Restructure

src-electron/ipc/download/FileTransfer.ts

@@ -0,0 +1,112 @@
+import { Dirent, readdir as _readdir } from 'fs'
+import mv from 'mv'
+import { join } from 'path'
+import { rimraf } from 'rimraf'
+import { promisify } from 'util'
+
+import { getSettings } from '../SettingsHandler.ipc'
+import { DownloadError } from './ChartDownload'
+
+const readdir = promisify(_readdir)
+
+interface EventCallback {
+	'start': (destinationFolder: string) => void
+	'error': (err: DownloadError, retry: () => void | Promise<void>) => void
+	'complete': () => void
+}
+type Callbacks = { [E in keyof EventCallback]: EventCallback[E] }
+
+const transferErrors = {
+	readError: (err: NodeJS.ErrnoException) => fsError(err, 'Failed to read file.'),
+	deleteError: (err: NodeJS.ErrnoException) => fsError(err, 'Failed to delete file.'),
+	rimrafError: (err: NodeJS.ErrnoException) => fsError(err, 'Failed to delete folder.'),
+	mvError: (err: NodeJS.ErrnoException) => fsError(
+		err,
+		`Failed to move folder to library.${err.code == 'EPERM' ? ' (does the chart already exist?)' : ''}`,
+	),
+}
+
+function fsError(err: NodeJS.ErrnoException, description: string) {
+	return { header: description, body: `${err.name}: ${err.message}` }
+}
+
+export class FileTransfer {
+
+	private callbacks = {} as Callbacks
+	private wasCanceled = false
+	private destinationFolder: string
+	private nestedSourceFolder: string // The top-level folder that is copied to the library folder
+	constructor(private sourceFolder: string, destinationFolderName: string) {
+		this.destinationFolder = join(getSettings().libraryPath, destinationFolderName)
+		this.nestedSourceFolder = sourceFolder
+	}
+
+	/**
+	 * Calls `callback` when `event` fires. (no events will be fired after `this.cancelTransfer()` is called)
+	 */
+	on<E extends keyof EventCallback>(event: E, callback: EventCallback[E]) {
+		this.callbacks[event] = callback
+	}
+
+	async beginTransfer() {
+		this.callbacks.start(this.destinationFolder)
+		await this.cleanFolder()
+		if (this.wasCanceled) { return }
+		this.moveFolder()
+	}
+
+	/**
+	 * Fixes common problems with the download chart folder.
+	 */
+	private async cleanFolder() {
+		let files: Dirent[]
+		try {
+			files = await readdir(this.nestedSourceFolder, { withFileTypes: true })
+		} catch (err) {
+			this.callbacks.error(transferErrors.readError(err), () => this.cleanFolder())
+			return
+		}
+
+		// Remove nested folders
+		if (files.length == 1 && !files[0].isFile()) {
+			this.nestedSourceFolder = join(this.nestedSourceFolder, files[0].name)
+			await this.cleanFolder()
+			return
+		}
+
+		// Delete '__MACOSX' folder
+		for (const file of files) {
+			if (!file.isFile() && file.name == '__MACOSX') {
+				try {
+					await rimraf(join(this.nestedSourceFolder, file.name))
+				} catch (err) {
+					this.callbacks.error(transferErrors.rimrafError(err), () => this.cleanFolder())
+					return
+				}
+			} else {
+				// TODO: handle other common problems, like chart/audio files not named correctly
+			}
+		}
+	}
+
+	/**
+	 * Moves the downloaded chart to the library path.
+	 */
+	private moveFolder() {
+		mv(this.nestedSourceFolder, this.destinationFolder, { mkdirp: true }, err => {
+			if (err) {
+				this.callbacks.error(transferErrors.mvError(err), () => this.moveFolder())
+			} else {
+				rimraf(this.sourceFolder) // Delete temp folder
+				this.callbacks.complete()
+			}
+		})
+	}
+
+	/**
+	 * Stop the process of transfering the file. (no more events will be fired after this is called)
+	 */
+	cancelTransfer() {
+		this.wasCanceled = true
+	}
+}