refactor: avoid Buffer in workers environment

src/auth.ts

@@ -3,6 +3,7 @@ import type { EndpointOutput } from "@sveltejs/kit/types/endpoint";
 import { RequestEvent } from "@sveltejs/kit/types/hooks";
 import cookie from "cookie";
 import { JWTPayload, jwtVerify, KeyLike, SignJWT } from "jose";
+import { base64Encode } from "./helpers";
 import type { JWT, Session } from "./interfaces";
 import { join } from "./path";
 import type { Provider } from "./providers";
@@ -40,7 +41,7 @@ export class Auth {
 
     if (this.config?.providers?.length) {
       const provs = this.config?.providers?.map((provider) => provider.id).join("+");
-      return encoder.encode(provs);
+      return encoder.encode(base64Encode(provs));
     }
 
     return encoder.encode("svelte_auth_secret");

src/helpers.ts

@@ -1,3 +1,17 @@
 export function ucFirst(val: string) {
   return val.charAt(0).toUpperCase() + val.slice(1);
 }
+
+export function base64Encode(str: string): string {
+  if (typeof btoa === 'undefined') {
+    return Buffer.from(str).toString('base64');
+  }
+  return btoa(str);
+} 
+
+export function base64Decode(str: string): string {
+  if (typeof atob === 'undefined') {
+    return Buffer.from(str, 'base64').toString();
+  }
+  return atob(str);
+} 

src/providers/oauth2.base.ts

@@ -1,5 +1,6 @@
 import type { EndpointOutput } from "@sveltejs/kit/types/endpoint";
 import { RequestEvent } from "@sveltejs/kit/types/hooks";
+import { base64Encode, base64Decode } from "../helpers";
 import type { Auth } from "../auth";
 import type { CallbackResult } from "../types";
 import { Provider, ProviderConfig } from "./base";
@@ -39,7 +40,7 @@ export abstract class OAuth2BaseProvider<
     const state = [
       `redirect=${url.searchParams.get("redirect") ?? this.getUri(auth, "/", url.host)}`,
     ].join(",");
-    const base64State = Buffer.from(state).toString("base64");
+    const base64State = base64Encode(state);
     const nonce = Math.round(Math.random() * 1000).toString(); // TODO: Generate random based on user values
     const authUrl = await this.getAuthorizationUrl(event, auth, base64State, nonce);
 
@@ -61,7 +62,7 @@ export abstract class OAuth2BaseProvider<
 
   getStateValue(query: URLSearchParams, name: string) {
     if (query.get("state")) {
-      const state = Buffer.from(query.get("state")!, "base64").toString();
+      const state = base64Decode(query.get("state")!);
       return state
         .split(",")
         .find((state) => state.startsWith(`${name}=`))

src/providers/reddit.ts

@@ -1,3 +1,4 @@
+import { base64Encode } from "../helpers";
 import { OAuth2Provider, OAuth2ProviderConfig } from "./oauth2";
 
 export interface RedditProfile {
@@ -228,7 +229,7 @@ export class RedditOAuth2Provider extends OAuth2Provider<
       headers: {
         ...config.headers,
         Authorization:
-          "Basic " + Buffer.from(`${config.apiKey}:${config.apiSecret}`).toString("base64"),
+          "Basic " + base64Encode(`${config.apiKey}:${config.apiSecret}`),
       },
       authorizationParams: {
         ...config.authorizationParams,