using System.Collections.Generic;
using ColdMint.scripts.utils;
using Godot;

namespace ColdMint.scripts.inventory;

/// <summary>
/// <para>HotBar</para>
/// <para>快捷物品栏</para>
/// </summary>
public partial class HotBar : HBoxContainer, IItemContainer
{
    private PackedScene? _itemSlotPackedScene;

    private List<ItemSlotNode>? _itemSlotNodes;

    /// <summary>
    /// <para>UnknownIndex</para>
    /// <para>未知位置</para>
    /// </summary>
    private const int UnknownIndex = -1;

    //_selectIndex默认为0.
    private int _selectIndex;

    public override void _Ready()
    {
        base._Ready();
        NodeUtils.DeleteAllChild(this);
        _itemSlotNodes = new List<ItemSlotNode>();
        _itemSlotPackedScene = GD.Load<PackedScene>("res://prefab/ui/ItemSlot.tscn");
        for (var i = 0; i < Config.HotBarSize; i++)
        {
            AddItemSlot(i);
        }
    }

    /// <summary>
    /// <para>Select the next item slot</para>
    /// <para>选择下一个物品槽</para>
    /// </summary>
    private void SelectTheNextItemSlot()
    {
        if (_itemSlotNodes == null)
        {
            return;
        }

        var count = _itemSlotNodes.Count;
        if (count == 0)
        {
            return;
        }

        var oldSelectIndex = _selectIndex;
        _selectIndex++;
        if (_selectIndex >= count)
        {
            _selectIndex = 0;
        }

        SelectItemSlot(oldSelectIndex, _selectIndex);
    }

    /// <summary>
    /// <para>Select the previous item slot</para>
    /// <para>选择上一个物品槽</para>
    /// </summary>
    private void SelectThePreviousItemSlot()
    {
        if (_itemSlotNodes == null)
        {
            return;
        }

        var count = _itemSlotNodes.Count;
        if (count == 0)
        {
            return;
        }

        var oldSelectIndex = _selectIndex;
        _selectIndex--;
        if (_selectIndex < 0)
        {
            _selectIndex = count - 1;
        }

        SelectItemSlot(oldSelectIndex, _selectIndex);
    }

    public override void _Process(double delta)
    {
        base._Process(delta);
        if (Input.IsActionJustPressed("hotbar_next"))
        {
            //Mouse wheel down
            //鼠标滚轮向下
            SelectTheNextItemSlot();
        }

        if (Input.IsActionJustPressed("hotbar_previous"))
        {
            //Mouse wheel up
            //鼠标滚轮向上
            SelectThePreviousItemSlot();
        }

        if (Input.IsActionJustPressed("hotbar_1"))
        {
            SelectItemSlotByHotBarShortcutKey(0);
        }

        if (Input.IsActionJustPressed("hotbar_2"))
        {
            SelectItemSlotByHotBarShortcutKey(1);
        }

        if (Input.IsActionJustPressed("hotbar_3"))
        {
            SelectItemSlotByHotBarShortcutKey(2);
        }

        if (Input.IsActionJustPressed("hotbar_4"))
        {
            SelectItemSlotByHotBarShortcutKey(3);
        }

        if (Input.IsActionJustPressed("hotbar_5"))
        {
            SelectItemSlotByHotBarShortcutKey(4);
        }

        if (Input.IsActionJustPressed("hotbar_6"))
        {
            SelectItemSlotByHotBarShortcutKey(5);
        }

        if (Input.IsActionJustPressed("hotbar_7"))
        {
            SelectItemSlotByHotBarShortcutKey(6);
        }

        if (Input.IsActionJustPressed("hotbar_8"))
        {
            SelectItemSlotByHotBarShortcutKey(7);
        }

        if (Input.IsActionJustPressed("hotbar_9"))
        {
            SelectItemSlotByHotBarShortcutKey(8);
        }
    }

    /// <summary>
    /// <para>Select the HotBar project using the shortcut keys</para>
    /// <para>通过快捷键选择HotBar项目</para>
    /// </summary>
    /// <para>The Pc version of the shortcut key index is 0-9</para>
    /// <para>Pc版本的快捷键索引为0-9</para>
    /// <param name="shortcutKeyIndex"></param>
    private void SelectItemSlotByHotBarShortcutKey(int shortcutKeyIndex)
    {
        if (_itemSlotNodes == null)
        {
            return;
        }

        var safeIndex = GetSafeIndex(shortcutKeyIndex);
        if (safeIndex == UnknownIndex)
        {
            return;
        }

        SelectItemSlot(_selectIndex, safeIndex);
        _selectIndex = safeIndex;
    }


    /// <summary>
    /// <para>Removes an item from the currently selected inventory</para>
    /// <para>移除当前选中的物品栏内的物品</para>
    /// </summary>
    /// <param name="number"></param>
    /// <returns></returns>
    public bool RemoveItemFromItemSlotBySelectIndex(int number)
    {
        return RemoveItemFromItemSlot(_selectIndex, number);
    }

    public int GetItemSlotCount()
    {
        if (_itemSlotNodes == null)
        {
            return 0;
        }

        return _itemSlotNodes.Count;
    }

    public ItemSlotNode? GetItemSlotNode(int index)
    {
        if (_itemSlotNodes == null)
        {
            return null;
        }

        var safeIndex = GetSafeIndex(index);
        return _itemSlotNodes[safeIndex];
    }

    /// <summary>
    /// <para>Remove items from the item slot</para>
    /// <para>从物品槽内移除物品</para>
    /// </summary>
    /// <param name="itemSlotIndex">
    ///<para>When this number is greater than the number of item slots, residual filtering is used.</para>
    ///<para>当此数量大于物品槽的数量时，会使用余数筛选。</para>
    /// </param>
    /// <param name="number">
    ///<para>The number of items removed</para>
    ///<para>移除物品的数量</para>
    /// </param>
    public bool RemoveItemFromItemSlot(int itemSlotIndex, int number)
    {
        if (_itemSlotNodes == null)
        {
            return false;
        }

        var safeIndex = GetSafeIndex(itemSlotIndex);
        if (safeIndex == UnknownIndex)
        {
            return false;
        }

        var itemSlot = _itemSlotNodes[safeIndex];
        return itemSlot.RemoveItem(number);
    }

    /// <summary>
    /// <para>Gets a secure subscript index</para>
    /// <para>获取安全的下标索引</para>
    /// </summary>
    /// <param name="itemSlotIndex"></param>
    /// <returns>
    ///<para>-1 is returned on failure, and the index that does not result in an out-of-bounds subscript is returned on success</para>
    ///<para>失败返回-1，成功返回不会导致下标越界的索引</para>
    /// </returns>
    private int GetSafeIndex(int itemSlotIndex)
    {
        if (_itemSlotNodes == null)
        {
            return UnknownIndex;
        }

        var count = _itemSlotNodes.Count;
        if (count == 0)
        {
            //Prevents the dividend from being 0
            //防止被除数为0
            return UnknownIndex;
        }

        return itemSlotIndex % count;
    }

    /// <summary>
    /// <para>Select an item slot</para>
    /// <para>选中某个物品槽</para>
    /// </summary>
    private void SelectItemSlot(int oldSelectIndex, int newSelectIndex)
    {
        if (oldSelectIndex == newSelectIndex)
        {
            return;
        }

        if (_itemSlotNodes == null)
        {
            return;
        }

        _itemSlotNodes[oldSelectIndex].IsSelect = false;
        _itemSlotNodes[newSelectIndex].IsSelect = true;
        var oldItem = _itemSlotNodes[oldSelectIndex].GetItem();
        if (oldItem != null && oldItem is Node2D oldNode2D)
        {
            oldNode2D.ProcessMode = ProcessModeEnum.Disabled;
            oldNode2D.Hide();
        }

        var item = _itemSlotNodes[newSelectIndex].GetItem();
        if (item == null)
        {
            if (GameSceneNodeHolder.Player != null)
            {
                GameSceneNodeHolder.Player.CurrentItem = null;
            }
        }
        else
        {
            if (item is Node2D node2D)
            {
                node2D.ProcessMode = ProcessModeEnum.Inherit;
                node2D.Show();
                if (GameSceneNodeHolder.Player != null)
                {
                    GameSceneNodeHolder.Player.CurrentItem = node2D;
                }
            }
            else
            {
                if (GameSceneNodeHolder.Player != null)
                {
                    GameSceneNodeHolder.Player.CurrentItem = null;
                }
            }
        }
    }


    public bool CanAddItem(IItem item)
    {
        return Matching(item) != null;
    }


    /// <summary>
    /// <para>Add an item to the HotBar</para>
    /// <para>在HotBar内添加一个物品</para>
    /// </summary>
    /// <param name="item"></param>
    /// <returns></returns>
    public bool AddItem(IItem item)
    {
        var itemSlotNode = Matching(item);
        if (itemSlotNode == null)
        {
            return false;
        }
        return itemSlotNode.SetItem(item);
    }

    public int GetSelectIndex()
    {
        return _selectIndex;
    }

    public ItemSlotNode? GetSelectItemSlotNode()
    {
        if (_itemSlotNodes == null || _itemSlotNodes.Count == 0)
        {
            return null;
        }

        if (_selectIndex < _itemSlotNodes.Count)
        {
            //Prevent subscripts from going out of bounds.
            //防止下标越界。
            return _itemSlotNodes[_selectIndex];
        }

        return null;
    }

    public ItemSlotNode? Matching(IItem item)
    {
        if (_itemSlotNodes == null || _itemSlotNodes.Count == 0)
        {
            return null;
        }


        foreach (var itemSlotNode in _itemSlotNodes)
        {
            if (itemSlotNode.CanSetItem(item))
            {
                //If there is an item slot to put this item in, then we return it.
                //如果有物品槽可放置此物品，那么我们返回它。
                return itemSlotNode;
            }
        }

        return null;
    }

    /// <summary>
    /// <para>Add items tank</para>
    /// <para>添加物品槽</para>
    /// </summary>
    private void AddItemSlot(int index)
    {
        if (_itemSlotNodes == null || _itemSlotPackedScene == null)
        {
            return;
        }

        if (_itemSlotPackedScene.Instantiate() is not ItemSlotNode itemSlotNode)
        {
            return;
        }

        AddChild(itemSlotNode);
        itemSlotNode.IsSelect = index == _selectIndex;
        _itemSlotNodes.Add(itemSlotNode);
    }
}