import { createDecipheriv } from "crypto";
import type { TidalManifest } from "../../Caches/PlaybackInfoTypes";

// Do not change this
const mastKey = "UIlTTEMmmLfGowo/UC60x2H45W6MdGgTRfo/umg4754=";
const mastKeyBuffer = Buffer.from(mastKey, "base64");

type DecryptedKey = {
    key: Buffer;
    nonce: Buffer;
};

const decryptKeyId = (keyId: string): DecryptedKey => {
    // Decode the base64 strings to buffers
    const keyIdBuffer = Buffer.from(keyId, "base64");

    // Get the IV from the first 16 bytes of the securityToken
    const iv = keyIdBuffer.subarray(0, 16);
    const keyIdEnc = keyIdBuffer.subarray(16);

    // Initialize decryptor
    const decryptor = createDecipheriv("aes-256-cbc", Uint8Array.from(mastKeyBuffer), Uint8Array.from(iv));

    // Decrypt the security token
    const keyIdDec = decryptor.update(Uint8Array.from(keyIdEnc));

    // Get the audio stream decryption key and nonce from the decrypted security token
    const key = keyIdDec.subarray(0, 16);
    const nonce = keyIdDec.subarray(16, 24);

    return { key, nonce };
};

// Extend nonce to 16 bytes (nonce + counter)
const makeDecipheriv = ({ key, nonce }: DecryptedKey) => {
    const iv = new Uint8Array([...nonce, ...new Uint8Array(8)]);
    return createDecipheriv("aes-128-ctr", Uint8Array.from(key), iv);
};

export const makeDecipher = (manifest: { keyId: string; encryptionType: string }) => {
    switch (manifest.encryptionType) {
        case "OLD_AES": {
            return makeDecipheriv(decryptKeyId(manifest.keyId));
        }
        case "NONE": {
            return undefined;
        }
        default: {
            throw new Error(`Unexpected manifest encryption type ${manifest.encryptionType}`);
        }
    }
};