Hashtags

README.md

@@ -32,6 +32,7 @@ Amethyst brings the best social network to your Android phone. Just insert your
 - [x] Online Relay Search (NIP-50)
 - [x] Internationalization
 - [x] Badges (NIP-58)
+- [x] Hashtags
 - [ ] Local Database 
 - [ ] View Individual Reactions (Like, Boost, Zaps, Reports) per Post
 - [ ] Bookmarks, Pinned Posts, Muted Events (NIP-51)

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

@@ -0,0 +1,38 @@
+package com.vitorpamplona.amethyst.service
+
+import androidx.compose.ui.text.capitalize
+import com.vitorpamplona.amethyst.service.model.ChannelMessageEvent
+import com.vitorpamplona.amethyst.service.model.LongTextNoteEvent
+import com.vitorpamplona.amethyst.service.model.TextNoteEvent
+import com.vitorpamplona.amethyst.service.relays.FeedType
+import com.vitorpamplona.amethyst.service.relays.JsonFilter
+import com.vitorpamplona.amethyst.service.relays.TypedFilter
+
+object NostrHashtagDataSource : NostrDataSource("SingleHashtagFeed") {
+    private var hashtagToWatch: String? = null
+
+    fun createLoadHashtagFilter(): TypedFilter? {
+        val hashToLoad = hashtagToWatch ?: return null
+
+        return TypedFilter(
+            types = FeedType.values().toSet(),
+            filter = JsonFilter(
+                tags = mapOf("t" to listOf(hashToLoad, hashToLoad.lowercase(), hashToLoad.uppercase(), hashToLoad.capitalize())),
+                kinds = listOf(TextNoteEvent.kind, ChannelMessageEvent.kind, LongTextNoteEvent.kind),
+                limit = 200
+            )
+        )
+    }
+
+    val loadHashtagChannel = requestNewChannel()
+
+    override fun updateChannelFilters() {
+        loadHashtagChannel.typedFilters = listOfNotNull(createLoadHashtagFilter()).ifEmpty { null }
+    }
+
+    fun loadHashtag(tag: String?) {
+        hashtagToWatch = tag
+
+        invalidateFilters()
+    }
+}

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

@@ -39,8 +39,12 @@ open class Event(
 
     fun taggedUsers() = tags.filter { it.firstOrNull() == "p" }.mapNotNull { it.getOrNull(1) }
 
+    fun hashtags() = tags.filter { it.firstOrNull() == "t" }.mapNotNull { it.getOrNull(1) }
+
     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) }
+
     /**
      * 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

@@ -24,4 +24,6 @@ interface EventInterface {
     fun hasValidSignature(): Boolean
 
     fun isTaggedUser(loggedInUser: String): Boolean
+
+    fun isTaggedHash(hashtag: String): Boolean
 }

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

@@ -2,6 +2,7 @@ package com.vitorpamplona.amethyst.service.model
 
 import com.vitorpamplona.amethyst.model.HexKey
 import com.vitorpamplona.amethyst.model.toHexKey
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.findHashtags
 import nostr.postr.Utils
 import java.util.Date
 
@@ -29,6 +30,9 @@ class TextNoteEvent(
             addresses?.forEach {
                 tags.add(listOf("a", it.toTag()))
             }
+            findHashtags(msg).forEach {
+                tags.add(listOf("t", it))
+            }
             val id = generateId(pubKey, createdAt, kind, tags, msg)
             val sig = Utils.sign(id, privateKey)
             return TextNoteEvent(id.toHexKey(), pubKey, createdAt, tags, msg, sig.toHexKey())

app/src/main/java/com/vitorpamplona/amethyst/ui/components/RichTextViewer.kt

@@ -8,6 +8,7 @@ import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.text.ClickableText
 import androidx.compose.material.LocalTextStyle
 import androidx.compose.material.MaterialTheme
 import androidx.compose.material.Text
@@ -17,6 +18,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.compositeOver
+import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.ui.text.SpanStyle
 import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.text.font.FontFamily
@@ -46,8 +48,8 @@ val videoExtension = Pattern.compile("(.*/)*.+\\.(mp4|avi|wmv|mpg|amv|webm|mov)$
 val noProtocolUrlValidator = Pattern.compile("^[-a-zA-Z0-9@:%._\\+~#=]{1,256}\\.[a-zA-Z0-9()]{1,6}\\b(?:[-a-zA-Z0-9()@:%_\\+.~#?&//=]*)$")
 val tagIndex = Pattern.compile(".*\\#\\[([0-9]+)\\].*")
 
-val mentionsPattern: Pattern = Pattern.compile("@([A-Za-z0-9_-]+)")
+val mentionsPattern: Pattern = Pattern.compile("@([A-Za-z0-9_\\-]+)")
-val hashTagsPattern: Pattern = Pattern.compile("#([A-Za-z0-9_-]+)")
+val hashTagsPattern: Pattern = Pattern.compile("#([A-Za-z0-9_\\-]+)")
 val urlPattern: Pattern = Patterns.WEB_URL
 
 fun isValidURL(url: String?): Boolean {
@@ -144,6 +146,8 @@ fun RichTextViewer(
                                 UrlPreview("https://$word", word)
                             } else if (tagIndex.matcher(word).matches() && tags != null) {
                                 TagLink(word, tags, canPreview, backgroundColor, accountViewModel, navController)
+                            } else if (hashTagsPattern.matcher(word).matches()) {
+                                HashTag(word, accountViewModel, navController)
                             } else if (isBechLink(word)) {
                                 BechLink(word, navController)
                             } else {
@@ -163,6 +167,8 @@ fun RichTextViewer(
                                 ClickableUrl(word, "https://$word")
                             } else if (tagIndex.matcher(word).matches() && tags != null) {
                                 TagLink(word, tags, canPreview, backgroundColor, accountViewModel, navController)
+                            } else if (hashTagsPattern.matcher(word).matches()) {
+                                HashTag(word, accountViewModel, navController)
                             } else if (isBechLink(word)) {
                                 BechLink(word, navController)
                             } else {
@@ -212,6 +218,29 @@ fun BechLink(word: String, navController: NavController) {
     }
 }
 
+@Composable
+fun HashTag(word: String, accountViewModel: AccountViewModel, navController: NavController) {
+    val hashtagMatcher = hashTagsPattern.matcher(word)
+
+    val tag = try {
+        hashtagMatcher.find()
+        hashtagMatcher.group(1)
+    } catch (e: Exception) {
+        println("Couldn't link hashtag $word")
+        null
+    }
+
+    if (tag != null) {
+        ClickableText(
+            text = AnnotatedString("#$tag "),
+            onClick = { navController.navigate("Hashtag/$tag") },
+            style = LocalTextStyle.current.copy(color = MaterialTheme.colors.primary)
+        )
+    } else {
+        Text(text = "$word ")
+    }
+}
+
 @Composable
 fun TagLink(word: String, tags: List<List<String>>, canPreview: Boolean, backgroundColor: Color, accountViewModel: AccountViewModel, navController: NavController) {
     val matcher = tagIndex.matcher(word)

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

@@ -0,0 +1,39 @@
+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.ChannelMessageEvent
+import com.vitorpamplona.amethyst.service.model.LongTextNoteEvent
+import com.vitorpamplona.amethyst.service.model.PrivateDmEvent
+import com.vitorpamplona.amethyst.service.model.TextNoteEvent
+
+object HashtagFeedFilter : FeedFilter<Note>() {
+    lateinit var account: Account
+    var tag: String? = null
+
+    override fun feed(): List<Note> {
+        val myTag = tag ?: return emptyList()
+
+        return LocalCache.notes.values
+            .asSequence()
+            .filter {
+                (
+                    it.event is TextNoteEvent ||
+                        it.event is LongTextNoteEvent ||
+                        it.event is ChannelMessageEvent ||
+                        it.event is PrivateDmEvent
+                    ) &&
+                    it.event?.isTaggedHash(myTag) == true
+            }
+            .filter { account.isAcceptable(it) }
+            .sortedBy { it.createdAt() }
+            .toList()
+            .reversed()
+    }
+
+    fun loadHashtag(account: Account, tag: String?) {
+        this.account = account
+        this.tag = tag
+    }
+}

app/src/main/java/com/vitorpamplona/amethyst/ui/navigation/AppNavigation.kt

@@ -20,6 +20,7 @@ import com.vitorpamplona.amethyst.ui.screen.loggedIn.ChannelScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.ChatroomListScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.ChatroomScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.FiltersScreen
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.HashtagScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.HomeScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.NotificationScreen
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.ProfileScreen
@@ -94,6 +95,16 @@ fun AppNavigation(
             })
         }
 
+        Route.Hashtag.let { route ->
+            composable(route.route, route.arguments, content = {
+                HashtagScreen(
+                    tag = it.arguments?.getString("id"),
+                    accountViewModel = accountViewModel,
+                    navController = navController
+                )
+            })
+        }
+
         Route.Room.let { route ->
             composable(route.route, route.arguments, content = {
                 ChatroomScreen(

app/src/main/java/com/vitorpamplona/amethyst/ui/navigation/AppTopBar.kt

@@ -47,6 +47,7 @@ import com.vitorpamplona.amethyst.service.NostrChannelDataSource
 import com.vitorpamplona.amethyst.service.NostrChatroomDataSource
 import com.vitorpamplona.amethyst.service.NostrChatroomListDataSource
 import com.vitorpamplona.amethyst.service.NostrGlobalDataSource
+import com.vitorpamplona.amethyst.service.NostrHashtagDataSource
 import com.vitorpamplona.amethyst.service.NostrHomeDataSource
 import com.vitorpamplona.amethyst.service.NostrSearchEventOrUserDataSource
 import com.vitorpamplona.amethyst.service.NostrSingleChannelDataSource
@@ -138,6 +139,7 @@ fun MainTopBar(scaffoldState: ScaffoldState, accountViewModel: AccountViewModel)
                                     NostrSingleChannelDataSource.printCounter()
                                     NostrSingleUserDataSource.printCounter()
                                     NostrThreadDataSource.printCounter()
+                                    NostrHashtagDataSource.printCounter()
 
                                     NostrUserProfileDataSource.printCounter()
 

app/src/main/java/com/vitorpamplona/amethyst/ui/navigation/Routes.kt

@@ -65,6 +65,12 @@ sealed class Route(
         arguments = listOf(navArgument("id") { type = NavType.StringType })
     )
 
+    object Hashtag : Route(
+        route = "Hashtag/{id}",
+        icon = R.drawable.ic_moments,
+        arguments = listOf(navArgument("id") { type = NavType.StringType })
+    )
+
     object Room : Route(
         route = "Room/{id}",
         icon = R.drawable.ic_moments,

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

@@ -11,6 +11,7 @@ import com.vitorpamplona.amethyst.ui.dal.ChatroomListKnownFeedFilter
 import com.vitorpamplona.amethyst.ui.dal.ChatroomListNewFeedFilter
 import com.vitorpamplona.amethyst.ui.dal.FeedFilter
 import com.vitorpamplona.amethyst.ui.dal.GlobalFeedFilter
+import com.vitorpamplona.amethyst.ui.dal.HashtagFeedFilter
 import com.vitorpamplona.amethyst.ui.dal.HomeConversationsFeedFilter
 import com.vitorpamplona.amethyst.ui.dal.HomeNewThreadFeedFilter
 import com.vitorpamplona.amethyst.ui.dal.ThreadFeedFilter
@@ -33,6 +34,7 @@ class NostrChannelFeedViewModel : FeedViewModel(ChannelFeedFilter)
 class NostrChatRoomFeedViewModel : FeedViewModel(ChatroomFeedFilter)
 class NostrGlobalFeedViewModel : FeedViewModel(GlobalFeedFilter)
 class NostrThreadFeedViewModel : FeedViewModel(ThreadFeedFilter)
+class NostrHashtagFeedViewModel : FeedViewModel(HashtagFeedFilter)
 class NostrUserProfileNewThreadsFeedViewModel : FeedViewModel(UserProfileNewThreadFeedFilter)
 class NostrUserProfileConversationsFeedViewModel : FeedViewModel(UserProfileConversationsFeedFilter)
 class NostrUserProfileReportFeedViewModel : FeedViewModel(UserProfileReportsFeedFilter)

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

@@ -0,0 +1,109 @@
+package com.vitorpamplona.amethyst.ui.screen.loggedIn
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxHeight
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.Divider
+import androidx.compose.material.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.livedata.observeAsState
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalLifecycleOwner
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleEventObserver
+import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.navigation.NavController
+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
+
+@Composable
+fun HashtagScreen(tag: String?, accountViewModel: AccountViewModel, navController: NavController) {
+    val accountState by accountViewModel.accountLiveData.observeAsState()
+    val account = accountState?.account ?: return
+
+    val lifeCycleOwner = LocalLifecycleOwner.current
+
+    if (tag != null) {
+        val feedViewModel: NostrHashtagFeedViewModel = viewModel()
+
+        LaunchedEffect(tag) {
+            HashtagFeedFilter.loadHashtag(account, tag)
+            NostrHashtagDataSource.loadHashtag(tag)
+            feedViewModel.invalidateData()
+        }
+
+        DisposableEffect(accountViewModel) {
+            val observer = LifecycleEventObserver { _, event ->
+                if (event == Lifecycle.Event.ON_RESUME) {
+                    println("Hashtag Start")
+                    HashtagFeedFilter.loadHashtag(account, tag)
+                    NostrHashtagDataSource.loadHashtag(tag)
+                    NostrHashtagDataSource.start()
+                    feedViewModel.invalidateData()
+                }
+                if (event == Lifecycle.Event.ON_PAUSE) {
+                    println("Hashtag Stop")
+                    HashtagFeedFilter.loadHashtag(account, null)
+                    NostrHashtagDataSource.loadHashtag(null)
+                    NostrHashtagDataSource.stop()
+                }
+            }
+
+            lifeCycleOwner.lifecycle.addObserver(observer)
+            onDispose {
+                lifeCycleOwner.lifecycle.removeObserver(observer)
+            }
+        }
+
+        Column(Modifier.fillMaxHeight()) {
+            Column(
+                modifier = Modifier.padding(vertical = 0.dp)
+            ) {
+                HashtagHeader(tag)
+                FeedView(feedViewModel, accountViewModel, navController, null)
+            }
+        }
+    }
+}
+
+@Composable
+fun HashtagHeader(tag: String) {
+    Column() {
+        Column(modifier = Modifier.padding(12.dp)) {
+            Row(verticalAlignment = Alignment.CenterVertically) {
+                Column(
+                    modifier = Modifier
+                        .padding(start = 10.dp)
+                        .weight(1f)
+                ) {
+                    Row(
+                        verticalAlignment = Alignment.CenterVertically,
+                        horizontalArrangement = Arrangement.Center,
+                        modifier = Modifier.fillMaxWidth()
+                    ) {
+                        Text(
+                            "#$tag",
+                            fontWeight = FontWeight.Bold
+                        )
+                    }
+                }
+            }
+        }
+
+        Divider(
+            modifier = Modifier.padding(start = 12.dp, end = 12.dp),
+            thickness = 0.25.dp
+        )
+    }
+}

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

@@ -12,6 +12,7 @@ import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.itemsIndexed
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material.Divider
@@ -72,6 +73,7 @@ import kotlinx.coroutines.flow.filter
 import kotlinx.coroutines.flow.receiveAsFlow
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
+import java.util.regex.Pattern
 import kotlinx.coroutines.channels.Channel as CoroutineChannel
 
 @Composable
@@ -126,7 +128,9 @@ private fun SearchBar(accountViewModel: AccountViewModel, navController: NavCont
     val searchResults = remember { mutableStateOf<List<User>>(emptyList()) }
     val searchResultsNotes = remember { mutableStateOf<List<Note>>(emptyList()) }
     val searchResultsChannels = remember { mutableStateOf<List<Channel>>(emptyList()) }
+    val hashtagResults = remember { mutableStateOf<List<String>>(emptyList()) }
     val scope = rememberCoroutineScope()
+    val listState = rememberLazyListState()
 
     val onlineSearch = NostrSearchEventOrUserDataSource
 
@@ -149,6 +153,8 @@ private fun SearchBar(accountViewModel: AccountViewModel, navController: NavCont
                 .distinctUntilChanged()
                 .debounce(300)
                 .collectLatest {
+                    hashtagResults.value = findHashtags(it)
+
                     if (it.removePrefix("npub").removePrefix("note").length >= 4) {
                         onlineSearch.search(it.trim())
                     }
@@ -156,6 +162,9 @@ private fun SearchBar(accountViewModel: AccountViewModel, navController: NavCont
                     searchResults.value = LocalCache.findUsersStartingWith(it)
                     searchResultsNotes.value = LocalCache.findNotesStartingWith(it).sortedBy { it.createdAt() }.reversed()
                     searchResultsChannels.value = LocalCache.findChannelsStartingWith(it)
+
+                    // makes sure to show the top of the search
+                    scope.launch(Dispatchers.Main) { listState.animateScrollToItem(0) }
                 }
         }
     }
@@ -236,8 +245,15 @@ private fun SearchBar(accountViewModel: AccountViewModel, navController: NavCont
             contentPadding = PaddingValues(
                 top = 10.dp,
                 bottom = 10.dp
-            )
+            ),
+            state = listState
         ) {
+            itemsIndexed(hashtagResults.value, key = { _, item -> "#" + item }) { _, item ->
+                HashtagLine(item) {
+                    navController.navigate("Hashtag/$item")
+                }
+            }
+
             itemsIndexed(searchResults.value, key = { _, item -> "u" + item.pubkeyHex }) { _, item ->
                 UserCompose(item, accountViewModel = accountViewModel, navController = navController)
             }
@@ -266,6 +282,57 @@ private fun SearchBar(accountViewModel: AccountViewModel, navController: NavCont
     }
 }
 
+val hashtagSearch = Pattern.compile("(?:\\s|\\A)#([A-Za-z0-9_\\-]+)")
+
+fun findHashtags(content: String): List<String> {
+    val matcher = hashtagSearch.matcher(content)
+    val returningList = mutableSetOf<String>()
+    while (matcher.find()) {
+        try {
+            val tag = matcher.group(1)
+            if (tag != null && tag.isNotBlank()) {
+                returningList.add(tag)
+            }
+        } catch (e: Exception) {
+        }
+    }
+    return returningList.toList()
+}
+
+@Composable
+fun HashtagLine(tag: String, onClick: () -> Unit) {
+    Column(
+        modifier = Modifier
+            .fillMaxWidth()
+            .clickable(onClick = onClick)
+    ) {
+        Row(
+            modifier = Modifier
+                .padding(
+                    start = 12.dp,
+                    end = 12.dp,
+                    top = 10.dp
+                )
+        ) {
+            Row(
+                verticalAlignment = Alignment.CenterVertically,
+                horizontalArrangement = Arrangement.Center,
+                modifier = Modifier.fillMaxWidth()
+            ) {
+                Text(
+                    "Search hashtag: #$tag",
+                    fontWeight = FontWeight.Bold
+                )
+            }
+        }
+
+        Divider(
+            modifier = Modifier.padding(top = 10.dp),
+            thickness = 0.25.dp
+        )
+    }
+}
+
 @Composable
 fun UserLine(
     baseUser: User,