import React, { useCallback, useEffect, useMemo, useState } from 'react'
import {
  DndContext,
  DragOverlay,
  DragEndEvent,
  DragStartEvent,
  KeyboardSensor,
  PointerSensor,
  closestCenter,
  useSensor,
  useSensors,
} from '@dnd-kit/core'
import {
  SortableContext,
  sortableKeyboardCoordinates,
  useSortable,
  verticalListSortingStrategy,
} from '@dnd-kit/sortable'
import { CSS } from '@dnd-kit/utilities'
import { MenuItemComponent, MenuItemComponentProps } from './MenuItemComponent'
import { findMenuItem, indentMenuItem, moveMenuItem, outdentMenuItem } from './menuTree.utils'
import { MenuItem } from '@/proxy/menus/menu'
import { PermissionDefinitionRecord } from '@/proxy/admin/models'
import { getPermissionsList } from '@/services/identity.service'
import { SelectBoxOption } from '@/types/shared'

interface SortableMenuTreeProps {
  /** Ekranda gösterilen (filtrelenmiş olabilir) ağaç */
  items: MenuItem[]
  /** Taşıma işlemlerinin uygulanacağı tam ağaç */
  sourceItems: MenuItem[]
  onItemsChange: (items: MenuItem[]) => void
  isDesignMode: boolean
  isFiltered?: boolean
  matchedIds?: Set<string>
  collapsedIds: Set<string>
  onToggleExpand: (id: string) => void
  refetch: () => void
}

type SortableRowProps = Omit<MenuItemComponentProps, 'setNodeRef' | 'dragHandleProps' | 'style'> & {
  disabled: boolean
}

const SortableMenuRow: React.FC<SortableRowProps> = ({ disabled, ...props }) => {
  const { attributes, listeners, setNodeRef, transform, transition, isDragging } = useSortable({
    id: props.item.id ?? '',
    data: { type: 'menu-item' },
    disabled,
  })

  return (
    <MenuItemComponent
      {...props}
      isDragging={isDragging}
      setNodeRef={setNodeRef}
      dragHandleProps={disabled ? undefined : { ...attributes, ...listeners }}
      style={{ transform: CSS.Transform.toString(transform), transition }}
    />
  )
}

export const SortableMenuTree: React.FC<SortableMenuTreeProps> = ({
  items,
  sourceItems,
  onItemsChange,
  isDesignMode,
  isFiltered = false,
  matchedIds,
  collapsedIds,
  onToggleExpand,
  refetch,
}) => {
  const [permissions, setPermissions] = useState<SelectBoxOption[]>([])
  const [activeItem, setActiveItem] = useState<MenuItem | null>(null)

  // Filtre açıkken ara düğümler gizli olduğu için sürükle-bırak kapatılır.
  const dragEnabled = isDesignMode && !isFiltered

  const sensors = useSensors(
    useSensor(PointerSensor, { activationConstraint: { distance: 8 } }),
    useSensor(KeyboardSensor, { coordinateGetter: sortableKeyboardCoordinates }),
  )

  useEffect(() => {
    let cancelled = false

    getPermissionsList()
      .then((response) => {
        if (cancelled || !response.data) return

        const options = response.data
          .filter((permission: PermissionDefinitionRecord) => Boolean(permission.name))
          .map((permission: PermissionDefinitionRecord) => ({
            value: permission.name,
            label: permission.name,
          }))
          .sort((a, b) => (a.label ?? '').localeCompare(b.label ?? ''))

        setPermissions(options)
      })
      .catch(() => {
        if (!cancelled) setPermissions([])
      })

    return () => {
      cancelled = true
    }
  }, [])

  const handleDragStart = useCallback(
    (event: DragStartEvent) => setActiveItem(findMenuItem(sourceItems, event.active.id as string)),
    [sourceItems],
  )

  const handleDragEnd = useCallback(
    (event: DragEndEvent) => {
      setActiveItem(null)

      const { active, over } = event
      if (!over || !dragEnabled || active.id === over.id) return

      const next = moveMenuItem(sourceItems, active.id as string, over.id as string)
      if (next) onItemsChange(next)
    },
    [dragEnabled, onItemsChange, sourceItems],
  )

  const handleIndent = useCallback(
    (id: string) => {
      const next = indentMenuItem(sourceItems, id)
      if (next) onItemsChange(next)
    },
    [onItemsChange, sourceItems],
  )

  const handleOutdent = useCallback(
    (id: string) => {
      const next = outdentMenuItem(sourceItems, id)
      if (next) onItemsChange(next)
    },
    [onItemsChange, sourceItems],
  )

  const renderMenuItem = (item: MenuItem, depth: number, index: number) => {
    const id = item.id ?? ''
    const children = item.children ?? []
    const isExpanded = isFiltered || !collapsedIds.has(id)

    return (
      <div key={id || `${depth}-${index}`} className="rounded-md">
        <SortableMenuRow
          canIndent={isDesignMode && !isFiltered && index > 0}
          canOutdent={isDesignMode && !isFiltered && depth > 0}
          depth={depth}
          disabled={!dragEnabled}
          isDesignMode={isDesignMode}
          isExpanded={isExpanded}
          isHighlighted={Boolean(matchedIds?.has(id))}
          item={item}
          permissions={permissions}
          refetch={refetch}
          onIndent={handleIndent}
          onOutdent={handleOutdent}
          onToggleExpand={onToggleExpand}
        >
          {children.length > 0 && (
            <SortableContext
              items={children.map((child) => child.id ?? '').filter(Boolean)}
              strategy={verticalListSortingStrategy}
            >
              <div className="ml-4 border-l border-gray-200 dark:border-gray-700 pl-1">
                {children.map((child, childIndex) =>
                  renderMenuItem(child, depth + 1, childIndex),
                )}
              </div>
            </SortableContext>
          )}
        </SortableMenuRow>
      </div>
    )
  }

  const rootIds = useMemo(
    () => items.map((item) => item.id ?? '').filter(Boolean),
    [items],
  )

  return (
    <DndContext
      collisionDetection={closestCenter}
      sensors={sensors}
      onDragStart={handleDragStart}
      onDragEnd={handleDragEnd}
      onDragCancel={() => setActiveItem(null)}
    >
      <SortableContext items={rootIds} strategy={verticalListSortingStrategy}>
        <div className="space-y-1">
          {items.map((item, index) => renderMenuItem(item, 0, index))}
        </div>
      </SortableContext>

      <DragOverlay>
        {activeItem && (
          <div className="bg-white dark:bg-gray-800 rounded-md shadow-lg">
            <MenuItemComponent
              isDragOverlay
              depth={0}
              isDesignMode={isDesignMode}
              item={activeItem}
              permissions={permissions}
              refetch={refetch}
            />
          </div>
        )}
      </DragOverlay>
    </DndContext>
  )
}