From fb14eb4ef25623b8b967b074ef8f1f230f7ada8a Mon Sep 17 00:00:00 2001
From: Zoe Roux <zoe.roux@sdg.moe>
Date: Fri, 11 Sep 2020 00:35:21 +0200
Subject: [PATCH] Creating an expression rewritter that work with members

---
 Kyoo.Common/Controllers/IRepository.cs        |  3 +-
 Kyoo.Common/ExpressionRewrite.cs              | 46 +++++++++++++++++++
 Kyoo.Common/Models/PeopleRole.cs              |  2 +
 Kyoo.CommonAPI/ApiHelper.cs                   |  5 +-
 .../Repositories/PeopleRepository.cs          | 20 --------
 Kyoo/Models/Resources/CollectionDE.cs         |  4 +-
 6 files changed, 56 insertions(+), 24 deletions(-)
 create mode 100644 Kyoo.Common/ExpressionRewrite.cs

diff --git a/Kyoo.Common/Controllers/IRepository.cs b/Kyoo.Common/Controllers/IRepository.cs
index 62bf0250..47419e88 100644
--- a/Kyoo.Common/Controllers/IRepository.cs
+++ b/Kyoo.Common/Controllers/IRepository.cs
@@ -30,7 +30,7 @@ namespace Kyoo.Controllers
 		
 		public Sort(Expression<Func<T, object>> key, bool descendant = false)
 		{
-			Key = key;
+			Key = ExpressionRewrite.Rewrite<Func<T, object>>(key);
 			Descendant = descendant;
 			
 			if (Key == null || 
@@ -58,6 +58,7 @@ namespace Kyoo.Controllers
 			Key = property.Type.IsValueType
 				? Expression.Lambda<Func<T, object>>(Expression.Convert(property, typeof(object)), param)
 				: Expression.Lambda<Func<T, object>>(property, param);
+			Key = ExpressionRewrite.Rewrite<Func<T, object>>(Key);
 					
 			Descendant = order switch
 			{
diff --git a/Kyoo.Common/ExpressionRewrite.cs b/Kyoo.Common/ExpressionRewrite.cs
new file mode 100644
index 00000000..fadc26b2
--- /dev/null
+++ b/Kyoo.Common/ExpressionRewrite.cs
@@ -0,0 +1,46 @@
+using System;
+using System.Linq.Expressions;
+using System.Reflection;
+
+namespace Kyoo
+{
+	public class ExpressionRewriteAttribute : Attribute
+	{
+		public string Link { get; }
+		public string Inner { get; }
+
+		public ExpressionRewriteAttribute(string link, string inner = null)
+		{
+			Link = link;
+			Inner = inner;
+		}
+	}
+
+	public class ExpressionRewrite : ExpressionVisitor
+	{
+		public static Expression Rewrite(Expression expression)
+		{
+			return new ExpressionRewrite().Visit(expression);
+		}
+		
+		public static Expression<T> Rewrite<T>(Expression expression) where T : Delegate
+		{
+			return (Expression<T>)new ExpressionRewrite().Visit(expression);
+		}
+
+		protected override Expression VisitMember(MemberExpression node)
+		{
+			ExpressionRewriteAttribute attr = node.Member.GetCustomAttribute<ExpressionRewriteAttribute>();
+			if (attr == null)
+				return base.VisitMember(node);
+			
+			Expression property = node.Expression;
+			foreach (string child in attr.Link.Split('.'))
+				property = Expression.Property(property, child);
+			
+			if (property is MemberExpression member)
+				Visit(member.Expression);
+			return property;
+		}
+	}
+}
\ No newline at end of file
diff --git a/Kyoo.Common/Models/PeopleRole.cs b/Kyoo.Common/Models/PeopleRole.cs
index edb760b9..870309a8 100644
--- a/Kyoo.Common/Models/PeopleRole.cs
+++ b/Kyoo.Common/Models/PeopleRole.cs
@@ -11,12 +11,14 @@ namespace Kyoo.Models
 		[JsonIgnore] public int PeopleID { get; set; }
 		[JsonIgnore] public virtual People People { get; set; }
 		
+		[ExpressionRewrite(nameof(People) + "." + nameof(Models.People.Slug))]
 		public string Slug
 		{
 			get => People.Slug;
 			set => People.Slug = value;
 		}
 		
+		[ExpressionRewrite(nameof(People) + "."+ nameof(Models.People.Name))]
 		public string Name
 		{
 			get => People.Name;
diff --git a/Kyoo.CommonAPI/ApiHelper.cs b/Kyoo.CommonAPI/ApiHelper.cs
index 7db41430..55b43878 100644
--- a/Kyoo.CommonAPI/ApiHelper.cs
+++ b/Kyoo.CommonAPI/ApiHelper.cs
@@ -71,8 +71,9 @@ namespace Kyoo.CommonApi
 				else
 					expression = condition;
 			}
-			
-			return Expression.Lambda<Func<T, bool>>(expression!, param);
+
+			expression = ExpressionRewrite.Rewrite(expression);
+			return Expression.Lambda<Func<T, bool>>(expression, param);
 		}
 
 		private static Expression ContainsResourceExpression(MemberExpression xProperty, string value)
diff --git a/Kyoo/Controllers/Repositories/PeopleRepository.cs b/Kyoo/Controllers/Repositories/PeopleRepository.cs
index 9ef29490..8bf57f02 100644
--- a/Kyoo/Controllers/Repositories/PeopleRepository.cs
+++ b/Kyoo/Controllers/Repositories/PeopleRepository.cs
@@ -98,16 +98,6 @@ namespace Kyoo.Controllers
 			Sort<PeopleRole> sort = default, 
 			Pagination limit = default)
 		{
-			if (sort.Key?.Body is MemberExpression member)
-			{
-				sort.Key = member.Member.Name switch
-				{
-					"Name" => x => x.People.Name,
-					"Slug" => x => x.People.Slug,
-					_ => sort.Key
-				};
-			}
-
 			ICollection<PeopleRole> people = await ApplyFilters(_database.PeopleRoles.Where(x => x.ShowID == showID),
 				id => _database.PeopleRoles.FirstOrDefaultAsync(x => x.ID == id),
 				x => x.People.Name,
@@ -124,16 +114,6 @@ namespace Kyoo.Controllers
 			Sort<PeopleRole> sort = default, 
 			Pagination limit = default)
 		{
-			if (sort.Key?.Body is MemberExpression member)
-			{
-				sort.Key = member.Member.Name switch
-				{
-					"Name" => x => x.People.Name,
-					"Slug" => x => x.People.Slug,
-					_ => sort.Key
-				};
-			}
-			
 			ICollection<PeopleRole> people = await ApplyFilters(_database.PeopleRoles.Where(x => x.Show.Slug == showSlug),
 				id => _database.PeopleRoles.FirstOrDefaultAsync(x => x.ID == id),
 				x => x.People.Name,
diff --git a/Kyoo/Models/Resources/CollectionDE.cs b/Kyoo/Models/Resources/CollectionDE.cs
index 8235b993..e1368a0c 100644
--- a/Kyoo/Models/Resources/CollectionDE.cs
+++ b/Kyoo/Models/Resources/CollectionDE.cs
@@ -15,7 +15,9 @@ namespace Kyoo.Models
 		}
 		
 		[JsonIgnore] [NotMergable] public virtual IEnumerable<LibraryLink> LibraryLinks { get; set; }
-		/*[ExpressionRewrite(x => x.LibraryLinks, y => y.Genre)]*/ public override IEnumerable<Library> Libraries
+		
+		[ExpressionRewrite(nameof(LibraryLinks), nameof(GenreLink.Genre))]
+		public override IEnumerable<Library> Libraries
 		{
 			get => LibraryLinks?.Select(x => x.Library);
 			set => LibraryLinks = value?.Select(x => new LibraryLink(x, this));