Adds a Deletion event cache.

app/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt

@@ -24,6 +24,7 @@ import android.util.Log
 import android.util.LruCache
 import androidx.compose.runtime.Stable
 import com.vitorpamplona.amethyst.Amethyst
+import com.vitorpamplona.amethyst.commons.data.DeletionIndex
 import com.vitorpamplona.amethyst.commons.data.LargeCache
 import com.vitorpamplona.amethyst.service.checkNotInMainThread
 import com.vitorpamplona.amethyst.service.relays.Relay
@@ -133,6 +134,8 @@ object LocalCache {
     val channels = LargeCache<HexKey, Channel>()
     val awaitingPaymentRequests = ConcurrentHashMap<HexKey, Pair<Note?, (LnZapPaymentResponseEvent) -> Unit>>(10)
 
+    val deletionIndex = DeletionIndex()
+
     fun checkGetOrCreateUser(key: String): User? {
         // checkNotInMainThread()
 
@@ -956,10 +959,11 @@ object LocalCache {
     }
 
     fun consume(event: DeletionEvent) {
+        deletionIndex.add(event)
+
         var deletedAtLeastOne = false
 
-        event
-            .deleteEvents()
+        event.deleteEvents()
             .mapNotNull { getNoteIfExists(it) }
             .forEach { deleteNote ->
                 // must be the same author
@@ -2210,6 +2214,8 @@ object LocalCache {
         event: Event,
         relay: Relay?,
     ) {
+        if (deletionIndex.hasBeenDeleted(event)) return
+
         checkNotInMainThread()
 
         try {

commons/src/main/java/com/vitorpamplona/amethyst/commons/data/DeletionIndex.kt

@@ -0,0 +1,80 @@
+/**
+ * Copyright (c) 2024 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.data
+
+import com.vitorpamplona.quartz.encoders.HexKey
+import com.vitorpamplona.quartz.events.AddressableEvent
+import com.vitorpamplona.quartz.events.DeletionEvent
+import com.vitorpamplona.quartz.events.Event
+
+class DeletionIndex {
+    data class DeletionRequest(val reference: String, val publicKey: HexKey)
+
+    // stores a set of id OR atags (kind:pubkey:dtag) by pubkey with the created at of the deletion event.
+    // Anything newer than the date should not be deleted.
+    private val deletedReferencesBefore = LargeCache<DeletionRequest, Long>()
+
+    fun add(event: DeletionEvent) {
+        event.tags.forEach {
+            if (it.size > 1 && (it[0] == "a" || it[0] == "e")) {
+                add(it[1], event.createdAt, event.pubKey)
+            }
+        }
+    }
+
+    private fun add(
+        ref: String,
+        createdAt: Long,
+        byPubKey: HexKey,
+    ) {
+        val key = DeletionRequest(ref, byPubKey)
+        val deletionTime = deletedReferencesBefore.get(key)
+        if (deletionTime == null) {
+            deletedReferencesBefore.put(key, createdAt)
+        } else {
+            // updates with newer deletion.
+            if (createdAt > deletionTime) {
+                deletedReferencesBefore.put(key, createdAt)
+            }
+        }
+    }
+
+    fun hasBeenDeleted(event: Event): Boolean {
+        val key = DeletionRequest(event.id, event.pubKey)
+        if (hasBeenDeleted(key)) return true
+
+        if (event is AddressableEvent) {
+            if (hasBeenDeleted(key, event.createdAt)) return true
+        }
+
+        return false
+    }
+
+    private fun hasBeenDeleted(key: DeletionRequest) = deletedReferencesBefore.containsKey(key)
+
+    private fun hasBeenDeleted(
+        key: DeletionRequest,
+        createdAt: Long,
+    ): Boolean {
+        val deletionTime = deletedReferencesBefore.get(key)
+        return deletionTime != null && createdAt < deletionTime
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/encoders/ATag.kt

@@ -25,7 +25,7 @@ import androidx.compose.runtime.Immutable
 
 @Immutable
 data class ATag(val kind: Int, val pubKeyHex: String, val dTag: String, val relay: String?) {
-    fun toTag() = "$kind:$pubKeyHex:$dTag"
+    fun toTag() = assembleATag(kind, pubKeyHex, dTag)
 
     fun toNAddr(): String {
         return TlvBuilder()
@@ -40,6 +40,12 @@ data class ATag(val kind: Int, val pubKeyHex: String, val dTag: String, val rela
     }
 
     companion object {
+        fun assembleATag(
+            kind: Int,
+            pubKeyHex: String,
+            dTag: String,
+        ) = "$kind:$pubKeyHex:$dTag"
+
         fun isATag(key: String): Boolean {
             return key.startsWith("naddr1") || key.contains(":")
         }

quartz/src/main/java/com/vitorpamplona/quartz/events/Event.kt

@@ -514,6 +514,8 @@ interface AddressableEvent {
     fun dTag(): String
 
     fun address(): ATag
+
+    fun addressTag(): String
 }
 
 @Immutable
@@ -529,6 +531,11 @@ open class BaseAddressableEvent(
     override fun dTag() = tags.firstOrNull { it.size > 1 && it[0] == "d" }?.get(1) ?: ""
 
     override fun address() = ATag(kind, pubKey, dTag(), null)
+
+    /**
+     * Creates the tag in a memory effecient way (without creating the ATag class
+     */
+    override fun addressTag() = ATag.assembleATag(kind, pubKey, dTag())
 }
 
 fun String.bytesUsedInMemory(): Int {

quartz/src/main/java/com/vitorpamplona/quartz/events/LongTextNoteEvent.kt

@@ -39,6 +39,8 @@ class LongTextNoteEvent(
 
     override fun address() = ATag(kind, pubKey, dTag(), null)
 
+    override fun addressTag() = ATag.assembleATag(kind, pubKey, dTag())
+
     fun topics() = hashtags()
 
     fun title() = tags.firstOrNull { it.size > 1 && it[0] == "title" }?.get(1)

quartz/src/main/java/com/vitorpamplona/quartz/events/WikiNoteEvent.kt

@@ -39,6 +39,8 @@ class WikiNoteEvent(
 
     override fun address() = ATag(kind, pubKey, dTag(), null)
 
+    override fun addressTag() = ATag.assembleATag(kind, pubKey, dTag())
+
     fun topics() = hashtags()
 
     fun title() = tags.firstOrNull { it.size > 1 && it[0] == "title" }?.get(1)