168 lines
6.2 KiB
C#
168 lines
6.2 KiB
C#
using System.Diagnostics;
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using System.Net;
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using System.Net.Http;
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using System.Text;
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using System.Text.Json;
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using ytLive.Models;
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namespace ytLive.Services;
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/// <summary>
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/// Handles YouTube OAuth2 authentication flow.
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/// Uses a local HTTP listener for the redirect callback.
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/// </summary>
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public class YouTubeAuthService
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{
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private const string AuthorizationEndpoint = "https://accounts.google.com/o/oauth2/v2/auth";
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private const string TokenEndpoint = "https://oauth2.googleapis.com/token";
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private const string Scope = "https://www.googleapis.com/auth/youtube https://www.googleapis.com/auth/youtube.force-ssl";
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private readonly string _clientId;
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private readonly string _clientSecret;
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private readonly HttpClient _http = new();
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public YouTubeChannel? CurrentChannel { get; private set; }
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public YouTubeAuthService(string clientId, string clientSecret)
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{
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_clientId = clientId;
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_clientSecret = clientSecret;
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}
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public string GetAuthorizationUrl(string redirectUri)
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{
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var query = new[]
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{
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("client_id", _clientId),
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("redirect_uri", redirectUri),
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("response_type", "code"),
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("scope", Scope),
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("access_type", "offline"),
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("prompt", "consent"),
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};
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var encoded = string.Join("&", query.Select(kv =>
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$"{Uri.EscapeDataString(kv.Item1)}={Uri.EscapeDataString(kv.Item2)}"));
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return $"{AuthorizationEndpoint}?{encoded}";
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}
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public async Task<YouTubeChannel?> AuthenticateAsync()
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{
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const int port = 8765;
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var redirectUri = $"http://localhost:{port}/oauth2/callback";
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if (string.IsNullOrWhiteSpace(_clientId) || string.IsNullOrWhiteSpace(_clientSecret))
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return null;
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using var listener = new HttpListener();
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listener.Prefixes.Add($"{redirectUri}/");
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listener.Start();
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Process.Start(new ProcessStartInfo(GetAuthorizationUrl(redirectUri)) { UseShellExecute = true });
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HttpListenerContext context;
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try
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{
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using var cts = new CancellationTokenSource(TimeSpan.FromMinutes(5));
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context = await listener.GetContextAsync().WaitAsync(cts.Token);
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}
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catch (OperationCanceledException)
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{
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return null;
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}
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var code = context.Request.QueryString["code"];
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var error = context.Request.QueryString["error"];
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var html = error != null
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? "<html><body style=\"font-family:sans-serif\"><h2>Sign-in failed</h2><p>You can close this window and return to ytLlive.</p></body></html>"
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: "<html><body style=\"font-family:sans-serif\"><h2>Sign-in successful!</h2><p>You can close this window and return to ytLlive.</p></body></html>";
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var buffer = Encoding.UTF8.GetBytes(html);
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context.Response.ContentType = "text/html; charset=utf-8";
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context.Response.ContentLength64 = buffer.Length;
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await context.Response.OutputStream.WriteAsync(buffer);
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context.Response.Close();
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if (error != null || string.IsNullOrEmpty(code))
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return null;
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return await ExchangeCodeForToken(code, redirectUri);
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}
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public async Task<YouTubeChannel?> ExchangeCodeForToken(string code, string redirectUri)
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{
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var body = new FormUrlEncodedContent(new Dictionary<string, string>
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{
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["code"] = code,
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["client_id"] = _clientId,
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["client_secret"] = _clientSecret,
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["redirect_uri"] = redirectUri,
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["grant_type"] = "authorization_code"
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});
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var response = await _http.PostAsync(TokenEndpoint, body);
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if (!response.IsSuccessStatusCode)
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return null;
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var json = await response.Content.ReadAsStringAsync();
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var tokenData = JsonSerializer.Deserialize<JsonElement>(json);
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var accessToken = tokenData.GetProperty("access_token").GetString()!;
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var refreshToken = tokenData.GetProperty("refresh_token").GetString()!;
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var expiresIn = tokenData.GetProperty("expires_in").GetInt32();
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// Fetch channel info
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return await FetchChannelInfo(accessToken, refreshToken, expiresIn);
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}
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public async Task<bool> RefreshToken()
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{
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if (CurrentChannel == null) return false;
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var body = new FormUrlEncodedContent(new Dictionary<string, string>
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{
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["refresh_token"] = CurrentChannel.RefreshToken,
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["client_id"] = _clientId,
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["client_secret"] = _clientSecret,
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["grant_type"] = "refresh_token"
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});
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var response = await _http.PostAsync(TokenEndpoint, body);
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if (!response.IsSuccessStatusCode) return false;
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var json = await response.Content.ReadAsStringAsync();
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var tokenData = JsonSerializer.Deserialize<JsonElement>(json);
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CurrentChannel.AccessToken = tokenData.GetProperty("access_token").GetString()!;
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CurrentChannel.TokenExpiry = DateTime.UtcNow.AddSeconds(tokenData.GetProperty("expires_in").GetInt32());
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return true;
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}
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private async Task<YouTubeChannel?> FetchChannelInfo(string accessToken, string refreshToken, int expiresIn)
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{
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_http.DefaultRequestHeaders.Authorization = new("Bearer", accessToken);
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var response = await _http.GetAsync("https://www.googleapis.com/youtube/v3/channels?part=snippet&mine=true");
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if (!response.IsSuccessStatusCode) return null;
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var json = await response.Content.ReadAsStringAsync();
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var data = JsonSerializer.Deserialize<JsonElement>(json);
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var items = data.GetProperty("items");
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if (items.GetArrayLength() == 0) return null;
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var snippet = items[0].GetProperty("snippet");
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CurrentChannel = new YouTubeChannel
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{
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ChannelId = items[0].GetProperty("id").GetString()!,
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DisplayName = snippet.GetProperty("title").GetString()!,
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ProfileImageUrl = snippet.GetProperty("thumbnails").GetProperty("default").GetProperty("url").GetString()!,
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AccessToken = accessToken,
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RefreshToken = refreshToken,
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TokenExpiry = DateTime.UtcNow.AddSeconds(expiresIn)
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};
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return CurrentChannel;
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}
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}
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