Refactor FileServerService: Extract file handling logic into dedicated handlers (#17090)

- Introduced FileServerDriveHandler to manage drive file requests.
- Created FileServerFileResolver for resolving file access keys and downloading files.
- Added FileServerProxyHandler to handle proxy requests and image processing.
- Moved utility functions to FileServerUtils for better organization.
- Removed redundant methods from FileServerService, improving readability and maintainability.

1 files changed, 126 insertions, 0 deletions

diff --git a/packages/backend/src/server/file/FileServerFileResolver.ts b/packages/backend/src/server/file/FileServerFileResolver.ts
new file mode 100644
index 0000000000..687d486efd
--- /dev/null
+++ b/packages/backend/src/server/file/FileServerFileResolver.ts
@@ -0,0 +1,126 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import * as fs from 'node:fs';
+import type { DriveFilesRepository, MiDriveFile } from '@/models/_.js';
+import { createTemp } from '@/misc/create-temp.js';
+import type { DownloadService } from '@/core/DownloadService.js';
+import type { FileInfoService } from '@/core/FileInfoService.js';
+import type { InternalStorageService } from '@/core/InternalStorageService.js';
+
+export type DownloadedFileResult = {
+	kind: 'downloaded';
+	mime: string;
+	ext: string | null;
+	path: string;
+	cleanup: () => void;
+	filename: string;
+};
+
+export type FileResolveResult =
+	| { kind: 'not-found' }
+	| { kind: 'unavailable' }
+	| {
+		kind: 'stored';
+		fileRole: 'thumbnail' | 'webpublic' | 'original';
+		file: MiDriveFile;
+		filename: string;
+		mime: string;
+		ext: string | null;
+		path: string;
+	}
+	| {
+		kind: 'remote';
+		fileRole: 'thumbnail' | 'webpublic' | 'original';
+		file: MiDriveFile;
+		filename: string;
+		url: string;
+		mime: string;
+		ext: string | null;
+		path: string;
+		cleanup: () => void;
+	};
+
+export class FileServerFileResolver {
+	constructor(
+		private driveFilesRepository: DriveFilesRepository,
+		private fileInfoService: FileInfoService,
+		private downloadService: DownloadService,
+		private internalStorageService: InternalStorageService,
+	) {}
+
+	public async downloadAndDetectTypeFromUrl(url: string): Promise<DownloadedFileResult> {
+		const [path, cleanup] = await createTemp();
+		try {
+			const { filename } = await this.downloadService.downloadUrl(url, path);
+
+			const { mime, ext } = await this.fileInfoService.detectType(path);
+
+			return {
+				kind: 'downloaded',
+				mime, ext,
+				path, cleanup,
+				filename,
+			};
+		} catch (e) {
+			cleanup();
+			throw e;
+		}
+	}
+
+	public async resolveFileByAccessKey(key: string): Promise<FileResolveResult> {
+		// Fetch drive file
+		const file = await this.driveFilesRepository.createQueryBuilder('file')
+			.where('file.accessKey = :accessKey', { accessKey: key })
+			.orWhere('file.thumbnailAccessKey = :thumbnailAccessKey', { thumbnailAccessKey: key })
+			.orWhere('file.webpublicAccessKey = :webpublicAccessKey', { webpublicAccessKey: key })
+			.getOne();
+
+		if (file == null) return { kind: 'not-found' };
+
+		const isThumbnail = file.thumbnailAccessKey === key;
+		const isWebpublic = file.webpublicAccessKey === key;
+
+		if (!file.storedInternal) {
+			if (!(file.isLink && file.uri)) return { kind: 'unavailable' };
+			const result = await this.downloadAndDetectTypeFromUrl(file.uri);
+			const { kind: _kind, ...downloaded } = result;
+			file.size = (await fs.promises.stat(downloaded.path)).size;	// DB file.sizeは正確とは限らないので
+			return {
+				kind: 'remote',
+				...downloaded,
+				url: file.uri,
+				fileRole: isThumbnail ? 'thumbnail' : isWebpublic ? 'webpublic' : 'original',
+				file,
+				filename: file.name,
+			};
+		}
+
+		const path = this.internalStorageService.resolvePath(key);
+
+		if (isThumbnail || isWebpublic) {
+			const { mime, ext } = await this.fileInfoService.detectType(path);
+			return {
+				kind: 'stored',
+				fileRole: isThumbnail ? 'thumbnail' : 'webpublic',
+				file,
+				filename: file.name,
+				mime, ext,
+				path,
+			};
+		}
+
+		return {
+			kind: 'stored',
+			fileRole: 'original',
+			file,
+			filename: file.name,
+			// 古いファイルは修正前のmimeを持っているのでできるだけ修正してあげる
+			mime: this.fileInfoService.fixMime(file.type),
+			ext: null,
+			path,
+		};
+	}
+}