namespace Dpz.Core.Service;

public class ServiceMapper
{
    private static readonly Lazy<ServiceMapper> LazyMapper = new(() => new ServiceMapper());

    private ServiceMapper()
    {
        Mapper = ConfigGlobalMapper();
    }

    public IMapper Mapper { get; }

    public static ServiceMapper GetInstance()
    {
        return LazyMapper.Value;
    }

    public static ServiceMapper Instance => LazyMapper.Value;

    private IMapper ConfigGlobalMapper()
    {
        var types = Assembly.Load("Dpz.Core.Public.ViewModel").GetExportedTypes();
        var config = new MapperConfigurationExpression();

        // 默认规则Mapper
        var maps = from x in types
            from y in x.GetInterfaces()
            let faceType = y.GetTypeInfo()
            where faceType.IsGenericType && y.GetGenericTypeDefinition() == typeof(IMapFrom<>) &&
                  !x.IsAbstract && !x.IsInterface
            select new
            {
                Source = y.GetGenericArguments()[0],
                Destination = x
            };
        foreach (var item in maps)
        {
            config.CreateMap(item.Source, item.Destination);
            config.CreateMap(item.Destination, item.Source);
        }

        // 自定义Mapper
        var customMaps = from x in types
            from y in x.GetInterfaces()
            where typeof(IHaveCustomMapping).IsAssignableFrom(x) &&
                  !x.GetTypeInfo().IsAbstract &&
                  !x.GetTypeInfo().IsInterface
            let instance = Activator.CreateInstance(x) as IHaveCustomMapping
            where instance != null
            select instance;            
        foreach (var item in customMaps)
        {
            item.CreateMappings(config);
        }

        config.CreateMap<string, ObjectId>().ConstructUsing((x, y) =>
            !string.IsNullOrEmpty(x) && ObjectId.TryParse(x, out var oid) ? oid : ObjectId.Empty);
        // config.CreateMap<DateTime, DateTime>().ConvertUsing((utc, local, context) =>
        // {
        //     if (local == new DateTime())
        //     {
        //         if (utc.Kind == DateTimeKind.Utc)
        //             return utc.ToLocalTime();
        //         return utc;
        //     }
        //     if (local.Kind == DateTimeKind.Local)
        //         return utc.ToUniversalTime();
        //     return local;
        // });
        var cfg = new MapperConfiguration(config);
        IMapper mapper = new Mapper(cfg);
        return mapper;
    }
}