using System;
using System.Collections.Generic;

namespace AlicizaX.UI
{
    /// <summary>
    /// RecyclerView 的通用适配器，支持数据绑定、选中状态和列表操作
    /// </summary>
    /// <typeparam name="T">数据类型，必须实现 ISimpleViewData 接口</typeparam>
    public class Adapter<T> : IAdapter where T : ISimpleViewData
    {
        protected RecyclerView recyclerView;

        protected List<T> list;
        protected Action<T> onItemClick;

        protected int choiceIndex = -1;

        /// <summary>
        /// 当前选中项的索引
        /// </summary>
        public int ChoiceIndex
        {
            get => choiceIndex;
            set { SetChoiceIndex(value); }
        }

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="recyclerView">RecyclerView 实例</param>
        public Adapter(RecyclerView recyclerView) : this(recyclerView, new List<T>(), null)
        {
        }

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="recyclerView">RecyclerView 实例</param>
        /// <param name="list">数据列表</param>
        public Adapter(RecyclerView recyclerView, List<T> list) : this(recyclerView, list, null)
        {
        }

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="recyclerView">RecyclerView 实例</param>
        /// <param name="list">数据列表</param>
        /// <param name="onItemClick">列表项点击回调</param>
        public Adapter(RecyclerView recyclerView, List<T> list, Action<T> onItemClick)
        {
            this.recyclerView = recyclerView;
            this.list = list;
            this.onItemClick = onItemClick;
        }

        /// <summary>
        /// 获取列表项总数
        /// </summary>
        public virtual int GetItemCount()
        {
            return list == null ? 0 : list.Count;
        }

        /// <summary>
        /// 获取实际数据项数量
        /// </summary>
        public virtual int GetRealCount()
        {
            return GetItemCount();
        }

        /// <summary>
        /// 获取指定索引位置的视图名称
        /// </summary>
        public virtual string GetViewName(int index)
        {
            return "";
        }

        /// <summary>
        /// 绑定视图持有者与数据
        /// </summary>
        public virtual void OnBindViewHolder(ViewHolder viewHolder, int index)
        {
            if (index < 0 || index >= GetItemCount()) return;

            T data = list[index];

            viewHolder.BindViewData(data);
            viewHolder.BindItemClick(data, t =>
            {
                SetChoiceIndex(index);
                onItemClick?.Invoke(data);
            });
            viewHolder.BindChoiceState(index == choiceIndex);
        }

        /// <summary>
        /// 通知数据已更改
        /// </summary>
        public virtual void NotifyDataChanged()
        {
            recyclerView.RequestLayout();
            recyclerView.Refresh();
        }

        /// <summary>
        /// 设置数据列表并刷新视图
        /// </summary>
        /// <param name="list">新的数据列表</param>
        public  virtual void SetList(List<T> list)
        {
            this.list = list;
            recyclerView.Reset();
            NotifyDataChanged();
        }

        /// <summary>
        /// 获取指定索引的数据
        /// </summary>
        /// <param name="index">数据索引</param>
        /// <returns>数据对象，索引无效时返回 default</returns>
        public T GetData(int index)
        {
            if (index < 0 || index >= GetItemCount()) return default;

            return list[index];
        }

        /// <summary>
        /// 添加单个数据项
        /// </summary>
        /// <param name="item">要添加的数据项</param>
        public void Add(T item)
        {
            list.Add(item);
            NotifyDataChanged();
        }

        /// <summary>
        /// 批量添加数据项
        /// </summary>
        /// <param name="collection">要添加的数据集合</param>
        public void AddRange(IEnumerable<T> collection)
        {
            list.AddRange(collection);
            NotifyDataChanged();
        }

        /// <summary>
        /// 在指定位置插入数据项
        /// </summary>
        /// <param name="index">插入位置</param>
        /// <param name="item">要插入的数据项</param>
        public void Insert(int index, T item)
        {
            list.Insert(index, item);
            NotifyDataChanged();
        }

        /// <summary>
        /// 在指定位置批量插入数据项
        /// </summary>
        /// <param name="index">插入位置</param>
        /// <param name="collection">要插入的数据集合</param>
        public void InsertRange(int index, IEnumerable<T> collection)
        {
            list.InsertRange(index, collection);
            NotifyDataChanged();
        }

        /// <summary>
        /// 移除指定的数据项
        /// </summary>
        /// <param name="item">要移除的数据项</param>
        public void Remove(T item)
        {
            int index = list.IndexOf(item);
            RemoveAt(index);
        }

        /// <summary>
        /// 移除指定索引位置的数据项
        /// </summary>
        /// <param name="index">要移除的索引</param>
        public void RemoveAt(int index)
        {
            if (index < 0 || index >= GetItemCount()) return;

            list.RemoveAt(index);
            NotifyDataChanged();
        }

        /// <summary>
        /// 移除指定范围的数据项
        /// </summary>
        /// <param name="index">起始索引</param>
        /// <param name="count">移除数量</param>
        public void RemoveRange(int index, int count)
        {
            list.RemoveRange(index, count);
            NotifyDataChanged();
        }

        /// <summary>
        /// 移除所有符合条件的数据项
        /// </summary>
        /// <param name="match">匹配条件</param>
        public void RemoveAll(Predicate<T> match)
        {
            list.RemoveAll(match);
            NotifyDataChanged();
        }

        /// <summary>
        /// 清空所有数据
        /// </summary>
        public void Clear()
        {
            list.Clear();
            NotifyDataChanged();
        }

        /// <summary>
        /// 反转指定范围的数据项顺序
        /// </summary>
        /// <param name="index">起始索引</param>
        /// <param name="count">反转数量</param>
        public void Reverse(int index, int count)
        {
            list.Reverse(index, count);
            NotifyDataChanged();
        }

        /// <summary>
        /// 反转所有数据项顺序
        /// </summary>
        public void Reverse()
        {
            list.Reverse();
            NotifyDataChanged();
        }

        /// <summary>
        /// 使用指定的比较器排序数据
        /// </summary>
        /// <param name="comparison">比较器</param>
        public void Sort(Comparison<T> comparison)
        {
            list.Sort(comparison);
            NotifyDataChanged();
        }

        /// <summary>
        /// 设置列表项点击回调
        /// </summary>
        /// <param name="onItemClick">点击回调</param>
        public void SetOnItemClick(Action<T> onItemClick)
        {
            this.onItemClick = onItemClick;
        }

        /// <summary>
        /// 设置选中项索引
        /// </summary>
        /// <param name="index">要选中的索引</param>
        protected void SetChoiceIndex(int index)
        {
            if (index == choiceIndex) return;

            if (choiceIndex != -1)
            {
                if (TryGetViewHolder(choiceIndex, out var viewHolder))
                {
                    viewHolder.BindChoiceState(false);
                }
            }

            choiceIndex = index;

            if (choiceIndex != -1)
            {
                if (TryGetViewHolder(choiceIndex, out var viewHolder))
                {
                    viewHolder.BindChoiceState(true);
                }
            }
        }

        /// <summary>
        /// 尝试获取指定索引的视图持有者
        /// </summary>
        /// <param name="index">数据索引</param>
        /// <param name="viewHolder">输出的视图持有者</param>
        /// <returns>是否成功获取</returns>
        private bool TryGetViewHolder(int index, out ViewHolder viewHolder)
        {
            viewHolder = recyclerView.ViewProvider.GetViewHolder(index);
            return viewHolder != null;
        }
    }
}