namespace Yw.WinFrmUI
{
    /// <summary>
    /// 步骤管理器
    /// </summary>
    public class WizardManager<T> : IWizardManager<T> where T : class, new()
    {

        #region 事件

        /// <summary>
        /// 选择页面改变事件
        /// </summary>
        public event Action<IWizardPage<T>, int> SelectedPageChangedEvent;

        /// <summary>
        /// 选择页面状态改变事件
        /// </summary>
        public event Action<IWizardPage<T>, int> SelectedPageStateChangedEvent;

        #endregion

        #region 初始化

        /// <summary>
        /// 初始化管理器
        /// </summary>
        /// <param name="pages">步骤页面数组</param>
        public virtual void InitialManager(IWizardPage<T>[] pages)
        {
            _pages = pages;
            if (_pages != null && _pages.Length > 0)
            {
                _isInitialize = true;
                foreach (var page in _pages)
                {
                    page.PageStateChangedEvent += () =>
                    {
                        if (page == this.SelectedPage)
                        {
                            TriggerSelectedPageStateChangedEvent();
                        }
                    };
                }
                _selectedIndex = 0;
                this.SelectedPage.InitialPage(_vm);
                TriggerSelectedPageChangedEvent();
            }
            else
            {
                _isInitialize = false;
            }
        }

        /// <summary>
        /// 步骤页面数组
        /// </summary>
        protected IWizardPage<T>[] _pages;

        /// <summary>
        /// 是否初始化
        /// </summary>
        protected bool _isInitialize = false;

        /// <summary>
        /// vm对象
        /// </summary>
        protected readonly T _vm = new();

        #endregion

        #region 选择

        /// <summary>
        /// 选择页面
        /// </summary>
        public virtual IWizardPage<T> SelectedPage
        {
            get
            {
                if (_isInitialize)
                {
                    return _pages[this.SelectedIndex];
                }
                return default;
            }
        }

        /// <summary>
        /// 选择索引
        /// </summary>
        public virtual int SelectedIndex
        {
            get { return _selectedIndex; }
        }

        /// <summary>
        /// 选择索引
        /// </summary>
        protected int _selectedIndex;

        #endregion

        #region 操作

        /// <summary>
        /// 上一步
        /// </summary>
        public virtual bool Prev()
        {
            if (!_isInitialize)
            {
                return false;
            }
            if (!this.SelectedPage.AllowPrev)
            {
                return false;
            }
            if (this.SelectedPage.CanPrev())
            {
                --_selectedIndex;
                this.SelectedPage.InitialPage(_vm);
                TriggerSelectedPageChangedEvent();
                return true;
            }
            return false;
        }

        /// <summary>
        /// 下一步
        /// </summary>
        public virtual bool Next()
        {
            if (!_isInitialize)
            {
                return false;
            }
            if (!this.SelectedPage.AllowNext)
            {
                return false;
            }
            if (this.SelectedPage.CanNext())
            {
                ++_selectedIndex;
                this.SelectedPage.InitialPage(_vm);
                TriggerSelectedPageChangedEvent();
                return true;
            }
            return false;
        }

        /// <summary>
        /// 取消
        /// </summary>
        public virtual bool Cancel()
        {
            if (!_isInitialize)
            {
                return false;
            }
            if (!this.SelectedPage.AllowCancel)
            {
                return false;
            }
            if (this.SelectedPage.CanCancel())
            {
                return true;
            }
            return false;
        }

        /// <summary>
        /// 完成
        /// </summary>
        public virtual bool Complete()
        {
            if (!_isInitialize)
            {
                return false;
            }
            if (!this.SelectedPage.AllowComplete)
            {
                return false;
            }
            if (this.SelectedPage.CanComplete())
            {
                return true;
            }
            return false;
        }

        #endregion

        #region 方法

        /// <summary>
        /// 触发选择页面改变事件
        /// </summary>
        protected void TriggerSelectedPageChangedEvent()
        {
            this.SelectedPageChangedEvent?.Invoke(this.SelectedPage, this.SelectedIndex);
        }

        /// <summary>
        /// 触发选择页面状态改变事件
        /// </summary>
        protected void TriggerSelectedPageStateChangedEvent()
        {
            this.SelectedPageStateChangedEvent?.Invoke(this.SelectedPage, this.SelectedIndex);
        }

        #endregion


    }
}