JavaScript認証クイックスタート

// Replace both values with your registered application configuration.
const AUTH_BASE = "https://YOUR_SLUG.sandbox.auth.didit.me/";
const REDIRECT_URI = "https://YOUR_APP_ORIGIN/auth/callback";
const PENDING = "didit.auth.pending";
let tokens = null;

function base64url(bytes) {
  return btoa(String.fromCharCode(...bytes))
    .replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, "");
}

export async function signIn() {
  const verifier = base64url(crypto.getRandomValues(new Uint8Array(32)));
  const state = base64url(crypto.getRandomValues(new Uint8Array(32)));
  const digest = await crypto.subtle.digest("SHA-256", new TextEncoder().encode(verifier));
  sessionStorage.setItem(PENDING, JSON.stringify({ verifier, state, startedAt: Date.now() }));
  const url = new URL("sign-in", AUTH_BASE);
  url.search = new URLSearchParams({
    redirect_uri: REDIRECT_URI,
    state,
    code_challenge: base64url(new Uint8Array(digest)),
    code_challenge_method: "S256",
  }).toString();
  window.location.assign(url.href);
}

export async function handleCallback() {
  const query = new URLSearchParams(window.location.search);
  const saved = sessionStorage.getItem(PENDING);
  sessionStorage.removeItem(PENDING);
  history.replaceState(null, "", window.location.pathname);
  if (!saved) throw new Error("Start sign-in again.");
  const pending = JSON.parse(saved);
  if (query.get("state") !== pending.state || Date.now() - pending.startedAt > 600000) {
    throw new Error("Invalid or expired sign-in. Start again.");
  }
  if (query.has("error") || !query.get("code")) throw new Error("Sign-in was not completed.");
  const response = await fetch(new URL("token/", AUTH_BASE), {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({
      grant_type: "authorization_code",
      code: query.get("code"),
      code_verifier: pending.verifier,
      redirect_uri: REDIRECT_URI,
    }),
  });
  if (!response.ok) throw new Error("Code exchange failed. Start sign-in again.");
  tokens = await response.json();
  return getSession();
}

export async function getSession() {
  if (!tokens) return null;
  const response = await fetch(new URL("session/", AUTH_BASE), {
    headers: { Authorization: `Bearer ${tokens.access_token}` },
    cache: "no-store",
  });
  if (!response.ok) {
    tokens = null;
    throw new Error("Session check failed. Sign in again.");
  }
  return response.json();
}

export async function signOut() {
  const current = tokens;
  tokens = null;
  if (!current) return;
  const response = await fetch(new URL("session/", AUTH_BASE), {
    method: "DELETE",
    headers: { Authorization: `Bearer ${current.access_token}` },
  });
  if (response.status !== 204) throw new Error("Local state cleared; server logout failed.");
}