using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;

internal class ChildInventotyWithCallback
{
    public readonly IInventory inventory;
    public readonly Action callback;

    public ChildInventotyWithCallback(IInventory inventory, Action callback)
    {
        this.inventory = inventory;
        this.callback = callback;
    }
}

[Serializable]
public class VirtualInventory : IInventory
{
    private readonly List<ChildInventotyWithCallback> _children =
        new List<ChildInventotyWithCallback>();

    public override IReadOnlyDictionary<string, float> Items
    {
        get
        {
            var items = new Dictionary<string, float>();

            foreach (var child in _children)
            {
                foreach (var childItem in child.inventory.Items)
                {
                    if (!items.ContainsKey(childItem.Key))
                        items.Add(childItem.Key, childItem.Value);
                    else
                        items[childItem.Key] += childItem.Value;
                }
            }

            return items;
        }
    }

    public override float Capacity
    {
        get => _children.Sum(c => c.inventory.Capacity);
        set { throw new NotSupportedException(); }
    }

    public void RegisterChild(IInventory child)
    {
        Debug.Log($"Registered child {child}");
        var reg = new ChildInventotyWithCallback(child, () => OnChildChange(child));
        _children.Add(reg);
        child.RegisterOnChangeCallback(reg.callback);
    }

    public void UnregisterChild(IInventory child)
    {
        int index = _children.FindIndex(c => c.inventory == child);
        if (index < 0)
            return;

        child.UnregisterOnChangeCallback(_children[index].callback);
        _children.RemoveAt(index);
    }

    private void OnChildChange(IInventory child)
    {
        Debug.Log($"child has changed {child}");
        base.InvokeOnChange();
    }

    public override float GetAmount(string item)
    {
        float amount = 0;
        Items.TryGetValue(item, out amount);
        return amount;
    }

    protected override float DoAdd(string item, float amount, bool allowPartialAdd = false)
    {
        throw new NotSupportedException();
    }

    protected override int DoClear()
    {
        throw new NotSupportedException();
    }

    protected override float DoRemove(string item, float amount, bool allowPartialRemoval = false)
    {
        throw new NotSupportedException();
    }
}