Implemented a SpotifyAuthorizationCredential Wrapper class

Hopefully fixes #17 by checking for access token validity before refreshing.

src/main/java/de/b00tload/tools/lastfmtospotifyplaylist/LastFMToSpotify.java

@@ -6,6 +6,7 @@ import de.b00tload.tools.lastfmtospotifyplaylist.arguments.ArgumentHandler;
 import de.b00tload.tools.lastfmtospotifyplaylist.arguments.Arguments;
 import de.b00tload.tools.lastfmtospotifyplaylist.util.PeriodHelper;
 
+import de.b00tload.tools.lastfmtospotifyplaylist.util.SpotifyCredentials;
 import de.b00tload.tools.lastfmtospotifyplaylist.util.TokenHelper;
 import de.umass.lastfm.Caller;
 import de.umass.lastfm.Track;
@@ -14,7 +15,6 @@ import io.javalin.Javalin;
 import io.javalin.http.ContentType;
 import io.javalin.http.HttpStatus;
 import se.michaelthelin.spotify.SpotifyApi;
-import se.michaelthelin.spotify.model_objects.credentials.AuthorizationCodeCredentials;
 import se.michaelthelin.spotify.model_objects.specification.Playlist;
 
 import java.net.URI;
@@ -82,12 +82,18 @@ public class LastFMToSpotify {
             AtomicBoolean waiting = new AtomicBoolean(true);
             if (configuration.containsKey("cache.crypto") && TokenHelper.existsTokens()) {
                 logLn("Cached credentials have been found.", 2);
-                logLn("Fetching old credentials, refreshing them and saving to cache", 2);
-                AuthorizationCodeCredentials oldcred = TokenHelper.fetchTokens();
+                logLn("Fetching credentials from cache.", 2);
+                SpotifyCredentials oldcred = TokenHelper.fetchTokens();
                 api.setRefreshToken(oldcred.getRefreshToken());
-                AuthorizationCodeCredentials newcred = api.authorizationCodeRefresh().build().execute();
-                TokenHelper.saveTokens(newcred);
-                configuration.put("spotify.access", newcred.getAccessToken());
+                SpotifyCredentials cred;
+                if(oldcred.isValid()){
+                    cred=oldcred;
+                } else {
+                    logLn("Cached credentials are invalid due to age. Refreshing and saving to cache", 2);
+                    cred = new SpotifyCredentials(api.authorizationCodeRefresh().build().execute());
+                    TokenHelper.saveTokens(cred);
+                }
+                configuration.put("spotify.access", cred.getAccessToken());
             } else {
                 try (Javalin webserver = Javalin.create().start(9876)) {
                     if (configuration.containsKey("cache.crypto")) logLn("No cached credentials have been found.", 2);
@@ -99,7 +105,7 @@ public class LastFMToSpotify {
                     webserver.get("/callback/spotify", ctx -> {
                         if(ctx.queryParamMap().containsKey("code")) {
                             logLn("Received spotify authentication code. Requesting credentials.", 2);
-                            AuthorizationCodeCredentials cred = api.authorizationCode(ctx.queryParam("code")).setHeader("User-Agent", configuration.get("requests.useragent")).build().execute();
+                            SpotifyCredentials cred = new SpotifyCredentials(api.authorizationCode(ctx.queryParam("code")).setHeader("User-Agent", configuration.get("requests.useragent")).build().execute());
                             configuration.put("spotify.access", cred.getAccessToken());
                             if(configuration.containsKey("cache.crypto")) {
                                 logLn("Saving credentials to cache.", 2);

src/main/java/de/b00tload/tools/lastfmtospotifyplaylist/util/SpotifyCredentials.java

@@ -0,0 +1,34 @@
+package de.b00tload.tools.lastfmtospotifyplaylist.util;
+import se.michaelthelin.spotify.model_objects.credentials.AuthorizationCodeCredentials;
+
+import java.io.Serializable;
+import java.time.Clock;
+import java.time.LocalDateTime;
+
+public class SpotifyCredentials implements Serializable {
+
+    private final AuthorizationCodeCredentials cred;
+    private final LocalDateTime validUntil;
+
+    public SpotifyCredentials(AuthorizationCodeCredentials cred){
+        this.cred = cred;
+        this.validUntil = LocalDateTime.now(Clock.systemDefaultZone()).plusSeconds(cred.getExpiresIn());
+    }
+
+    public String getAccessToken(){
+        return cred.getAccessToken();
+    }
+
+    public String getRefreshToken(){
+        return cred.getRefreshToken();
+    }
+
+    public LocalDateTime getValidUntil(){
+        return validUntil;
+    }
+
+    public boolean isValid(){
+        return LocalDateTime.now(Clock.systemDefaultZone()).isBefore(validUntil);
+    }
+
+}

src/main/java/de/b00tload/tools/lastfmtospotifyplaylist/util/TokenHelper.java

@@ -1,7 +1,5 @@
 package de.b00tload.tools.lastfmtospotifyplaylist.util;
 
-import se.michaelthelin.spotify.model_objects.credentials.AuthorizationCodeCredentials;
-
 import java.nio.file.Path;
 
 import static de.b00tload.tools.lastfmtospotifyplaylist.LastFMToSpotify.USER_HOME;
@@ -10,23 +8,23 @@ import static de.b00tload.tools.lastfmtospotifyplaylist.LastFMToSpotify.configur
 public class TokenHelper {
 
     /**
-     * Manages saving a <code>se.michaelthelin.spotify.model_objects.credentials.AuthorizationCodeCredentials</code> into "~/.lfm2s/spotify.lfm2scred" using <code>de.b00tload.tools.lastfmtospotifyplaylist.util.CryptoHelper.serializeEncrypted(...)</code>
-     * @param cred The <code>se.michaelthelin.spotify.model_objects.credentials.AuthorizationCodeCredentials</code> to be saved
+     * Manages saving a <codede.b00tload.tools.lastfmtospotifyplaylist.util.SpotifyCredentials</code> into "~/.lfm2s/spotify.lfm2scred" using <code>de.b00tload.tools.lastfmtospotifyplaylist.util.CryptoHelper.serializeEncrypted(...)</code>
+     * @param cred The <code>de.b00tload.tools.lastfmtospotifyplaylist.util.SpotifyCredentials</code> to be saved
      */
-    public static void saveTokens(AuthorizationCodeCredentials cred) {
+    public static void saveTokens(SpotifyCredentials cred) {
         CryptoHelper.serializeEncrypted(cred, Path.of(USER_HOME, "/.lfm2s/spotify.lfm2scred"), CryptoHelper.createKeyFromPassword(configuration.get("cache.crypto")));
     }
 
     /**
-     * Manages retrieving a <code>se.michaelthelin.spotify.model_objects.credentials.AuthorizationCodeCredentials</code> from "~/.lfm2s/spotify.lfm2scred" using <code>de.b00tload.tools.lastfmtospotifyplaylist.util.CryptoHelper.deserializeEncrypted(...)</code>
-     * @return The retrieved <code>se.michaelthelin.spotify.model_objects.credentials.AuthorizationCodeCredentials</code>
+     * Manages retrieving a <code>de.b00tload.tools.lastfmtospotifyplaylist.util.SpotifyCredentials</code> from "~/.lfm2s/spotify.lfm2scred" using <code>de.b00tload.tools.lastfmtospotifyplaylist.util.CryptoHelper.deserializeEncrypted(...)</code>
+     * @return The retrieved <code>de.b00tload.tools.lastfmtospotifyplaylist.util.SpotifyCredentials</code>
      */
-    public static AuthorizationCodeCredentials fetchTokens() {
-        return (AuthorizationCodeCredentials) CryptoHelper.deserializeEncrypted(Path.of(USER_HOME, "/.lfm2s/spotify.lfm2scred"), CryptoHelper.createKeyFromPassword(configuration.get("cache.crypto")));
+    public static SpotifyCredentials fetchTokens() {
+        return (SpotifyCredentials) CryptoHelper.deserializeEncrypted(Path.of(USER_HOME, "/.lfm2s/spotify.lfm2scred"), CryptoHelper.createKeyFromPassword(configuration.get("cache.crypto")));
     }
 
     /**
-     * Checks whether the saved spotify AuthorizationCodeCredentials at "~/.lfm2s/spotify.lfm2scred" exist
+     * Checks whether the saved SpotifyCredentials at "~/.lfm2s/spotify.lfm2scred" exist
      * @return true if file exists, false if not
      */
     public static boolean existsTokens(){