < numColumns) {
        const idx = next.length
        next.push(DEFAULT_TYPE_SEQUENCE[idx] || 'column_text')
      }
      while (next.length > numColumns) {
        next.pop()
      }
      return next
    })
  }, [dividers.length])

  const getXPercent = useCallback((clientX: number): number => {
    if (!containerRef.current) return 0
    const rect = containerRef.current.getBoundingClientRect()
    const pct = ((clientX - rect.left) / rect.width) * 100
    return Math.max(0, Math.min(100, pct))
  }, [])

  const canPlaceDivider = useCallback((xPct: number, excludeIndex?: number): boolean => {
    for (let i = 0; i < dividers.length; i++) {
      if (i === excludeIndex) continue
      if (Math.abs(dividers[i] - xPct) < MIN_DIVIDER_DISTANCE_PERCENT) return false
    }
    return xPct > MIN_DIVIDER_DISTANCE_PERCENT && xPct < (100 - MIN_DIVIDER_DISTANCE_PERCENT)
  }, [dividers])

  // Click on image to add a divider
  const handleImageClick = useCallback((e: React.MouseEvent) => {
    if (dragging !== null) return
    // Don't add if clicking on a divider handle
    if ((e.target as HTMLElement).dataset.divider) return

    const xPct = getXPercent(e.clientX)
    if (!canPlaceDivider(xPct)) return

    setDividers(prev => [...prev, xPct].sort((a, b) => a - b))
  }, [dragging, getXPercent, canPlaceDivider])

  // Drag handlers
  const handleDividerMouseDown = useCallback((e: React.MouseEvent, index: number) => {
    e.stopPropagation()
    e.preventDefault()
    setDragging(index)
  }, [])

  useEffect(() => {
    if (dragging === null) return

    const handleMouseMove = (e: MouseEvent) => {
      const xPct = getXPercent(e.clientX)
      if (canPlaceDivider(xPct, dragging)) {
        setDividers(prev => {
          const next = [...prev]
          next[dragging] = xPct
          return next.sort((a, b) => a - b)
        })
      }
    }

    const handleMouseUp = () => {
      setDragging(null)
    }

    window.addEventListener('mousemove', handleMouseMove)
    window.addEventListener('mouseup', handleMouseUp)
    return () => {
      window.removeEventListener('mousemove', handleMouseMove)
      window.removeEventListener('mouseup', handleMouseUp)
    }
  }, [dragging, getXPercent, canPlaceDivider])

  const removeDivider = useCallback((index: number) => {
    setDividers(prev => prev.filter((_, i) => i !== index))
  }, [])

  const updateColumnType = useCallback((colIndex: number, type: ColumnTypeKey) => {
    setColumnTypes(prev => {
      const next = [...prev]
      next[colIndex] = type
      return next
    })
  }, [])

  const handleApply = useCallback(() => {
    // Build PageRegion array from dividers
    const sorted = [...dividers].sort((a, b) => a - b)
    const columns: PageRegion[] = []

    for (let i = 0; i <= sorted.length; i++) {
      const leftPct = i === 0 ? 0 : sorted[i - 1]
      const rightPct = i === sorted.length ? 100 : sorted[i]
      const x = Math.round((leftPct / 100) * imageWidth)
      const w = Math.round(((rightPct - leftPct) / 100) * imageWidth)

      columns.push({
        type: columnTypes[i] || 'column_text',
        x,
        y: 0,
        width: w,
        height: imageHeight,
        classification_confidence: 1.0,
        classification_method: 'manual',
      })
    }

    onApply(columns)
  }, [dividers, columnTypes, imageWidth, imageHeight, onApply])

  // Compute column regions for overlay
  const sorted = [...dividers].sort((a, b) => a - b)
  const columnRegions = Array.from({ length: sorted.length + 1 }, (_, i) => ({
    leftPct: i === 0 ? 0 : sorted[i - 1],
    rightPct: i === sorted.length ? 100 : sorted[i],
    type: columnTypes[i] || 'column_text',
  }))

  return (
    <div className="space-y-4">
      {/* Layout: image + controls */}
      <div className={layout === 'stacked' ? 'space-y-4' : 'grid grid-cols-2 gap-4'}>
        {/* Left: Interactive image */}
        <div>
          <div className="flex items-center justify-between mb-1">
            <div className="text-xs font-medium text-gray-500 dark:text-gray-400">
              Klicken um Trennlinien zu setzen
            </div>
            <button
              onClick={onCancel}
              className="text-xs px-2 py-0.5 text-gray-500 hover:text-gray-700 dark:text-gray-400 dark:hover:text-gray-200"
            >
              Abbrechen
            </button>
          </div>
          <div
            ref={containerRef}
            className="relative border rounded-lg overflow-hidden dark:border-gray-700 bg-gray-50 dark:bg-gray-900 cursor-crosshair select-none"
            onClick={handleImageClick}
          >
            {/* eslint-disable-next-line @next/next/no-img-element */}
            <img
              src={imageUrl}
              alt="Entzerrtes Bild"
              className="w-full h-auto block"
              draggable={false}
              onLoad={() => setImageLoaded(true)}
            />

            {imageLoaded && (
              <>
                {/* Column overlays */}
                {columnRegions.map((region, i) => (
                  <div
                    key={`col-${i}`}
                    className="absolute top-0 bottom-0 pointer-events-none"
                    style={{
                      left: `${region.leftPct}%`,
                      width: `${region.rightPct - region.leftPct}%`,
                      backgroundColor: TYPE_OVERLAY_COLORS[region.type] || 'rgba(128,128,128,0.08)',
                    }}
                  >
                    <span className="absolute top-1 left-1/2 -translate-x-1/2 text-[10px] font-medium text-gray-600 dark:text-gray-300 bg-white/80 dark:bg-gray-800/80 px-1 rounded">
                      {i + 1}
                    </span>
                  </div>
                ))}

                {/* Divider lines */}
                {sorted.map((xPct, i) => (
                  <div
                    key={`div-${i}`}
                    data-divider="true"
                    className="absolute top-0 bottom-0 group"
                    style={{
                      left: `${xPct}%`,
                      transform: 'translateX(-50%)',
                      width: '12px',
                      cursor: 'col-resize',
                      zIndex: 10,
                    }}
                    onMouseDown={(e) => handleDividerMouseDown(e, i)}
                  >
                    {/* Visible line */}
                    <div
                      data-divider="true"
                      className="absolute top-0 bottom-0 left-1/2 -translate-x-1/2 w-0.5 border-l-2 border-dashed border-red-500"
                    />
                    {/* Delete button */}
                    <button
                      data-divider="true"
                      onClick={(e) => {
                        e.stopPropagation()
                        removeDivider(i)
                      }}
                      className="absolute top-2 left-1/2 -translate-x-1/2 w-4 h-4 bg-red-500 text-white rounded-full text-[10px] leading-none flex items-center justify-center opacity-0 group-hover:opacity-100 transition-opacity z-20"
                      title="Linie entfernen"
                    >
                      x
                    </button>
                  </div>
                ))}
              </>
            )}
          </div>
        </div>

        {/* Right: Column type assignment + actions */}
        <div className="space-y-4">
          <div className="text-xs font-medium text-gray-500 dark:text-gray-400 mb-1">
            Spaltentypen
          </div>

          {dividers.length === 0 ? (
            <div className="bg-white dark:bg-gray-800 rounded-xl border border-gray-200 dark:border-gray-700 p-6 text-center">
              <div className="text-3xl mb-2">👆</div>
              <p className="text-sm text-gray-500 dark:text-gray-400">
                Klicken Sie auf das Bild links, um vertikale Trennlinien zwischen den Spalten zu setzen.
              </p>
              <p className="text-xs text-gray-400 dark:text-gray-500 mt-2">
                Linien koennen per Drag verschoben und per Hover geloescht werden.
              </p>
            </div>
          ) : (
            <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="text-sm text-gray-600 dark:text-gray-400">
                <span className="font-medium text-gray-800 dark:text-gray-200">
                  {dividers.length} Linien = {dividers.length + 1} Spalten
                </span>
              </div>
              <div className="grid gap-2">
                {columnRegions.map((region, i) => (
                  <div key={i} className="flex items-center gap-3">
                    <span className={`w-16 text-center px-2 py-0.5 rounded text-xs font-medium ${TYPE_BADGE_COLORS[region.type] || 'bg-gray-100 text-gray-600'}`}>
                      Spalte {i + 1}
                    </span>
                    <select
                      value={columnTypes[i] || 'column_text'}
                      onChange={(e) => updateColumnType(i, e.target.value as ColumnTypeKey)}
                      className="text-sm border border-gray-200 dark:border-gray-600 rounded px-2 py-1 bg-white dark:bg-gray-700 text-gray-800 dark:text-gray-200"
                    >
                      {COLUMN_TYPES.map(t => (
                        <option key={t.value} value={t.value}>{t.label}</option>
                      ))}
                    </select>
                    <span className="text-xs text-gray-400 font-mono">
                      {Math.round(region.rightPct - region.leftPct)}%
                    </span>
                  </div>
                ))}
              </div>
            </div>
          )}

          {/* Action buttons */}
          <div className="flex flex-col gap-2">
            <button
              onClick={handleApply}
              disabled={dividers.length === 0 || applying}
              className="w-full px-4 py-2 bg-teal-600 text-white rounded-lg hover:bg-teal-700 transition-colors text-sm font-medium disabled:opacity-50 disabled:cursor-not-allowed"
            >
              {applying
                ? 'Wird gespeichert...'
                : isGT
                  ? `${dividers.length + 1} Spalten als Ground Truth speichern`
                  : `${dividers.length + 1} Spalten uebernehmen`}
            </button>
            <button
              onClick={() => setDividers([])}
              disabled={dividers.length === 0}
              className="text-xs px-3 py-2 text-gray-500 hover:text-gray-700 dark:text-gray-400 dark:hover:text-gray-200 disabled:opacity-50"
            >
              Alle Linien entfernen
            </button>
          </div>
        </div>
      </div>
    </div>
  )
}