using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Reflection;
using UnityEditor;
using UnityEngine;
using UnityEngine.UI;

[CreateAssetMenu(menuName = "Scriptable Object Variables/Interface")]
public class InterfaceVariable : ScriptableObjectInterface<IInterface>
{
}

public class ScriptableObjectInterface<T> : ScriptableObjectVariable<T>
{
    public int implementationTypeIndex;
    private T _implementation;

    public override T Value
    {
        get
        {
            if (_implementation == null)
            {
                _implementation = (T)Activator.CreateInstance(GetImplementations()[implementationTypeIndex]);
            }
            return _implementation;
        }
        set => _implementation = value;
    }

    public Type[] GetImplementations()
    {
        var types = AppDomain.CurrentDomain.GetAssemblies().SelectMany(assembly => assembly.GetTypes());

        var interfaceType = typeof(T);
        return types.Where(p => interfaceType.IsAssignableFrom(p) && !p.IsAbstract).ToArray();
    }
}

[CustomEditor(typeof(InterfaceVariable))]
public class ScriptableObjectInterfaceVariable : ScriptableObjectInterfaceVariable<IInterface,ScriptableObjectVariable<IInterface>>
{
}

public class ScriptableObjectInterfaceVariable<TBase,TVar> : Editor where TVar : ScriptableObjectVariable<TBase>
{
    private Type[] _implementations;

    [SuppressMessage("ReSharper", "PossibleMultipleEnumeration")]
    public override void OnInspectorGUI()
    {
        var scriptableObject = target as ScriptableObjectInterface<TBase>;

        if (scriptableObject == null)
        {
            return;
        }

        if (_implementations == null || GUILayout.Button("Refresh implementations"))
        {
            _implementations = scriptableObject.GetImplementations();
        }

        EditorGUILayout.LabelField($"Found {_implementations.Count()} implementations");

        scriptableObject.implementationTypeIndex = EditorGUILayout.Popup(new GUIContent("Implementation"),
            scriptableObject.implementationTypeIndex, _implementations.Select(impl => impl.FullName).ToArray());
    }
}