/**
 * File selection composable
 * Provides reactive selection management for file manager
 */

import { ref, computed } from 'vue'
import type { Ref, ComputedRef } from 'vue'
import { FileCollectionObject } from '@FileManager/models/collection'
import { FileEntityObject } from '@FileManager/models/entity'

type NodeRecord = FileCollectionObject | FileEntityObject

export interface UseFileSelectionOptions {
  multiple?: boolean
  allowFolders?: boolean
  allowFiles?: boolean
}

export function useFileSelection(options: UseFileSelectionOptions = {}) {
  const { 
    multiple = true, 
    allowFolders = true, 
    allowFiles = true 
  } = options

  const selectedIds: Ref<Set<string>> = ref(new Set())
  const selectedNodes: Ref<Map<string, NodeRecord>> = ref(new Map())

  // Get selected count
  const count: ComputedRef<number> = computed(() => selectedIds.value.size)

  // Check if any selected
  const hasSelection: ComputedRef<boolean> = computed(() => selectedIds.value.size > 0)

  // Get selected IDs as array
  const selectedIdArray: ComputedRef<string[]> = computed(() => 
    Array.from(selectedIds.value)
  )

  // Get selected nodes as array
  const selectedNodeArray: ComputedRef<NodeRecord[]> = computed(() => 
    Array.from(selectedNodes.value.values())
  )

  // Get selected collections only
  const selectedCollections: ComputedRef<FileCollectionObject[]> = computed(() =>
    selectedNodeArray.value.filter(
      (node): node is FileCollectionObject => node['@type'] === 'files.collection'
    )
  )

  // Get selected entities only
  const selectedEntities: ComputedRef<FileEntityObject[]> = computed(() =>
    selectedNodeArray.value.filter(
      (node): node is FileEntityObject => node['@type'] === 'files.entity'
    )
  )

  // Check if a node is selected
  const isSelected = (nodeId: string): boolean => {
    return selectedIds.value.has(nodeId)
  }

  // Check if node type is allowed
  const isTypeAllowed = (node: NodeRecord): boolean => {
    if (node['@type'] === 'files.collection' && !allowFolders) {
      return false
    }
    if (node['@type'] === 'files.entity' && !allowFiles) {
      return false
    }
    return true
  }

  // Select a node
  const select = (node: NodeRecord) => {
    if (!isTypeAllowed(node)) {
      return
    }

    if (!multiple) {
      // Clear previous selection for single select
      selectedIds.value.clear()
      selectedNodes.value.clear()
    }

    selectedIds.value.add(node.id)
    selectedNodes.value.set(node.id, node)
  }

  // Deselect a node
  const deselect = (nodeId: string) => {
    selectedIds.value.delete(nodeId)
    selectedNodes.value.delete(nodeId)
  }

  // Toggle selection
  const toggle = (node: NodeRecord) => {
    if (isSelected(node.id)) {
      deselect(node.id)
    } else {
      select(node)
    }
  }

  // Select multiple nodes
  const selectMultiple = (nodes: NodeRecord[]) => {
    if (!multiple) {
      // For single select, only select the last one
      const lastNode = nodes[nodes.length - 1]
      if (lastNode && isTypeAllowed(lastNode)) {
        selectedIds.value.clear()
        selectedNodes.value.clear()
        selectedIds.value.add(lastNode.id)
        selectedNodes.value.set(lastNode.id, lastNode)
      }
      return
    }

    for (const node of nodes) {
      if (isTypeAllowed(node)) {
        selectedIds.value.add(node.id)
        selectedNodes.value.set(node.id, node)
      }
    }
  }

  // Select all from a list
  const selectAll = (nodes: NodeRecord[]) => {
    if (!multiple) {
      return
    }
    selectMultiple(nodes)
  }

  // Clear selection
  const clear = () => {
    selectedIds.value.clear()
    selectedNodes.value.clear()
  }

  // Set selection (replace current)
  const setSelection = (nodes: NodeRecord[]) => {
    clear()
    selectMultiple(nodes)
  }

  return {
    // State
    selectedIds,
    selectedNodes,
    
    // Computed
    count,
    hasSelection,
    selectedIdArray,
    selectedNodeArray,
    selectedCollections,
    selectedEntities,
    
    // Methods
    isSelected,
    select,
    deselect,
    toggle,
    selectMultiple,
    selectAll,
    clear,
    setSelection,
  }
}

export default useFileSelection