import type {ClientPerspective, ContentSourceMapDocuments} from '@sanity/client'

import {useCallback, useEffect, useRef} from 'react'

import type {ElementState, SanityNode, VisualEditingNode} from '../types'

function isEqualSets(a: Set<string>, b: Set<string>) {
  if (a === b) return true
  if (a.size !== b.size) return false
  for (const value of a) if (!b.has(value)) return false
  return true
}

/**
 * Hook for reporting in use documents to Presentation
 * @internal
 */
export function useReportDocuments(
  comlink: VisualEditingNode | undefined,
  elements: ElementState[],
  perspective: ClientPerspective,
): void {
  const lastReported = useRef<
    | {
        nodeIds: Set<string>
        perspective: ClientPerspective
      }
    | undefined
  >(undefined)

  const reportDocuments = useCallback(
    (documents: ContentSourceMapDocuments, perspective: ClientPerspective) => {
      comlink?.post('visual-editing/documents', {
        documents,
        perspective,
      })
    },
    [comlink],
  )

  useEffect(() => {
    // Report only nodes of type `SanityNode`. Untransformed `SanityStegaNode`
    // nodes without an `id`, are not reported as they will not contain the
    // necessary document data.
    const nodes = elements
      .map((e) => {
        const {sanity} = e
        if (!sanity || !('id' in sanity)) return null
        return sanity
      })
      .filter((s) => !!s) as SanityNode[]

    const nodeIds = new Set<string>(nodes.map((e) => e.id))
    // Report if:
    // - Documents not yet reported
    // - Document IDs changed
    // - Perspective changed
    if (
      !lastReported.current ||
      !isEqualSets(nodeIds, lastReported.current.nodeIds) ||
      perspective !== lastReported.current.perspective
    ) {
      const documentsOnPage: ContentSourceMapDocuments = Array.from(nodeIds).map((_id) => {
        const node = nodes.find((node) => node.id === _id)!
        const {type, projectId: _projectId, dataset: _dataset} = node
        return _projectId && _dataset
          ? {_id, _type: type!, _projectId, _dataset}
          : {_id, _type: type!}
      })
      lastReported.current = {nodeIds, perspective}
      reportDocuments(documentsOnPage, perspective)
    }
  }, [elements, perspective, reportDocuments])
}