using System;
using System.Collections;
using System.Collections.Generic;
using Unity.Collections.LowLevel.Unsafe;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.U2D;

/// <summary>
/// This class is applied to a button that represents an Item in the View. It is a visual representation of the item
/// when it is visible in the store. The class holds a link to the original Item, it sets the icon of the button to
/// the one specified in the Item data, and it enables or disables the infoPanel to indicate if the item is selected
/// and display the details of the item. The original implementation was hardcoded for the grid view. We use patterns to
/// make this one a little more universally useful
/// </summary>
public class ViewItemContainer : MonoBehaviour, IItemContainer, IShopModelObserver<Item>
{
    public Item Item => item;//Public getter for the item, required by IItemContainer interface.
    // IItemContainer interface requires to know whether an item is selected visually or not. This implementation determines that by checking the info panel
    public bool IsSelected {
        get { return infoPanel.gameObject.activeSelf; }
        set { infoPanel.SetActive(value); highLight.SetActive(value);}
    }


    //Link to the highlight image (set in prefab)
    [SerializeField]
    private GameObject highLight;

    //Link to the infomation panel (set in prefab), prototype pattern
    [SerializeField]
    private GameObject infoPanel;

    [SerializeField]
    private Image icon;

    //Link to the atlas of all the item icons, use to retrieve sprites for items. For more information of the API check:
    // https://docs.unity3d.com/2019.3/Documentation/Manual/class-SpriteAtlas.html
    [SerializeField]
    private SpriteAtlas iconAtlas;

    //link to the original item (set in Initialize)
    private Item item;

    private IDisposable _unsubscriber;    // If this item manages its own lifetime, this will not be null
    //------------------------------------------------------------------------------------------------------------------------
    //                                                  Initialize()
    //------------------------------------------------------------------------------------------------------------------------
    public void Initialize(Item item, IDisposable unsubscriber = null){     // pass unsubscriber to this object to make it manage its own lifetime
        //Stores the item
        this.item = item;

        //Sets the highlight image and infoPanel's visibility
        //if (isSelected) {
        //    highLight.SetActive(true);
        //    infoPanel.SetActive(true);
        //}

        // Clones the first Sprite in the icon atlas that matches the iconName and uses it as the sprite of the icon image.
        Sprite sprite = iconAtlas.GetSprite(item.iconName);

        if (sprite != null) {
            icon.sprite = sprite;
        }
    }
    
    // When the observable fires, check if we're the view corresponding to the selected item. Select if we are!
    public void OnSelected(Item item)
    {
        IsSelected = this.item == item;
    }

    public void OnRemoved(Item item)
    {
        if (item != Item) return;    // Well we only want this if the item removed from the model is actually ours!
        _unsubscriber?.Dispose();    // Careful! If we don't make this thing aware that it manages itself, and we forget to manage it, we have a memory leak
        Destroy(gameObject);
    }

    public void OnAdded(Item item)
    {
        throw new NotImplementedException();
    }
}