misskey-oauth.ts

import { nanoid } from "https://esm.sh/nanoid/";
import { encodeBase64 } from "https://deno.land/std/encoding/base64.ts";

const base64uri = (data: ArrayBuffer) =>
  encodeBase64(data)
    .replaceAll("+", "-")
    .replaceAll("/", "_")
    .replaceAll("=", "");

const clientId = "https://ikasoba.github.io/misskey-oauth2-client-example";
const redirectUri =
  "https://ikasoba.github.io/misskey-oauth2-client-example/redirect";

const codeChallengeMethod = "S256";
const codeVerifier = nanoid();
const codeChallenge = base64uri(
  await crypto.subtle.digest("sha-256", new TextEncoder().encode(codeVerifier))
);

const host = new URL("https://misskey.systems");

const meta = await fetch(
  new URL("/.well-known/oauth-authorization-server", host)
).then((res) => res.json());

const authRequest = new URL(meta.authorization_endpoint, host);
authRequest.searchParams.set("response_type", "code");
authRequest.searchParams.set("client_id", clientId);
authRequest.searchParams.set("redirect_uri", redirectUri);
authRequest.searchParams.set("code_challenge", codeChallenge);
authRequest.searchParams.set("code_challenge_method", codeChallengeMethod);
authRequest.searchParams.set("scope", "write:notes");

console.log("ブラウザでリクエスト", authRequest.toString());

const code = prompt("認可コードを入力")!;

const tokenResponse = await fetch(new URL(meta.token_endpoint, host), {
  method: "POST",
  headers: {
    "Content-Type": "application/x-www-form-urlencoded",
  },
  body: new URLSearchParams({
    grant_type: "authorization_code",
    code: code,
    client_id: clientId,
    redirect_uri: redirectUri,
    code_verifier: codeVerifier,
  }).toString(),
}).then((res) => res.json());

const token = tokenResponse.access_token;

await fetch(new URL("/api/notes/create", host), {
  method: "POST",
  headers: {
    Authorization: `Bearer ${token}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    text: "OAuth2.0 テスト",
  }),
});