Adds methods to follow a bunch of users at the same time

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

@@ -935,6 +935,8 @@ class Account(
 
     fun upgradeAttestations() = otsState.upgradeAttestationsIfNeeded(::sendAutomatic)
 
+    suspend fun follow(users: List<User>) = sendMyPublicAndPrivateOutbox(kind3FollowList.follow(users))
+
     suspend fun follow(user: User) = sendMyPublicAndPrivateOutbox(kind3FollowList.follow(user))
 
     suspend fun unfollow(user: User) = sendMyPublicAndPrivateOutbox(kind3FollowList.unfollow(user))

amethyst/src/main/java/com/vitorpamplona/amethyst/model/nip02FollowLists/Kind3FollowListState.kt

@@ -113,6 +113,25 @@ class Kind3FollowListState(
         )
     }
 
+    suspend fun follow(users: List<User>): ContactListEvent {
+        val contactList = getFollowListEvent()
+
+        val contacts =
+            users.map {
+                ContactTag(user.pubkeyHex, user.bestRelayHint(), null)
+            }
+
+        return if (contactList != null) {
+            ContactListEvent.followUsers(contactList, contacts, signer)
+        } else {
+            ContactListEvent.createFromScratch(
+                followUsers = contacts,
+                relayUse = emptyMap(),
+                signer = signer,
+            )
+        }
+    }
+
     suspend fun follow(user: User): ContactListEvent {
         val contactList = getFollowListEvent()
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/AccountViewModel.kt

@@ -914,6 +914,8 @@ class AccountViewModel(
 
     fun unfollow(channel: EphemeralChatChannel) = launchSigner { account.unfollow(channel) }
 
+    fun follow(users: List<User>) = launchSigner { account.follow(users) }
+
     fun follow(user: User) = launchSigner { account.follow(user) }
 
     fun unfollow(user: User) = launchSigner { account.unfollow(user) }

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip02FollowList/ContactListEvent.kt

@@ -123,6 +123,25 @@ class ContactListEvent(
             )
         }
 
+        suspend fun followUsers(
+            earlierVersion: ContactListEvent,
+            users: List<ContactTag>,
+            signer: NostrSigner,
+            createdAt: Long = TimeUtils.now(),
+        ): ContactListEvent {
+            val follows = earlierVersion.verifiedFollowKeySet()
+            val toBeAdded = users.filter { it.pubKey !in follows }.distinctBy { it.pubKey }.map { it.toTagArray() }
+
+            if (toBeAdded.isEmpty()) return earlierVersion
+
+            return create(
+                content = earlierVersion.content,
+                tags = earlierVersion.tags + toBeAdded,
+                signer = signer,
+                createdAt = createdAt,
+            )
+        }
+
         suspend fun unfollowUser(
             earlierVersion: ContactListEvent,
             pubKeyHex: String,