feat(dm): explain the mutual-follow rule when the recipient list is empty (#86)

app/src/main/java/com/interlinedlist/android/navigation/InterlinedListNavHost.kt

@@ -329,6 +329,10 @@ private fun MainShell(
                 onBack = { tabNav.popBackStack() },
                 onOpenThread = { username -> tabNav.navigateToDmThread(username) },
                 onComposeNew = { tabNav.navigateToNewDm() },
+                // DMs are limited to mutual follows; when the recipient set is
+                // empty the picker routes to the existing user search so the
+                // user can go and follow someone.
+                onFindPeople = { tabNav.navigate(Routes.USER_SEARCH) },
             )
 
             // ---- Lists ----

feature/directmessages/src/androidTest/kotlin/com/interlinedlist/android/feature/directmessages/ui/NewMessageScreenTest.kt

@@ -0,0 +1,109 @@
+package com.interlinedlist.android.feature.directmessages.ui
+
+import androidx.compose.ui.test.assertIsDisplayed
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.test.onNodeWithTag
+import androidx.compose.ui.test.onNodeWithText
+import androidx.compose.ui.test.performClick
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.common.truth.Truth.assertThat
+import com.interlinedlist.android.core.designsystem.theme.InterlinedListTheme
+import com.interlinedlist.android.feature.directmessages.data.Recipient
+import com.interlinedlist.android.feature.directmessages.ui.newmessage.NewMessageScreen
+import com.interlinedlist.android.feature.directmessages.ui.newmessage.NewMessageTestTags
+import com.interlinedlist.android.feature.directmessages.ui.newmessage.NewMessageUiState
+import com.interlinedlist.android.feature.directmessages.ui.newmessage.RecipientRuleCopy
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+/**
+ * The recipient picker must tell three stories apart: still loading, loaded but
+ * nobody is messageable yet (the mutual-follow rule), and an actual failure.
+ */
+@RunWith(AndroidJUnit4::class)
+class NewMessageScreenTest {
+
+    @get:Rule
+    val composeRule = createComposeRule()
+
+    private val adron = Recipient("u1", "adron", "Adron Hall", null)
+
+    private fun setScreen(
+        state: NewMessageUiState,
+        onFindPeople: () -> Unit = {},
+        onRetry: () -> Unit = {},
+    ) {
+        composeRule.setContent {
+            InterlinedListTheme {
+                NewMessageScreen(
+                    state = state,
+                    onQueryChange = {},
+                    onBack = {},
+                    onRecipientChosen = {},
+                    onFindPeople = onFindPeople,
+                    onRetry = onRetry,
+                )
+            }
+        }
+    }
+
+    @Test
+    fun emptyRecipients_explainsTheRule_andOffersAWayOut() {
+        setScreen(NewMessageUiState(recipients = emptyList(), isLoading = false))
+
+        composeRule.onNodeWithTag(NewMessageTestTags.EMPTY).assertIsDisplayed()
+        composeRule.onNodeWithText(RecipientRuleCopy.TITLE).assertIsDisplayed()
+        composeRule.onNodeWithText(RecipientRuleCopy.EXPLANATION).assertIsDisplayed()
+        composeRule.onNodeWithTag(NewMessageTestTags.FIND_PEOPLE).assertIsDisplayed()
+        composeRule.onNodeWithTag(NewMessageTestTags.LIST).assertDoesNotExist()
+        composeRule.onNodeWithTag(NewMessageTestTags.ERROR).assertDoesNotExist()
+    }
+
+    @Test
+    fun findPeople_routesToUserSearch() {
+        var tapped = false
+        setScreen(
+            state = NewMessageUiState(recipients = emptyList(), isLoading = false),
+            onFindPeople = { tapped = true },
+        )
+
+        composeRule.onNodeWithTag(NewMessageTestTags.FIND_PEOPLE).performClick()
+
+        assertThat(tapped).isTrue()
+    }
+
+    @Test
+    fun recipients_areStillListed() {
+        setScreen(NewMessageUiState(recipients = listOf(adron), isLoading = false))
+
+        composeRule.onNodeWithTag(NewMessageTestTags.LIST).assertIsDisplayed()
+        composeRule.onNodeWithTag(NewMessageTestTags.row("adron")).assertIsDisplayed()
+        composeRule.onNodeWithTag(NewMessageTestTags.EMPTY).assertDoesNotExist()
+    }
+
+    @Test
+    fun loading_showsProgress_notTheEmptyExplanation() {
+        setScreen(NewMessageUiState(isLoading = true))
+
+        composeRule.onNodeWithTag(NewMessageTestTags.PROGRESS).assertIsDisplayed()
+        composeRule.onNodeWithTag(NewMessageTestTags.EMPTY).assertDoesNotExist()
+    }
+
+    @Test
+    fun error_showsRetry_notTheEmptyExplanation() {
+        var retried = false
+        setScreen(
+            state = NewMessageUiState(isLoading = false, errorMessage = "No connection."),
+            onRetry = { retried = true },
+        )
+
+        composeRule.onNodeWithTag(NewMessageTestTags.ERROR).assertIsDisplayed()
+        composeRule.onNodeWithText(RecipientRuleCopy.TITLE).assertDoesNotExist()
+        composeRule.onNodeWithTag(NewMessageTestTags.EMPTY).assertDoesNotExist()
+
+        composeRule.onNodeWithTag(NewMessageTestTags.RETRY).performClick()
+
+        assertThat(retried).isTrue()
+    }
+}

feature/directmessages/src/main/kotlin/com/interlinedlist/android/feature/directmessages/navigation/DirectMessagesNavigation.kt

@@ -37,12 +37,14 @@ fun NavController.navigateToNewDm() = navigate(DirectMessagesDestinations.NEW_ME
  *
  * The app wires this into its top-level NavHost (see the module's report for the
  * exact snippet). [onBack] pops the current destination; [onOpenThread] lets the
- * host decide how threads are pushed.
+ * host decide how threads are pushed. [onFindPeople] should open the host's user
+ * search so someone with no messageable contacts can go and follow people.
  */
 fun NavGraphBuilder.directMessagesGraph(
     onBack: () -> Unit,
     onOpenThread: (username: String) -> Unit,
     onComposeNew: () -> Unit,
+    onFindPeople: () -> Unit,
 ) {
     composable(DirectMessagesDestinations.INBOX) {
         InboxRoute(
@@ -64,6 +66,7 @@ fun NavGraphBuilder.directMessagesGraph(
         NewMessageRoute(
             onBack = onBack,
             onRecipientChosen = onOpenThread,
+            onFindPeople = onFindPeople,
         )
     }
 }

feature/directmessages/src/main/kotlin/com/interlinedlist/android/feature/directmessages/ui/newmessage/NewMessageScreen.kt

@@ -2,17 +2,23 @@ package com.interlinedlist.android.feature.directmessages.ui.newmessage
 
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 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.layout.size
 import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material.icons.filled.PersonAddAlt
+import androidx.compose.material3.Button
+import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
@@ -27,6 +33,7 @@ import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import androidx.hilt.navigation.compose.hiltViewModel
@@ -39,6 +46,11 @@ object NewMessageTestTags {
     const val SEARCH = "dmNewSearch"
     const val LIST = "dmNewList"
     const val EMPTY = "dmNewEmpty"
+    const val FIND_PEOPLE = "dmNewFindPeople"
+    const val NO_MATCHES = "dmNewNoMatches"
+    const val PROGRESS = "dmNewProgress"
+    const val ERROR = "dmNewError"
+    const val RETRY = "dmNewRetry"
     const val BACK = "dmNewBack"
     fun row(username: String) = "dmNewRow_$username"
 }
@@ -48,6 +60,7 @@ object NewMessageTestTags {
 fun NewMessageRoute(
     onBack: () -> Unit,
     onRecipientChosen: (username: String) -> Unit,
+    onFindPeople: () -> Unit,
     modifier: Modifier = Modifier,
     viewModel: NewMessageViewModel = hiltViewModel(),
 ) {
@@ -57,6 +70,8 @@ fun NewMessageRoute(
         onQueryChange = viewModel::onQueryChange,
         onBack = onBack,
         onRecipientChosen = { onRecipientChosen(it.username) },
+        onFindPeople = onFindPeople,
+        onRetry = viewModel::load,
         modifier = modifier,
     )
 }
@@ -69,6 +84,8 @@ fun NewMessageScreen(
     onQueryChange: (String) -> Unit,
     onBack: () -> Unit,
     onRecipientChosen: (Recipient) -> Unit,
+    onFindPeople: () -> Unit,
+    onRetry: () -> Unit,
     modifier: Modifier = Modifier,
 ) {
     Scaffold(
@@ -92,20 +109,49 @@ fun NewMessageScreen(
                 .fillMaxSize()
                 .padding(padding),
         ) {
-            OutlinedTextField(
-                value = state.query,
-                onValueChange = onQueryChange,
-                singleLine = true,
-                placeholder = { Text("Search people") },
-                modifier = Modifier
-                    .fillMaxWidth()
-                    .padding(horizontal = 16.dp, vertical = 8.dp)
-                    .testTag(NewMessageTestTags.SEARCH),
-            )
-            if (state.isEmpty) {
-                EmptyRecipients(modifier = Modifier.fillMaxSize())
-            } else {
-                LazyColumn(
+            // Searching is only meaningful once there is something to search.
+            if (state.content == NewMessageContent.Recipients ||
+                state.content == NewMessageContent.NoMatches
+            ) {
+                OutlinedTextField(
+                    value = state.query,
+                    onValueChange = onQueryChange,
+                    singleLine = true,
+                    placeholder = { Text("Search people") },
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .padding(horizontal = 16.dp, vertical = 8.dp)
+                        .testTag(NewMessageTestTags.SEARCH),
+                )
+            }
+            when (state.content) {
+                NewMessageContent.Loading -> Centered {
+                    CircularProgressIndicator(
+                        modifier = Modifier.testTag(NewMessageTestTags.PROGRESS),
+                    )
+                }
+
+                NewMessageContent.Error -> Centered {
+                    ErrorRecipients(
+                        message = state.errorMessage.orEmpty(),
+                        onRetry = onRetry,
+                    )
+                }
+
+                NewMessageContent.NoRecipients -> Centered {
+                    NoRecipients(onFindPeople = onFindPeople)
+                }
+
+                NewMessageContent.NoMatches -> Centered {
+                    Text(
+                        text = RecipientRuleCopy.NO_MATCHES,
+                        style = MaterialTheme.typography.bodyLarge,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        modifier = Modifier.testTag(NewMessageTestTags.NO_MATCHES),
+                    )
+                }
+
+                NewMessageContent.Recipients -> LazyColumn(
                     modifier = Modifier
                         .fillMaxSize()
                         .testTag(NewMessageTestTags.LIST),
@@ -123,6 +169,19 @@ fun NewMessageScreen(
     }
 }
 
+/** Fills the remaining space and centres [content]; used by the non-list states. */
+@Composable
+private fun Centered(content: @Composable () -> Unit) {
+    Box(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(24.dp),
+        contentAlignment = Alignment.Center,
+    ) {
+        content()
+    }
+}
+
 @Composable
 private fun RecipientRow(
     recipient: Recipient,
@@ -158,21 +217,64 @@ private fun RecipientRow(
     }
 }
 
+/**
+ * Loaded, but the user may not message anyone yet. This is the normal state for
+ * a new account, so it explains the rule (see [RecipientRuleCopy]) and offers a
+ * way out instead of leaving the user on a blank list.
+ */
 @Composable
-private fun EmptyRecipients(modifier: Modifier = Modifier) {
+private fun NoRecipients(onFindPeople: () -> Unit) {
     Column(
-        modifier = modifier.testTag(NewMessageTestTags.EMPTY),
+        modifier = Modifier.testTag(NewMessageTestTags.EMPTY),
         horizontalAlignment = Alignment.CenterHorizontally,
         verticalArrangement = Arrangement.Center,
     ) {
+        Icon(
+            imageVector = Icons.Filled.PersonAddAlt,
+            contentDescription = null,
+            tint = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.size(48.dp),
+        )
+        Spacer(Modifier.height(12.dp))
         Text(
-            text = "No one to message yet",
+            text = RecipientRuleCopy.TITLE,
             style = MaterialTheme.typography.titleMedium,
+            textAlign = TextAlign.Center,
         )
+        Spacer(Modifier.height(8.dp))
         Text(
-            text = "Follow people to start conversations.",
+            text = RecipientRuleCopy.EXPLANATION,
             style = MaterialTheme.typography.bodyMedium,
             color = MaterialTheme.colorScheme.onSurfaceVariant,
+            textAlign = TextAlign.Center,
+        )
+        Spacer(Modifier.height(20.dp))
+        Button(
+            onClick = onFindPeople,
+            modifier = Modifier.testTag(NewMessageTestTags.FIND_PEOPLE),
+        ) {
+            Text(RecipientRuleCopy.FIND_PEOPLE)
+        }
+    }
+}
+
+/** A genuine failure to load the recipient set — retryable, never the rule copy. */
+@Composable
+private fun ErrorRecipients(message: String, onRetry: () -> Unit) {
+    Column(
+        horizontalAlignment = Alignment.CenterHorizontally,
+        verticalArrangement = Arrangement.Center,
+    ) {
+        Text(
+            text = message,
+            style = MaterialTheme.typography.bodyLarge,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            textAlign = TextAlign.Center,
+            modifier = Modifier.testTag(NewMessageTestTags.ERROR),
         )
+        Spacer(Modifier.height(16.dp))
+        Button(onClick = onRetry, modifier = Modifier.testTag(NewMessageTestTags.RETRY)) {
+            Text("Retry")
+        }
     }
 }