maintain all not synchronized ranks when the ranks get updated

based on Safiro's comment https://www.spigotmc.org/resources/ranksync.61393/reviews#review-269706-89164

api/src/main/java/com/gmail/chickenpowerrr/ranksync/api/rank/RankFactory.java

@@ -67,4 +67,19 @@ public interface RankFactory<R> {
    * Returns the Bot that uses this factory
    */
   Bot<?, R> getBot();
+
+  /**
+   * Adds a RankHelper to validate all ranks
+   *
+   * @param rankHelper the helper that validates if the given ranks exist
+   */
+  void addRankHelper(RankHelper rankHelper);
+
+  /**
+   * Returns if the given rank is a valid platform rank according to the RankHelpers
+   *
+   * @param rank the rank that could be synchronized
+   * @return if the given rank is a valid platform rank according to the RankHelpers
+   */
+  boolean isValidRank(Rank rank);
 }

api/src/main/java/com/gmail/chickenpowerrr/ranksync/api/rank/RankHelper.java

@@ -0,0 +1,37 @@
+package com.gmail.chickenpowerrr.ranksync.api.rank;
+
+import com.gmail.chickenpowerrr.ranksync.api.bot.Bot;
+
+/**
+ * This interface contains the methods needed to validate all given ranks
+ *
+ * @author Chickenpowerrr
+ * @since 1.2.1
+ */
+public interface RankHelper {
+
+  /**
+   * Returns if the given rank has been synchronized over the platforms
+   *
+   * @param bot the bot that could synchronize the rank
+   * @param rank the rank that could be synchronized
+   * @return if the given rank has been synchronized over the platforms
+   */
+  boolean isSynchronized(Bot bot, Rank rank);
+
+  /**
+   * Returns a Rank based on the Bot that is able to give to users and the name of the service's
+   * Rank
+   *
+   * @param bot the running Bot
+   * @param serviceGroupName the name of the Minecraft Rank
+   * @return a Rank based on the Bot that is able to give to users and the name of the Rank
+   */
+  Rank getRank(Bot bot, String serviceGroupName);
+
+  /**
+   * Validates all cached ranks and if they don't exist in the given Bot or service, a message will
+   * be send to the console
+   */
+  void validateRanks();
+}

discord/src/main/java/com/gmail/chickenpowerrr/ranksync/discord/player/Player.java

@@ -97,7 +97,10 @@ public void setRanks(Collection<Rank> ranks) {
     Collection<Role> roles = this.member.getRoles();
 
     Collection<Role> toRemove = new HashSet<>(roles);
-    toRemove.removeIf(role -> ranks.contains(this.rankFactory.getRankFromRole(role)));
+    toRemove.removeIf(role -> {
+      Rank rank = this.rankFactory.getRankFromRole(role);
+      return ranks.contains(rank) || !this.rankFactory.isValidRank(rank);
+    });
 
     Collection<Role> toAdd = this.rankFactory.getRolesFromRanks(ranks);
     toAdd.removeIf(roles::contains);

discord/src/main/java/com/gmail/chickenpowerrr/ranksync/discord/rank/RankFactory.java

@@ -2,15 +2,16 @@
 
 import com.gmail.chickenpowerrr.ranksync.api.bot.Bot;
 import com.gmail.chickenpowerrr.ranksync.api.rank.Rank;
-import lombok.Getter;
-import net.dv8tion.jda.core.entities.Guild;
-import net.dv8tion.jda.core.entities.Role;
-
+import com.gmail.chickenpowerrr.ranksync.api.rank.RankHelper;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
+import lombok.Getter;
+import net.dv8tion.jda.core.entities.Guild;
+import net.dv8tion.jda.core.entities.Role;
 
 /**
  * This class contains the functionalities to get a representation of a Discord role
@@ -25,7 +26,9 @@ public class RankFactory implements com.gmail.chickenpowerrr.ranksync.api.rank.R
   private final Map<Role, Rank> ranks = new HashMap<>();
   private final Map<String, Role> roles = new HashMap<>();
   private final Guild guild;
-  @Getter private final Bot<?, Role> bot;
+  @Getter
+  private final Bot<?, Role> bot;
+  private final Collection<RankHelper> rankHelpers = new HashSet<>();
 
   /**
    * @param bot the Bot that is running
@@ -150,4 +153,26 @@ public Role getRoleFromRank(Rank rank) {
   public Collection<Role> getRolesFromRanks(Collection<Rank> ranks) {
     return ranks.stream().map(this::getRoleFromRank).collect(Collectors.toSet());
   }
+
+  /**
+   * Adds a RankHelper to validate all ranks
+   *
+   * @param rankHelper the helper that validates if the given ranks exist
+   */
+  @Override
+  public void addRankHelper(RankHelper rankHelper) {
+    this.rankHelpers.add(rankHelper);
+  }
+
+  /**
+   * Returns if the given rank is a valid platform rank according to the RankHelpers
+   *
+   * @param rank the rank that could be synchronized
+   * @return if the given rank is a valid platform rank according to the RankHelpers
+   */
+  @Override
+  public boolean isValidRank(Rank rank) {
+    return this.rankHelpers.stream()
+        .anyMatch(rankHelper -> rankHelper.isSynchronized(this.bot, rank));
+  }
 }

spigot/src/main/java/com/gmail/chickenpowerrr/ranksync/spigot/listener/ranksyc/BotEnabledEventListener.java

@@ -22,12 +22,13 @@ public Class<BotEnabledEvent> getTarget() {
   }
 
   /**
-   * Validates the ranks used by this Bot
+   * Validates the ranks used by this Bot and adds the validator to the RankFactory
    *
    * @param event the event that triggered the method
    */
   @Override
   public void onEvent(BotEnabledEvent event) {
     this.rankHelper.validateRanks();
+    event.getBot().getRankFactory().addRankHelper(this.rankHelper);
   }
 }

spigot/src/main/java/com/gmail/chickenpowerrr/ranksync/spigot/roleresource/RankHelper.java

@@ -15,7 +15,7 @@
  * @since 1.0.0
  */
 @Slf4j
-public class RankHelper {
+public class RankHelper implements com.gmail.chickenpowerrr.ranksync.api.rank.RankHelper {
 
   private static final Logger LOGGER = Logger.getLogger(RankHelper.class.getSimpleName());
 
@@ -29,6 +29,19 @@ public RankHelper(Map<String, Map<Bot<?, ?>, String>> ranks) {
     this.ranks = ranks;
   }
 
+  /**
+   * Returns if the given rank has been synchronized over the platforms
+   *
+   * @param bot the bot that could synchronize the rank
+   * @param rank the rank that could be synchronized
+   * @return if the given rank has been synchronized over the platforms
+   */
+  @Override
+  public boolean isSynchronized(Bot bot, Rank rank) {
+    return this.ranks.values().stream()
+        .anyMatch((map) -> map.containsKey(bot) && map.get(bot).equalsIgnoreCase(rank.getName()));
+  }
+
   /**
    * Returns a Rank based on the Bot that is able to give to users and the name of the Minecraft
    * Rank
@@ -38,7 +51,7 @@ public RankHelper(Map<String, Map<Bot<?, ?>, String>> ranks) {
    * @return a Rank based on the Bot that is able to give to users and the name of the Rank
    */
   @SuppressWarnings("unchecked")
-  Rank getRank(Bot bot, String minecraftGroupName) {
+  public Rank getRank(Bot bot, String minecraftGroupName) {
     if (this.ranks.containsKey(minecraftGroupName) && this.ranks.get(minecraftGroupName)
         .containsKey(bot)) {
       return bot.getRankFactory().getRankFromRole(
@@ -49,9 +62,10 @@ Rank getRank(Bot bot, String minecraftGroupName) {
   }
 
   /**
-   * Validates all cached and if they don't exist in the given Bot or Minecraft server, a message
-   * will be send to the console
+   * Validates all cached ranks and if they don't exist in the given Bot or Minecraft server, a
+   * message will be send to the console
    */
+  @Override
   public void validateRanks() {
     this.ranks.forEach((minecraftRank, syncedRanks) -> {
       AtomicBoolean minecraftChecked = new AtomicBoolean(false);