Catel - Part 4 of n: Unit testing with Catel

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="LLBLGenHelper.cs" company="Catel development team">
//   Copyright (c) 2008 - 2011 Catel development team. All rights reserved.
// </copyright>
// <summary>
//   LLBLGen Pro helper class.
// </summary>
// --------------------------------------------------------------------------------------------------------------------

using System;
using System.Reflection;
using log4net;

namespace Catel.LLBLGen
{
	/// <summary>
	/// LLBLGen Pro helper class.
	/// </summary>
	/// <remarks>
	/// This class extensively use reflection so no actual reference to LLBLGen is required.
	/// </remarks>
	public static class LLBLGenHelper
	{
		#region Variables
        /// <summary>
        /// The <see cref="ILog">log</see> object.
        /// </summary>
		private static readonly ILog Log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
		#endregion

		/// <summary>
		/// Determines whether the specified type is an LLBLGen type (entity or collection).
		/// </summary>
		/// <param name="type">The type to check.</param>
		/// <returns>
		/// 	<c>true</c> if the specified type is an LLBLGen type; otherwise, <c>false</c>.
		/// </returns>
		/// <remarks>
		/// This method uses the <see cref="IsEntityCollection(System.Type)"/> and <see cref="IsEntity(System.Type)"/> methods.
		/// </remarks>
		public static bool IsLLBLGenType(Type type)
		{
			return IsEntity(type) || IsEntityCollection(type);
		}

		/// <summary>
		/// Determines whether the specified object is an LLBLGen type (entity or collection).
		/// </summary>
		/// <param name="entity">The entity to check.</param>
		/// <returns>
		/// 	<c>true</c> if the specified object is an LLBLGen type; otherwise, <c>false</c>.
		/// </returns>
		/// <remarks>
		/// This method uses the <see cref="IsEntityCollection(System.Type)"/> and <see cref="IsEntity(System.Type)"/> methods.
		/// </remarks>
		public static bool IsLLBLGenType(object entity)
		{
			return IsEntity(entity) || IsEntityCollection(entity);
		}

		/// <summary>
		/// Determines whether the specified type is an LLBLGen entity.
		/// </summary>
		/// <param name="type">The type to check.</param>
		/// <returns>
		/// 	<c>true</c> if the specified type is an LLBLGen entity; otherwise, <c>false</c>.
		/// </returns>
		public static bool IsEntity(Type type)
		{
			return GetIEntityCore(type) != null;
		}

		/// <summary>
		/// Determines whether the specified object is an LLBLGen entity.
		/// </summary>
		/// <param name="entity">The entity to check.</param>
		/// <returns>
		/// 	<c>true</c> if the specified object is an LLBLGen entity; otherwise, <c>false</c>.
		/// </returns>
		public static bool IsEntity(object entity)
		{
			return GetIEntityCore(entity) != null;
		}

		/// <summary>
		/// Determines whether the specified type is an LLBLGen entity collection.
		/// </summary>
        /// <param name="type">The typ to checke.</param>
		/// <returns>
		/// 	<c>true</c> if the specified type is an LLBLGen entity collection; otherwise, <c>false</c>.
		/// </returns>
		public static bool IsEntityCollection(Type type)
		{
			return GetIEntityCollectionCore(type) != null;
		}

		/// <summary>
		/// Determines whether the specified object is an LLBLGen entity collection.
		/// </summary>
        /// <param name="entity">The entity to check.</param>
		/// <returns>
		/// 	<c>true</c> if the specified object is an LLBLGen entity collection; otherwise, <c>false</c>.
		/// </returns>
		public static bool IsEntityCollection(object entity)
		{
			return GetIEntityCollectionCore(entity) != null;
		}

		/// <summary>
        /// Gets the <c>IEntityCore.ValidateEntity</c> method if available.
		/// </summary>
		/// <param name="entity">The entity to get the method from.</param>
		/// <returns><see cref="MethodInfo"/> or <c>null</c> if the method is not found.</returns>
		public static MethodInfo GetValidateEntityMethod(object entity)
		{
			return GetMethod(entity, "ValidateEntity");
		}

		/// <summary>
        /// Gets the <c>IEntityCore.SaveFields(string)</c> method if available.
		/// </summary>
		/// <param name="entity">The entity to get the method from.</param>
		/// <returns><see cref="MethodInfo"/> or <c>null</c> if the method is not found.</returns>
		public static MethodInfo GetSaveFieldsMethod(object entity)
		{
			return GetMethod(entity, "SaveFields", new[] { typeof(string) });
		}

		/// <summary>
        /// Gets the <c>IEntityCore.GetDiscardSavedFieldsMethod()</c> method if available.
		/// </summary>
        /// <param name="entity">The entity to get the method from.</param>
		/// <returns><see cref="MethodInfo"/> or <c>null</c> if the method is not found.</returns>
		public static MethodInfo GetDiscardSavedFieldsMethod(object entity)
		{
			return GetMethod(entity, "DiscardSavedFields");
		}

		/// <summary>
        /// Gets the <c>IEntityCore.RollbackFields(string)</c> method if available.
		/// </summary>
        /// <param name="entity">The entity to get the method from.</param>
		/// <returns><see cref="MethodInfo"/> or <c>null</c> if the method is not found.</returns>
		public static MethodInfo GetRollbackFieldsMethod(object entity)
		{
			return GetMethod(entity, "RollbackFields", new[] { typeof(string) });
		}

		/// <summary>
		/// Gets the refetch method.
		/// </summary>
        /// <param name="entity">The entity to get the method from.</param>
		/// <returns><see cref="MethodInfo"/> or <c>null</c> if the method is not found.</returns>
		public static MethodInfo GetRefetchMethod(object entity)
		{
			return GetMethod(entity, "Refetch");
		}

		/// <summary>
		/// Gets the name of the related entity property. For example, if <c>Product</c> is passed of an <c>Order</c> entity, this
		/// method will return <c>ProductID</c>.
		/// </summary>
		/// <param name="type">The type of the LLBLGen entity.</param>
		/// <param name="property">The property to map.</param>
		/// <returns>
		/// The name of the mapped property, or <c>null</c> if the property cannot be mapped.
		/// </returns>
		/// <remarks>
		/// For now, this method returns the property name with "ID" appended. Still waiting for feedback from LLBLGen team.
		/// TODO: actually retrieve the property name correctly
		/// </remarks>
		public static string GetRelatedEntityPropertyName(Type type, string property)
		{
			return string.Format("{0}ID", property);
		}

		/// <summary>
        /// Gets a method with the specified name of the <c>IEntityCore</c> interface.
		/// </summary>
        /// <param name="entity">The entity to get the method from.</param>
		/// <param name="methodName">Name of the method.</param>
		/// <returns><see cref="MethodInfo"/> or <c>null</c> if the method is not found.</returns>
		/// <remarks>
		/// This method only supports the retrieval of public instance methods that have no parameters.
		/// </remarks>
		public static MethodInfo GetMethod(object entity, string methodName)
		{
			return GetMethod(entity, methodName, Type.EmptyTypes);
		}

		/// <summary>
        /// Gets a method with the specified name of the <c>IEntityCore</c> interface.
		/// </summary>
		/// <param name="entity">The entity to get the method from.</param>
		/// <param name="methodName">Name of the method.</param>
		/// <param name="types">The types of the parameters.</param>
		/// <returns>
		/// 	<see cref="MethodInfo"/> or <c>null</c> if the method is not found.
		/// </returns>
		/// <remarks>
		/// This method only supports the retrieval of public instance methods.
		/// </remarks>
		public static MethodInfo GetMethod(object entity, string methodName, Type[] types)
		{
			if (entity == null)
			{
				return null;
			}

			Type type = entity.GetType();
			return type.GetMethod(methodName, types);
		}

		/// <summary>
        /// Gets the object ID of a <c>IEntityCore</c> if the object is an LLBLGen entity.
		/// </summary>
		/// <param name="entity">The entity to get the object ID from.</param>
		/// <returns>
		/// The object ID of the entity, or <c>null</c> if the object is not an entity.
		/// </returns>
		public static object GetEntityObjectID(object entity)
		{
			var entityInterface = GetIEntityCore(entity);
			if (entityInterface == null)
			{
				return null;
			}

			var propertyInfo = entityInterface.GetProperty("ObjectID");
			if (propertyInfo == null)
			{
				return null;
			}

			if (!propertyInfo.CanRead)
			{
				return null;
			}

			return propertyInfo.GetValue(entity, null);
		}

        /// <summary>
        /// Gets the <c>IEntityCore</c> interface of the type if available.
        /// </summary>
        /// <param name="type">The type to get the interface from.</param>
        /// <returns>
        /// 	<c>IEntityCore</c> or <c>null</c> if this type has no support for LLBLGen Pro.
        /// </returns>
		public static Type GetIEntityCore(Type type)
		{
			return type.GetInterface("IEntityCore", false);
		}

		/// <summary>
		/// Gets the <c>IEntityCore</c> interface of the object if available.
		/// </summary>
		/// <param name="entity">The entity to get the interface from.</param>
		/// <returns><c>IEntityCore</c> or <c>null</c> if this object has no support for LLBLGen Pro.</returns>
		public static Type GetIEntityCore(object entity)
		{
			if (entity == null)
			{
				return null;
			}

			return GetIEntityCore(entity.GetType());
		}

		/// <summary>
		/// Gets the <c>IEntityCollectionCore</c> interface of the type if available.
		/// </summary>
		/// <param name="type">The type to get the interface from.</param>
		/// <returns><c>IEntityCollectionCore</c> or <c>null</c> if this type has no support for LLBLGen Pro.</returns>
		public static Type GetIEntityCollectionCore(Type type)
		{
			return type.GetInterface("IEntityCollectionCore", false);
		}

		/// <summary>
		/// Gets the <c>IEntityCollectionCore</c> interface of the object if available.
		/// </summary>
        /// <param name="entity">The entity to get the interface from.</param>
		/// <returns><c>IEntityCollectionCore</c> or <c>null</c> if this object has no support for LLBLGen Pro.</returns>
		public static Type GetIEntityCollectionCore(object entity)
		{
			if (entity == null)
			{
				return null;
			}

			return GetIEntityCollectionCore(entity.GetType());
		}
	}
}