Add the add-chapter flow with paragraph chunking

Add a chapter (markdown original text) to an artifact from its detail
screen, deriving word/character counts from the text and splitting it into
paragraph chunks.

- MantraRepository.addChapter attaches the chapter to the artifact's latest
  version (index = existing chapter count), computes word/character counts,
  and persists the MantraChapter plus a MarmotInnerEvent rumor
  (kind = ChapterEvent.KIND). It then splits the markdown by paragraph into
  MantraChunks, each with its own index/counts and a rumor
  (kind = ChunkEvent.KIND). New DAO query getChaptersByArtifactVersionId.
- New press.mantra.compose.text.Markdown helpers: wordCount, characterCount,
  splitParagraphs (blank-line separated).
- ChapterEvent.build / ChunkEvent.build now take the real fields (fixing the
  phantom generics); toChapterEvent / toChunkEvent tag order matches build
  and fromChapterEventTemplate / fromChunkEventTemplate are added so the
  event ids round-trip, mirroring the other models.
- New AddChapterScreen (route + ViewModel + UIState) with a name field and a
  markdown text field plus a live "words · characters · chunks" preview,
  reached from an Add Chapter button in ArtifactDetailScreen (disabled until
  the artifact has a version). On success it lands on a freshly-loaded
  artifact detail via popUpTo<ArtifactDetailRoute>.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

composeApp/src/commonMain/kotlin/press/mantra/compose/database/dao/MantraChapterDao.kt

@@ -23,4 +23,7 @@ interface MantraChapterDao {
         """
     )
     suspend fun getChaptersByArtifactId(artifactId: String): List<MantraChapter>
+
+    @Query("SELECT * FROM MantraChapter WHERE artifactVersionId = :artifactVersionId ORDER BY `index` ASC")
+    suspend fun getChaptersByArtifactVersionId(artifactVersionId: String): List<MantraChapter>
 }

composeApp/src/commonMain/kotlin/press/mantra/compose/database/model/MantraChapter.kt

@@ -5,9 +5,11 @@ import androidx.room3.ForeignKey
 import androidx.room3.PrimaryKey
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip01Core.core.TagArrayBuilder
+import com.vitorpamplona.quartz.nip01Core.crypto.EventHasher
+import com.vitorpamplona.quartz.nip01Core.signers.EventTemplate
+import com.vitorpamplona.quartz.nip31Alts.AltTag
 import press.mantra.compose.database.model.traits.OptionalNostrEventEntity
 import press.mantra.compose.database.model.traits.TimestampedEntity
-import press.mantra.compose.nostr.nip30303.ArtifactVersionEvent
 import press.mantra.compose.nostr.nip30303.ChapterEvent
 import press.mantra.compose.nostr.nip30303.tags.ArtifactVersionIdTag
 import press.mantra.compose.nostr.nip30303.tags.IndexTag
@@ -71,7 +73,9 @@ data class MantraChapter(
             id = id,
             pubKey = publicKey,
             createdAt = createdAt.epochSeconds,
-            tags = TagArrayBuilder<ArtifactVersionEvent>()
+            // Tag order matches ChapterEvent.build so the event id round-trips.
+            tags = TagArrayBuilder<ChapterEvent>()
+                .addUnique(AltTag.assemble(ChapterEvent.ALT_DESCRIPTION))
                 .addUnique(
                     ArtifactVersionIdTag.assemble(artifactVersionId)
                 )
@@ -92,6 +96,30 @@ data class MantraChapter(
     }
 
     companion object {
+        fun fromChapterEventTemplate(
+            chapterEventTemplate: EventTemplate<ChapterEvent>,
+            chatRoomId: HexKey,
+            userPublicKey: HexKey,
+        ): MantraChapter? {
+            return fromChapterEvent(
+                ChapterEvent(
+                    id = EventHasher.hashId(
+                        pubKey = userPublicKey,
+                        tags = chapterEventTemplate.tags,
+                        content = chapterEventTemplate.content,
+                        createdAt = chapterEventTemplate.createdAt,
+                        kind = chapterEventTemplate.kind,
+                    ),
+                    content = chapterEventTemplate.content,
+                    tags = chapterEventTemplate.tags,
+                    createdAt = chapterEventTemplate.createdAt,
+                    pubKey = userPublicKey,
+                    sig = "", // Unsigned rumor
+                ),
+                chatRoomId = chatRoomId,
+            )
+        }
+
         fun fromChapterEvent(chapterEvent: ChapterEvent, chatRoomId: HexKey): MantraChapter? {
             return chapterEvent.name()?.let { name ->
                 chapterEvent.originalText()?.let { originalText ->

composeApp/src/commonMain/kotlin/press/mantra/compose/database/model/MantraChunk.kt

@@ -5,6 +5,9 @@ import androidx.room3.ForeignKey
 import androidx.room3.PrimaryKey
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import com.vitorpamplona.quartz.nip01Core.core.TagArrayBuilder
+import com.vitorpamplona.quartz.nip01Core.crypto.EventHasher
+import com.vitorpamplona.quartz.nip01Core.signers.EventTemplate
+import com.vitorpamplona.quartz.nip31Alts.AltTag
 import press.mantra.compose.database.model.traits.OptionalNostrEventEntity
 import press.mantra.compose.database.model.traits.TimestampedEntity
 import press.mantra.compose.nostr.nip30303.ChunkEvent
@@ -66,7 +69,9 @@ data class MantraChunk(
             id = id,
             pubKey = publicKey,
             createdAt = createdAt.epochSeconds,
+            // Tag order matches ChunkEvent.build so the event id round-trips.
             tags = TagArrayBuilder<ChunkEvent>()
+                .addUnique(AltTag.assemble(ChunkEvent.ALT_DESCRIPTION))
                 .addUnique(
                     ChapterIdTag.assemble(chapterId)
                 )
@@ -85,6 +90,30 @@ data class MantraChunk(
     }
 
     companion object {
+        fun fromChunkEventTemplate(
+            chunkEventTemplate: EventTemplate<ChunkEvent>,
+            chatRoomId: HexKey,
+            userPublicKey: HexKey,
+        ): MantraChunk? {
+            return fromChunkEvent(
+                ChunkEvent(
+                    id = EventHasher.hashId(
+                        pubKey = userPublicKey,
+                        tags = chunkEventTemplate.tags,
+                        content = chunkEventTemplate.content,
+                        createdAt = chunkEventTemplate.createdAt,
+                        kind = chunkEventTemplate.kind,
+                    ),
+                    content = chunkEventTemplate.content,
+                    tags = chunkEventTemplate.tags,
+                    createdAt = chunkEventTemplate.createdAt,
+                    pubKey = userPublicKey,
+                    sig = "", // Unsigned rumor
+                ),
+                chatRoomId = chatRoomId,
+            )
+        }
+
         fun fromChunkEvent(chunkEvent: ChunkEvent, chatRoomId: HexKey): MantraChunk? {
             return chunkEvent.wordStatisticsTag?.let { wordStatisticsTag ->
                 chunkEvent.index()?.let { index ->

composeApp/src/commonMain/kotlin/press/mantra/compose/database/repository/DatabaseMantraRepository.kt

@@ -7,14 +7,18 @@ import press.mantra.compose.database.MantraDatabase
 import press.mantra.compose.database.model.MantraArtifact
 import press.mantra.compose.database.model.MantraArtifactVersion
 import press.mantra.compose.database.model.MantraChapter
+import press.mantra.compose.database.model.MantraChunk
 import press.mantra.compose.database.model.MantraDialect
 import press.mantra.compose.database.model.MantraTranslationArtifactVersion
 import press.mantra.compose.database.model.MarmotInnerEvent
 import press.mantra.compose.nostr.nip30303.ArtifactEvent
 import press.mantra.compose.nostr.nip30303.ArtifactVersionEvent
+import press.mantra.compose.nostr.nip30303.ChapterEvent
+import press.mantra.compose.nostr.nip30303.ChunkEvent
 import press.mantra.compose.nostr.nip30303.DialectEvent
 import press.mantra.compose.nostr.nip30303.tags.ArtifactIdTag
 import press.mantra.compose.repository.MantraRepository
+import press.mantra.compose.text.Markdown
 
 class DatabaseMantraRepository(
     val database: MantraDatabase,
@@ -38,6 +42,87 @@ class DatabaseMantraRepository(
     override suspend fun getTranslationsForArtifact(artifactId: String): List<MantraTranslationArtifactVersion> =
         database.mantraTranslationArtifactVersionDao().getTranslationsByArtifactId(artifactId)
 
+    override suspend fun addChapter(
+        artifactId: String,
+        name: String,
+        originalText: String,
+        chatRoomId: String,
+        userPublicKey: HexKey,
+    ): MantraChapter? {
+        // Chapters attach to an artifact version; use the latest one.
+        val version = database.mantraArtifactVersionDao()
+            .getArtifactVersionsByArtifactId(artifactId)
+            .firstOrNull() ?: return null
+
+        val chapterIndex = database.mantraChapterDao()
+            .getChaptersByArtifactVersionId(version.id)
+            .size
+
+        val chapterEventTemplate = ChapterEvent.build(
+            artifactVersionId = version.id,
+            name = name,
+            originalText = originalText,
+            index = chapterIndex,
+            wordCount = Markdown.wordCount(originalText),
+            characterCount = Markdown.characterCount(originalText),
+        )
+
+        val chapter = MantraChapter.fromChapterEventTemplate(
+            chapterEventTemplate = chapterEventTemplate,
+            chatRoomId = chatRoomId,
+            userPublicKey = userPublicKey,
+        ) ?: return null
+
+        return try {
+            database.mantraChapterDao().upsert(chapter)
+            database.marmotInnerEventDao().upsert(
+                MarmotInnerEvent(
+                    id = chapter.id,
+                    publicKey = chapter.publicKey,
+                    kind = ChapterEvent.KIND,
+                    createdAt = chapter.createdAt,
+                    tags = chapterEventTemplate.tags,
+                    content = chapterEventTemplate.content,
+                    chatRoomId = chapter.chatRoomId,
+                )
+            )
+
+            // Split the markdown into paragraph chunks.
+            Markdown.splitParagraphs(originalText).forEachIndexed { chunkIndex, paragraph ->
+                val chunkEventTemplate = ChunkEvent.build(
+                    chapterId = chapter.id,
+                    text = paragraph,
+                    index = chunkIndex,
+                    wordCount = Markdown.wordCount(paragraph),
+                    characterCount = Markdown.characterCount(paragraph),
+                )
+                MantraChunk.fromChunkEventTemplate(
+                    chunkEventTemplate = chunkEventTemplate,
+                    chatRoomId = chatRoomId,
+                    userPublicKey = userPublicKey,
+                )?.let { chunk ->
+                    database.mantraChunkDao().upsert(chunk)
+                    database.marmotInnerEventDao().upsert(
+                        MarmotInnerEvent(
+                            id = chunk.id,
+                            publicKey = chunk.publicKey,
+                            kind = ChunkEvent.KIND,
+                            createdAt = chunk.createdAt,
+                            tags = chunkEventTemplate.tags,
+                            content = chunkEventTemplate.content,
+                            chatRoomId = chunk.chatRoomId,
+                        )
+                    )
+                }
+            }
+
+            chapter
+        } catch (error: Throwable) {
+            logger.e("Failed to add chapter \"$name\" to artifact $artifactId", error)
+            null
+        }
+    }
+
     override suspend fun getDialects(chatRoomId: String): List<MantraDialect> =
         database.mantraDialectDao().getDialectsByChatRoomId(chatRoomId)
 

composeApp/src/commonMain/kotlin/press/mantra/compose/nostr/nip30303/ChapterEvent.kt

@@ -40,11 +40,21 @@ class ChapterEvent(
         const val ALT_DESCRIPTION = "Chapter"
 
         fun build(
-            content: String,
+            artifactVersionId: String,
+            name: String,
+            originalText: String,
+            index: Int,
+            wordCount: Int,
+            characterCount: Int,
             createdAt: Long = TimeUtils.now(),
-            initializer: TagArrayBuilder<ArtifactEvent>.() -> Unit = {},
-        ) = eventTemplate(KIND, content, createdAt) {
+            initializer: TagArrayBuilder<ChapterEvent>.() -> Unit = {},
+        ) = eventTemplate(KIND, "", createdAt) {
             alt(ALT_DESCRIPTION)
+            addUnique(ArtifactVersionIdTag.assemble(artifactVersionId))
+            addUnique(NameTag.assemble(name))
+            addUnique(OriginalTextTag.assemble(originalText))
+            addUnique(IndexTag.assemble(index))
+            addUnique(WordStatisticsTag.assemble(wordCount, characterCount))
             initializer()
         }
     }

composeApp/src/commonMain/kotlin/press/mantra/compose/nostr/nip30303/ChunkEvent.kt

@@ -37,11 +37,18 @@ class ChunkEvent(
         const val ALT_DESCRIPTION = "Chunk"
 
         fun build(
-            content: String,
+            chapterId: String,
+            text: String,
+            index: Int,
+            wordCount: Int,
+            characterCount: Int,
             createdAt: Long = TimeUtils.now(),
-            initializer: TagArrayBuilder<ArtifactEvent>.() -> Unit = {},
-        ) = eventTemplate(KIND, content, createdAt) {
+            initializer: TagArrayBuilder<ChunkEvent>.() -> Unit = {},
+        ) = eventTemplate(KIND, text, createdAt) {
             alt(ALT_DESCRIPTION)
+            addUnique(ChapterIdTag.assemble(chapterId))
+            addUnique(IndexTag.assemble(index))
+            addUnique(WordStatisticsTag.assemble(wordCount, characterCount))
             initializer()
         }
     }

composeApp/src/commonMain/kotlin/press/mantra/compose/repository/MantraRepository.kt

@@ -19,6 +19,20 @@ interface MantraRepository {
 
     suspend fun getTranslationsForArtifact(artifactId: String): List<MantraTranslationArtifactVersion>
 
+    /**
+     * Add a chapter (markdown [originalText]) to the artifact's latest version.
+     * Word/character counts are derived from the text, and the chapter is split
+     * by paragraph into associated chunks. Returns null when the artifact has no
+     * version to attach to.
+     */
+    suspend fun addChapter(
+        artifactId: String,
+        name: String,
+        originalText: String,
+        chatRoomId: String,
+        userPublicKey: HexKey,
+    ): MantraChapter?
+
     suspend fun getDialects(chatRoomId: String): List<MantraDialect>
 
     suspend fun addDialect(
@@ -62,6 +76,14 @@ interface MantraRepository {
 
             override suspend fun getTranslationsForArtifact(artifactId: String): List<MantraTranslationArtifactVersion> = emptyList()
 
+            override suspend fun addChapter(
+                artifactId: String,
+                name: String,
+                originalText: String,
+                chatRoomId: String,
+                userPublicKey: HexKey,
+            ): MantraChapter? = null
+
             override suspend fun getDialects(chatRoomId: String): List<MantraDialect> = emptyList()
 
             override suspend fun addDialect(

composeApp/src/commonMain/kotlin/press/mantra/compose/text/Markdown.kt

@@ -0,0 +1,30 @@
+package press.mantra.compose.text
+
+/**
+ * Lightweight helpers for the markdown original text of chapters/chunks.
+ *
+ * Counts are computed on the raw markdown text (no rendering/stripping):
+ * words are whitespace-separated tokens and characters are the string length.
+ */
+object Markdown {
+    private val WHITESPACE = Regex("\\s+")
+
+    /** A paragraph break is one or more blank lines. */
+    private val PARAGRAPH_BREAK = Regex("(?:\\r?\\n){2,}")
+
+    fun wordCount(text: String): Int {
+        val trimmed = text.trim()
+        return if (trimmed.isEmpty()) 0 else trimmed.split(WHITESPACE).count { it.isNotBlank() }
+    }
+
+    fun characterCount(text: String): Int = text.length
+
+    /**
+     * Split markdown into paragraphs (blocks separated by blank lines),
+     * trimmed and with empties removed. Each paragraph becomes a chunk.
+     */
+    fun splitParagraphs(text: String): List<String> =
+        text.split(PARAGRAPH_BREAK)
+            .map { it.trim() }
+            .filter { it.isNotEmpty() }
+}

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/composable/AddChapterScreen.kt

@@ -0,0 +1,222 @@
+package press.mantra.compose.ui.composable
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.text.input.rememberTextFieldState
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material.icons.filled.Add
+import androidx.compose.material.icons.filled.DriveFileRenameOutline
+import androidx.compose.material3.BottomAppBar
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.ExtendedFloatingActionButton
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.viewmodel.compose.viewModel
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import press.mantra.compose.database.model.MantraArtifact
+import press.mantra.compose.repository.MantraRepository
+import press.mantra.compose.text.Markdown
+import press.mantra.compose.ui.composable.navigation.routes.ArtifactDetailRoute
+import press.mantra.compose.ui.composable.navigation.routes.Route
+import press.mantra.compose.ui.composable.widgets.LoadingDataIndicator
+import press.mantra.compose.ui.theme.TorchTheme
+import press.mantra.compose.ui.view.model.AddChapterViewModel
+import press.mantra.compose.ui.view.state.AddChapterUIState
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun AddChapterScreen(
+    activeUserPublicKey: HexKey,
+    artifactId: String,
+    chatRoomId: String,
+    relayHint: String?,
+    initialAddChapterUIState: AddChapterUIState = AddChapterUIState.Loading,
+    mantraRepository: MantraRepository,
+    onNavigateToRoute: (Route) -> Unit,
+    onNavigateBack: () -> Unit,
+) {
+    val addChapterViewModel: AddChapterViewModel = viewModel(
+        factory = AddChapterViewModel.factory(
+            activeUserPublicKey = activeUserPublicKey,
+            artifactId = artifactId,
+            chatRoomId = chatRoomId,
+            relayHint = relayHint,
+            initialAddChapterUIState = initialAddChapterUIState,
+            mantraRepository = mantraRepository,
+        )
+    )
+
+    when (val addChapterUIState = addChapterViewModel.addChapterUIState) {
+        is AddChapterUIState.Error -> {
+            Column(
+                modifier = Modifier.fillMaxWidth(),
+                horizontalAlignment = Alignment.CenterHorizontally
+            ) {
+                Spacer(modifier = Modifier.height(50.dp))
+                Text(text = addChapterUIState.message)
+            }
+        }
+
+        is AddChapterUIState.Loaded -> {
+            val nameFieldState = rememberTextFieldState()
+            val originalTextFieldState = rememberTextFieldState()
+
+            // Live counts / paragraph (chunk) preview from the markdown text.
+            val originalText = originalTextFieldState.text.toString()
+            val wordCount = Markdown.wordCount(originalText)
+            val characterCount = Markdown.characterCount(originalText)
+            val paragraphCount = Markdown.splitParagraphs(originalText).size
+
+            Scaffold(
+                topBar = {
+                    TopAppBar(
+                        title = { Text("Add chapter to ${addChapterUIState.artifact.name}") },
+                        navigationIcon = {
+                            IconButton(onClick = onNavigateBack) {
+                                Icon(
+                                    Icons.AutoMirrored.Filled.ArrowBack,
+                                    contentDescription = "Back"
+                                )
+                            }
+                        },
+                    )
+                },
+                bottomBar = {
+                    BottomAppBar(
+                        actions = {},
+                        floatingActionButton = {
+                            ExtendedFloatingActionButton(
+                                onClick = {
+                                    addChapterViewModel.addChapter(
+                                        nameField = nameFieldState,
+                                        originalTextField = originalTextFieldState,
+                                        onSuccess = {
+                                            onNavigateToRoute.invoke(
+                                                ArtifactDetailRoute(
+                                                    activeUserPublicKey = activeUserPublicKey,
+                                                    artifactId = artifactId,
+                                                    chatRoomId = chatRoomId,
+                                                    relayHint = relayHint
+                                                )
+                                            )
+                                        },
+                                        onFailure = {}
+                                    )
+                                }
+                            ) {
+                                Icon(
+                                    Icons.Default.Add,
+                                    contentDescription = "Add chapter"
+                                )
+                                Text("Add Chapter")
+                            }
+                        }
+                    )
+                }
+            ) { innerPadding ->
+                Column(
+                    modifier = Modifier.padding(innerPadding).fillMaxSize().padding(20.dp),
+                    verticalArrangement = Arrangement.spacedBy(10.dp)
+                ) {
+                    OutlinedTextField(
+                        modifier = Modifier.fillMaxWidth(),
+                        state = nameFieldState,
+                        leadingIcon = {
+                            Icon(
+                                Icons.Default.DriveFileRenameOutline,
+                                contentDescription = "Name of the chapter"
+                            )
+                        },
+                        label = { Text("Chapter Name") },
+                        placeholder = { Text("eg. Chapter 1 — The Beginning") },
+                    )
+
+                    OutlinedTextField(
+                        modifier = Modifier.fillMaxWidth().weight(1f),
+                        state = originalTextFieldState,
+                        label = { Text("Original text (markdown)") },
+                        placeholder = { Text("Paste the chapter's markdown. Blank lines separate paragraphs into chunks.") },
+                    )
+
+                    Text(
+                        text = "$wordCount words · $characterCount characters · $paragraphCount ${if (paragraphCount == 1) "chunk" else "chunks"}",
+                        style = MaterialTheme.typography.labelMedium
+                    )
+                }
+            }
+        }
+
+        AddChapterUIState.Loading -> {
+            Column(
+                modifier = Modifier.fillMaxWidth().padding(20.dp),
+                horizontalAlignment = Alignment.CenterHorizontally,
+                verticalArrangement = Arrangement.spacedBy(20.dp)
+            ) {
+                Spacer(modifier = Modifier.weight(1f))
+                Text(
+                    text = "Add Chapter",
+                    style = MaterialTheme.typography.bodyLarge,
+                    textAlign = TextAlign.Center
+                )
+                LoadingDataIndicator(fillScreen = false)
+                Spacer(modifier = Modifier.weight(2f))
+            }
+        }
+    }
+
+    LaunchedEffect(true) {
+        if (initialAddChapterUIState == AddChapterUIState.Loading) {
+            addChapterViewModel.initiateAddChapter()
+        }
+    }
+}
+
+@Preview
+@Composable
+private fun AddChapterScreenPreview() {
+    TorchTheme {
+        Surface(modifier = Modifier.fillMaxSize()) {
+            AddChapterScreen(
+                activeUserPublicKey = "",
+                artifactId = "artifactId",
+                chatRoomId = "chatRoomId",
+                relayHint = null,
+                initialAddChapterUIState = AddChapterUIState.Loaded(
+                    artifact = MantraArtifact(
+                        id = "artifactId",
+                        publicKey = "author",
+                        name = "To Kill a Mockingbird",
+                        url = "https://harper.com/2-kill-Bird",
+                        visibility = "private",
+                        dialectId = "dialectId",
+                        license = "cc",
+                        chatRoomId = "chatRoomId",
+                        signature = ""
+                    )
+                ),
+                mantraRepository = MantraRepository.NO_OP_MANTRA_REPOSITORY,
+                onNavigateToRoute = {},
+                onNavigateBack = {}
+            )
+        }
+    }
+}

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/composable/ArtifactDetailScreen.kt

@@ -9,9 +9,11 @@ import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.layout.width
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.ArrowBack
 import androidx.compose.material.icons.filled.Article
+import androidx.compose.material.icons.filled.PostAdd
 import androidx.compose.material.icons.filled.Translate
 import androidx.compose.material3.Card
 import androidx.compose.material3.ExperimentalMaterial3Api
@@ -23,6 +25,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Scaffold
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
 import androidx.compose.material3.TopAppBar
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
@@ -35,6 +38,8 @@ import androidx.lifecycle.viewmodel.compose.viewModel
 import com.vitorpamplona.quartz.nip01Core.core.HexKey
 import press.mantra.compose.database.model.MantraArtifact
 import press.mantra.compose.repository.MantraRepository
+import press.mantra.compose.ui.composable.navigation.routes.AddChapterRoute
+import press.mantra.compose.ui.composable.navigation.routes.Route
 import press.mantra.compose.ui.composable.widgets.LoadingDataIndicator
 import press.mantra.compose.ui.theme.TorchTheme
 import press.mantra.compose.ui.view.model.ArtifactDetailViewModel
@@ -49,6 +54,7 @@ fun ArtifactDetailScreen(
     relayHint: String?,
     initialArtifactDetailUIState: ArtifactDetailUIState = ArtifactDetailUIState.Loading,
     mantraRepository: MantraRepository,
+    onNavigateToRoute: (Route) -> Unit,
     onNavigateBack: () -> Unit,
 ) {
     val artifactDetailViewModel: ArtifactDetailViewModel = viewModel(
@@ -170,6 +176,29 @@ fun ArtifactDetailScreen(
                         }
                     }
 
+                    item {
+                        TextButton(
+                            enabled = artifactDetailUIState.versions.isNotEmpty(),
+                            onClick = {
+                                onNavigateToRoute.invoke(
+                                    AddChapterRoute(
+                                        activeUserPublicKey = activeUserPublicKey,
+                                        artifactId = artifact.id,
+                                        chatRoomId = chatRoomId,
+                                        relayHint = relayHint
+                                    )
+                                )
+                            }
+                        ) {
+                            Icon(
+                                Icons.Default.PostAdd,
+                                contentDescription = "Add chapter"
+                            )
+                            Spacer(modifier = Modifier.width(10.dp))
+                            Text("Add Chapter")
+                        }
+                    }
+
                     item { HorizontalDivider() }
 
                     // Translations
@@ -261,6 +290,7 @@ private fun ArtifactDetailScreenPreview() {
                     )
                 ),
                 mantraRepository = MantraRepository.NO_OP_MANTRA_REPOSITORY,
+                onNavigateToRoute = {},
                 onNavigateBack = {}
             )
         }

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/composable/navigation/MantraNavHost.kt

@@ -89,8 +89,10 @@ import kotlinx.coroutines.launch
 import press.mantra.compose.database.repository.DatabaseMantraRepository
 import press.mantra.compose.ui.composable.AddArtifactScreen
 import press.mantra.compose.ui.composable.navigation.routes.AddArtifactRoute
+import press.mantra.compose.ui.composable.navigation.routes.AddChapterRoute
 import press.mantra.compose.ui.composable.navigation.routes.ArtifactDetailRoute
 import press.mantra.compose.ui.composable.ArtifactDetailScreen
+import press.mantra.compose.ui.composable.AddChapterScreen
 
 @Composable
 fun MantraNavHost(
@@ -686,6 +688,34 @@ fun MantraNavHost(
                 chatRoomId = route.chatRoomId,
                 relayHint = route.relayHint,
                 mantraRepository = databaseMantraRepository,
+                onNavigateToRoute = { actionRoute ->
+                    navController.navigate(
+                        route = actionRoute
+                    )
+                },
+                onNavigateBack = {
+                    navController.popBackStack()
+                }
+            )
+        }
+        composable<AddChapterRoute> { backStackEntry ->
+            val route = backStackEntry.toRoute<AddChapterRoute>()
+
+            AddChapterScreen(
+                activeUserPublicKey = route.activeUserPublicKey,
+                artifactId = route.artifactId,
+                chatRoomId = route.chatRoomId,
+                relayHint = route.relayHint,
+                mantraRepository = databaseMantraRepository,
+                onNavigateToRoute = { actionRoute ->
+                    // Replace both this add screen and the stale artifact detail
+                    // beneath it so we land on a freshly-loaded detail screen.
+                    navController.navigate(route = actionRoute) {
+                        popUpTo<ArtifactDetailRoute> {
+                            inclusive = true
+                        }
+                    }
+                },
                 onNavigateBack = {
                     navController.popBackStack()
                 }

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/composable/navigation/routes/AddChapterRoute.kt

@@ -0,0 +1,11 @@
+package press.mantra.compose.ui.composable.navigation.routes
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class AddChapterRoute(
+    val activeUserPublicKey: String,
+    val artifactId: String,
+    val chatRoomId: String,
+    val relayHint: String?
+): Route()

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/view/model/AddChapterViewModel.kt

@@ -0,0 +1,115 @@
+package press.mantra.compose.ui.view.model
+
+import androidx.compose.foundation.text.input.TextFieldState
+import androidx.compose.foundation.text.input.clearText
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.viewModelScope
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import co.touchlab.kermit.Logger
+import com.vitorpamplona.quartz.nip01Core.core.HexKey
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.IO
+import kotlinx.coroutines.launch
+import press.mantra.compose.repository.MantraRepository
+import press.mantra.compose.ui.view.state.AddChapterUIState
+
+class AddChapterViewModel(
+    val artifactId: String,
+    val chatRoomId: String,
+    val activeUserPublicKey: HexKey,
+    val relayHint: String?,
+    initialAddChapterUIState: AddChapterUIState,
+    val mantraRepository: MantraRepository,
+): ViewModel() {
+
+    var addChapterUIState: AddChapterUIState by mutableStateOf(initialAddChapterUIState)
+        private set
+
+    private val logger = Logger.withTag(TAG)
+
+    val isActionPending: MutableState<Boolean> = mutableStateOf(false)
+
+    fun initiateAddChapter() {
+        viewModelScope.launch(Dispatchers.IO) {
+            val artifact = mantraRepository.getArtifact(artifactId)
+            addChapterUIState = if (artifact == null) {
+                AddChapterUIState.Error("Couldn't find the artifact")
+            } else {
+                AddChapterUIState.Loaded(artifact = artifact)
+            }
+        }
+    }
+
+    fun addChapter(
+        nameField: TextFieldState,
+        originalTextField: TextFieldState,
+        onSuccess: () -> Unit,
+        onFailure: () -> Unit
+    ) {
+        val name = nameField.text.toString()
+        val originalText = originalTextField.text.toString()
+
+        if (name.isBlank() || originalText.isBlank()) {
+            onFailure.invoke()
+            return
+        }
+
+        // Guard against double submits from repeated FAB taps.
+        if (isActionPending.value) return
+        isActionPending.value = true
+
+        viewModelScope.launch(Dispatchers.IO) {
+            val chapter = runCatching {
+                mantraRepository.addChapter(
+                    artifactId = artifactId,
+                    name = name,
+                    originalText = originalText,
+                    chatRoomId = chatRoomId,
+                    userPublicKey = activeUserPublicKey,
+                )
+            }.onFailure { error ->
+                logger.e("Failed to add chapter", error)
+            }.getOrNull()
+
+            if (chapter != null) {
+                nameField.clearText()
+                originalTextField.clearText()
+                onSuccess.invoke()
+            } else {
+                onFailure.invoke()
+            }
+
+            isActionPending.value = false
+        }
+    }
+
+    companion object {
+        private const val TAG = "AddChapterViewModel"
+
+        fun factory(
+            activeUserPublicKey: HexKey,
+            artifactId: String,
+            chatRoomId: String,
+            relayHint: String?,
+            initialAddChapterUIState: AddChapterUIState = AddChapterUIState.Loading,
+            mantraRepository: MantraRepository,
+        ): ViewModelProvider.Factory = viewModelFactory {
+            initializer {
+                AddChapterViewModel(
+                    activeUserPublicKey = activeUserPublicKey,
+                    artifactId = artifactId,
+                    chatRoomId = chatRoomId,
+                    relayHint = relayHint,
+                    initialAddChapterUIState = initialAddChapterUIState,
+                    mantraRepository = mantraRepository,
+                )
+            }
+        }
+    }
+}

composeApp/src/commonMain/kotlin/press/mantra/compose/ui/view/state/AddChapterUIState.kt

@@ -0,0 +1,15 @@
+package press.mantra.compose.ui.view.state
+
+import press.mantra.compose.database.model.MantraArtifact
+
+sealed interface AddChapterUIState {
+    data class Loaded(
+        val artifact: MantraArtifact
+    ): AddChapterUIState
+
+    data class Error(
+        val message: String
+    ): AddChapterUIState
+
+    data object Loading: AddChapterUIState
+}