import { Service } from "typedi";
import { FrontendVariables } from "@Front/Config/VariablesFront";
import crypto from "crypto";

@Service()
export default class CryptoService {
	private jwkKey: JsonWebKey;
	private subtle: SubtleCrypto = window.crypto.subtle;
	constructor(protected variables: FrontendVariables) {
		this.jwkKey = {
			kty: "oct",
			k: variables.KEY_DATA,
			alg: "A256GCM",
			ext: true,
		};
	}

	private async getKey() {
		return await this.subtle.importKey("jwk", this.jwkKey, { name: "AES-GCM" }, false, ["encrypt", "decrypt"]);
	}

	/**
	 * @description : encrypt data
	 * @throws {Error} If data cannot be encrypted
	 */
	public async encrypt(data: string) {
		const encodedData = Buffer.from(data);
		const iv = crypto.getRandomValues(new Uint8Array(16));
		const key = await this.getKey();
		const cipherData = await this.subtle.encrypt(
			{
				name: "AES-GCM",
				iv,
			},
			key,
			encodedData,
		);

		const cipherText = Buffer.from(cipherData).toString("base64");
		const ivStringified = Buffer.from(iv).toString("base64");

		return { cipherText, ivStringified };
	}

	/**
	 * @description : decrypt data with an initialization vector
	 * @throws {Error} If data cannot be decrypted
	 */
	public async decrypt(cipherText: string, ivStringified: string): Promise<string> {
		const cipherData = Buffer.from(cipherText, "base64");
		const iv = Buffer.from(ivStringified, "base64");
		const key = await this.getKey();
		const decryptedData = await this.subtle.decrypt(
			{
				name: "AES-GCM",
				iv,
			},
			key,
			cipherData,
		);

		return Buffer.from(decryptedData).toString("utf-8");
	}
}