using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace 全自动水压检测仪.DATA
{
    /// <summary>
    /// 基于单例模式的WinForm窗口管理器
    /// 提供流畅的窗口切换API
    /// </summary>
    public sealed class FormManager
    {
        // 单例实例
        private static readonly Lazy<FormManager> _instance = new Lazy<FormManager>(() => new FormManager());

        // 存储所有窗口实例
        private readonly Dictionary<Type, Form> _formInstances = new Dictionary<Type, Form>();

        // 私有构造函数，防止外部实例化
        private FormManager() { }

        /// <summary>
        /// 获取单例实例
        /// </summary>
        public static FormManager Instance => _instance.Value;

        /// <summary>
        /// 注册窗口实例
        /// </summary>
        /// <typeparam name="T">窗口类型</typeparam>
        /// <param name="formInstance">窗口实例</param>
        /// <returns>返回自身，支持链式调用</returns>
        public FormManager RegisterForm<T>(T formInstance) where T : Form
        {
            Type formType = typeof(T);
            if (!_formInstances.ContainsKey(formType))
            {
                _formInstances[formType] = formInstance;
                // 监听窗口关闭事件，自动移除注册
                formInstance.FormClosed += (s, e) => _formInstances.Remove(formType);
            }
            return this;
        }

        /// <summary>
        /// 显示指定窗口并隐藏当前活动窗口
        /// </summary>
        /// <typeparam name="T">要显示的窗口类型</typeparam>
        /// <returns>返回自身，支持链式调用</returns>
        public FormManager SwitchTo<T>() where T : Form
        {
            Type targetType = typeof(T);

            // 检查目标窗口是否已注册
            if (!_formInstances.TryGetValue(targetType, out Form targetForm))
            {
                throw new InvalidOperationException($"窗口 {targetType.Name} 未注册，请先调用 RegisterForm 方法");
            }

            // 隐藏当前活动窗口
            Form activeForm = Form.ActiveForm;
            if (activeForm != null && activeForm != targetForm)
            {
                activeForm.Hide();
            }

            // 显示目标窗口并置于顶层
            targetForm.Show();
            targetForm.BringToFront();

            return this;
        }

        /// <summary>
        /// 显示指定窗口
        /// </summary>
        /// <typeparam name="T">要显示的窗口类型</typeparam>
        /// <returns>返回自身，支持链式调用</returns>
        public FormManager ShowForm<T>() where T : Form
        {
            Type targetType = typeof(T);
            if (_formInstances.TryGetValue(targetType, out Form targetForm))
            {
                targetForm.Show();
                targetForm.BringToFront();
            }
            return this;
        }

        /// <summary>
        /// 隐藏指定窗口
        /// </summary>
        /// <typeparam name="T">要隐藏的窗口类型</typeparam>
        /// <returns>返回自身，支持链式调用</returns>
        public FormManager HideForm<T>() where T : Form
        {
            Type targetType = typeof(T);
            if (_formInstances.TryGetValue(targetType, out Form targetForm))
            {
                targetForm.Hide();
            }
            return this;
        }

        /// <summary>
        /// 获取已注册的窗口实例
        /// </summary>
        /// <typeparam name="T">窗口类型</typeparam>
        /// <returns>窗口实例</returns>
        public T GetForm<T>() where T : Form
        {
            Type targetType = typeof(T);
            if (_formInstances.TryGetValue(targetType, out Form form))
            {
                return form as T;
            }
            return null;
        }
    }
}