Ignores duplicated hashtags in different char cases when processing hashtag spam

amethyst/src/main/java/com/vitorpamplona/amethyst/model/Account.kt

@@ -158,7 +158,7 @@ import com.vitorpamplona.quartz.nip01Core.signers.NostrSigner
 import com.vitorpamplona.quartz.nip01Core.signers.NostrSignerInternal
 import com.vitorpamplona.quartz.nip01Core.tags.aTag.ATag
 import com.vitorpamplona.quartz.nip01Core.tags.events.ETag
-import com.vitorpamplona.quartz.nip01Core.tags.hashtags.countHashtags
+import com.vitorpamplona.quartz.nip01Core.tags.hashtags.hasMoreHashtagsThan
 import com.vitorpamplona.quartz.nip01Core.tags.hashtags.hashtags
 import com.vitorpamplona.quartz.nip01Core.tags.people.PTag
 import com.vitorpamplona.quartz.nip01Core.tags.people.taggedUserIds
@@ -3035,7 +3035,7 @@ class Account(
 
     private fun hasExcessiveHashtags(note: Note): Boolean {
         val limit = settings.syncedSettings.security.maxHashtagLimit.value
-        return limit > 0 && (note.event?.countHashtags() ?: 0) > limit
+        return limit > 0 && note.event?.hasMoreHashtagsThan(limit) == true
     }
 
     override fun isAcceptable(note: Note): Boolean {

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/dal/FilterByListParams.kt

@@ -30,7 +30,7 @@ import com.vitorpamplona.quartz.nip01Core.core.Address
 import com.vitorpamplona.quartz.nip01Core.core.Event
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
-import com.vitorpamplona.quartz.nip01Core.tags.hashtags.countHashtags
+import com.vitorpamplona.quartz.nip01Core.tags.hashtags.hasMoreHashtagsThan
 import com.vitorpamplona.quartz.nip10Notes.threadRootIdOrSelf
 import com.vitorpamplona.quartz.nip51Lists.muteList.MuteListEvent
 import com.vitorpamplona.quartz.nip51Lists.peopleList.PeopleListEvent
@@ -51,7 +51,7 @@ class FilterByListParams(
 
     fun isNotInTheFuture(noteEvent: Event) = noteEvent.createdAt <= now
 
-    fun hasExcessiveHashtags(noteEvent: Event) = hiddenLists.maxHashtagLimit > 0 && noteEvent.countHashtags() > hiddenLists.maxHashtagLimit
+    fun hasExcessiveHashtags(noteEvent: Event) = hiddenLists.maxHashtagLimit > 0 && noteEvent.hasMoreHashtagsThan(hiddenLists.maxHashtagLimit)
 
     fun isAuthorInFollows(author: HexKey): Boolean {
         if (followLists == null) return false

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/tags/hashtags/EventExt.kt

@@ -26,6 +26,8 @@ fun Event.anyHashTag(onEach: (str: String) -> Boolean) = tags.anyHashTag(onEach)
 
 fun Event.countHashtags() = tags.countHashtags()
 
+fun Event.hasMoreHashtagsThan(limit: Int) = tags.hasMoreHashtagsThan(limit)
+
 fun Event.hasHashtags() = tags.hasHashtags()
 
 fun Event.hashtags() = tags.hashtags()

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/tags/hashtags/HashtagTag.kt

@@ -46,6 +46,13 @@ class HashtagTag {
             return tag[1]
         }
 
+        fun parseLowercase(tag: Array<String>): String? {
+            ensure(tag.has(1)) { return null }
+            ensure(tag[0] == TAG_NAME) { return null }
+            ensure(tag[1].isNotEmpty()) { return null }
+            return tag[1].lowercase()
+        }
+
         fun assemble(name: String) = arrayOf(TAG_NAME, name)
 
         fun assembleDualCase(name: String): List<Array<String>> {

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip01Core/tags/hashtags/TagArrayExt.kt

@@ -38,8 +38,29 @@ fun TagArray.hashtags() = this.mapNotNull(HashtagTag::parse)
 
 fun TagArray.countHashtags() = this.count(HashtagTag::isTagged)
 
+fun TagArray.hasMoreHashtagsThan(limit: Int): Boolean {
+    val count = this.count(HashtagTag::isTagged)
+    return count > limit && this.countUnique(count, HashtagTag::parseLowercase) > limit
+}
+
 fun TagArray.isTaggedHash(hashtag: String) = this.isTagged(HashtagTag.TAG_NAME, hashtag, true)
 
 fun TagArray.isTaggedHashes(hashtags: Set<String>) = this.isAnyLowercaseTagged(HashtagTag.TAG_NAME, hashtags)
 
 fun TagArray.firstIsTaggedHashes(hashtags: Set<String>) = this.firstAnyLowercaseTaggedValue(HashtagTag.TAG_NAME, hashtags)
+
+public inline fun <T, U> Array<out T>.countUnique(
+    size: Int,
+    transform: (T) -> U?,
+): Int {
+    // Pre-allocate hash set to avoid frequent resizing for larger arrays
+    val seen = HashSet<U>(size)
+    var count = 0
+    for (element in this) {
+        val value = transform(element)
+        if (value != null && seen.add(value)) {
+            ++count
+        }
+    }
+    return count
+}