Add slash command mentions

src/main/java/net/dv8tion/jda/api/entities/Mentions.java

@@ -20,6 +20,7 @@
 import net.dv8tion.jda.api.entities.channel.concrete.PrivateChannel;
 import net.dv8tion.jda.api.entities.channel.middleman.GuildChannel;
 import net.dv8tion.jda.api.entities.emoji.CustomEmoji;
+import net.dv8tion.jda.api.interactions.commands.SlashCommandReference;
 import org.apache.commons.collections4.Bag;
 
 import javax.annotation.Nonnull;
@@ -325,6 +326,48 @@ public interface Mentions
     @Nonnull
     Bag<Member> getMembersBag();
 
+    /**
+     * An immutable list of all mentioned {@link SlashCommandReference slash commands}.
+     * <br>If none were mentioned, this list is empty. Elements are sorted in order of appearance.
+     *
+     * <p>Be aware these mentions could be not mentioning an actual command
+     *
+     * @return Immutable list of mentioned slash commands, or an empty list
+     */
+    @Nonnull
+    List<SlashCommandReference> getSlashCommands();
+
+    /**
+     * A {@link org.apache.commons.collections4.Bag Bag} of mentioned {@link SlashCommandReference slash commands}.
+     * <br>This can be used to retrieve the amount of times a slash commands was mentioned.
+     *
+     * <p>Be aware these mentions could be not mentioning an actual command
+     *
+     * <p><b>Example</b><br>
+     * <pre>{@code
+     * void sendCount(Message msg)
+     * {
+     *     List<SlashCommandReference> mentions = msg.getMentions().getSlashCommands(); // distinct list, in order of appearance
+     *     Bag<SlashCommandReference> count = msg.getMentions().getSlashCommandsBag();
+     *     StringBuilder content = new StringBuilder();
+     *     for (SlashCommandReference commandRef : mentions)
+     *     {
+     *         content.append(commandRef.getAsMention())
+     *                .append(": ")
+     *                .append(count.getCount(commandRef))
+     *                .append("\n");
+     *     }
+     *     msg.getChannel().sendMessage(content.toString()).queue();
+     * }
+     * }</pre>
+     *
+     * @return {@link org.apache.commons.collections4.Bag Bag} of mentioned slash commands
+     *
+     * @see    #getSlashCommands()
+     */
+    @Nonnull
+    Bag<SlashCommandReference> getSlashCommandsBag();
+
     /**
      * Combines all instances of {@link net.dv8tion.jda.api.entities.IMentionable IMentionable}
      * filtered by the specified {@link net.dv8tion.jda.api.entities.Message.MentionType MentionType} values.

src/main/java/net/dv8tion/jda/api/entities/Message.java

@@ -1990,7 +1990,13 @@ enum MentionType
         /**
          * Represents a mention for all users in a server, literal {@code @everyone}.
          */
-        EVERYONE("@everyone", "everyone");
+        EVERYONE("@everyone", "everyone"),
+        /**
+         * Represents a mention for a slash command.
+         * <br>The first group is the command name, the second group is the subcommand group (nullable),
+         * the third group is the subcommand (nullable), and the fourth group is the command ID.
+         */
+        SLASH_COMMAND("</([\\w-]+)(?> ([\\w-]+))??(?> ([\\w-]+))?:(\\d+)>", null);
 
         private final Pattern pattern;
         private final String parseKey;

src/main/java/net/dv8tion/jda/api/interactions/commands/Command.java

@@ -48,7 +48,7 @@
  * @see Guild#retrieveCommandById(String)
  * @see Guild#retrieveCommands()
  */
-public interface Command extends ISnowflake
+public interface Command extends ISnowflake, ICommandReference
 {
     /**
      * Delete this command.
@@ -830,22 +830,35 @@ public String toString()
     /**
      * An Subcommand for a command.
      */
-    class Subcommand
+    class Subcommand implements ICommandReference
     {
+        private final ICommandReference parentCommand; //Could be Command or SubcommandGroup
         private final String name, description;
         private final LocalizationMap nameLocalizations;
         private final LocalizationMap descriptionLocalizations;
         private final List<Option> options;
 
-        public Subcommand(DataObject json)
+        public Subcommand(ICommandReference parentCommand, DataObject json)
         {
+            this.parentCommand = parentCommand;
             this.name = json.getString("name");
             this.nameLocalizations = LocalizationUtils.unmodifiableFromProperty(json, "name_localizations");
             this.description = json.getString("description");
             this.descriptionLocalizations = LocalizationUtils.unmodifiableFromProperty(json, "description_localizations");
             this.options = CommandImpl.parseOptions(json, CommandImpl.OPTION_TEST, Option::new);
         }
 
+        /**
+         * {@inheritDoc}
+         *
+         * <p><b>This will return the ID of the top level command</b>
+         */
+        @Override
+        public long getIdLong()
+        {
+            return parentCommand.getIdLong();
+        }
+
         /**
          * The name of this subcommand.
          *
@@ -868,6 +881,13 @@ public LocalizationMap getNameLocalizations()
             return nameLocalizations;
         }
 
+        @Nonnull
+        @Override
+        public String getCommandPath()
+        {
+            return parentCommand.getCommandPath() + " " + getName();
+        }
+
         /**
          * The description of this subcommand.
          *
@@ -928,20 +948,33 @@ public String toString()
     /**
      * An Subcommand Group for a command.
      */
-    class SubcommandGroup
+    class SubcommandGroup implements ICommandReference
     {
+        private final Command parentCommand;
         private final String name, description;
         private final LocalizationMap nameLocalizations;
         private final LocalizationMap descriptionLocalizations;
         private final List<Subcommand> subcommands;
 
-        public SubcommandGroup(DataObject json)
+        public SubcommandGroup(Command parentCommand, DataObject json)
         {
+            this.parentCommand = parentCommand;
             this.name = json.getString("name");
             this.nameLocalizations = LocalizationUtils.unmodifiableFromProperty(json, "name_localizations");
             this.description = json.getString("description");
             this.descriptionLocalizations = LocalizationUtils.unmodifiableFromProperty(json, "description_localizations");
-            this.subcommands = CommandImpl.parseOptions(json, CommandImpl.SUBCOMMAND_TEST, Subcommand::new);
+            this.subcommands = CommandImpl.parseOptions(json, CommandImpl.SUBCOMMAND_TEST, (DataObject o) -> new Subcommand(this, o));
+        }
+
+        /**
+         * {@inheritDoc}
+         *
+         * <p><b>This will return the ID of the top level command</b>
+         */
+        @Override
+        public long getIdLong()
+        {
+            return parentCommand.getIdLong();
         }
 
         /**
@@ -966,6 +999,13 @@ public LocalizationMap getNameLocalizations()
             return nameLocalizations;
         }
 
+        @Nonnull
+        @Override
+        public String getCommandPath()
+        {
+            return parentCommand.getCommandPath() + " " + getName();
+        }
+
         /**
          * The description of this subcommand group.
          *

src/main/java/net/dv8tion/jda/api/interactions/commands/ICommandReference.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2015 Austin Keener, Michael Ritter, Florian Spieß, and the JDA contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.dv8tion.jda.api.interactions.commands;
+
+import net.dv8tion.jda.api.entities.IMentionable;
+
+import javax.annotation.Nonnull;
+
+/**
+ * Represents a mentionable slash command.
+ */
+public interface ICommandReference extends IMentionable
+{
+    /**
+     * Returns the name of the slash command
+     *
+     * @return the name of the slash command
+     */
+    @Nonnull
+    String getName();
+
+    /**
+     * Returns the entire path (separated with spaces) of this command
+     *
+     * @return the entire path (separated with spaces) of this command
+     */
+    @Nonnull
+    String getCommandPath();
+
+    /**
+     * {@inheritDoc}
+     *
+     * <p><b>This will only work on slash commands!</b>
+     *
+     * @throws IllegalStateException
+     *         If the command is not a slash command (i.e. not of type {@link Command.Type#SLASH})
+     */
+    @Nonnull
+    @Override
+    default String getAsMention()
+    {
+        return "</" + getCommandPath() + ":" + getIdLong() + ">";
+    }
+}

src/main/java/net/dv8tion/jda/api/interactions/commands/SlashCommandReference.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2015 Austin Keener, Michael Ritter, Florian Spieß, and the JDA contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.dv8tion.jda.api.interactions.commands;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.util.Objects;
+import java.util.StringJoiner;
+
+/**
+ * Represents a slash command mention, such as {@code </ban soft:1021082477038678126>}
+ */
+public class SlashCommandReference implements ICommandReference
+{
+    private final long id;
+    private final String name;
+    private final String subcommand;
+    private final String subcommandGroup;
+
+    public SlashCommandReference(String name, String subcommandGroup, String subcommand, long id)
+    {
+        this.name = name;
+        this.subcommandGroup = subcommandGroup;
+        this.subcommand = subcommand;
+        this.id = id;
+    }
+
+    @Override
+    public long getIdLong()
+    {
+        return id;
+    }
+
+    @Nonnull
+    @Override
+    public String getName()
+    {
+        return name;
+    }
+
+    /**
+     * Returns the subcommand of the slash command
+     *
+     * @return the subcommand of the slash command
+     */
+    @Nullable
+    public String getSubcommand()
+    {
+        return subcommand;
+    }
+
+    /**
+     * Returns the subcommand group of the slash command
+     *
+     * @return the subcommand group of the slash command
+     */
+    @Nullable
+    public String getSubcommandGroup()
+    {
+        return subcommandGroup;
+    }
+
+    @Nonnull
+    @Override
+    public String getCommandPath()
+    {
+        final StringJoiner joiner = new StringJoiner(" ");
+        joiner.add(name);
+        if (subcommandGroup != null)
+            joiner.add(subcommandGroup);
+        if (subcommand != null)
+            joiner.add(subcommand);
+
+        return joiner.toString();
+    }
+
+    @Override
+    public String toString()
+    {
+        return "SlashCommandReference: " + getCommandPath() + " (" + getId() + ")";
+    }
+
+    @Override
+    public boolean equals(Object o)
+    {
+        if (this == o) return true;
+        if (!(o instanceof SlashCommandReference)) return false;
+
+        SlashCommandReference that = (SlashCommandReference) o;
+
+        if (id != that.id) return false;
+        if (!name.equals(that.name)) return false;
+        if (!Objects.equals(subcommand, that.subcommand)) return false;
+        return Objects.equals(subcommandGroup, that.subcommandGroup);
+    }
+
+    @Override
+    public int hashCode()
+    {
+        int result = Long.hashCode(id);
+        result = 31 * result + name.hashCode();
+        result = 31 * result + (subcommand != null ? subcommand.hashCode() : 0);
+        result = 31 * result + (subcommandGroup != null ? subcommandGroup.hashCode() : 0);
+        return result;
+    }
+}