resolve #39, add youtube grid preview

BotNet.Services/BotCommands/Preview.cs

@@ -0,0 +1,77 @@
+using System;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using BotNet.Services.Preview;
+using Microsoft.Extensions.DependencyInjection;
+using Telegram.Bot;
+using Telegram.Bot.Types;
+using Telegram.Bot.Types.Enums;
+
+namespace BotNet.Services.BotCommands {
+	public static class Preview {
+		public static async Task GetPreviewAsync(ITelegramBotClient botClient, IServiceProvider serviceProvider, Message message, CancellationToken cancellationToken) {
+			if (message.Entities?.FirstOrDefault() is { Type: MessageEntityType.BotCommand, Offset: 0, Length: int commandLength }
+				&& message.Text![commandLength..].Trim() is string commandArgument) {
+
+				if (commandArgument.Length <= 0 && message.ReplyToMessage?.Text is null) {
+					await botClient.SendTextMessageAsync(
+						chatId: message.Chat.Id,
+						text: "Gunakan <code>/preview youtoube link </code> atau reply message dengan command <code>/preview</code>",
+						parseMode: ParseMode.Html,
+						replyToMessageId: message.MessageId,
+						cancellationToken: cancellationToken);
+
+					return;
+				}
+
+				Uri? youtubeLink;
+				Uri? previewYoutubeStoryboard;
+
+				if (message.ReplyToMessage?.Text is string repliedToMessage) {
+					youtubeLink = YoutubePreview.ValidateYoutubeLink(repliedToMessage);
+					if (youtubeLink is null) {
+						await botClient.SendTextMessageAsync(
+							chatId: message.Chat.Id,
+							text: "Youtube link tidak valid",
+							parseMode: ParseMode.Html,
+							replyToMessageId: message.MessageId,
+							cancellationToken: cancellationToken);
+
+						return;
+					}
+
+					previewYoutubeStoryboard = await serviceProvider.GetRequiredService<YoutubePreview>().YoutubeStoryBoardAsync(youtubeLink, cancellationToken);
+
+					await botClient.SendPhotoAsync(
+						chatId: message.Chat.Id,
+						photo: previewYoutubeStoryboard.ToString(),
+						replyToMessageId: message.MessageId,
+						parseMode: ParseMode.Html,
+						cancellationToken: cancellationToken);
+				} else if (commandArgument.Length >= 0) {
+					youtubeLink = YoutubePreview.ValidateYoutubeLink(commandArgument);
+					if (youtubeLink is null) {
+						await botClient.SendTextMessageAsync(
+							chatId: message.Chat.Id,
+							text: "Youtube link tidak valid",
+							parseMode: ParseMode.Html,
+							replyToMessageId: message.MessageId,
+							cancellationToken: cancellationToken);
+
+						return;
+					}
+
+					previewYoutubeStoryboard = await serviceProvider.GetRequiredService<YoutubePreview>().YoutubeStoryBoardAsync(youtubeLink, cancellationToken);
+
+					await botClient.SendPhotoAsync(
+						chatId: message.Chat.Id,
+						photo: previewYoutubeStoryboard.ToString(),
+						replyToMessageId: message.MessageId,
+						parseMode: ParseMode.Html,
+						cancellationToken: cancellationToken);
+				}
+			}
+		}
+	}
+}

BotNet.Services/Preview/ServiceCollectionExtensions.cs

@@ -0,0 +1,10 @@
+using Microsoft.Extensions.DependencyInjection;
+
+namespace BotNet.Services.Preview {
+	public static class ServiceCollectionExtensions {
+		public static IServiceCollection AddPreviewServices(this IServiceCollection services) {
+			services.AddTransient<YoutubePreview>();
+			return services;
+		}
+	}
+}

BotNet.Services/Preview/YoutubePreview.cs

@@ -0,0 +1,127 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.Linq;
+using System.Net.Http;
+using System.Text;
+using System.Text.Json.Nodes;
+using System.Text.RegularExpressions;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Web;
+
+namespace BotNet.Services.Preview {
+	public class YoutubePreview : IDisposable {
+		private readonly HttpClientHandler _httpClientHandler;
+		private readonly HttpClient _httpClient;
+		private readonly string _userAgent;
+		private bool _disposedValue;
+
+		public YoutubePreview() {
+			_httpClientHandler = new() {
+				AllowAutoRedirect = false
+			};
+			_userAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/106.0.0.0 Safari/537.36";
+			_httpClient = new(_httpClientHandler);
+			_httpClient.DefaultRequestHeaders.UserAgent.ParseAdd(_userAgent);
+		}
+
+		public static Uri? ValidateYoutubeLink(string message) {
+			return Regex.Matches(message, @"(https?://)?(www.)?youtube.com/watch\?v=[a-zA-Z0-9_-]+")
+				.Select(match => new Uri(match.Value))
+				.FirstOrDefault();
+		}
+
+
+		/// <summary>
+		/// Grid Preview, or in terms of youtube is called storyboard.
+		/// Generally youtube will fetch image when the progress bar is hovered. But fortunately,
+		/// youtube response gave us clue.
+		/// We can get the image from JSON inside their javascript. We only need this link
+		/// eg: https://i.ytimg.com/sb/<id>/storyboard3_L$L/$N.jpg
+		/// 
+		/// We only need to change the id, $L and $N.
+		/// $L and $N is the grid length, 2 is recommended, so it will be
+		/// eg: https://i.ytimg.com/sb/<id>/storyboard3_L2/M2.jpg
+		/// </summary>
+		/// <param name="youtubeLink"></param>
+		/// <param name="cancellationToken"></param>
+		/// <returns></returns>
+		/// <exception cref="InvalidOperationException"></exception>
+		public async Task<Uri> YoutubeStoryBoardAsync(Uri youtubeLink, CancellationToken cancellationToken) {
+			using HttpResponseMessage response = await _httpClient.GetAsync(youtubeLink.ToString(), cancellationToken);
+			response.EnsureSuccessStatusCode();
+			string responseBody = await response.Content.ReadAsStringAsync();
+
+			string jsPattern = @"[^<]*ytInitialPlayerResponse\s*=\s*({.*?});[^<]*<\/script>";
+			Match match = Regex.Match(responseBody, jsPattern, RegexOptions.Singleline);
+
+			if (!match.Success) {
+				throw new InvalidOperationException("Failed to get preview image");
+			}
+
+			string jsonData = match.Groups[1].Value.Trim();
+			if (string.IsNullOrWhiteSpace(jsonData)) {
+				throw new InvalidOperationException("Failed to get JSON data");
+			}
+
+			JsonNode? jsonObject = JsonNode.Parse(jsonData);
+			if (string.IsNullOrWhiteSpace(jsonData)) {
+				throw new InvalidOperationException("Failed parse JSON");
+			}
+
+			JsonNode? storyBoards = jsonObject?["storyboards"]?["playerStoryboardSpecRenderer"]?["spec"];
+			if (storyBoards == null) {
+				throw new InvalidOperationException("Failed to get storyboards link");
+			}
+
+			string storyBoardsLink = storyBoards.ToString();
+
+			Uri uri = new(storyBoardsLink);
+
+			// The "spec" key from storyboard is having a query string with "|" (pipe) delimiter.
+			// Somehow the Uri class cannot read "|" (pipe) delimiter and make the query string chopped.
+			string queryString = storyBoardsLink.TrimStart('?');
+			queryString = queryString.Replace('|', '&');
+			// Parse the query string manually
+			NameValueCollection queryParams = HttpUtility.ParseQueryString(queryString);
+
+			// We need to take last dynamically generated "sigh" key from the querystring
+			string sighQueryKey = storyBoardsLink.Split(@"rs$").Last();
+
+			// We need to take last dynamically generated "sqp" key from the querystring
+			string sqpQueryKey = storyBoardsLink.Split('|').First();
+
+			Uri sqp = new(sqpQueryKey);
+
+			// Currently only L2 and M2 combination.
+			// The other combination L1 - LN and M1 - MN is need different "sigh" query string
+			string path = uri.AbsolutePath.Replace("$L", "2").Replace("$N", "M2");
+
+			// Rebuilt the Uri 
+			Uri storyboardYoutube = new(uri.Scheme + "://" + uri.Host + path + sqp.Query + "&sigh=rs%24" + sighQueryKey);
+
+			return storyboardYoutube;
+
+		}
+
+		protected virtual void Dispose(bool disposing) {
+			if (!_disposedValue) {
+				if (disposing) {
+					// dispose managed state (managed objects)
+					_httpClient.Dispose();
+					_httpClientHandler.Dispose();
+				}
+
+				_disposedValue = true;
+			}
+		}
+
+		public void Dispose() {
+			// Do not change this code. Put cleanup code in 'Dispose(bool disposing)' method
+			Dispose(disposing: true);
+			GC.SuppressFinalize(this);
+		}
+	}
+
+}

BotNet.Tests/Services/Preview/RegexTests.cs

@@ -0,0 +1,45 @@
+using System;
+using BotNet.Services.Preview;
+using FluentAssertions;
+using Xunit;
+
+namespace BotNet.Tests.Services.Preview {
+	public class RegexTests {
+
+		[Theory]
+		[InlineData("https://www.youtube.com/watch?v=wUGbUERmhJM&t=2711s", "https://www.youtube.com/watch?v=wUGbUERmhJM")]
+		[InlineData("https://www.youtube.com/watch?v=L8JJernNrS8", "https://www.youtube.com/watch?v=L8JJernNrS8")]
+		[InlineData("https://www.youtube.com/watch?v=JdqL89ZZwFw", "https://www.youtube.com/watch?v=JdqL89ZZwFw")]
+		public void YoutubeLink(string url, string validLink) {
+			Uri? uri = YoutubePreview.ValidateYoutubeLink(url);
+			uri.Should().Be(validLink);
+		}
+
+		[Theory]
+		[InlineData("https://www.youtube.com/v=wUGbUERmhJM&t=2711s", null)]
+		[InlineData("https://www.youtube.com/?t=2711s", null)]
+		[InlineData("http://www.example.com", null)]
+		public void InvalidYoutubeLink(string url, string? validLink) {
+			Uri? uri = YoutubePreview.ValidateYoutubeLink(url);
+			uri.Should().BeNull(validLink);
+		}
+
+		[Theory]
+		[InlineData("Tonton ini https://www.youtube.com/watch?v=wUGbUERmhJM&t=2711s", "https://www.youtube.com/watch?v=wUGbUERmhJM")]
+		[InlineData("https://www.youtube.com/watch?v=wUGbUERmhJM&t=2711s cocok", "https://www.youtube.com/watch?v=wUGbUERmhJM")]
+		[InlineData("http://www.example.com https://www.youtube.com/watch?v=wUGbUERmhJM&t=2711s", "https://www.youtube.com/watch?v=wUGbUERmhJM")]
+		public void LinkWithMessage(string url, string validLink) {
+			Uri? uri = YoutubePreview.ValidateYoutubeLink(url);
+			uri.Should().Be(validLink);
+		}
+
+		[Theory]
+		[InlineData("Tonton ini https://www.youtube.com/v=wUGbUERmhJM&t=2711s", null)]
+		[InlineData("https://www.youtube.com/?t=2711s cocok", null)]
+		[InlineData("http://www.example.com salah link", null)]
+		public void InvalidLinkWithMessage(string url, string? validLink) {
+			Uri? uri = YoutubePreview.ValidateYoutubeLink(url);
+			uri.Should().BeNull(validLink);
+		}
+	}
+}

BotNet/Bot/UpdateHandler.cs

@@ -290,6 +290,9 @@ await botClient.SendTextMessageAsync(
 								case "/bmkg":
 									await BMKG.GetLatestEarthQuakeAsync(botClient, _serviceProvider, update.Message, cancellationToken);
 									break;
+								case "/preview":
+									await Preview.GetPreviewAsync(botClient, _serviceProvider, update.Message, cancellationToken);
+									break;
 							}
 						}
 						break;

BotNet/Program.cs

@@ -13,6 +13,7 @@
 using BotNet.Services.OpenGraph;
 using BotNet.Services.Piston;
 using BotNet.Services.Pesto;
+using BotNet.Services.Preview;
 using BotNet.Services.ProgrammerHumor;
 using BotNet.Services.Stability;
 using BotNet.Services.Tenor;
@@ -71,6 +72,7 @@
 		services.AddGoogleMaps();
 		services.AddWeatherService();
 		services.AddBMKG();
+		services.AddPreviewServices();
 
 		// Hosted Services
 		services.Configure<BotOptions>(configuration.GetSection("BotOptions"));
@@ -78,7 +80,7 @@
 		services.AddHostedService<BotService>();
 
 		// Telegram Bot
 		services.AddTelegramBot(botToken: configuration["BotOptions:AccessToken"]);
 	})
 	.UseOrleans((hostBuilderContext, siloBuilder) => {
 		siloBuilder