using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using System.Web;
using Microsoft.AspNetCore.Mvc.RazorPages;

namespace webmusic.Pages {
	public class IndexModel : PageModel {
		private const string       Root        = "music";
		public        List<string> Dirs        = new();
		public        string       Displaypath = "";
		public        List<string> Files       = new();
		public        string       Fullpath    = "";
		public        string       Path        = "";
		public        string       PathOneup   = "";

		public void OnGet() {
			if (Request.QueryString.HasValue)
				if (Request.QueryString.Value != null)
					Path = HttpUtility.UrlDecode(Request.QueryString.Value.TrimStart('?').Replace("+", "%2B"));
			if (Path.Contains("/..")) {
				Response.Redirect("/Error");
				return;
			}

			if (Path.EndsWith(".m3u"))
				Path = Path.Substring(0, Path.Length - 4);

			if (Path.EndsWith(".lrc"))
				return;

			PathOneup   = Regex.Match(Path, @".*(?=\/)").Value;
			Fullpath    = Root + Path;
			Displaypath = string.IsNullOrWhiteSpace(Path) ? "/" : Path;
			Dirs        = Directory.GetDirectories(Fullpath).Select(System.IO.Path.GetFileName).ToList();
			Dirs.RemoveAll(p => p.StartsWith("."));
			Dirs.Sort();
			Files = Directory.GetFiles(Fullpath).Select(System.IO.Path.GetFileName).ToList();
			Files.RemoveAll(p => p.EndsWith(".m3u"));
			Files.RemoveAll(p => p.EndsWith(".lrc"));
			Files.RemoveAll(p => p.StartsWith("."));
			Files.Sort(new NaturalSortComparer());
		}

		public static string Encode(string str) => str.Replace("\"", "%22").Replace("'", "%27").Replace("?", "%3F").Replace("&", "%26").Replace(" ", "%20");

		private class NaturalSortComparer : IComparer<string>, IDisposable {
			private readonly bool _isAscending;

			public NaturalSortComparer(bool inAscendingOrder = true) {
				_isAscending = inAscendingOrder;
			}

			int IComparer<string>.Compare(string x, string y) {
				if (x == y)
					return 0;

				if (!_table.TryGetValue(x!, out var x1)) {
					x1 = Regex.Split(x.Replace(" ", ""), "([0-9]+)");
					_table.Add(x, x1);
				}

				if (!_table.TryGetValue(y!, out var y1)) {
					y1 = Regex.Split(y.Replace(" ", ""), "([0-9]+)");
					_table.Add(y, y1);
				}

				int returnVal;

				for (var i = 0; i < x1.Length && i < y1.Length; i++) {
					if (x1[i] != y1[i]) {
						returnVal = PartCompare(x1[i], y1[i]);
						return _isAscending ? returnVal : -returnVal;
					}
				}

				if (y1.Length > x1.Length) {
					returnVal = 1;
				}
				else if (x1.Length > y1.Length) {
					returnVal = -1;
				}
				else {
					returnVal = 0;
				}

				return _isAscending ? returnVal : -returnVal;
			}

			private static int PartCompare(string left, string right) {
				if (!int.TryParse(left, out var x))
					return string.Compare(left, right, StringComparison.Ordinal);

				return !int.TryParse(right, out var y) ? string.Compare(left, right, StringComparison.Ordinal) : x.CompareTo(y);
			}

			private Dictionary<string, string[]> _table = new();

			public void Dispose() {
				_table.Clear();
				_table = null;
			}
		}
	}
}