using System.Security.Cryptography;
using System.Text;

namespace Authinator.Backend.Utils;

public static class CryptoUtils {
	public static string Hmac(this string text, string key) {
		using var hmac = new HMACSHA256(ConvertFromBase64WithUtf8Fallback(key));
		return Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(text)));
	}

	public static string HmacWithMessage(this string text, string key) => text + text.Hmac(key);

	public static byte[] GetRandomBytes(int size) {
		var random = new Random(Guid.NewGuid().GetHashCode());
		var buffer = new byte[size];
		random.NextBytes(buffer);
		return buffer;
	}

	public static string GetRandomBytesBase64(int size) => Convert.ToBase64String(GetRandomBytes(size));
	
	public static string FixUrlEncodedBase64(this string str) => str.Replace("%2F", "/").Replace("%2f", "/");

	public static byte[] ConvertFromBase64WithUtf8Fallback(string text) {
		var buffer  = new Span<byte>(new byte[text.Length]);
		var success = Convert.TryFromBase64String(text, buffer, out var bytesParsed);
		return success ? buffer[..bytesParsed].ToArray() : Encoding.UTF8.GetBytes(text);
	}
}