refactor mastodon API and preserve remote user agent for requests

packages/backend/src/server/api/mastodon/MastodonClientService.ts

@@ -0,0 +1,69 @@
+/*
+ * SPDX-FileCopyrightText: hazelnoot and other Sharkey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { megalodon, MegalodonInterface } from 'megalodon';
+import { Injectable } from '@nestjs/common';
+import { MiLocalUser } from '@/models/User.js';
+import { AuthenticateService } from '@/server/api/AuthenticateService.js';
+import type { FastifyRequest } from 'fastify';
+
+@Injectable()
+export class MastodonClientService {
+	constructor(
+		private readonly authenticateService: AuthenticateService,
+	) {}
+
+	/**
+	 * Gets the authenticated user and API client for a request.
+	 */
+	public async getAuthClient(request: FastifyRequest, accessToken?: string | null): Promise<{ client: MegalodonInterface, me: MiLocalUser | null }> {
+		const authorization = request.headers.authorization;
+		accessToken = accessToken !== undefined ? accessToken : getAccessToken(authorization);
+
+		const me = await this.getAuth(request, accessToken);
+		const client = this.getClient(request, accessToken);
+
+		return { client, me };
+	}
+
+	/**
+	 * Gets the authenticated client user for a request.
+	 */
+	public async getAuth(request: FastifyRequest, accessToken?: string | null): Promise<MiLocalUser | null> {
+		const authorization = request.headers.authorization;
+		accessToken = accessToken !== undefined ? accessToken : getAccessToken(authorization);
+		const [me] = await this.authenticateService.authenticate(accessToken);
+		return me;
+	}
+
+	/**
+	 * Creates an authenticated API client for a request.
+	 */
+	public getClient(request: FastifyRequest, accessToken?: string | null): MegalodonInterface {
+		const authorization = request.headers.authorization;
+		accessToken = accessToken !== undefined ? accessToken : getAccessToken(authorization);
+
+		// TODO pass agent?
+		const baseUrl = this.getBaseUrl(request);
+		const userAgent = request.headers['user-agent'];
+		return megalodon('misskey', baseUrl, accessToken, userAgent);
+	}
+
+	/**
+	 * Gets the base URL (origin) of the incoming request
+	 */
+	public getBaseUrl(request: FastifyRequest): string {
+		return `${request.protocol}://${request.host}`;
+	}
+}
+
+/**
+ * Extracts the first access token from an authorization header
+ * Returns null if none were found.
+ */
+function getAccessToken(authorization: string | undefined): string | null {
+	const accessTokenArr = authorization?.split(' ') ?? [null];
+	return accessTokenArr[accessTokenArr.length - 1];
+}