Gallery Server Pro - An ASP.NET Gallery for Sharing Photos, Video, Audio and Other Media

using System;
using GalleryServerPro.Licensing.GspWeb;

namespace GalleryServerPro.Licensing
{
	/// <summary>
	/// Contains functionality for managing the license for Gallery Server Pro.
	/// </summary>
	public static class LicenseManager
	{
		private const string GspDnnProductType = "GspDnnModule";

		/// <summary>
		/// Validates the specified <paramref name="productKey"/> is valid against the specified <paramref name="version"/>.
		/// Inspect the properties of the returned <see cref="ProductKeyEntity"/> for details of the validation results.
		/// </summary>
		/// <param name="productKey">The product key to validate.</param>
		/// <param name="version">The current version of Gallery Server Pro. Example: 2.3.3750</param>
		/// <param name="performWebServiceValidation">if set to <c>true</c> validate the license using a web service invocation
		/// against a server run by Tech Info Systems. This parameter is ignored in stand-alone versions of GSP, since it 
		/// never invokes a web service.</param>
		/// <returns>
		/// Returns a <see cref="ProductKeyEntity"/> with details of the validation results.
		/// </returns>
		public static ProductKeyEntity Validate(string productKey, string version, bool performWebServiceValidation)
		{
			return ValidateProductKey(productKey, version, performWebServiceValidation);
		}

		private static ProductKeyEntity ValidateProductKey(string productKey, string version, bool performWebServiceValidation)
		{
			ProductKeyEntity pk = DecryptAndParseProductKey(productKey);

			pk.ProductType = GspDnnProductType;

			pk = ValidateDecryptedProductKey(pk, version);

			if (performWebServiceValidation)
			{
				pk = ValidateWithWebService(pk);
			}

			return pk;
		}

		private static ProductKeyEntity ValidateDecryptedProductKey(ProductKeyEntity pk, string version)
		{
			if (!pk.KeyIsValid)
				return pk;

			if (String.IsNullOrEmpty(pk.Email) || String.IsNullOrEmpty(pk.LicenseType) || String.IsNullOrEmpty(pk.Version))
			{
				pk.KeyIsValid = false;
				pk.KeyInvalidReason = "Invalid product key";
			}

			pk = ValidateVersion(pk, version);

			pk = ValidateEmail(pk);

			return pk;
		}

		private static ProductKeyEntity ValidateVersion(ProductKeyEntity pk, string version)
		{
			if (!pk.KeyIsValid)
				return pk;

			if (pk.Version.CompareTo(GetMajorMinorVersion(version)) < 0)
			{
				// The application is running a newer version than the product key is valid for.
				pk.KeyIsValid = false;
				pk.KeyInvalidReason = string.Format("Product key is for version {0}, but the application is running version {1} ({2}). Purchase a new product key.", pk.Version, GetMajorMinorVersion(version), version);
			}

			return pk;
		}

		private static ProductKeyEntity ValidateEmail(ProductKeyEntity pk)
		{
			if (!pk.KeyIsValid)
				return pk;

			if (!Email.IsValidEmail(pk.Email))
			{
				pk.KeyIsValid = false;
				pk.KeyInvalidReason = "Product key does not contain a valid e-mail address.";
			}

			return pk;
		}

		private static ProductKeyEntity DecryptAndParseProductKey(string productKey)
		{
			ProductKeyEntity pk = new ProductKeyEntity();
			pk.ProductKey = productKey;

			if (String.IsNullOrEmpty(productKey))
			{
				pk.KeyIsValid = false;
				pk.KeyInvalidReason = "No product key entered.";
				return pk;
			}

			pk.KeyIsValid = true; // Assume it is valid, we'll set to false if any test fails.
			string decryptedProductKey;

			try
			{
				decryptedProductKey = Encrypt.DecryptString(productKey);
			}
			catch (FormatException)
			{
				pk.KeyIsValid = false;
				pk.KeyInvalidReason = "Invalid product key";

				return pk;
			}
			catch (System.Security.Cryptography.CryptographicException)
			{
				pk.KeyIsValid = false;
				pk.KeyInvalidReason = "Invalid product key";

				return pk;
			}

			return PopulateProductKeyEntity(pk, decryptedProductKey);
		}

		private static string GetMajorMinorVersion(string fullVersion)
		{
			// If fullVersion = "2.4.2395", return 2.4.
			string version = String.Empty;
			int versionPartCounter = 0;

			foreach (string versionPart in fullVersion.Split(new char[] { '.' }))
			{
				version += versionPart;
				versionPartCounter++;

				if (versionPartCounter >= 2)
				{
					break;
				}

				version += ".";
			}

			return version;
		}

		private static ProductKeyEntity ValidateWithWebService(ProductKeyEntity pk)
		{
			if (!pk.KeyIsValid)
				return pk;

			Gallery webservice = new GspWeb.Gallery();

			try
			{
				pk = webservice.ValidateProductKey(pk);
			}
			catch (System.Web.Services.Protocols.SoapException) {}
			catch (System.Net.WebException) {}

			return pk;
		}

		private static ProductKeyEntity PopulateProductKeyEntity(ProductKeyEntity pk, string decryptedProductKey)
		{
			if (pk == null)
			{
				throw new ArgumentNullException("pk");
			}

			if (String.IsNullOrEmpty(decryptedProductKey))
			{
				pk.KeyIsValid = false;
				pk.KeyInvalidReason = "Invalid product key. Does not contain expected information.";

				return pk;
			}

			string[] productKeyParts = decryptedProductKey.Split(new char[] { '|' });

			if (productKeyParts.Length == 3)
			{
				pk.Email = productKeyParts[0];
				pk.Version = productKeyParts[1];
				pk.LicenseType = productKeyParts[2];
			}
			else
			{
				pk.KeyIsValid = false;
				pk.KeyInvalidReason = "Invalid product key. Does not contain expected information.";
			}

			return pk;
		}
	}
}