const getKeyFromPassword = async function (password) {
    const enc = new TextEncoder();
    const keyMaterial = await crypto.subtle.importKey(
        "raw",
        enc.encode(password),
        "PBKDF2",
        false,
        ["deriveKey"]
    );
    return crypto.subtle.deriveKey(
        {
            name: "PBKDF2",
            salt: new TextEncoder().encode("fixed-salt"),
            iterations: 100000,
            hash: "SHA-256",
        },
        keyMaterial,
        { name: "AES-GCM", length: 256 },
        false,
        ["encrypt", "decrypt"]
    );
};

const encrypt = async function (text, password) {
    const key = await getKeyFromPassword(password);
    const enc = new TextEncoder();
    const iv = crypto.getRandomValues(new Uint8Array(12));
    const ciphertext = await crypto.subtle.encrypt(
        { name: "AES-GCM", iv },
        key,
        enc.encode(text)
    );
    const buffer = new Uint8Array(iv.byteLength + ciphertext.byteLength);
    buffer.set(iv, 0);
    buffer.set(new Uint8Array(ciphertext), iv.byteLength);
    return btoa(String.fromCharCode(...buffer));
};

const decrypt = async function (encrypted, password) {
    const data = Uint8Array.from(atob(encrypted), c => c.charCodeAt(0));
    const iv = data.slice(0, 12);
    const ciphertext = data.slice(12);
    const key = await getKeyFromPassword(password);
    const decrypted = await crypto.subtle.decrypt(
        { name: "AES-GCM", iv },
        key,
        ciphertext
    );
    return new TextDecoder().decode(decrypted);
};