From ccfbfeffe22697c33d5f1e2f5906551a13ee9505 Mon Sep 17 00:00:00 2001
From: Vitor Pamplona <vitor@vitorpamplona.com>
Date: Wed, 7 Jun 2023 12:25:11 -0400
Subject: [PATCH] Moves ChatroomList's New Feed to an Additive filter.

---
 .../ui/dal/ChatroomListNewFeedFilter.kt       | 83 ++++++++++++++++++-
 1 file changed, 82 insertions(+), 1 deletion(-)

diff --git a/app/src/main/java/com/vitorpamplona/amethyst/ui/dal/ChatroomListNewFeedFilter.kt b/app/src/main/java/com/vitorpamplona/amethyst/ui/dal/ChatroomListNewFeedFilter.kt
index ec361e012..cad55b4a2 100644
--- a/app/src/main/java/com/vitorpamplona/amethyst/ui/dal/ChatroomListNewFeedFilter.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/ui/dal/ChatroomListNewFeedFilter.kt
@@ -1,9 +1,14 @@
 package com.vitorpamplona.amethyst.ui.dal
 
 import com.vitorpamplona.amethyst.model.Account
+import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.model.Note
+import com.vitorpamplona.amethyst.service.model.PrivateDmEvent
+import com.vitorpamplona.amethyst.ui.actions.updated
+import kotlin.time.ExperimentalTime
+import kotlin.time.measureTimedValue
 
-class ChatroomListNewFeedFilter(val account: Account) : FeedFilter<Note>() {
+class ChatroomListNewFeedFilter(val account: Account) : AdditiveFeedFilter<Note>() {
 
     // returns the last Note of each user.
     override fun feed(): List<Note> {
@@ -26,4 +31,80 @@ class ChatroomListNewFeedFilter(val account: Account) : FeedFilter<Note>() {
             .sortedWith(compareBy({ it.createdAt() }, { it.idHex }))
             .reversed()
     }
+
+    @OptIn(ExperimentalTime::class)
+    override fun updateListWith(oldList: List<Note>, newItems: Set<Note>): List<Note> {
+        val (feed, elapsed) = measureTimedValue {
+            val me = account.userProfile()
+
+            // Gets the latest message by room from the new items.
+            val newRelevantPrivateMessages = filterRelevantPrivateMessages(newItems, account)
+
+            if (newRelevantPrivateMessages.isEmpty()) {
+                return oldList
+            }
+
+            var myNewList = oldList
+
+            newRelevantPrivateMessages.forEach { newNotePair ->
+                oldList.forEach { oldNote ->
+                    val oldRoom = (oldNote.event as? PrivateDmEvent)?.talkingWith(me.pubkeyHex)
+
+                    if (
+                        (newNotePair.key == oldRoom) && (newNotePair.value.createdAt() ?: 0) > (oldNote.createdAt() ?: 0)
+                    ) {
+                        myNewList = myNewList.updated(oldNote, newNotePair.value)
+                    }
+                }
+            }
+
+            sort(myNewList.toSet()).take(1000)
+        }
+
+        // Log.d("Time", "${this.javaClass.simpleName} Modified Additive Feed in $elapsed with ${feed.size} objects")
+        return feed
+    }
+
+    override fun applyFilter(newItems: Set<Note>): Set<Note> {
+        // Gets the latest message by room from the new items.
+        val newRelevantPrivateMessages = filterRelevantPrivateMessages(newItems, account)
+
+        return if (newRelevantPrivateMessages.isEmpty()) {
+            emptySet()
+        } else {
+            newRelevantPrivateMessages.values.toSet()
+        }
+    }
+
+    private fun filterRelevantPrivateMessages(newItems: Set<Note>, account: Account): MutableMap<String, Note> {
+        val me = account.userProfile()
+        val followingKeySet = account.followingKeySet()
+
+        val newRelevantPrivateMessages = mutableMapOf<String, Note>()
+        newItems.filter { it.event is PrivateDmEvent }.forEach { newNote ->
+            val roomUserHex = (newNote.event as? PrivateDmEvent)?.talkingWith(me.pubkeyHex)
+            val roomUser = roomUserHex?.let { LocalCache.users[it] }
+
+            if (roomUserHex != null &&
+                (newNote.author?.pubkeyHex != me.pubkeyHex && roomUserHex !in followingKeySet && !me.hasSentMessagesTo(roomUser)) &&
+                !account.isHidden(roomUserHex)
+            ) {
+                val lastNote = newRelevantPrivateMessages.get(roomUserHex)
+                if (lastNote != null) {
+                    if ((newNote.createdAt() ?: 0) > (lastNote.createdAt() ?: 0)) {
+                        newRelevantPrivateMessages.put(roomUserHex, newNote)
+                    }
+                } else {
+                    newRelevantPrivateMessages.put(roomUserHex, newNote)
+                }
+            }
+        }
+        return newRelevantPrivateMessages
+    }
+
+    override fun sort(collection: Set<Note>): List<Note> {
+        return collection
+            .sortedWith(compareBy({ it.createdAt() }, { it.idHex }))
+            .reversed()
+    }
 }