using System.Dynamic;
using System.Reflection;

namespace adas_core.Domain.Utils;

public static class Mapper<T>
    // We can only use reference types
    where T : class
{
    private static readonly Dictionary<string, PropertyInfo> PropertyMap;

    static Mapper()
    {
        // At this point we can convert each
        // property name to lower case so we avoid 
        // creating a new string more than once.
        PropertyMap =
            typeof(T)
                .GetProperties()
                .ToDictionary(
                    p => p.Name.ToLower(),
                    p => p
                );
    }

    public static void Map(ExpandoObject source, T destination)
    {
        // Might as well take care of null references early.
        if (source == null) throw new ArgumentNullException(nameof(source));

        if (destination == null) throw new ArgumentNullException(nameof(destination));

        // By iterating the KeyValuePair<string, object> of
        // source we can avoid manually searching the keys of
        // source as we see in your original code.
        foreach (var kv in source)
            if (PropertyMap.TryGetValue(kv.Key.ToLower(), out var p))
            {
                var propType = p.PropertyType;
                if (kv.Value == null)
                {
                    if (propType is { IsByRef: false } && propType.Name != "Nullable`1")
                        // Throw if type is a value type 
                        // but not Nullable<>
                        throw new ArgumentException("not nullable");
                }
                else if (kv.Value.GetType() != propType)
                {
                    // You could make this a bit less strict 
                    // but I don't recommend it.
                    p.SetValue(destination, Convert.ToDouble(kv.Value), null);
                }

                p.SetValue(destination, kv.Value, null);
            }
    }
}