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

namespace AlicizaX.PackageManager.Editor
{
    internal class PackageListView : ListView
    {
        public event Action<IEnumerable<RepositoryPackageData>> OnSelectionChangedEvent;

        private void OnSelectionChangedInternal(IEnumerable<object> selectedItems)
        {
            // 转换对象类型为实际数据类型
            var packages = selectedItems.Cast<RepositoryPackageData>();
            OnSelectionChangedEvent?.Invoke(packages);

            // 刷新列表项显示
            RefreshItems();
        }

        public PackageListView()
        {
            style.paddingTop = new Length(2, LengthUnit.Pixel);
            virtualizationMethod = CollectionVirtualizationMethod.FixedHeight;
            fixedItemHeight = 25f;
            horizontalScrollingEnabled = false;
            ScrollView scrollView = this.Q<ScrollView>();
            scrollView.horizontalScrollerVisibility = ScrollerVisibility.Hidden;
            style.flexShrink = 1;
            style.height = Length.Percent(95);
            makeItem = MakeItem;
            bindItem = BindItem;
            selectionChanged += OnSelectionChanged;
            selectionChanged += OnSelectionChangedInternal;
            selectionType = SelectionType.Single;
        }

        private void OnSelectionChanged(IEnumerable<object> selectedItems)
        {
            RefreshItems();
        }

        private VisualElement MakeItem()
        {
            return new PackageInfoListItem();
        }

        private void BindItem(VisualElement item, int index)
        {
            if (!(item is PackageInfoListItem packageItem))
            {
                return;
            }

            RepositoryPackageData packageData = GetVisualStateByIndex(index);
            packageItem.RefreshDataSource(packageData);

            // 绑定数据后更新选中状态
            bool isSelected = selectedIndices.Contains(index);
            packageItem.SetSelected(isSelected);
        }

        private RepositoryPackageData GetVisualStateByIndex(int index)
        {
            return this.itemsSource is List<RepositoryPackageData> itemsSource ? itemsSource.ElementAtOrDefault<RepositoryPackageData>(index) : (RepositoryPackageData)null;
        }
    }
}