feat: Add Conjugate tab to Conjugate app (#563)

app/src/main/java/be/scri/App.kt

@@ -15,15 +15,12 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.pager.HorizontalPager
 import androidx.compose.foundation.pager.PagerState
-import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Scaffold
-import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
-import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
@@ -44,6 +41,7 @@ import be.scri.ui.screens.SelectTranslationSourceLanguageScreen
 import be.scri.ui.screens.ThirdPartyScreen
 import be.scri.ui.screens.WikimediaScreen
 import be.scri.ui.screens.about.AboutScreen
+import be.scri.ui.screens.conjugate.ConjugateScreen
 import be.scri.ui.screens.download.CheckUpdateActions
 import be.scri.ui.screens.download.DataDownloadViewModel
 import be.scri.ui.screens.download.DownloadActions
@@ -167,13 +165,12 @@ fun ScribeApp(
                             }
                             is BottomBarScreen.Conjugate -> {
                                 Box(
-                                    modifier =
-                                        Modifier.fillMaxSize(),
-                                    contentAlignment = Alignment.Center,
+                                    modifier = Modifier.fillMaxSize(),
                                 ) {
-                                    Text(
-                                        text = "Conjugate App",
-                                        style = MaterialTheme.typography.headlineMedium,
+                                    ConjugateScreen(
+                                        isDarkTheme = isDarkTheme,
+                                        downloadStates = downloadStates,
+                                        onDownloadAction = onDownloadAction,
                                     )
                                 }
                                 HandleBackPress(pagerState, coroutineScope)

app/src/main/java/be/scri/ui/screens/conjugate/ConjugateScreen.kt

@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package be.scri.ui.screens.conjugate
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+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.layout.size
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.viewmodel.compose.viewModel
+import be.scri.R
+import be.scri.ui.common.appcomponents.PageTitle
+import be.scri.ui.common.components.DownloadDataOptionComp
+import be.scri.ui.screens.download.DownloadState
+
+/**
+ * Main Conjugate Screen displaying empty state and download action.
+ */
+@Composable
+fun ConjugateScreen(
+    isDarkTheme: Boolean,
+    downloadStates: Map<String, DownloadState>,
+    onDownloadAction: (String, Boolean) -> Unit,
+    modifier: Modifier = Modifier,
+    viewModel: ConjugateViewModel = viewModel(),
+) {
+    val isDataAvailable by viewModel.isDataAvailable.collectAsState()
+    val conjugateDownloadState = downloadStates["conjugate_data"] ?: DownloadState.Ready
+
+    Scaffold(
+        topBar = {
+            // Using PageTitle as a stand-in for the shared TabBar from issue #560
+            // if an explicit TabBar component is not present in the current branch.
+            PageTitle(
+                pageTitle = "Conjugate", // Can be replaced by i18n string
+                modifier = Modifier.fillMaxWidth(),
+            )
+        },
+        modifier = modifier.fillMaxSize(),
+    ) { paddingValues ->
+        Box(
+            modifier =
+                Modifier
+                    .fillMaxSize()
+                    .padding(paddingValues),
+            contentAlignment = Alignment.Center,
+        ) {
+            if (!isDataAvailable) {
+                ConjugateEmptyState(
+                    isDarkTheme = isDarkTheme,
+                    downloadState = conjugateDownloadState,
+                    onDownloadClick = {
+                        onDownloadAction("conjugate_data", false)
+                    },
+                )
+            } else {
+                // Next page content (out of scope for #563)
+                Text("Conjugation UI will be here")
+            }
+        }
+    }
+}
+
+/**
+ * The "No Data" Empty state representation for Conjugation.
+ */
+@Composable
+fun ConjugateEmptyState(
+    isDarkTheme: Boolean,
+    downloadState: DownloadState,
+    onDownloadClick: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    Column(
+        modifier = modifier.padding(16.dp),
+        horizontalAlignment = Alignment.CenterHorizontally,
+        verticalArrangement = Arrangement.Center,
+    ) {
+        // SVG Placeholder logo
+        Icon(
+            painter = painterResource(id = R.drawable.scribe_logo),
+            contentDescription = null,
+            modifier = Modifier.size(120.dp),
+            tint = MaterialTheme.colorScheme.onSurfaceVariant,
+        )
+
+        Spacer(modifier = Modifier.height(24.dp))
+
+        Text(
+            text = stringResource(id = R.string.i18n_app_download_menu_option_conjugate_description),
+            style = MaterialTheme.typography.bodyLarge,
+            textAlign = TextAlign.Center,
+            color = MaterialTheme.colorScheme.onSurface,
+        )
+
+        Spacer(modifier = Modifier.height(32.dp))
+
+        DownloadDataOptionComp(
+            onClick = onDownloadClick,
+            isDarkTheme = isDarkTheme,
+            downloadState = downloadState,
+            modifier = Modifier.padding(horizontal = 16.dp),
+        )
+
+        Spacer(modifier = Modifier.height(16.dp))
+
+        Text(
+            text = stringResource(id = R.string.i18n_app_download_menu_option_conjugate_download_data_start),
+            style = MaterialTheme.typography.bodyMedium,
+            textAlign = TextAlign.Center,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+        )
+    }
+}

app/src/main/java/be/scri/ui/screens/conjugate/ConjugateViewModel.kt

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package be.scri.ui.screens.conjugate
+
+import androidx.lifecycle.ViewModel
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+
+class ConjugateViewModel : ViewModel() {
+    private val _isDataAvailable = MutableStateFlow(false)
+    val isDataAvailable: StateFlow<Boolean> = _isDataAvailable.asStateFlow()
+
+    // Assuming we would check actual data availability via a repository or ConjugateDataManager.
+    fun checkDataAvailability(hasData: Boolean) {
+        _isDataAvailable.value = hasData
+    }
+}