using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ShenTun.Ecg.Test
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        public static IEnumerable<string> GetAllMatchingPaths(string pattern)
        {
            char separator = Path.DirectorySeparatorChar;
            string[] parts = pattern.Split(separator);

            if (parts[0].Contains('*') || parts[0].Contains('?'))
                throw new ArgumentException("path root must not have a wildcard", nameof(parts));

            return GetAllMatchingPathsInternal(String.Join(separator.ToString(), parts.Skip(1)), parts[0]);
        }

        private static IEnumerable<string> GetAllMatchingPathsInternal(string pattern, string root)
        {
            char separator = Path.DirectorySeparatorChar;
            string[] parts = pattern.Split(separator);

            for (int i = 0; i < parts.Length; i++)
            {
                // if this part of the path is a wildcard that needs expanding
                if (parts[i].Contains('*') || parts[i].Contains('?'))
                {
                    // create an absolute path up to the current wildcard and check if it exists
                    var combined = root + separator + String.Join(separator.ToString(), parts.Take(i));
                    if (!Directory.Exists(combined))
                        return new string[0];

                    if (i == parts.Length - 1) // if this is the end of the path (a file name)
                    {
                        return Directory.EnumerateFiles(combined, parts[i], SearchOption.TopDirectoryOnly);
                    }
                    else // if this is in the middle of the path (a directory name)
                    {
                        var directories = Directory.EnumerateDirectories(combined, parts[i], SearchOption.TopDirectoryOnly);
                        var paths = directories.SelectMany(dir =>
                            GetAllMatchingPathsInternal(String.Join(separator.ToString(), parts.Skip(i + 1)), dir));
                        return paths;
                    }
                }
            }

            // if pattern ends in an absolute path with no wildcards in the filename
            var absolute = root + separator + String.Join(separator.ToString(), parts);
            if (File.Exists(absolute))
                return new[] { absolute };

            return new string[0];
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string pattern = @"D:\\log\\*3450.pdf";
            var list= GetAllMatchingPaths(pattern);
            foreach (var st in GetAllMatchingPaths(pattern))
                Console.WriteLine(st);
        }
    }
}