using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.AccessControl;
using System.Text;
using System.Threading.Tasks;

namespace RandomFileRunner.IO
{
    public class SmartFileSystem
    {


        public static List<string> GetFiles(string path, string pattern)
        {
            List<string> fileList = new List<string>();
            List<string> directoryList = new List<string>();

            directoryList.Add(path);

            while (true)
            {
                if (directoryList.Count <= 0)
                {
                    break;
                }

                string directory = directoryList.First();
                directoryList.RemoveAt(0);

                if (IsDirectoryAccessible(directory))
                {
                    IEnumerable<string> searchDirList = new List<string>();

                    try
                    {
                        searchDirList = Directory.EnumerateDirectories(directory, "*", SearchOption.TopDirectoryOnly);
                    }
                    catch (Exception)
                    {
                        continue;
                    }

                    foreach (string item in searchDirList)
                    {
                        if (!IsDirectoryAccessible(item))
                        {
                            continue;
                        }

                        directoryList.Add(item);
                    }

                    foreach (string item in Directory.EnumerateFiles(directory, pattern, SearchOption.TopDirectoryOnly))
                    {
                        if (!IsFileAccessible(item))
                        {
                            continue;
                        }

                        fileList.Add(item);
                    }
                }
            }

            return fileList;
        }

        public static void GetFiles(string path, string pattern, Func<string, ulong, int, bool> callback)
        {
            List<string> directoryList = new List<string>();
            ulong searchCount = 0;

            directoryList.Add(path);
            searchCount++;

            while (true)
            {
                if (directoryList.Count <= 0)
                {
                    break;
                }

                string directory = directoryList.First();
                directoryList.RemoveAt(0);

                callback(null, searchCount, directoryList.Count);

                if (IsDirectoryAccessible(directory))
                {
                    IEnumerable<string> searchDirList = new List<string>();

                    try
                    {
                        searchDirList = Directory.EnumerateDirectories(directory, "*", SearchOption.TopDirectoryOnly);
                    }
                    catch (Exception)
                    {
                        continue;
                    }

                    foreach (string item in searchDirList)
                    {
                        if (!IsDirectoryAccessible(item))
                        {
                            continue;
                        }

                        directoryList.Add(item);
                        searchCount++;

                        callback(null, searchCount, directoryList.Count);
                    }

                    foreach (string item in Directory.EnumerateFiles(directory, pattern, SearchOption.TopDirectoryOnly))
                    {
                        if (!IsFileAccessible(item))
                        {
                            continue;
                        }

                        callback(item, searchCount, directoryList.Count);
                    }
                }
            }
        }

        public static bool IsFileAccessible(string filename)
        {
            if (string.IsNullOrWhiteSpace(filename)) return false;
            if (!File.Exists(filename)) return false;

            try
            {
                FileInfo fi = new FileInfo(filename);
                fi.GetAccessControl();
            }
            catch
            {
                return false;
            }

            return true;
        }

        public static bool IsDirectoryAccessible(string path)
        {
            if (string.IsNullOrWhiteSpace(path)) return false;
            if (!Directory.Exists(path)) return false;

            try
            {
                DirectoryInfo di = new DirectoryInfo(path);
                di.GetAccessControl();
            }
            catch
            {
                return false;
            }

            return true;
        }

    }
}