feat: add filepicker package

packages/filepicker/example/src/file_system_api.ts

@@ -0,0 +1,68 @@
+import { StreamingFileReader, StreamingFileSaver } from '../../../filepicker'
+import { SNApplication, FileItem, ClientDisplayableError } from '../../../snjs'
+
+export class FileSystemApi {
+  private uploadedFiles: FileItem[] = []
+
+  constructor(private application: SNApplication) {
+    this.configureFilePicker()
+    this.configureDownloadButton()
+  }
+
+  get downloadButton(): HTMLButtonElement {
+    return document.getElementById('downloadButton') as HTMLButtonElement
+  }
+
+  configureDownloadButton(): void {
+    this.downloadButton.onclick = this.downloadFiles
+    this.downloadButton.style.display = 'none'
+  }
+
+  configureFilePicker(): void {
+    const button = document.getElementById('fileSystemUploadButton') as HTMLButtonElement
+    button.onclick = this.uploadFiles
+    console.log('File picker ready.')
+  }
+
+  uploadFiles = async (): Promise<void> => {
+    const snFiles = []
+    const selectedFiles = await StreamingFileReader.selectFiles()
+    for (const file of selectedFiles) {
+      const operation = await this.application.files.beginNewFileUpload()
+      if (operation instanceof ClientDisplayableError) {
+        continue
+      }
+      const fileResult = await StreamingFileReader.readFile(file, 2_000_000, async (chunk, index, isLast) => {
+        await this.application.files.pushBytesForUpload(operation, chunk, index, isLast)
+      })
+
+      const snFile = await this.application.files.finishUpload(operation, fileResult)
+
+      snFiles.push(snFile)
+    }
+
+    this.downloadButton.style.display = ''
+
+    this.uploadedFiles = snFiles
+  }
+
+  downloadFiles = async (): Promise<void> => {
+    for (const snFile of this.uploadedFiles) {
+      console.log('Downloading file', snFile.remoteIdentifier)
+
+      const saver = new StreamingFileSaver(snFile.name)
+      await saver.selectFileToSaveTo()
+      saver.loggingEnabled = true
+
+      await this.application.files.downloadFile(snFile, async (decryptedBytes: Uint8Array) => {
+        console.log(`Pushing ${decryptedBytes.length} decrypted bytes to disk`)
+        await saver.pushBytes(decryptedBytes)
+      })
+
+      console.log('Closing file saver reader')
+      await saver.finish()
+
+      console.log('Successfully downloaded and decrypted file!')
+    }
+  }
+}