Support for Following Hashtags

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

@@ -91,10 +91,12 @@ class Account(
 
         val contactList = userProfile().latestContactList
         val follows = contactList?.follows() ?: emptyList()
+        val followsTags = contactList?.unverifiedFollowTagSet() ?: emptyList()
 
         if (contactList != null && follows.isNotEmpty()) {
             val event = ContactListEvent.create(
                 follows,
+                followsTags,
                 relays,
                 loggedIn.privKey!!
             )
@@ -102,7 +104,7 @@ class Account(
             Client.send(event)
             LocalCache.consume(event)
         } else {
-            val event = ContactListEvent.create(listOf(), relays, loggedIn.privKey!!)
+            val event = ContactListEvent.create(listOf(), listOf(), relays, loggedIn.privKey!!)
 
             // Keep this local to avoid erasing a good contact list.
             // Client.send(event)
@@ -246,11 +248,13 @@ class Account(
         if (!isWriteable()) return
 
         val contactList = userProfile().latestContactList
-        val follows = contactList?.follows() ?: emptyList()
+        val followingUsers = contactList?.follows() ?: emptyList()
+        val followingTags = contactList?.unverifiedFollowTagSet() ?: emptyList()
 
-        val event = if (contactList != null && follows.isNotEmpty()) {
+        val event = if (contactList != null) {
             ContactListEvent.create(
-                follows.plus(Contact(user.pubkeyHex, null)),
+                followingUsers.plus(Contact(user.pubkeyHex, null)),
+                followingTags,
                 contactList.relays(),
                 loggedIn.privKey!!
             )
@@ -258,6 +262,35 @@ class Account(
             val relays = Constants.defaultRelays.associate { it.url to ContactListEvent.ReadWrite(it.read, it.write) }
             ContactListEvent.create(
                 listOf(Contact(user.pubkeyHex, null)),
+                followingTags,
+                relays,
+                loggedIn.privKey!!
+            )
+        }
+
+        Client.send(event)
+        LocalCache.consume(event)
+    }
+
+    fun follow(tag: String) {
+        if (!isWriteable()) return
+
+        val contactList = userProfile().latestContactList
+        val followingUsers = contactList?.follows() ?: emptyList()
+        val followingTags = contactList?.unverifiedFollowTagSet() ?: emptyList()
+
+        val event = if (contactList != null) {
+            ContactListEvent.create(
+                followingUsers,
+                followingTags.plus(tag),
+                contactList.relays(),
+                loggedIn.privKey!!
+            )
+        } else {
+            val relays = Constants.defaultRelays.associate { it.url to ContactListEvent.ReadWrite(it.read, it.write) }
+            ContactListEvent.create(
+                followingUsers,
+                followingTags.plus(tag),
                 relays,
                 loggedIn.privKey!!
             )
@@ -271,11 +304,33 @@ class Account(
         if (!isWriteable()) return
 
         val contactList = userProfile().latestContactList
-        val follows = contactList?.follows() ?: emptyList()
+        val followingUsers = contactList?.follows() ?: emptyList()
+        val followingTags = contactList?.unverifiedFollowTagSet() ?: emptyList()
 
-        if (contactList != null && follows.isNotEmpty()) {
+        if (contactList != null && (followingUsers.isNotEmpty() || followingTags.isNotEmpty())) {
             val event = ContactListEvent.create(
-                follows.filter { it.pubKeyHex != user.pubkeyHex },
+                followingUsers.filter { it.pubKeyHex != user.pubkeyHex },
+                followingTags,
+                contactList.relays(),
+                loggedIn.privKey!!
+            )
+
+            Client.send(event)
+            LocalCache.consume(event)
+        }
+    }
+
+    fun unfollow(tag: String) {
+        if (!isWriteable()) return
+
+        val contactList = userProfile().latestContactList
+        val followingUsers = contactList?.follows() ?: emptyList()
+        val followingTags = contactList?.unverifiedFollowTagSet() ?: emptyList()
+
+        if (contactList != null && (followingUsers.isNotEmpty() || followingTags.isNotEmpty())) {
+            val event = ContactListEvent.create(
+                followingUsers,
+                followingTags.filter { it != tag },
                 contactList.relays(),
                 loggedIn.privKey!!
             )
@@ -503,7 +558,11 @@ class Account(
     fun isHidden(user: User) = user.pubkeyHex in hiddenUsers || user.pubkeyHex in transientHiddenUsers
 
     fun followingKeySet(): Set<HexKey> {
-        return userProfile().latestContactList?.verifiedFollowKeySet ?: emptySet()
+        return userProfile().cachedFollowingKeySet() ?: emptySet()
+    }
+
+    fun followingTagSet(): Set<HexKey> {
+        return userProfile().cachedFollowingTagSet() ?: emptySet()
     }
 
     fun isAcceptable(user: User): Boolean {

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

@@ -249,6 +249,12 @@ class User(val pubkeyHex: String) {
         } ?: false
     }
 
+    fun isFollowingHashtag(tag: String): Boolean {
+        return latestContactList?.unverifiedFollowTagSet()?.toSet()?.let {
+            return tag in it
+        } ?: false
+    }
+
     fun isFollowingCached(user: User): Boolean {
         return latestContactList?.verifiedFollowKeySet?.let {
             return user.pubkeyHex in it
@@ -267,6 +273,10 @@ class User(val pubkeyHex: String) {
         return latestContactList?.verifiedFollowKeySet ?: emptySet()
     }
 
+    fun cachedFollowingTagSet(): Set<HexKey> {
+        return latestContactList?.verifiedFollowTagSet ?: emptySet()
+    }
+
     fun cachedFollowCount(): Int? {
         return latestContactList?.verifiedFollowKeySet?.size
     }

app/src/main/java/com/vitorpamplona/amethyst/service/NostrHomeDataSource.kt

@@ -58,9 +58,28 @@ object NostrHomeDataSource : NostrDataSource("HomeFeed") {
         )
     }
 
+    fun createFollowTagsFilter(): TypedFilter? {
+        val hashToLoad = account.followingTagSet()
+
+        if (hashToLoad.isEmpty()) return null
+
+        return TypedFilter(
+            types = setOf(FeedType.FOLLOWS),
+            filter = JsonFilter(
+                kinds = listOf(TextNoteEvent.kind, LongTextNoteEvent.kind),
+                tags = mapOf(
+                    "t" to hashToLoad.map {
+                        listOf(it, it.lowercase(), it.uppercase(), it.capitalize())
+                    }.flatten()
+                ),
+                limit = 100
+            )
+        )
+    }
+
     val followAccountChannel = requestNewChannel()
 
     override fun updateChannelFilters() {
-        followAccountChannel.typedFilters = listOf(createFollowAccountsFilter()).ifEmpty { null }
+        followAccountChannel.typedFilters = listOfNotNull(createFollowAccountsFilter(), createFollowTagsFilter()).ifEmpty { null }
     }
 }

app/src/main/java/com/vitorpamplona/amethyst/service/model/ContactListEvent.kt

@@ -33,11 +33,16 @@ class ContactListEvent(
         }.toSet()
     }
 
+    val verifiedFollowTagSet: Set<String> by lazy {
+        unverifiedFollowTagSet().map { it.lowercase() }.toSet()
+    }
+
     val verifiedFollowKeySetAndMe: Set<HexKey> by lazy {
         verifiedFollowKeySet + pubKey
     }
 
     fun unverifiedFollowKeySet() = tags.filter { it[0] == "p" }.mapNotNull { it.getOrNull(1) }
+    fun unverifiedFollowTagSet() = tags.filter { it[0] == "t" }.mapNotNull { it.getOrNull(1) }
 
     fun follows() = tags.filter { it[0] == "p" }.mapNotNull {
         try {
@@ -48,6 +53,10 @@ class ContactListEvent(
         }
     }
 
+    fun followsTags() = tags.filter { it[0] == "t" }.mapNotNull {
+        it.getOrNull(2)
+    }
+
     fun relays(): Map<String, ReadWrite>? = try {
         if (content.isNotEmpty()) {
             gson.fromJson(content, object : TypeToken<Map<String, ReadWrite>>() {}.type) as Map<String, ReadWrite>
@@ -62,7 +71,7 @@ class ContactListEvent(
     companion object {
         const val kind = 3
 
-        fun create(follows: List<Contact>, relayUse: Map<String, ReadWrite>?, privateKey: ByteArray, createdAt: Long = Date().time / 1000): ContactListEvent {
+        fun create(follows: List<Contact>, followTags: List<String>, relayUse: Map<String, ReadWrite>?, privateKey: ByteArray, createdAt: Long = Date().time / 1000): ContactListEvent {
             val content = if (relayUse != null) {
                 gson.toJson(relayUse)
             } else {
@@ -75,7 +84,10 @@ class ContactListEvent(
                 } else {
                     listOf("p", it.pubKeyHex)
                 }
+            } + followTags.map {
+                listOf("t", it)
             }
+
             val id = generateId(pubKey, createdAt, kind, tags, content)
             val sig = Utils.sign(id, privateKey)
             return ContactListEvent(id.toHexKey(), pubKey, createdAt, tags, content, sig.toHexKey())

app/src/main/java/com/vitorpamplona/amethyst/service/model/Event.kt

@@ -44,6 +44,8 @@ open class Event(
     override fun isTaggedUser(idHex: String) = tags.any { it.getOrNull(0) == "p" && it.getOrNull(1) == idHex }
 
     override fun isTaggedHash(hashtag: String) = tags.any { it.getOrNull(0) == "t" && it.getOrNull(1).equals(hashtag, true) }
+    override fun isTaggedHashes(hashtags: Set<String>) = tags.any { it.getOrNull(0) == "t" && it.getOrNull(1)?.lowercase() in hashtags }
+    override fun firstIsTaggedHashes(hashtags: Set<String>) = tags.firstOrNull { it.getOrNull(0) == "t" && it.getOrNull(1)?.lowercase() in hashtags }?.getOrNull(1)
 
     /**
      * Checks if the ID is correct and then if the pubKey's secret key signed the event.

app/src/main/java/com/vitorpamplona/amethyst/service/model/EventInterface.kt

@@ -26,4 +26,6 @@ interface EventInterface {
     fun isTaggedUser(loggedInUser: String): Boolean
 
     fun isTaggedHash(hashtag: String): Boolean
+    fun isTaggedHashes(hashtag: Set<String>): Boolean
+    fun firstIsTaggedHashes(hashtag: Set<String>): String?
 }

app/src/main/java/com/vitorpamplona/amethyst/ui/dal/HomeConversationsFeedFilter.kt

@@ -12,11 +12,12 @@ object HomeConversationsFeedFilter : FeedFilter<Note>() {
     override fun feed(): List<Note> {
         val user = account.userProfile()
         val followingKeySet = user.cachedFollowingKeySet()
+        val followingTagSet = user.cachedFollowingTagSet()
 
         return LocalCache.notes.values
             .filter {
                 (it.event is TextNoteEvent || it.event is RepostEvent) &&
-                    it.author?.pubkeyHex in followingKeySet &&
+                    (it.author?.pubkeyHex in followingKeySet || (it.event?.isTaggedHashes(followingTagSet) ?: false)) &&
                     // && account.isAcceptable(it)  // This filter follows only. No need to check if acceptable
                     it.author?.let { !account.isHidden(it) } ?: true &&
                     !it.isNewThread()

app/src/main/java/com/vitorpamplona/amethyst/ui/dal/HomeNewThreadFeedFilter.kt

@@ -13,11 +13,12 @@ object HomeNewThreadFeedFilter : FeedFilter<Note>() {
     override fun feed(): List<Note> {
         val user = account.userProfile()
         val followingKeySet = user.cachedFollowingKeySet()
+        val followingTagSet = user.cachedFollowingTagSet()
 
         val notes = LocalCache.notes.values
             .filter { it ->
                 (it.event is TextNoteEvent || it.event is RepostEvent || it.event is LongTextNoteEvent) &&
-                    it.author?.pubkeyHex in followingKeySet &&
+                    (it.author?.pubkeyHex in followingKeySet || (it.event?.isTaggedHashes(followingTagSet) ?: false)) &&
                     // && account.isAcceptable(it)  // This filter follows only. No need to check if acceptable
                     it.author?.let { !account.isHidden(it) } ?: true &&
                     it.isNewThread()
@@ -26,7 +27,7 @@ object HomeNewThreadFeedFilter : FeedFilter<Note>() {
         val longFormNotes = LocalCache.addressables.values
             .filter { it ->
                 (it.event is TextNoteEvent || it.event is RepostEvent || it.event is LongTextNoteEvent) &&
-                    it.author?.pubkeyHex in followingKeySet &&
+                    (it.author?.pubkeyHex in followingKeySet || (it.event?.isTaggedHashes(followingTagSet) ?: false)) &&
                     // && account.isAcceptable(it)  // This filter follows only. No need to check if acceptable
                     it.author?.let { !account.isHidden(it) } ?: true &&
                     it.isNewThread()

app/src/main/java/com/vitorpamplona/amethyst/ui/note/NoteCompose.kt

@@ -6,6 +6,7 @@ import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.CutCornerShape
 import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.text.ClickableText
 import androidx.compose.material.*
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.ExpandMore
@@ -268,6 +269,15 @@ fun NoteCompose(
                             )
                         }
 
+                        val firstTag = noteEvent.firstIsTaggedHashes(account.followingTagSet())
+                        if (firstTag != null) {
+                            ClickableText(
+                                text = AnnotatedString(" #$firstTag"),
+                                onClick = { navController.navigate("Hashtag/$firstTag") },
+                                style = LocalTextStyle.current.copy(color = MaterialTheme.colors.primary.copy(alpha = 0.52f))
+                            )
+                        }
+
                         Text(
                             timeAgo(note.createdAt(), context = context),
                             color = MaterialTheme.colors.onSurface.copy(alpha = 0.32f),

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

@@ -13,6 +13,7 @@ import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.livedata.observeAsState
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalLifecycleOwner
@@ -22,10 +23,13 @@ import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.LifecycleEventObserver
 import androidx.lifecycle.viewmodel.compose.viewModel
 import androidx.navigation.NavController
+import com.vitorpamplona.amethyst.model.Account
 import com.vitorpamplona.amethyst.service.NostrHashtagDataSource
 import com.vitorpamplona.amethyst.ui.dal.HashtagFeedFilter
 import com.vitorpamplona.amethyst.ui.screen.FeedView
 import com.vitorpamplona.amethyst.ui.screen.NostrHashtagFeedViewModel
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
 
 @Composable
 fun HashtagScreen(tag: String?, accountViewModel: AccountViewModel, navController: NavController) {
@@ -70,7 +74,7 @@ fun HashtagScreen(tag: String?, accountViewModel: AccountViewModel, navControlle
             Column(
                 modifier = Modifier.padding(vertical = 0.dp)
             ) {
-                HashtagHeader(tag)
+                HashtagHeader(tag, account)
                 FeedView(feedViewModel, accountViewModel, navController, null)
             }
         }
@@ -78,7 +82,12 @@ fun HashtagScreen(tag: String?, accountViewModel: AccountViewModel, navControlle
 }
 
 @Composable
-fun HashtagHeader(tag: String) {
+fun HashtagHeader(tag: String, account: Account) {
+    val userState by account.userProfile().live().follows.observeAsState()
+    val userFollows = userState?.user ?: return
+
+    val coroutineScope = rememberCoroutineScope()
+
     Column() {
         Column(modifier = Modifier.padding(12.dp)) {
             Row(verticalAlignment = Alignment.CenterVertically) {
@@ -94,8 +103,15 @@ fun HashtagHeader(tag: String) {
                     ) {
                         Text(
                             "#$tag",
-                            fontWeight = FontWeight.Bold
+                            fontWeight = FontWeight.Bold,
+                            modifier = Modifier.weight(1f)
                         )
+
+                        if (userFollows.isFollowingHashtag(tag)) {
+                            UnfollowButton { coroutineScope.launch(Dispatchers.IO) { account.unfollow(tag) } }
+                        } else {
+                            FollowButton { coroutineScope.launch(Dispatchers.IO) { account.follow(tag) } }
+                        }
                     }
                 }
             }