feat: add files package

packages/files/src/Domain/Operations/DownloadAndDecrypt.ts

@@ -0,0 +1,75 @@
+import { ClientDisplayableError } from '@standardnotes/responses'
+import { AbortFunction, FileDownloader } from '../UseCase/FileDownloader'
+import { FileDecryptor } from '../UseCase/FileDecryptor'
+import { FileDownloadProgress } from '../Types/FileDownloadProgress'
+import { FilesApiInterface } from '@standardnotes/services'
+import { PureCryptoInterface } from '@standardnotes/sncrypto-common'
+import { FileContent } from '@standardnotes/models'
+import { DecryptedBytes, EncryptedBytes } from '@standardnotes/filepicker'
+
+export type DownloadAndDecryptResult = { success: boolean; error?: ClientDisplayableError; aborted?: boolean }
+
+type OnBytesCallback = (results: {
+  decrypted: DecryptedBytes
+  encrypted: EncryptedBytes
+  progress: FileDownloadProgress
+}) => Promise<void>
+
+export class DownloadAndDecryptFileOperation {
+  private downloader: FileDownloader
+
+  constructor(
+    private readonly file: {
+      encryptedChunkSizes: FileContent['encryptedChunkSizes']
+      encryptionHeader: FileContent['encryptionHeader']
+      remoteIdentifier: FileContent['remoteIdentifier']
+      key: FileContent['key']
+    },
+    private readonly crypto: PureCryptoInterface,
+    private readonly api: FilesApiInterface,
+  ) {
+    this.downloader = new FileDownloader(this.file, this.api)
+  }
+
+  private createDecryptor(): FileDecryptor {
+    return new FileDecryptor(this.file, this.crypto)
+  }
+
+  public async run(onBytes: OnBytesCallback): Promise<DownloadAndDecryptResult> {
+    const decryptor = this.createDecryptor()
+
+    let decryptError: ClientDisplayableError | undefined
+
+    const onDownloadBytes = async (
+      encryptedBytes: Uint8Array,
+      progress: FileDownloadProgress,
+      abortDownload: AbortFunction,
+    ) => {
+      const result = decryptor.decryptBytes(encryptedBytes)
+
+      if (!result || result.decryptedBytes.length === 0) {
+        decryptError = new ClientDisplayableError('Failed to decrypt chunk')
+
+        abortDownload()
+
+        return
+      }
+
+      const decryptedBytes = result.decryptedBytes
+
+      await onBytes({ decrypted: { decryptedBytes }, encrypted: { encryptedBytes }, progress })
+    }
+
+    const downloadResult = await this.downloader.run(onDownloadBytes)
+
+    return {
+      success: downloadResult instanceof ClientDisplayableError ? false : true,
+      error: downloadResult === 'aborted' ? undefined : downloadResult || decryptError,
+      aborted: downloadResult === 'aborted',
+    }
+  }
+
+  abort(): void {
+    this.downloader.abort()
+  }
+}