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Implement access token generation in spotify.ts
.refreshToken stores the refresh token in plaintext and should not be commited to git by mistake
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+133
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src/components/playing/spotify.ts
+133
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src/components/playing/spotify.ts
···
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import {
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SPOTIFY_CLIENT_ID,
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SPOTIFY_CLIENT_SECRET,
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SPOTIFY_REDIRECT_URI,
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} from "astro:env/server";
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import fs from "fs/promises";
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const throws = (val: unknown) => {
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throw val;
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};
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/** via: https://www.totaltypescript.com/concepts/the-prettify-helper */
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type Prettify<T> = {
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[K in keyof T]: T[K];
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} & {};
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type AuthToken = {
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access_token: string;
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token_type: "Bearer";
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scope: string;
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expires_in: number;
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refresh_token: string;
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};
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type RefreshToken = Prettify<
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Omit<AuthToken, "refresh_token"> & { refresh_token?: string }
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>;
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const isRefreshToken = (obj: unknown): obj is RefreshToken =>
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// validate is object
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typeof obj === "object" &&
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obj !== null &&
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// validate properties
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"access_token" in obj &&
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typeof obj.access_token === "string" &&
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"token_type" in obj &&
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obj.token_type === "Bearer" &&
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"scope" in obj &&
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typeof obj.scope === "string" &&
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"expires_in" in obj &&
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typeof obj.expires_in === "number" &&
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// either refresh token exists as string or not at all
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(("refresh_token" in obj && typeof obj.refresh_token === "string") ||
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!("refresh_token" in obj));
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// auth token is just refresh with a non optional refresh_token
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const isAuthToken = (obj: unknown): obj is AuthToken =>
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isRefreshToken(obj) && "refresh_token" in obj;
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export async function getAccessCode(userAuthCode?: string) {
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return "Not implemented!"
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}
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const refreshToken = await fs
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.readFile("./.refreshToken", { encoding: "utf-8" })
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.catch((_) => undefined)
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.then((x) => (x === "" || x === "REFRESH_TOKEN" ? undefined : x));
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if (!(userAuthCode || refreshToken))
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throw new Error(
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"No auth code or refresh token.\nGenerate an auth code at `/src/pages/_callback`\nA refresh token will be generated from this auth token.",
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);
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// prefer auth codes over refresh tokens
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// since the auth code may have updated scopes.
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const accessFrom:
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| {
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userAuthCode: string;
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}
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| {
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refreshToken: string;
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} = userAuthCode
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? { userAuthCode }
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: refreshToken
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? { refreshToken }
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: (undefined as never);
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const req = fetch("https://accounts.spotify.com/api/token", {
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method: "POST",
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headers: {
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"Content-Type": "application/x-www-form-urlencoded",
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Authorization: `Basic ${Buffer.from(SPOTIFY_CLIENT_ID + ":" + SPOTIFY_CLIENT_SECRET).toString("base64")}`,
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},
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body: new URLSearchParams({
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grant_type:
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"userAuthCode" in accessFrom ? "authorization_code" : "refresh_token",
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...("userAuthCode" in accessFrom
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? {
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code: accessFrom.userAuthCode,
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redirect_uri: SPOTIFY_REDIRECT_URI,
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}
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: {
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refresh_token: accessFrom.refreshToken,
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}),
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}).toString(),
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});
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return (
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req
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// if res isn't 200 handle it in the catch
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.then((res) => (res.ok ? res : throws(res)))
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// request is 200-299
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// json can throw SyntaxError in this case
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.then((res) => res.json())
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.then((res) =>
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"userAuthCode" in accessFrom
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? isAuthToken(res)
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? { code: res.access_token, refresh: res.refresh_token }
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: throws({ err: "INVALID_RESPONSE", res })
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: isRefreshToken(res)
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? {
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code: res.access_token,
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refresh: res.refresh_token ?? accessFrom.refreshToken,
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}
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: throws({ err: "INVALID_RESPONSE", res }),
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)
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// res is now an access token and refresh token
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.then((res) => {
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fs.writeFile("./.refreshToken", res.refresh, { encoding: "utf-8" });
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return res.code;
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})
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.catch((err) => {
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// SyntaxError
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// Response
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// {err: string, res: Response}
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if (err instanceof Response) console.error("Request failed:", err);
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else if (err instanceof SyntaxError)
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console.error("Response JSON failed", err);
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else if (err.err === "INVALID_RESPONSE")
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console.error("Response malformed:", err);
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else {
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console.error("Unhandled exception.");
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throw err;
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}
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})
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);
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}