import { useCallback, useEffect, useState } from 'react'
import type { GridResult, GridCell, StructureResult, StructureBox, StructureGraphic } from '@/app/(admin)/ai/ocr-kombi/types'
import type { EditableCell, EditorMode, PageRegion, RowItem, PageZone, ReconstructionStatus } from './StepReconstructionTypes'
import { KLAUSUR_API } from './StepReconstructionTypes'

interface ReconstructionData {
  status: ReconstructionStatus
  setStatus: (s: ReconstructionStatus) => void
  error: string
  setError: (e: string) => void
  cells: EditableCell[]
  setCells: (cells: EditableCell[]) => void
  gridCells: GridCell[]
  editorMode: EditorMode
  setEditorMode: (mode: EditorMode) => void
  isParentWithBoxes: boolean
  mergedGridCells: GridCell[]
  parentColumns: PageRegion[]
  parentRows: RowItem[]
  parentZones: PageZone[]
  imageNaturalSize: { w: number; h: number } | null
  setImageNaturalSize: (size: { w: number; h: number } | null) => void
  structureBoxes: StructureBox[]
  structureGraphics: StructureGraphic[]
  imageRotation: 0 | 180
  setImageRotation: (fn: (r: 0 | 180) => 0 | 180) => void
  loadSessionData: () => void
}

function gridCellToEditable(c: GridCell): EditableCell {
  return {
    cellId: c.cell_id,
    text: c.text,
    originalText: c.text,
    bboxPct: c.bbox_pct,
    colType: c.col_type,
    rowIndex: c.row_index,
    colIndex: c.col_index,
  }
}

/**
 * Loads reconstruction session data from the API, including sub-session
 * merging for parent sessions with box zones.
 */
export function useReconstructionData(
  sessionId: string | null,
  onResetEditing: () => void,
): ReconstructionData {
  const [status, setStatus] = useState<ReconstructionStatus>('loading')
  const [error, setError] = useState('')
  const [cells, setCells] = useState<EditableCell[]>([])
  const [gridCells, setGridCells] = useState<GridCell[]>([])
  const [editorMode, setEditorMode] = useState<EditorMode>('simple')

  const [isParentWithBoxes, setIsParentWithBoxes] = useState(false)
  const [mergedGridCells, setMergedGridCells] = useState<GridCell[]>([])
  const [parentColumns, setParentColumns] = useState<PageRegion[]>([])
  const [parentRows, setParentRows] = useState<RowItem[]>([])
  const [parentZones, setParentZones] = useState<PageZone[]>([])
  const [imageNaturalSize, setImageNaturalSize] = useState<{ w: number; h: number } | null>(null)
  const [imageRotation, setImageRotation] = useState<0 | 180>(0)
  const [structureBoxes, setStructureBoxes] = useState<StructureBox[]>([])
  const [structureGraphics, setStructureGraphics] = useState<StructureGraphic[]>([])

  const loadSessionData = useCallback(async () => {
    if (!sessionId) return
    setStatus('loading')
    try {
      const res = await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}`)
      if (!res.ok) throw new Error(`HTTP ${res.status}`)
      const data = await res.json()

      const wordResult: GridResult | undefined = data.word_result
      if (!wordResult) {
        setError('Keine Worterkennungsdaten gefunden. Bitte zuerst Schritt 5 abschliessen.')
        setStatus('error')
        return
      }

      const rawGridCells: GridCell[] = wordResult.cells || []
      setGridCells(rawGridCells)
      const allEditableCells = rawGridCells.map(gridCellToEditable)

      setCells(allEditableCells)
      onResetEditing()

      // Load structure result (boxes, graphics, colors)
      const structureResult: StructureResult | undefined = data.structure_result
      if (structureResult) {
        setStructureBoxes(structureResult.boxes || [])
        setStructureGraphics(structureResult.graphics || [])
      }

      // Check for parent with boxes (sub-sessions + zones)
      const columnResult = data.column_result as { columns?: PageRegion[]; zones?: PageZone[] } | undefined
      const rowResult = data.row_result as { rows?: RowItem[] } | undefined
      const subSessions: { id: string; box_index: number }[] = data.sub_sessions || []
      const zones: PageZone[] = columnResult?.zones || []
      const hasBoxes = subSessions.length > 0 && zones.some(z => z.zone_type === 'box')

      setIsParentWithBoxes(hasBoxes)
      if (hasBoxes) setImageRotation(() => 180)

      if (columnResult?.columns) setParentColumns(columnResult.columns)
      if (rowResult?.rows) setParentRows(rowResult.rows)
      if (zones.length > 0) setParentZones(zones)

      if (wordResult.image_width && wordResult.image_height) {
        setImageNaturalSize({ w: wordResult.image_width, h: wordResult.image_height })
      }

      if (hasBoxes) {
        setEditorMode('overlay')
        await loadMergedCells(rawGridCells, subSessions, zones, wordResult)
      } else {
        setMergedGridCells(rawGridCells)
      }

      setStatus('ready')
    } catch (e: unknown) {
      setError(e instanceof Error ? e.message : String(e))
      setStatus('error')
    }
  // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [sessionId])

  /** Load sub-session cells and merge into parent coordinate space */
  const loadMergedCells = async (
    rawGridCells: GridCell[],
    subSessions: { id: string; box_index: number }[],
    zones: PageZone[],
    wordResult: GridResult,
  ) => {
    const imgW = wordResult.image_width || 1
    const imgH = wordResult.image_height || 1
    const allMergedCells: GridCell[] = [...rawGridCells]

    for (const sub of subSessions) {
      try {
        const subRes = await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sub.id}`)
        if (!subRes.ok) continue
        const subData = await subRes.json()
        const subWordResult: GridResult | undefined = subData.word_result
        if (!subWordResult?.cells) continue

        const boxZone = zones.find(z => z.zone_type === 'box')
        if (!boxZone?.box) continue

        const box = boxZone.box
        const boxXPct = (box.x / imgW) * 100
        const boxYPct = (box.y / imgH) * 100
        const boxWPct = (box.width / imgW) * 100
        const boxHPct = (box.height / imgH) * 100

        for (const subCell of subWordResult.cells) {
          if (!subCell.bbox_pct) continue
          const parentCellX = boxXPct + (subCell.bbox_pct.x / 100) * boxWPct
          const parentCellY = boxYPct + (subCell.bbox_pct.y / 100) * boxHPct
          const parentCellW = (subCell.bbox_pct.w / 100) * boxWPct
          const parentCellH = (subCell.bbox_pct.h / 100) * boxHPct

          allMergedCells.push({
            ...subCell,
            cell_id: `sub_${sub.id}_${subCell.cell_id}`,
            bbox_pct: { x: parentCellX, y: parentCellY, w: parentCellW, h: parentCellH },
            bbox_px: {
              x: Math.round(parentCellX / 100 * imgW),
              y: Math.round(parentCellY / 100 * imgH),
              w: Math.round(parentCellW / 100 * imgW),
              h: Math.round(parentCellH / 100 * imgH),
            },
          })
        }
      } catch {
        // Skip failing sub-sessions
      }
    }

    setMergedGridCells(allMergedCells)
    setCells(allMergedCells.map(gridCellToEditable))
  }

  // Load session data on mount
  useEffect(() => {
    if (!sessionId) return
    loadSessionData()
  }, [sessionId, loadSessionData])

  return {
    status, setStatus, error, setError,
    cells, setCells, gridCells,
    editorMode, setEditorMode,
    isParentWithBoxes, mergedGridCells,
    parentColumns, parentRows, parentZones,
    imageNaturalSize, setImageNaturalSize,
    structureBoxes, structureGraphics,
    imageRotation, setImageRotation,
    loadSessionData,
  }
}