1 files changed, 22 insertions, 11 deletions

diff --git a/app/src/main/java/mygram/droid/Playlist.java b/app/src/main/java/mygram/droid/Playlist.java
index 98379fb..b885397 100644
--- a/app/src/main/java/mygram/droid/Playlist.java
+++ b/app/src/main/java/mygram/droid/Playlist.java
@@ -18,32 +18,43 @@ import android.content.Context;
 import android.content.Intent;
 
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
+import java.util.concurrent.Callable;
 import java.util.concurrent.ThreadLocalRandom;
 
 /** Hands a post list to ViewerActivity; intents cannot carry hundreds of posts. */
 final class Playlist {
+	/** Shared with the caller (e.g. a folder grid), not copied, so both see appended pages. */
 	static List<Post> posts = new ArrayList<>();
 	static int start;
-	/** Non-zero while the viewer plays endless Reels and pages for more. */
-	static int reelsSeed;
-	static int reelsPage;
+	/** Fetches the next page of posts; null when there is nothing more. */
+	static Callable<List<Post>> more;
 
 	private Playlist() {
 	}
 
-	static void open(Context c, List<Post> list, int startIndex) {
-		posts = new ArrayList<>(list);
+	static void open(Context c, List<Post> list, int startIndex, Callable<List<Post>> pager) {
+		posts = list;
 		start = startIndex;
-		reelsSeed = 0;
+		more = pager;
 		c.startActivity(new Intent(c, ViewerActivity.class));
 	}
 
 	static void openReels(Context c) {
-		posts = new ArrayList<>();
-		start = 0;
-		reelsSeed = 1 + ThreadLocalRandom.current().nextInt(1_000_000);
-		reelsPage = 0;
-		c.startActivity(new Intent(c, ViewerActivity.class));
+		open(c, new ArrayList<>(), 0, Api.reelsPages(1 + ThreadLocalRandom.current().nextInt(1_000_000)));
+	}
+
+	/** Appends the posts not already in the list; returns how many were added. */
+	static int append(List<Post> page) {
+		Set<Integer> ids = new HashSet<>();
+		for (Post p : posts)
+			ids.add(p.id);
+		int old = posts.size();
+		for (Post p : page)
+			if (ids.add(p.id))
+				posts.add(p);
+		return posts.size() - old;
 	}
 }