using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

namespace WxOrder.Framework.Commons;

public enum InputType
{
	Text,     // 任意文本
	Integer,  // 整数
	Decimal   // 小数
}
/// <summary>
/// InputDialog.xaml 的交互逻辑
/// </summary>
public partial class InputDialog : Window
{
	private readonly InputType _type;
	private readonly bool _allowEmpty;

	// 输入过程中允许的"部分输入"格式（如 "-"、"1." 也允许）
	private static readonly Regex IntPartial = new(@"^-?\d*$");
	private static readonly Regex DecPartial = new(@"^-?\d*\.?\d*$");

	/// <summary>用户输入的原始文本</summary>
	public string ResultText { get; private set; } = "";

	private InputDialog(Window? owner, string title, string prompt,
						string defaultValue, InputType type, bool allowEmpty)
	{
		InitializeComponent();
		Owner = owner ?? Application.Current.Windows
			.OfType<Window>()
			.FirstOrDefault(w => w.IsActive) ?? Application.Current.MainWindow;
		if (Owner == null) WindowStartupLocation = WindowStartupLocation.CenterScreen;

		Title = title;
		PromptText.Text = prompt;
		InputBox.Text = defaultValue;
		_type = type;
		_allowEmpty = allowEmpty;

		// 粘贴时同样校验
		DataObject.AddPastingHandler(InputBox, (s, e) =>
		{
			if (_type == InputType.Text) return;
			if (e.DataObject.GetData(DataFormats.Text) is not string pasted ||
				!IsPartialValid(Preview(pasted)))
				e.CancelCommand();
		});
	}

	private void Window_ContentRendered(object? sender, EventArgs e)
	{
		InputBox.Focus();
		InputBox.SelectAll();
	}

	// 按键输入时实时限制字符
	private void InputBox_PreviewTextInput(object sender, System.Windows.Input.TextCompositionEventArgs e)
	{
		if (_type == InputType.Text) return;
		e.Handled = !IsPartialValid(Preview(e.Text));
	}

	// 计算输入/粘贴后的文本
	private string Preview(string incoming)
	{
		var t = InputBox.Text;
		return t.Remove(InputBox.SelectionStart, InputBox.SelectionLength)
				.Insert(InputBox.SelectionStart, incoming);
	}

	private bool IsPartialValid(string text) => _type switch
	{
		InputType.Integer => IntPartial.IsMatch(text),
		InputType.Decimal => DecPartial.IsMatch(text),
		_ => true
	};

	private void Ok_Click(object sender, RoutedEventArgs e)
	{
		var text = InputBox.Text.Trim();

		if (text.Length == 0 && !_allowEmpty)
		{
			ShowError("内容不能为空");
			return;
		}

		if (text.Length > 0)
		{
			if (_type == InputType.Integer && !int.TryParse(text, NumberStyles.AllowLeadingSign,
					CultureInfo.InvariantCulture, out _))
			{
				ShowError("请输入有效的整数");
				return;
			}
			if (_type == InputType.Decimal && !double.TryParse(text, NumberStyles.Float,
					CultureInfo.InvariantCulture, out _))
			{
				ShowError("请输入有效的数字");
				return;
			}
		}

		ResultText = text;
		DialogResult = true;
	}

	private void ShowError(string msg)
	{
		ErrorText.Text = msg;
		ErrorText.Visibility = Visibility.Visible;
		InputBox.Focus();
		InputBox.SelectAll();
	}

	// ================= 静态帮助方法 =================

	/// <summary>输入文本。取消返回 null。</summary>
	public static string? ShowText(string prompt, string title = "输入",
		string defaultValue = "", bool allowEmpty = false, Window? owner = null)
	{
		var dlg = new InputDialog(owner, title, prompt, defaultValue, InputType.Text, allowEmpty);
		return dlg.ShowDialog() == true ? dlg.ResultText : null;
	}

	/// <summary>输入整数。取消返回 null。</summary>
	public static int? ShowInt(string prompt, string title = "输入",
		int? defaultValue = null, Window? owner = null)
	{
		var dlg = new InputDialog(owner, title, prompt,
			defaultValue?.ToString(CultureInfo.InvariantCulture) ?? "", InputType.Integer, false);
		return dlg.ShowDialog() == true
			? int.Parse(dlg.ResultText, CultureInfo.InvariantCulture)
			: null;
	}

	/// <summary>输入小数。取消返回 null。</summary>
	public static double? ShowDouble(string prompt, string title = "输入",
		double? defaultValue = null, Window? owner = null)
	{
		var dlg = new InputDialog(owner, title, prompt,
			defaultValue?.ToString(CultureInfo.InvariantCulture) ?? "", InputType.Decimal, false);
		return dlg.ShowDialog() == true
			? double.Parse(dlg.ResultText, CultureInfo.InvariantCulture)
			: null;
	}
}