const subtle = globalThis.crypto.subtle;

export type ValidEncAlg = 'AES256-GCM' | 'AES128-GCM' | 'AES256-CBC' | 'AES128-CBC';

const encAlgMap: Record<ValidEncAlg, AesDerivedKeyParams> = {
	'AES256-GCM': {
		name: 'AES-GCM',
		length: 256,
	},
	'AES128-GCM' : {
		name: 'AES-GCM',
		length: 128,
	},
	'AES256-CBC' : {
		name: 'AES-CBC',
		length: 256,
	},
	'AES128-CBC' : {
		name: 'AES-CBC',
		length: 128,
	},
}

export async function PBKDF2_SHA512(password: string, salt: BufferSource, alg: ValidEncAlg = 'AES256-GCM', iterations = 600000): Promise<CryptoKey> {
	const param: Pbkdf2Params = {
		name: 'PBKDF2',
		hash: 'SHA-512',
		salt: salt,
		iterations,
	};

	const encoder = new TextEncoder();
	const baseKey = await subtle.importKey(
		"raw",
		encoder.encode(password),
		{ name: "PBKDF2" },
		false,
		["deriveBits", "deriveKey"]
	);

	return await subtle.deriveKey(
		param,
		baseKey, 
		encAlgMap[alg],
		true,
		["encrypt", "decrypt"]
	);
}