using Prism.Commands;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using TeamAAS.Communication.Models;

namespace TeamAAS.ViewModels
{
    /// <summary>
    /// 全局变量编辑器 VM(可复用)。在独立工作集 <see cref="Items"/> 上增删改移，
    /// 与 live GlobalVariableManager.Variables 解耦——配合“克隆-编辑-提交”，取消可回滚。
    /// 调用方指定 Scope(新建变量盖此作用域)与初始项(通常为某作用域的克隆)。
    /// DataContext 供 GlobalVarEditorView 绑定。
    /// </summary>
    public class GlobalVarEditorViewModel : TeamAAS.BindableBase
    {
        /// <summary>工作集(克隆)，编辑不直接影响 live 列表；由调用方在确定时提交。</summary>
        public ObservableCollection<GlobalVariableModel> Items { get; }
            = new ObservableCollection<GlobalVariableModel>();

        /// <summary>本编辑器管理的作用域；新建变量盖此 Scope。</summary>
        public VarScope Scope { get; }

        /// <summary>可选变量类型(供类型下拉)。</summary>
        public Array VarTypes => GlobalVariableTypes.AllTypes;

        private GlobalVariableModel _selected;
        public GlobalVariableModel Selected
        {
            get => _selected;
            set
            {
                if (SetProperty(ref _selected, value))
                {
                    DeleteCommand?.RaiseCanExecuteChanged();
                    MoveUpCommand?.RaiseCanExecuteChanged();
                    MoveDownCommand?.RaiseCanExecuteChanged();
                }
            }
        }

        public bool HasSelected => _selected != null;

        public DelegateCommand<string> AddCommand { get; }
        public DelegateCommand DeleteCommand { get; }
        public DelegateCommand MoveUpCommand { get; }
        public DelegateCommand MoveDownCommand { get; }

        public GlobalVarEditorViewModel(VarScope scope, IEnumerable<GlobalVariableModel> initial)
        {
            Scope = scope;
            if (initial != null)
                foreach (var v in initial) Items.Add(v);
            Reindex();

            AddCommand = new DelegateCommand<string>(Add);
            DeleteCommand = new DelegateCommand(Delete, () => HasSelected);
            MoveUpCommand = new DelegateCommand(MoveUp, () => HasSelected);
            MoveDownCommand = new DelegateCommand(MoveDown, () => HasSelected);
        }

        private void Add(string dataType)
        {
            if (string.IsNullOrEmpty(dataType)) return;
            Items.Add(GlobalVariableModel.Create(dataType, Scope, Items.Count));
        }

        private void Delete()
        {
            if (_selected == null) return;
            Items.Remove(_selected);
            Selected = null;
            Reindex();
        }

        private void MoveUp()
        {
            if (_selected == null) return;
            int i = Items.IndexOf(_selected);
            if (i <= 0) return;
            Items.Move(i, i - 1);
            Reindex();
        }

        private void MoveDown()
        {
            if (_selected == null) return;
            int i = Items.IndexOf(_selected);
            if (i < 0 || i >= Items.Count - 1) return;
            Items.Move(i, i + 1);
            Reindex();
        }

        private void Reindex()
        {
            for (int i = 0; i < Items.Count; i++) Items[i].Index = i;
        }
    }
}