feat: message tail algorithm

app/build.gradle

@@ -49,6 +49,9 @@ android {
             excludes += '/META-INF/{AL2.0,LGPL2.1}'
         }
     }
+    lintOptions {
+        abortOnError false
+    }
     namespace 'chat.revolt'
 }
 
@@ -56,8 +59,9 @@ dependencies {
     // Android/Kotlin Core
     implementation 'androidx.core:core-ktx:1.9.0'
 
-    // JSON Serialization
+    // Kotlinx - various first-party extensions for Kotlin
     implementation "org.jetbrains.kotlinx:kotlinx-serialization-json:1.4.1"
+    implementation "org.jetbrains.kotlinx:kotlinx-datetime:0.4.0"
 
     // Compose BOM
     implementation platform("androidx.compose:compose-bom:$compose_bom_version")

app/src/main/java/chat/revolt/api/schemas/Messages.kt

@@ -18,7 +18,10 @@ data class Message(
     val edited: String? = null,
     val embeds: List<Embed>? = null,
     val mentions: List<String>? = null,
+    val masquerade: Masquerade? = null,
+    val system: SystemInfo? = null,
     val type: String? = null, // this is _only_ used for websocket events!
+    val tail: Boolean? = null, // this is used to determine if the message is the last in a message group
 ) {
     fun getAuthor(): User? {
         return author?.let { RevoltAPI.userCache[it] }
@@ -79,3 +82,16 @@ data class Image(
 data class Special(
     val type: String? = null
 )
+
+@Serializable
+data class Masquerade(
+    val name: String? = null,
+    val avatar: String? = null,
+    val colour: String? = null
+)
+
+@Serializable
+data class SystemInfo(
+    val type: String? = null,
+    val id: String? = null
+)

app/src/main/java/chat/revolt/components/chat/Message.kt

@@ -1,9 +1,12 @@
 package chat.revolt.components.chat
 
 import android.net.Uri
+import android.widget.Toast
 import androidx.browser.customtabs.CustomTabsIntent
+import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.background
 import androidx.compose.foundation.clickable
+import androidx.compose.foundation.combinedClickable
 import androidx.compose.foundation.layout.*
 import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.MaterialTheme
@@ -13,17 +16,21 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.platform.LocalClipboardManager
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
+import chat.revolt.R
 import chat.revolt.api.REVOLT_FILES
 import chat.revolt.api.RevoltAPI
 import chat.revolt.api.internals.ULID
 import chat.revolt.api.schemas.AutumnResource
 import chat.revolt.components.generic.RemoteImage
 import chat.revolt.components.generic.UserAvatar
+import chat.revolt.components.generic.UserAvatarWidthPlaceholder
 import chat.revolt.markdown.Renderer
 import chat.revolt.api.schemas.Message as MessageSchema
 
@@ -46,42 +53,66 @@ fun formatLongAsTime(time: Long): String {
     return format.format(date)
 }
 
+@OptIn(ExperimentalFoundationApi::class)
 @Composable
 fun Message(
     message: MessageSchema
 ) {
     val author = RevoltAPI.userCache[message.author] ?: return CircularProgressIndicator()
     val context = LocalContext.current
+    val clipboardManager = LocalClipboardManager.current
 
     Row(
         modifier = Modifier
-            .padding(8.dp)
+            .combinedClickable(
+                onClick = {},
+                onLongClick = {
+                    if (message.content != null && message.content.isNotEmpty()) {
+                        clipboardManager.setText(AnnotatedString(message.content))
+
+                        Toast
+                            .makeText(
+                                context,
+                                context.getString(R.string.copied),
+                                Toast.LENGTH_SHORT
+                            )
+                            .show()
+                    }
+                }
+            )
+            .padding(4.dp)
             .fillMaxWidth()
     ) {
-        UserAvatar(
+        if (message.tail == false) {
-            username = author.username ?: "",
+            UserAvatar(
-            userId = author.id!!,
+                username = author.username ?: "",
-            avatar = author.avatar
+                userId = author.id!!,
-        )
+                avatar = author.avatar
+            )
+        } else {
+            UserAvatarWidthPlaceholder()
+        }
 
         Column(modifier = Modifier.padding(start = 10.dp)) {
-            Row(verticalAlignment = Alignment.CenterVertically) {
+            if (message.tail == false) {
-                Text(
+                Row(verticalAlignment = Alignment.CenterVertically) {
-                    text = author.username ?: "",
+                    Text(
-                    fontWeight = FontWeight.Bold,
+                        text = author.username ?: "",
-                    maxLines = 1,
+                        fontWeight = FontWeight.Bold,
-                    overflow = TextOverflow.Ellipsis
+                        maxLines = 1,
-                )
+                        overflow = TextOverflow.Ellipsis
+                    )
 
-                Spacer(modifier = Modifier.width(5.dp))
+                    Spacer(modifier = Modifier.width(5.dp))
 
-                Text(
+                    Text(
-                    text = formatLongAsTime(ULID.asTimestamp(message.id!!)),
+                        text = formatLongAsTime(ULID.asTimestamp(message.id!!)),
-                    fontSize = 12.sp,
+                        fontSize = 12.sp,
-                    color = MaterialTheme.colorScheme.onBackground.copy(alpha = 0.5f),
+                        color = MaterialTheme.colorScheme.onBackground.copy(alpha = 0.5f),
-                    maxLines = 1,
+                        maxLines = 1,
-                    overflow = TextOverflow.Ellipsis
+                        overflow = TextOverflow.Ellipsis
-                )
+                    )
+                }
             }
 
             message.content?.let {

app/src/main/java/chat/revolt/components/generic/UserAvatar.kt

@@ -4,6 +4,7 @@ import androidx.compose.foundation.background
 import androidx.compose.foundation.border
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.runtime.Composable
@@ -85,3 +86,11 @@ fun UserAvatar(
         }
     }
 }
+
+@Composable
+fun UserAvatarWidthPlaceholder() {
+    Box(
+        modifier = Modifier
+            .width(40.dp)
+    )
+}

app/src/main/java/chat/revolt/screens/chat/views/ChannelScreen.kt

@@ -37,6 +37,7 @@ import chat.revolt.R
 import chat.revolt.RevoltTweenFloat
 import chat.revolt.RevoltTweenInt
 import chat.revolt.api.RevoltAPI
+import chat.revolt.api.internals.ULID
 import chat.revolt.api.realtime.RealtimeSocket
 import chat.revolt.api.realtime.frames.receivable.ChannelStartTypingFrame
 import chat.revolt.api.realtime.frames.receivable.ChannelStopTypingFrame
@@ -56,7 +57,9 @@ import chat.revolt.components.screens.chat.AttachmentManager
 import chat.revolt.components.screens.chat.ChannelIcon
 import io.ktor.http.*
 import kotlinx.coroutines.launch
+import kotlinx.datetime.Instant
 import java.io.File
+import kotlin.time.Duration.Companion.minutes
 import chat.revolt.api.schemas.Message as MessageSchema
 
 class ChannelScreenViewModel : ViewModel() {
@@ -186,7 +189,7 @@ class ChannelScreenViewModel : ViewModel() {
                     messages.add(message)
                 }
             }
-            setRenderableMessages(renderableMessages + messages)
+            regroupMessages(renderableMessages + messages)
         }
     }
 
@@ -211,7 +214,7 @@ class ChannelScreenViewModel : ViewModel() {
                     messages.add(message)
                 }
             }
-            setRenderableMessages(renderableMessages + messages)
+            regroupMessages(renderableMessages + messages)
         }
     }
 
@@ -276,6 +279,39 @@ class ChannelScreenViewModel : ViewModel() {
             } ?: it
         }
     }
+
+    private fun regroupMessages(newMessages: List<MessageSchema> = renderableMessages) {
+        val groupedMessages = arrayListOf<MessageSchema>()
+
+        // Verbatim implementation of https://wiki.rvlt.gg/index.php/Text_Channel_(UI)#Message_Grouping_Algorithm
+        // The exception is the date variable being pushed into cache, we don't need that here.
+        // Keep in mind: Recomposing UI is incredibly cheap in Jetpack Compose.
+        newMessages.forEach { message ->
+            var tail = true
+
+            val next = newMessages.getOrNull(newMessages.indexOf(message) + 1)
+            if (next != null) {
+                val dateA = Instant.fromEpochMilliseconds(ULID.asTimestamp(message.id!!))
+                val dateB = Instant.fromEpochMilliseconds(ULID.asTimestamp(next.id!!))
+
+                if (
+                    message.author != next.author ||
+                    dateB - dateA >= 7.minutes ||
+                    message.masquerade != next.masquerade ||
+                    message.system != null || next.system != null ||
+                    message.replies != null || next.replies != null
+                ) {
+                    tail = false
+                }
+            } else {
+                tail = false
+            }
+
+            groupedMessages.add(message.copy(tail = tail))
+        }
+
+        setRenderableMessages(groupedMessages)
+    }
 }
 
 @Composable

app/src/main/java/chat/revolt/ui/theme/Theme.kt

@@ -1,5 +1,6 @@
 package chat.revolt.ui.theme
 
+import android.annotation.SuppressLint
 import android.app.Activity
 import android.os.Build
 import androidx.compose.foundation.isSystemInDarkTheme
@@ -59,6 +60,7 @@ enum class Theme {
     Amoled,
 }
 
+@SuppressLint("NewApi")
 @Composable
 fun RevoltTheme(
     requestedTheme: Theme,