/**
 * AES 256 GCM 加密
 * @param {*} plaintext 纯文本
 * @param {*} password 密钥
 * @returns 
 */
async function AESEncrypt(plaintext, password) {
    const pwUtf8 = new TextEncoder().encode(password);
    const pwHash = await window.crypto.subtle.digest('SHA-256', pwUtf8);

    const iv = window.crypto.getRandomValues(new Uint8Array(12));
    const ivStr = Array.from(iv).map(b => String.fromCharCode(b)).join('');

    const alg = { name: 'AES-GCM', iv: iv };
    const key = await window.crypto.subtle.importKey('raw', pwHash, alg, false, ['encrypt']);
    const ptUint8 = new TextEncoder().encode(plaintext);

    const ctBuffer = await window.crypto.subtle.encrypt(alg, key, ptUint8);
    const ctArray = Array.from(new Uint8Array(ctBuffer));
    const ctStr = ctArray.map(byte => String.fromCharCode(byte)).join('');
    return window.btoa(ivStr + ctStr);
}

/**
 * AES 256 GCM 解密
 * @param {*} ciphertext 密文
 * @param {*} password 密钥
 * @returns 
 */
async function AESDecrypt(ciphertext, password) {
    const pwUtf8 = new TextEncoder().encode(password);
    const pwHash = await window.crypto.subtle.digest('SHA-256', pwUtf8);

    const ivStr = window.atob(ciphertext).slice(0, 12);
    const iv = new Uint8Array(Array.from(ivStr).map(ch => ch.charCodeAt(0)));

    const alg = { name: 'AES-GCM', iv: iv };
    const key = await window.crypto.subtle.importKey('raw', pwHash, alg, false, ['decrypt']);
    const ctStr = window.atob(ciphertext).slice(12);
    const ctUint8 = new Uint8Array(Array.from(ctStr).map(ch => ch.charCodeAt(0)));

    const plainBuffer = await window.crypto.subtle.decrypt(alg, key, ctUint8);
    return new TextDecoder().decode(plainBuffer);
}

var plaintext = 'Hello，世界，123!';
var password = "key";
console.debug(`plaintext: ${plaintext}`)
console.debug(`password: ${password}`)

AESEncrypt(plaintext, password).then(ciphertext => {
    console.debug(`AES Encrypt: ${ciphertext}`)

    AESDecrypt(ciphertext, password).then(plaintext => {
        console.debug(`AES Decrypt: ${plaintext}`)
    })
})

//ref https://gist.github.com/chrisveness/43bcda93af9f646d083fad678071b90a


/**
 * ref: crypto-js
 * aes-256-cbc Encrypt
 */
function aesEncrypt(data, key, iv) {
    key = (key || "").padEnd(32, ' ');
    iv = (iv || "").padEnd(16, ' ');

    var result = CryptoJS.AES.encrypt(data, CryptoJS.enc.Utf8.parse(key), {
        iv: CryptoJS.enc.Utf8.parse(iv),
        padding: CryptoJS.pad.Pkcs7,
        mode: CryptoJS.mode.CBC
    }).toString();
    return result;
}

/**
 * ref: crypto-js
 * aes-256-cbc Decrypt
 */
function aesDecrypt(data, key, iv) {
    key = (key || "").padEnd(32, ' ');
    iv = (iv || "").padEnd(16, ' ');

    var result = CryptoJS.AES.decrypt(data, CryptoJS.enc.Utf8.parse(key), {
        iv: CryptoJS.enc.Utf8.parse(iv),
        padding: CryptoJS.pad.Pkcs7,
        mode: CryptoJS.mode.CBC
    }).toString(CryptoJS.enc.Utf8);
    return result;
}

console.debug(`crypto-js aes-256-cbc 123: ${aesEncrypt("123")}`);
console.debug(`crypto-js aes-256-cbc: ${aesDecrypt("ObQj0pVbF5lUu8lKGIhMqw==")}`);