async function fetch_challenge () {
    const username = document.getElementById("user-name").value;
    const init_data = {
        username: username,
    };
    const challenge = await fetch("/login/init", {
        method: 'POST',
        body: JSON.stringify(init_data),
        headers: {
            'Content-Type': 'application/json'
        }
    });
    return await challenge.json();
}

async function solve_challenge (challenge) {
    // Decode challenge and credential ID base64 strings into JS arrays.
    challenge.publicKey.challenge = Base64.toUint8Array(challenge.publicKey.challenge);
    challenge.publicKey.allowCredentials = challenge.publicKey.allowCredentials.map((cred) => {
        return Object.assign({}, cred, {
            id: Base64.toUint8Array(cred.id)
        });
    });
    return navigator.credentials.get(challenge);
}

function encodeSolvedChallenge(solvedChallenge) {
    const uinttobase64 = (array) => Base64.fromUint8Array(new Uint8Array(array), true);
    return {
        id: solvedChallenge.id,
        rawId: uinttobase64(solvedChallenge.rawId),
        response: {
            authenticatorData: uinttobase64(solvedChallenge.response.authenticatorData),
            clientDataJSON: uinttobase64(solvedChallenge.response.clientDataJSON),
            signature: uinttobase64(solvedChallenge.response.signature),
            userHandle: solvedChallenge.response.userHandle
        },
        type: solvedChallenge.type
    };
}

async function finish_auth (challengeUuid, solvedChallenge) {
    // Encode challenge response
    const encodedSolvedChallenge = encodeSolvedChallenge(solvedChallenge);
    const resp = await fetch("/login/finish", {
        method: 'POST',
        body: JSON.stringify({uuid: challengeUuid, challenge: encodedSolvedChallenge}),
        headers: { 'Content-Type': 'application/json' }
    });
    return resp;
}

async function perform_webauthn_dance () {
    const challenge = await fetch_challenge()
    let solved = await solve_challenge(challenge.challenge);
    let finished = await finish_auth(challenge.uuid, solved);
}

// Main
(async () => {
    const button = document.getElementById("key-form");
    button.addEventListener("submit", async (e) => {
        e.preventDefault();
        await perform_webauthn_dance();
        window.location = "/";
    });
}) ();