// PKCE utilities
function generateCodeVerifier(length = 64) {
    const array = new Uint8Array(length);
    window.crypto.getRandomValues(array);
    return btoa(String.fromCharCode(...array)).replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, "");
}

async function generateCodeChallenge(codeVerifier) {
    const encoder = new TextEncoder();
    const data = encoder.encode(codeVerifier);
    const digest = await window.crypto.subtle.digest('SHA-256', data);
    return btoa(String.fromCharCode(...new Uint8Array(digest)))
        .replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');
}