using System;
using System.Linq;
using System.Reflection;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

namespace AppKit
{
    [RequireComponent(typeof(Slider))]
    public class BindSlider : UIBehaviour
    {
        [SerializeField]
        GameObject target;

        [SerializeField]
        string compName;

        [SerializeField]
        string propName;

        [SerializeField]
        Text label;

        Slider ui;
        Component comp;
        FieldInfo field;

        protected override void Start()
        {
            ui = GetComponent<Slider>();
            ui.onValueChanged.AddListener(OnValueChanged);

            comp = target.GetComponent(compName);
            if (comp == null)
            {
                Debug.LogErrorFormat("Component: {0} not found in {1}", compName, target);
                return;
            }

            Type type = comp.GetType();
            BindingFlags flag = BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public;
            field = type.GetField(propName, flag);
            if (field == null)
            {
                Debug.LogErrorFormat("Member: {0} not found in {1}", propName, compName);
                return;
            }
            float value = (float)field.GetValue(comp);
            ui.value = value;
        }

        protected override void OnDestroy()
        {
            if (ui != null)
            {
                ui.onValueChanged.RemoveListener(OnValueChanged);
                ui = null;
            }
            if (comp != null)
            {
                comp = null;
            }
            if (field != null)
            {
                field = null;
            }
        }

        void OnValueChanged(float value)
        {
            if (field == null)
            {
                return;
            }

            field.SetValue(comp, value);
            if (label != null)
            {
                label.text = string.Format("{0}: {1:0.0}", propName, value);
            }
        }
    }
}