using System;
using System.Linq;

namespace InABox.Core
{
    public interface IEntityLink
    {
        Guid ID { get; set; }
        
        Guid Deleted { get; set; }

        bool Synchronise(object entity);
        bool Clear();
        bool IsValid();
        
    }

    public interface IEntityLink<T> : IEntityLink
    {
    }

    public abstract class EntityLink<T> : BaseObject, IEntityLink<T> where T : BaseObject, new()
    {
        [DoNotSerialize]
        protected Entity LinkedEntity;

        //[Obsolete("Please supply linked Entity")]
        public EntityLink()
        {
        }

        public EntityLink(Entity entity)
        {
            LinkedEntity = entity;
        }

        [NullEditor]
        public abstract Guid ID { get; set; }
        
        [NullEditor]
        public Guid Deleted { get; set; }

        public virtual bool Synchronise(object Entity)
        {
            var result = false;
            var props = CoreUtils.PropertyList(GetType(),
                x => (!x.Name.Equals("ID") || Entity == null) && !x.DeclaringType.Equals(typeof(BaseObject)), false);
            foreach (var key in props.Keys)
            {
                if (CoreUtils.HasProperty(Entity.GetType(), key))
                {
                    var prop = CoreUtils.GetProperty(typeof(T), key);
                    if (prop != null && prop.PropertyType.Equals(props[key]) && !prop.PropertyType.GetInterfaces().Any(x => x == typeof(IEntityLink)))
                    {
                        var oldvalue = CoreUtils.GetPropertyValue(this, key);
                        var newvalue = CoreUtils.GetPropertyValue(Entity, key);
                        if ((oldvalue == null && newvalue != null) || (oldvalue != null && !oldvalue.Equals(newvalue)))
                        {
                            result = true;
                            try
                            {
                                CoreUtils.SetPropertyValue(this, key, newvalue);
                            }
                            catch (Exception e)
                            {
                                Logger.Send(LogType.Error, "", string.Format("*** Unknown Error: {0}\n{1}", e.Message, e.StackTrace));
                            }
                        }
                    }
                }
            }

            if (LinkedEntity != null)
                foreach (var link in LinkedEntity.LinkedProperties(GetType()))
                {
                    link.Update(this, LinkedEntity);
                    result = true;
                }

            return result;
        }

        public bool Clear()
        {
            var result = false;
            var props = CoreUtils.PropertyList(GetType(), x => !x.Name.Equals("ID"), false);
            foreach (var key in props.Keys)
            {
                var prop = CoreUtils.GetProperty(typeof(T), key);
                if (prop != null && prop.PropertyType.Equals(props[key]))
                {
                    var oldvalue = CoreUtils.GetPropertyValue(this, key);
                    var newvalue = prop.PropertyType.Equals(typeof(string)) ? "" : Activator.CreateInstance(prop.PropertyType);
                    if ((oldvalue == null && newvalue != null) || (oldvalue != null && !oldvalue.Equals(newvalue)))
                    {
                        result = true;
                        CoreUtils.SetPropertyValue(this, key, newvalue);
                    }
                }
            }

            return result;
        }

        protected override void DoPropertyChanged(string name, object before, object after)
        {
            if (IsObserving() && LinkedEntity != null)
            {
                var link = LinkedEntity.LinkedProperties(GetType()).FirstOrDefault(x => x.Source.Name.Equals(name));
                if (link != null)
                    link.Update(this, LinkedEntity);
            }
        }

        public bool IsValid() => !ID.Equals(Guid.Empty) && Deleted.Equals(Guid.Empty);
    }
}