public static ExpressionInfo GetExpressionInfo()

in src/Epam.GraphQL/Extensions/ExpressionExtensions.cs [40:94]
48 lines of code
7 McCabe index (conditional complexity)

        public static ExpressionInfo GetExpressionInfo<T1, T2>(this Expression<Func<T1, T2, bool>> expression)
        {
            if (expression.Body is not BinaryExpression logicalExpression)
            {
                throw new NotSupportedException("Only binary expressions are supported.");
            }

            if (logicalExpression.NodeType != ExpressionType.Equal)
            {
                throw new NotSupportedException("Only binary expressions of type ExpressionType.Equal are supported.");
            }

            var leftExpression = logicalExpression.Left.RemoveConvert();
            var rightExpression = logicalExpression.Right.RemoveConvert();

            var leftPropInfo = (leftExpression as MemberExpression)?.Member as PropertyInfo ??
                               throw new NotSupportedException(
                                   "Left operand does not refer to a property of the first argument of expression.");
            var rightPropInfo = (rightExpression as MemberExpression)?.Member as PropertyInfo ??
                                throw new NotSupportedException(
                                    "Right operand does not refer to a property of the second argument of expression.");

            var leftParameter = GetParameterOfType<T1>(leftExpression);
            if (leftParameter == null)
            {
                throw new NotSupportedException(
                    "Left operand does not refer to a property of the first argument of expression.");
            }

            var rightParameter = GetParameterOfType<T2>(rightExpression);
            if (rightParameter == null)
            {
                throw new NotSupportedException(
                    "Right operand does not refer to a property of the second argument of expression.");
            }

            if (leftParameter == expression.Parameters[1] && rightParameter == expression.Parameters[0])
            {
                return new ExpressionInfo
                {
                    RightPropertyInfo = leftPropInfo,
                    LeftPropertyInfo = rightPropInfo,
                    RightExpression = Expression.Lambda(typeof(Func<,>).MakeGenericType(typeof(T1), leftPropInfo.PropertyType), leftExpression, leftParameter),
                    LeftExpression = Expression.Lambda(typeof(Func<,>).MakeGenericType(typeof(T2), rightPropInfo.PropertyType), rightExpression, rightParameter),
                };
            }

            return new ExpressionInfo
            {
                LeftPropertyInfo = leftPropInfo,
                RightPropertyInfo = rightPropInfo,
                LeftExpression = Expression.Lambda(typeof(Func<,>).MakeGenericType(typeof(T1), leftPropInfo.PropertyType), leftExpression, leftParameter),
                RightExpression = Expression.Lambda(typeof(Func<,>).MakeGenericType(typeof(T2), rightPropInfo.PropertyType), rightExpression, rightParameter),
            };
        }