Implement spotify token and refresh flow from configuration

* makes headless usage of sldl easier #42
* fallback to outputting login flow URL if opening a browser fails (in headless environment)
* output token and refresh token on login complete
* parse token and refresh token from config and attempt to use before invoking login flow

README.md

@@ -126,6 +126,8 @@ Usage: sldl <input> [OPTIONS]
   Spotify
     --spotify-id <id>              spotify client ID
     --spotify-secret <secret>      spotify client secret
+    --spotify-token <token>        spotify access token
+    --spotify-refresh <token>      spotify refresh token
     --remove-from-source           Remove downloaded tracks from source playlist
 ```
 ```
@@ -243,10 +245,26 @@ Tip: For playlists containing music videos, it may be better to remove all text
 
 ### Spotify
 A playlist/album url or 'spotify-likes': Download a spotify playlist, album, or your
-liked songs. --spotify-id and --spotify-secret are required in addition when downloading
+liked songs. Credentials are required when downloading a private playlist or liked music.
-a private playlist or liked music.
+
-The id and secret can be obtained at https://developer.spotify.com/dashboard/applications.
+#### Using Credential/Application
-Create an app and add http://localhost:48721/callback as a redirect url in its settings.
+
+Create a [Spotify application](https://developer.spotify.com/dashboard/applications) with a redirect url of `http://localhost:48721/callback`. Obtain an application **ID** and **Secret** from the created application dashboard.
+
+Start sldl with the obtained credentials and an authorized action to trigger the Spotify app login flow:
+
+```shell
+sldl spotify-likes --number 1 --spotify-id 123456 --spotify-secret 123456 ...
+```
+sldl will try to open a browser automatically but will fallback to logging the login flow URL to output. After login flow is complete sldl will output a **Token** and **Refresh Token** and finish running the current command.
+
+To skip requiring login flow every time `sldl` is used the **Token** and **Refresh Token** can be provided to sldl (hint: use `--config` and store this info in the config file to make commands less verbose):
+
+```shell
+sldl spotify-likes --number 1 --spotify-id 123456 --spotify-secret 123456 --spotify-refresh 123456 --spotify-token 123456 ...
+```
+
+`spotify-token` access is only valid for 1 hour. `spotify-refresh` will enable sldl to renew access every time it is run (and can be used without including `spotify-token`)
 
 ### Bandcamp
 An bandcamp url: Download a single track, and album, or an artist's entire discography. 

slsk-batchdl/Config.cs

@@ -30,6 +30,8 @@ static class Config
     public static string defaultFolderName = "";
     public static string spotifyId = "";
     public static string spotifySecret = "";
+    public static string spotifyToken = "";
+    public static string spotifyRefresh = "";
     public static string ytKey = "";
     public static string username = "";
     public static string password = "";
@@ -642,6 +644,14 @@ static class Config
                     case "--spotify-secret":
                         spotifySecret = args[++i];
                         break;
+                    case "--stk":
+                    case "--spotify-token":
+                        spotifyToken = args[++i];
+                        break;
+                    case "--str":
+                    case "--spotify-refresh":
+                        spotifyRefresh = args[++i];
+                        break;
                     case "--yk":
                     case "--youtube-key":
                         ytKey = args[++i];

slsk-batchdl/Extractors/Spotify.cs

@@ -4,6 +4,7 @@ using Swan;
 
 using Data;
 using Enums;
+using System.Security;
 
 namespace Extractors
 {
@@ -34,15 +35,19 @@ namespace Extractors
                 Config.spotifyId = Console.ReadLine();
                 Console.Write("Spotify client secret:");
                 Config.spotifySecret = Console.ReadLine();
+                Console.Write("Spotify token:");
+                Config.spotifyToken = Console.ReadLine();
+                Console.Write("Spotify refresh token:");
+                Config.spotifyRefresh = Console.ReadLine();
                 Console.WriteLine();
             }
 
-            if (needLogin && (Config.spotifyId.Length == 0 || Config.spotifySecret.Length == 0))
+            if (needLogin && Config.spotifyToken.Length == 0 && (Config.spotifyId.Length == 0 || Config.spotifySecret.Length == 0))
             {
                 readSpotifyCreds();
             }
 
-            spotifyClient = new Spotify(Config.spotifyId, Config.spotifySecret);
+            spotifyClient = new Spotify(Config.spotifyId, Config.spotifySecret, Config.spotifyToken, Config.spotifyRefresh);
             await spotifyClient.Authorize(needLogin, Config.removeTracksFromSource);
 
             if (Config.input == "spotify-likes")
@@ -132,6 +137,8 @@ namespace Extractors
         private EmbedIOAuthServer _server;
         private readonly string _clientId;
         private readonly string _clientSecret;
+        private string _clientToken;
+        private string _clientRefreshToken;
         private SpotifyClient? _client;
         private bool loggedIn = false;
 
@@ -140,12 +147,14 @@ namespace Extractors
         public const string encodedSpotifySecret = "Y2JlM2QxYTE5MzJkNDQ2MmFiOGUy3shTuf4Y2JhY2M3ZDdjYWU=";
         public bool UsedDefaultCredentials { get; private set; }
 
-        public Spotify(string clientId = "", string clientSecret = "")
+        public Spotify(string clientId = "", string clientSecret = "", string token = "", string refreshToken = "")
         {
             _clientId = clientId;
             _clientSecret = clientSecret;
+            _clientToken = token;
+            _clientRefreshToken = refreshToken;
 
-            if (_clientId.Length == 0 || _clientSecret.Length == 0)
+            if (_clientToken.Length == 0 && (_clientId.Length == 0 || _clientSecret.Length == 0))
             {
                 _clientId = System.Text.Encoding.UTF8.GetString(Convert.FromBase64String(encodedSpotifyId.Replace("1bLaH9", "")));
                 _clientSecret = System.Text.Encoding.UTF8.GetString(Convert.FromBase64String(encodedSpotifySecret.Replace("3shTuf4", "")));
@@ -172,6 +181,15 @@ namespace Extractors
                 _server = new EmbedIOAuthServer(new Uri("http://localhost:48721/callback"), 48721);
                 await _server.Start();
 
+                var existingOk = false;
+                if (_clientToken.Length != 0 || _clientRefreshToken.Length != 0)
+                {
+                    existingOk = await this.TryExistingToken();
+                    loggedIn = true;
+                    //new OAuthClient(config).RequestToken()
+                }
+                if (!existingOk)
+                {
                     _server.AuthorizationCodeReceived += OnAuthorizationCodeReceived;
                     _server.ErrorReceived += OnErrorReceived;
 
@@ -187,12 +205,67 @@ namespace Extractors
 
                     var request = new LoginRequest(_server.BaseUri, _clientId, LoginRequest.ResponseType.Code) { Scope = scope };
 
+                    try
+                    {
                         BrowserUtil.Open(request.ToUri());
+                    }
+                    catch (Exception)
+                    {
+                        Console.WriteLine("Unable to open URL, manually open: {0}", request.ToUri());
+                    }
+                }
 
                 await IsClientReady();
             }
         }
 
+        private async Task<bool> TryExistingToken() 
+        {
+            if (_clientToken.Length != 0)
+            {
+                Console.WriteLine("Testing Spotify access with existing token...");
+                var client = new SpotifyClient(_clientToken);
+                try
+                {
+                    var me = await client.UserProfile.Current();
+                    Console.WriteLine("Spotify access is good!");
+                    _client = client;
+                    return true;
+                }
+                catch (Exception ex)
+                {
+                    Console.WriteLine($"Could not make an API call with existing token: {ex}");
+                }
+            }
+            if (_clientRefreshToken.Length != 0)
+            {
+                Console.WriteLine("Trying to renew access with refresh token...");
+            //     var refreshRequest = new TokenSwapRefreshRequest(
+            //     new Uri("http://localhost:48721/refresh"),
+            //     _clientRefreshToken
+            // );
+            var refreshRequest = new AuthorizationCodeRefreshRequest(_clientId, _clientSecret, _clientRefreshToken);
+                try
+                {
+                    var oauthClient = new OAuthClient();
+                    var refreshResponse = await oauthClient.RequestToken(refreshRequest);
+                    Console.WriteLine($"We got a new refreshed access token from server: {refreshResponse.AccessToken}");
+                    _clientToken = refreshResponse.AccessToken;
+                    _client = new SpotifyClient(_clientToken);
+                    return true;
+                }
+                catch (Exception ex)
+                {
+                    Console.WriteLine($"Could not refresh access token with refresh token: {ex}");
+                }
+            } else {
+                Console.WriteLine("No refresh token present, cannot refresh existing access");
+            }
+
+            Console.WriteLine("Not possible to access Spotify API without login! Falling back to login flow...");
+            return false;
+        }
+
         private async Task OnAuthorizationCodeReceived(object sender, AuthorizationCodeResponse response)
         {
             await _server.Stop();
@@ -204,6 +277,11 @@ namespace Extractors
                 )
             );
 
+            Console.WriteLine("Spotify token: " + tokenResponse.AccessToken);
+            _clientToken = tokenResponse.AccessToken;
+            Console.WriteLine("Spotify refresh token: " + tokenResponse.RefreshToken);
+            _clientRefreshToken = tokenResponse.RefreshToken;
+
             _client = new SpotifyClient(tokenResponse.AccessToken);
             loggedIn = true;
         }