From 901d126d6b6908c4c7b6fa4a19ec1ae08b866a7f Mon Sep 17 00:00:00 2001
From: Puyodead1 <puyodead@proton.me>
Date: Thu, 22 Dec 2022 21:23:55 -0500
Subject: [PATCH] Add facebook connection

---
 src/connections/Facebook/FacebookSettings.ts |   5 +
 src/connections/Facebook/index.ts            | 142 +++++++++++++++++++
 2 files changed, 147 insertions(+)
 create mode 100644 src/connections/Facebook/FacebookSettings.ts
 create mode 100644 src/connections/Facebook/index.ts

diff --git a/src/connections/Facebook/FacebookSettings.ts b/src/connections/Facebook/FacebookSettings.ts
new file mode 100644
index 00000000..cc3e3402
--- /dev/null
+++ b/src/connections/Facebook/FacebookSettings.ts
@@ -0,0 +1,5 @@
+export class FacebookSettings {
+	enabled: boolean = false;
+	clientId: string | null = null;
+	clientSecret: string | null = null;
+}
diff --git a/src/connections/Facebook/index.ts b/src/connections/Facebook/index.ts
new file mode 100644
index 00000000..80950a8e
--- /dev/null
+++ b/src/connections/Facebook/index.ts
@@ -0,0 +1,142 @@
+import {
+	Config,
+	ConnectedAccount,
+	ConnectionCallbackSchema,
+	ConnectionLoader,
+	DiscordApiErrors,
+} from "@fosscord/util";
+import fetch from "node-fetch";
+import Connection from "../../util/connections/Connection";
+import { FacebookSettings } from "./FacebookSettings";
+
+interface OAuthTokenResponse {
+	access_token: string;
+	token_type: string;
+	scope: string;
+	refresh_token?: string;
+	expires_in?: number;
+}
+
+export interface FacebookErrorResponse {
+	error: {
+		message: string;
+		type: string;
+		code: number;
+		fbtrace_id: string;
+	};
+}
+
+interface UserResponse {
+	name: string;
+	id: string;
+}
+
+export default class FacebookConnection extends Connection {
+	public readonly id = "facebook";
+	public readonly authorizeUrl =
+		"https://www.facebook.com/v14.0/dialog/oauth";
+	public readonly tokenUrl =
+		"https://graph.facebook.com/v14.0/oauth/access_token";
+	public readonly userInfoUrl = "https://graph.facebook.com/v14.0/me";
+	public readonly scopes = ["public_profile"];
+	settings: FacebookSettings = new FacebookSettings();
+
+	init(): void {
+		this.settings = ConnectionLoader.getConnectionConfig(
+			this.id,
+			this.settings,
+		) as FacebookSettings;
+	}
+
+	getAuthorizationUrl(userId: string): string {
+		const state = this.createState(userId);
+		const url = new URL(this.authorizeUrl);
+
+		url.searchParams.append("client_id", this.settings.clientId!);
+		// TODO: probably shouldn't rely on cdn as this could be different from what we actually want. we should have an api endpoint setting.
+		url.searchParams.append(
+			"redirect_uri",
+			`${
+				Config.get().cdn.endpointPrivate || "http://localhost:3001"
+			}/connections/${this.id}/callback`,
+		);
+		url.searchParams.append("state", state);
+		url.searchParams.append("response_type", "code");
+		url.searchParams.append("scope", this.scopes.join(" "));
+		url.searchParams.append("display", "popup");
+		return url.toString();
+	}
+
+	getTokenUrl(code: string): string {
+		const url = new URL(this.tokenUrl);
+		url.searchParams.append("client_id", this.settings.clientId!);
+		url.searchParams.append("client_secret", this.settings.clientSecret!);
+		url.searchParams.append("code", code);
+		url.searchParams.append(
+			"redirect_uri",
+			`${
+				Config.get().cdn.endpointPrivate || "http://localhost:3001"
+			}/connections/${this.id}/callback`,
+		);
+		return url.toString();
+	}
+
+	async exchangeCode(state: string, code: string): Promise<string> {
+		this.validateState(state);
+
+		const url = this.getTokenUrl(code);
+
+		return fetch(url.toString(), {
+			method: "GET",
+			headers: {
+				Accept: "application/json",
+			},
+		})
+			.then((res) => res.json())
+			.then((res: OAuthTokenResponse & FacebookErrorResponse) => {
+				if (res.error) throw new Error(res.error.message);
+				return res.access_token;
+			})
+			.catch((e) => {
+				console.error(
+					`Error exchanging token for ${this.id} connection: ${e}`,
+				);
+				throw DiscordApiErrors.INVALID_OAUTH_TOKEN;
+			});
+	}
+
+	async getUser(token: string): Promise<UserResponse> {
+		const url = new URL(this.userInfoUrl);
+		return fetch(url.toString(), {
+			method: "GET",
+			headers: {
+				Authorization: `Bearer ${token}`,
+			},
+		})
+			.then((res) => res.json())
+			.then((res: UserResponse & FacebookErrorResponse) => {
+				if (res.error) throw new Error(res.error.message);
+				return res;
+			});
+	}
+
+	async handleCallback(
+		params: ConnectionCallbackSchema,
+	): Promise<ConnectedAccount | null> {
+		const userId = this.getUserId(params.state);
+		const token = await this.exchangeCode(params.state, params.code!);
+		const userInfo = await this.getUser(token);
+
+		const exists = await this.hasConnection(userId, userInfo.id);
+
+		if (exists) return null;
+
+		return await this.createConnection({
+			user_id: userId,
+			external_id: userInfo.id,
+			friend_sync: params.friend_sync,
+			name: userInfo.name,
+			type: this.id,
+		});
+	}
+}