using System;
using System.Text;
using NUnit.Framework;
using Sarand.Net.Standard.Base.Helpers;

namespace Sacs.UnitTests.Net.Standard.Base.Helpers
{
	[TestFixture]
	public class SacsEncryptionHelper_Tester
	{
		// --- Base64 and Key Encoding ---

		[TestCase("AQID", 3, true)]
		[TestCase("AQID", 4, false)]
		[TestCase("not base64", 0, false)]
		[TestCase("", 0, true)]
		[TestCase(null, 0, false)]
		public void IsBase64_ValidatesContentAndDecodedLength(String value, Int32 expectedLength, Boolean expected)
		{
			Assert.That(SacsEncryptionHelper.IsBase64(value, expectedLength), Is.EqualTo(expected));
		}

		[Test]
		public void EncodePlainKey_RepeatsAndTruncatesToRequestedLength()
		{
			String encoded = SacsEncryptionHelper.EncodePlainKey("abc", 8, Encoding.UTF8);

			Assert.That(Convert.FromBase64String(encoded), Is.EqualTo(Encoding.UTF8.GetBytes("abcabcab")));
		}

		[TestCase(null)]
		[TestCase("")]
		[TestCase("   ")]
		public void EncodePlainKey_RejectsMissingKey(String value)
		{
			Assert.That(() => SacsEncryptionHelper.EncodePlainKey(value), Throws.TypeOf<NotSupportedException>());
		}

		// --- Key Generation ---

		[Test]
		public void InitSymmetricEncryptionKey_ReturnsAes256Key()
		{
			String key = SacsEncryptionHelper.InitSymmetricEncryptionKey();

			Assert.That(Convert.FromBase64String(key), Has.Length.EqualTo(32));
		}

		[Test]
		public void InitSymmetricEncryptionKey_ReturnsDifferentKeys()
		{
			String first = SacsEncryptionHelper.InitSymmetricEncryptionKey();
			String second = SacsEncryptionHelper.InitSymmetricEncryptionKey();

			Assert.That(second, Is.Not.EqualTo(first));
		}

		// --- Encryption ---

		[TestCase("")]
		[TestCase("Plain ASCII text")]
		[TestCase("Unicode £ € 漢字 and emoji 😀")]
		public void EncryptDecrypt_RoundTripsText(String value)
		{
			String key = SacsEncryptionHelper.InitSymmetricEncryptionKey();

			String encrypted = SacsEncryptionHelper.EncryptAuthenticated(value, key, "Tests:SacsEncryptionHelper");
			String decrypted = SacsEncryptionHelper.DecryptAuthenticated(encrypted, key, "Tests:SacsEncryptionHelper");

			Assert.That(encrypted, Is.Not.EqualTo(value));
			Assert.That(encrypted, Does.StartWith(SacsAuthenticatedEncryption.EnvelopePrefix));
			Assert.That(decrypted, Is.EqualTo(value));
		}

		// --- The End ---
	}
}