/**
 * Hook for canvas graph state and persistence. Wraps useGraphStateWithHistory
 * with initial graph from recollection storage (or example). Save is explicit via save().
 */

import { useCallback, useMemo, useRef, useState } from 'react'
import { useGraphStateWithHistory } from '@/hooks/useGraphStateWithHistory'
import { getInitialGraph } from '@/app/canvas/canvasGraphUtils'
import { saveGraphToStorage, RECOLLECTION_VERSION } from '@/app/recollections/recollectionGraphStorage'
import type { AppNode, AppEdge } from '@/lib/graph/nodeTypes'

export type SaveStatus = 'saved' | 'unsaved' | 'saving'

export type UseCanvasGraphResult = ReturnType<typeof useGraphStateWithHistory> & {
  /** Persist current nodes/edges to storage. No-op when recollectionId is missing. */
  save: () => void
  /** For menubar: show "Unsaved changes" | "Saving…" | "All changes saved". */
  saveStatus: SaveStatus
}

export function useCanvasGraph(recollectionId: string | undefined): UseCanvasGraphResult {
  const initialGraph = useMemo(() => getInitialGraph(recollectionId), [recollectionId])
  const result = useGraphStateWithHistory(initialGraph.nodes, initialGraph.edges)
  const { nodes, edges } = result

  const nodesRef = useRef(nodes)
  const edgesRef = useRef(edges)
  nodesRef.current = nodes
  edgesRef.current = edges

  const [isSaving, setIsSaving] = useState(false)
  const [lastSavedSerialized, setLastSavedSerialized] = useState(() =>
    JSON.stringify({ nodes: initialGraph.nodes, edges: initialGraph.edges })
  )

  const currentSerialized = useMemo(
    () => JSON.stringify({ nodes, edges }),
    [nodes, edges]
  )
  const isDirty = currentSerialized !== lastSavedSerialized
  const saveStatus: SaveStatus = isSaving ? 'saving' : isDirty ? 'unsaved' : 'saved'

  const save = useCallback(() => {
    if (!recollectionId) return
    const snapshot = JSON.stringify({
      nodes: nodesRef.current,
      edges: edgesRef.current,
    })
    setIsSaving(true)
    saveGraphToStorage(recollectionId, {
      version: RECOLLECTION_VERSION,
      nodes: nodesRef.current,
      edges: edgesRef.current,
    })
    const SAVING_DISPLAY_MS = 360
    setTimeout(() => {
      setLastSavedSerialized(snapshot)
      setIsSaving(false)
    }, SAVING_DISPLAY_MS)
  }, [recollectionId])

  return { ...result, save, saveStatus }
}