import crypto = require("crypto");

const ALGORITHM = "aes-256-gcm";
const BLOCK_SIZE_BYTES = 16;

export default class AesGCM {
	static encrypt(
		text: string,
		secret: string
	): { ciphertext: string; iv: string; tag: string } {
		const iv = crypto.randomBytes(BLOCK_SIZE_BYTES);
		const cipher = crypto.createCipheriv(ALGORITHM, secret, iv);

		let ciphertext = cipher.update(text, "utf8", "base64");
		ciphertext += cipher.final("base64");
		return {
			ciphertext,
			iv: iv.toString("base64"),
			tag: cipher.getAuthTag().toString("base64"),
		};
	}

	static decrypt(
		ciphertext: string,
		iv: string,
		tag: string,
		secret: string
	): string {
		const decipher = crypto.createDecipheriv(
			ALGORITHM,
			secret,
			Buffer.from(iv, "base64")
		);
		decipher.setAuthTag(Buffer.from(tag, "base64"));

		let cleartext = decipher.update(ciphertext, "base64", "utf8");
		cleartext += decipher.final("utf8");

		return cleartext;
	}
}