import {type ProgressEvent, type SanityAssetDocument, type SanityClient} from '@sanity/client'
import {type FileAsset, type ImageAsset} from '@sanity/types'
import {Observable, of as observableOf} from 'rxjs'
import {catchError, map, mergeMap} from 'rxjs/operators'

import {type DocumentPreviewStore} from '../../../../preview'
import {type UploadOptions} from '../../uploads/types'
import {withMaxConcurrency} from '../../utils'

const MAX_CONCURRENT_UPLOADS = 4

type UploadEvent = ProgressEvent | {type: 'complete'; id: string; asset: SanityAssetDocument}

function uploadSanityAsset(
  client: SanityClient,
  assetType: 'file' | 'image',
  file: File | Blob,
  options: UploadOptions = {},
): Observable<UploadEvent> {
  const extract = options.metadata
  const preserveFilename = options.storeOriginalFilename
  const {label, title, description, creditLine, source} = options
  return hashFile(file).pipe(
    catchError(() =>
      // ignore if hashing fails for some reason
      observableOf(null),
    ),

    mergeMap((hash) =>
      // note: the sanity api will still dedupe unique files, but this saves us from uploading the asset file entirely
      hash ? fetchExisting(client, `sanity.${assetType}Asset`, hash) : observableOf(null),
    ),

    mergeMap((existing: SanityAssetDocument | null) => {
      if (existing) {
        return observableOf({
          // complete with the existing asset document
          type: 'complete' as const,
          id: existing._id,
          asset: existing,
        })
      }
      return client.observable.assets
        .upload(assetType, file, {
          tag: 'asset.upload',
          extract,
          preserveFilename,
          label,
          title,
          description,
          creditLine,
          source,
        })
        .pipe(
          map((event) =>
            event.type === 'response'
              ? {
                  // rewrite to a 'complete' event
                  type: 'complete' as const,
                  id: event.body.document._id,
                  asset: event.body.document,
                }
              : event,
          ),
        )
    }),
  )
}

const uploadAsset = withMaxConcurrency(uploadSanityAsset, MAX_CONCURRENT_UPLOADS)

export const uploadImageAsset = (
  client: SanityClient,
  file: File | Blob,
  options?: UploadOptions,
) => uploadAsset(client, 'image', file, options)

export const uploadFileAsset = (client: SanityClient, file: File | Blob, options?: UploadOptions) =>
  uploadAsset(client, 'file', file, options)

// note: there's currently 100% overlap between the ImageAsset document and the FileAsset documents as per interface required by the image and file input
function observeAssetDoc(documentPreviewStore: DocumentPreviewStore, id: string) {
  return documentPreviewStore.observePaths({_type: 'reference', _ref: id}, [
    'originalFilename',
    'url',
    'metadata',
    'label',
    'title',
    'description',
    'creditLine',
    'source',
    'size',
  ])
}

export function observeImageAsset(documentPreviewStore: DocumentPreviewStore, id: string) {
  return observeAssetDoc(documentPreviewStore, id) as Observable<ImageAsset>
}

export function observeFileAsset(documentPreviewStore: DocumentPreviewStore, id: string) {
  return observeAssetDoc(documentPreviewStore, id) as Observable<FileAsset>
}

function fetchExisting(
  client: SanityClient,
  type: string,
  hash: string,
): Observable<ImageAsset | FileAsset | null> {
  return client.observable.fetch(
    '*[_type == $documentType && sha1hash == $hash][0]',
    {documentType: type, hash},
    {tag: 'asset.find-duplicate'},
  )
}

function readFile(file: Blob | File): Observable<ArrayBuffer> {
  return new Observable((subscriber) => {
    const reader = new FileReader()
    reader.onload = () => {
      subscriber.next(reader.result as ArrayBuffer)
      subscriber.complete()
    }
    reader.onerror = (err) => {
      subscriber.error(err)
    }
    reader.readAsArrayBuffer(file)
    return () => {
      reader.abort()
    }
  })
}

function hashFile(file: File | Blob): Observable<string | null> {
  if (!window.crypto || !window.crypto.subtle || !window.FileReader) {
    return observableOf(null)
  }
  return readFile(file).pipe(
    mergeMap((arrayBuffer) => crypto.subtle.digest('SHA-1', arrayBuffer)),
    map(hexFromBuffer),
  )
}

function hexFromBuffer(buffer: ArrayBuffer): string {
  return Array.prototype.map
    .call(new Uint8Array(buffer), (x) => `00${x.toString(16)}`.slice(-2))
    .join('')
}