Rework parental ratings (#12615)

Jellyfin.Server.Implementations/Extensions/ExpressionExtensions.cs

@@ -0,0 +1,70 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+
+namespace Jellyfin.Server.Implementations.Extensions;
+
+/// <summary>
+/// Provides <see cref="Expression"/> extension methods.
+/// </summary>
+public static class ExpressionExtensions
+{
+    /// <summary>
+    /// Combines two predicates into a single predicate using a logical OR operation.
+    /// </summary>
+    /// <typeparam name="T">The predicate parameter type.</typeparam>
+    /// <param name="firstPredicate">The first predicate expression to combine.</param>
+    /// <param name="secondPredicate">The second predicate expression to combine.</param>
+    /// <returns>A new expression representing the OR combination of the input predicates.</returns>
+    public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> firstPredicate, Expression<Func<T, bool>> secondPredicate)
+    {
+        ArgumentNullException.ThrowIfNull(firstPredicate);
+        ArgumentNullException.ThrowIfNull(secondPredicate);
+
+        var invokedExpression = Expression.Invoke(secondPredicate, firstPredicate.Parameters);
+        return Expression.Lambda<Func<T, bool>>(Expression.OrElse(firstPredicate.Body, invokedExpression), firstPredicate.Parameters);
+    }
+
+    /// <summary>
+    /// Combines multiple predicates into a single predicate using a logical OR operation.
+    /// </summary>
+    /// <typeparam name="T">The predicate parameter type.</typeparam>
+    /// <param name="predicates">A collection of predicate expressions to combine.</param>
+    /// <returns>A new expression representing the OR combination of all input predicates.</returns>
+    public static Expression<Func<T, bool>> Or<T>(this IEnumerable<Expression<Func<T, bool>>> predicates)
+    {
+        ArgumentNullException.ThrowIfNull(predicates);
+
+        return predicates.Aggregate((aggregatePredicate, nextPredicate) => aggregatePredicate.Or(nextPredicate));
+    }
+
+    /// <summary>
+    /// Combines two predicates into a single predicate using a logical AND operation.
+    /// </summary>
+    /// <typeparam name="T">The predicate parameter type.</typeparam>
+    /// <param name="firstPredicate">The first predicate expression to combine.</param>
+    /// <param name="secondPredicate">The second predicate expression to combine.</param>
+    /// <returns>A new expression representing the AND combination of the input predicates.</returns>
+    public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> firstPredicate, Expression<Func<T, bool>> secondPredicate)
+    {
+        ArgumentNullException.ThrowIfNull(firstPredicate);
+        ArgumentNullException.ThrowIfNull(secondPredicate);
+
+        var invokedExpression = Expression.Invoke(secondPredicate, firstPredicate.Parameters);
+        return Expression.Lambda<Func<T, bool>>(Expression.AndAlso(firstPredicate.Body, invokedExpression), firstPredicate.Parameters);
+    }
+
+    /// <summary>
+    /// Combines multiple predicates into a single predicate using a logical AND operation.
+    /// </summary>
+    /// <typeparam name="T">The predicate parameter type.</typeparam>
+    /// <param name="predicates">A collection of predicate expressions to combine.</param>
+    /// <returns>A new expression representing the AND combination of all input predicates.</returns>
+    public static Expression<Func<T, bool>> And<T>(this IEnumerable<Expression<Func<T, bool>>> predicates)
+    {
+        ArgumentNullException.ThrowIfNull(predicates);
+
+        return predicates.Aggregate((aggregatePredicate, nextPredicate) => aggregatePredicate.And(nextPredicate));
+    }
+}