feat: add MultiMonthGiftRedeemEvent

chat/src/main/java/com/github/twitch4j/chat/events/IRCEventHandler.java

@@ -201,8 +201,12 @@ public void onChannelSubscription(IRCMessageEvent event) {
         if (event.getCommandType().equals("USERNOTICE") && (msgId = event.getTags().get("msg-id")) != null) {
             EventChannel channel = event.getChannel();
 
+            // Resub message for a multi-month gifted subscription
+            if (msgId.equalsIgnoreCase("resub") && "true".equalsIgnoreCase(event.getTags().get("msg-param-was-gifted"))) {
+                eventManager.publish(new MultiMonthGiftRedeemEvent(event));
+            }
             // Sub
-            if (msgId.equalsIgnoreCase("sub") || msgId.equalsIgnoreCase("resub")) {
+            else if (msgId.equalsIgnoreCase("sub") || msgId.equalsIgnoreCase("resub")) {
                 // Load Info
                 EventUser user = event.getUser();
                 String subPlan = event.getTagValue("msg-param-sub-plan").get();

chat/src/main/java/com/github/twitch4j/chat/events/channel/MultiMonthGiftRedeemEvent.java

@@ -0,0 +1,94 @@
+package com.github.twitch4j.chat.events.channel;
+
+import com.github.twitch4j.chat.events.AbstractChannelEvent;
+import com.github.twitch4j.common.annotation.Unofficial;
+import com.github.twitch4j.common.enums.SubscriptionPlan;
+import com.github.twitch4j.common.events.domain.EventUser;
+import lombok.EqualsAndHashCode;
+import lombok.Value;
+
+import static com.github.twitch4j.common.util.TwitchUtils.ANONYMOUS_GIFTER;
+
+/**
+ * This event occurs when a recipient of a multi-month gift sub
+ * enters a new month of the subscription, and shares a
+ * re-subscription message, despite no additional monetary
+ * transaction accompanying their message.
+ * <p>
+ * Webchat shows these events with this accompanying text:
+ * {@code N month Gift Subscription courtesy of GIFTER_DISPLAY_NAME has entered month M.}
+ * <p>
+ * The parameters specific to this event are not officially documented.
+ */
+@Value
+@EqualsAndHashCode(callSuper = false)
+@Unofficial
+public class MultiMonthGiftRedeemEvent extends AbstractChannelEvent {
+
+    /**
+     * Raw message event.
+     */
+    IRCMessageEvent messageEvent;
+
+    /**
+     * The gift recipient that is sending this resub message.
+     */
+    EventUser user;
+
+    /**
+     * The user-specified message attached to this notification.
+     */
+    String message;
+
+    /**
+     * The tier of the multi-month gifted subscription.
+     */
+    SubscriptionPlan subscriptionPlan;
+
+    /**
+     * Whether the original multi-month gift was done by an anonymous user.
+     */
+    boolean wasAnonymous;
+
+    /**
+     * The user that originally gifted the multi-month gift subscription.
+     */
+    EventUser gifter;
+
+    /**
+     * The number of months that were originally gifted as part of the multi-month subscription.
+     */
+    Integer giftMonths;
+
+    /**
+     * The gift month that is being redeemed.
+     */
+    Integer redeemedMonth;
+
+    /**
+     * The cumulative number of months the user has been subscribed to this channel.
+     */
+    Integer cumulativeMonths;
+
+    /**
+     * Event Constructor
+     *
+     * @param event the raw message event
+     */
+    public MultiMonthGiftRedeemEvent(IRCMessageEvent event) {
+        super(event.getChannel());
+        this.messageEvent = event;
+        this.user = event.getUser();
+        this.message = event.getMessage().orElse(null);
+        this.subscriptionPlan = SubscriptionPlan.fromString(event.getTags().getOrDefault("msg-param-sub-plan", "1000"));
+        this.wasAnonymous = "true".equalsIgnoreCase(event.getTags().get("msg-param-anon-gift"));
+        this.gifter = wasAnonymous ? ANONYMOUS_GIFTER : new EventUser(
+            event.getTags().get("msg-param-gifter-id"),
+            event.getTagValue("msg-param-gifter-login").orElse(event.getTagValue("msg-param-gifter-name").orElse(null))
+        );
+        this.giftMonths = Integer.parseInt(event.getTags().getOrDefault("msg-param-gift-months", "0"));
+        this.redeemedMonth = Integer.parseInt(event.getTags().getOrDefault("msg-param-gift-month-being-redeemed", "0"));
+        this.cumulativeMonths = Integer.parseInt(event.getTags().getOrDefault("msg-param-cumulative-months", "0"));
+    }
+
+}