using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace AioNet.Reflection
{
    public static class DeepComparison
    {
        public static bool RecursiveFieldsEqual<T>(this T first, T second)
        {
            Type type = typeof(T);
            return first.RecursiveFieldsEqual(second, type);
        }

        public static bool RecursiveFieldsEqual(this object first, object second, Type type)
        {
            // If both are null, return true.
            if (first is null && second is null)
            {
                return true;
            }

            // If one of them is null and the other one isn't, return false.
            if (first is null || second is null)
            {
                return false;
            }

            // If type is value type or a String, simply return result of Equals.
            if (type.IsValueType || type.Equals(typeof(string)))
            {
                return first.Equals(second);
            }

            // If type is IEnumerable, compare individual elements.
            if (type.GetInterface("System.Collections.IEnumerable") != null)
            {
                throw new NotImplementedException();
            }

            IEnumerable<FieldInfo> fields = type.GetRuntimeFields();

            return fields.All(field =>
            {
                return RecursiveFieldsEqual(
                    field.GetValue(first),
                    field.GetValue(second),
                    field.FieldType
                );
            });
        }
    }
}