feat: add filepicker package

packages/filepicker/src/Streaming/StreamingReader.ts

@@ -0,0 +1,75 @@
+import { FileReaderInterface } from './../Interface/FileReader'
+import { ByteChunker } from '../Chunker/ByteChunker'
+import { OnChunkCallback, FileSelectionResponse } from '../types'
+
+interface StreamingFileReaderInterface {
+  getFilesFromHandles(handles: FileSystemFileHandle[]): Promise<File[]>
+}
+
+/**
+ * The File System Access API File Picker
+ * https://developer.mozilla.org/en-US/docs/Web/API/File_System_Access_API
+ */
+export const StreamingFileReader: StreamingFileReaderInterface & FileReaderInterface = {
+  getFilesFromHandles,
+  selectFiles,
+  readFile,
+  available,
+  maximumFileSize,
+}
+
+function maximumFileSize(): number | undefined {
+  return undefined
+}
+
+function getFilesFromHandles(handles: FileSystemFileHandle[]): Promise<File[]> {
+  return Promise.all(handles.map((handle) => handle.getFile()))
+}
+
+async function selectFiles(): Promise<File[]> {
+  let selectedFilesHandles: FileSystemFileHandle[]
+  try {
+    selectedFilesHandles = await window.showOpenFilePicker({ multiple: true })
+  } catch (error) {
+    selectedFilesHandles = []
+  }
+  return getFilesFromHandles(selectedFilesHandles)
+}
+
+async function readFile(
+  file: File,
+  minimumChunkSize: number,
+  onChunk: OnChunkCallback,
+): Promise<FileSelectionResponse> {
+  const byteChunker = new ByteChunker(minimumChunkSize, onChunk)
+  const stream = file.stream() as unknown as ReadableStream
+  const reader = stream.getReader()
+
+  let previousChunk: Uint8Array
+
+  const processChunk = async (result: ReadableStreamDefaultReadResult<Uint8Array>): Promise<void> => {
+    if (result.done) {
+      await byteChunker.addBytes(previousChunk, true)
+      return
+    }
+
+    if (previousChunk) {
+      await byteChunker.addBytes(previousChunk, false)
+    }
+
+    previousChunk = result.value
+
+    return reader.read().then(processChunk)
+  }
+
+  await reader.read().then(processChunk)
+
+  return {
+    name: file.name,
+    mimeType: file.type,
+  }
+}
+
+function available(): boolean {
+  return window.showOpenFilePicker != undefined
+}