implement language direction and shuffling logic in StartExerciseScreen

app/src/main/java/eu/gaudian/translator/view/composable/LanguageDropDown.kt

@@ -56,6 +56,8 @@ fun BaseLanguageDropDown(
     enableMultipleSelection: Boolean = false,
     onLanguagesSelected: (List<Language>) -> Unit = {},
     alternateLanguages: List<Language> = emptyList(),
+    restrictToAlternateLanguages: Boolean = false,
+    enabled: Boolean = true,
     iconEnabled: Boolean = true,
     noBorder: Boolean = false,
 ) {
@@ -68,9 +70,13 @@ fun BaseLanguageDropDown(
     var tempSelection by remember { mutableStateOf<List<Language>>(emptyList()) }
     var selectedLanguagesCount by remember { mutableIntStateOf(if (enableMultipleSelection) tempSelection.size else 0) }
 
-    val languages = remember(alternateLanguages, defaultLanguages) {
+    val languages = remember(alternateLanguages, defaultLanguages, restrictToAlternateLanguages) {
+        if (restrictToAlternateLanguages) {
+            alternateLanguages
+        } else {
             alternateLanguages.ifEmpty { defaultLanguages }
         }
+    }
 
     val buttonText = when {
         enableMultipleSelection && selectedLanguagesCount > 0 -> stringResource(
@@ -90,6 +96,7 @@ fun BaseLanguageDropDown(
         AppOutlinedButton(
             shape = RoundedCornerShape(8.dp),
             onClick = { expanded = true },
+            enabled = enabled,
             contentPadding = if (!iconEnabled) PaddingValues(0.dp) else PaddingValues(horizontal = 16.dp, vertical = 8.dp),
             borderColor = if (noBorder) Color.Unspecified else null
         ) {
@@ -222,7 +229,12 @@ fun BaseLanguageDropDown(
                         val isSearching = searchText.isNotBlank()
 
                     if (isSearching) {
-                            val searchResults = (favoriteLanguages + languageHistory + languages)
+                        val searchBase = if (restrictToAlternateLanguages) {
+                            alternateLanguages
+                        } else {
+                            favoriteLanguages + languageHistory + languages
+                        }
+                        val searchResults = searchBase
                                 .distinctBy { it.nameResId }
                                 .filter { language ->
                                     val matchesName = language.name.contains(searchText, ignoreCase = true)
@@ -237,6 +249,16 @@ fun BaseLanguageDropDown(
                                 searchResults.forEach { language -> SingleSelectItem(language) }
                             }
 
+                    } else if (restrictToAlternateLanguages) {
+                        val sortedAlternate = alternateLanguages.sortedBy { it.name }
+                        if (enableMultipleSelection) {
+                            DropdownHeader(text = stringResource(R.string.text_all_languages))
+                            sortedAlternate.forEach { language -> MultiSelectItem(language) }
+                        } else {
+                            DropdownHeader(text = stringResource(R.string.text_all_languages))
+                            sortedAlternate.forEach { language -> SingleSelectItem(language) }
+                        }
+
                     } else if (alternateLanguages.isNotEmpty()) {
                         val sortedAlternate = alternateLanguages.sortedBy { it.name }
                             if (enableMultipleSelection) {
@@ -458,7 +480,9 @@ fun SingleLanguageDropDown(
     onAutoSelected: () -> Unit = {},
     showNoneOption: Boolean = false,
     onNoneSelected: () -> Unit = {},
-    alternateLanguages: List<Language> = emptyList()
+    alternateLanguages: List<Language> = emptyList(),
+    restrictToAlternateLanguages: Boolean = false,
+    enabled: Boolean = true
 ) {
     val languageHistory by languageViewModel.languageHistory.collectAsState()
 
@@ -477,6 +501,10 @@ fun SingleLanguageDropDown(
         showNoneOption = showNoneOption,
         onNoneSelected = onNoneSelected,
         enableMultipleSelection = false,
-        alternateLanguages = alternateLanguages
+        alternateLanguages = alternateLanguages,
+        restrictToAlternateLanguages = restrictToAlternateLanguages,
+        enabled = enabled,
+        iconEnabled = enabled,
+        noBorder = !enabled
     )
 }

app/src/main/java/eu/gaudian/translator/view/exercises/StartExerciseScreen.kt

@@ -89,6 +89,7 @@ fun StartExerciseScreen(
 
     var selectedOriginLanguage by remember { mutableStateOf<Language?>(null) }
     var selectedTargetLanguage by remember { mutableStateOf<Language?>(null) }
+    val isDirectionPreferenceSet = selectedOriginLanguage != null || selectedTargetLanguage != null
 
     val selectedPairsIds = remember(selectedLanguagePairs) {
         selectedLanguagePairs.map { it.first.nameResId to it.second.nameResId }
@@ -115,6 +116,15 @@ fun StartExerciseScreen(
     val itemsToShow by filteredItemsFlow.collectAsState(initial = emptyList())
     val totalItemCount = itemsToShow.size
 
+    val availableLanguagesFromItems = remember(itemsToShow, selectedPairsIds) {
+        val ids = if (selectedPairsIds.isNotEmpty()) {
+            selectedPairsIds.flatMap { pair -> listOf(pair.first, pair.second) }.toSet()
+        } else {
+            itemsToShow.flatMap { listOfNotNull(it.languageFirstId, it.languageSecondId) }.toSet()
+        }
+        ids
+    }
+
     var amount by remember { mutableStateOf(0) }
     androidx.compose.runtime.LaunchedEffect(totalItemCount) {
         amount = totalItemCount
@@ -140,6 +150,7 @@ fun StartExerciseScreen(
                 onShuffleCardsChanged = { updateConfig(exerciseConfig.copy(shuffleCards = it)) },
                 shuffleLanguages = exerciseConfig.shuffleLanguages,
                 onShuffleLanguagesChanged = { updateConfig(exerciseConfig.copy(shuffleLanguages = it)) },
+                shuffleLanguagesEnabled = !isDirectionPreferenceSet,
                 trainingMode = exerciseConfig.trainingMode,
                 onTrainingModeChanged = { updateConfig(exerciseConfig.copy(trainingMode = it)) },
             )
@@ -154,21 +165,46 @@ fun StartExerciseScreen(
                 item {
                     LanguagePairSection(
                         selectedPairs = selectedLanguagePairs,
-                        onPairsChanged = { selectedLanguagePairs = it },
+                        availableLanguageIds = availableLanguagesFromItems,
+                        onPairsChanged = { updatedPairs ->
+                            val hadPairs = selectedLanguagePairs.isNotEmpty()
+                            selectedLanguagePairs = updatedPairs
+                            if (updatedPairs.isNotEmpty()) {
+                                selectedOriginLanguage = null
+                                selectedTargetLanguage = null
+                                updateConfig(exerciseConfig.copy(originLanguageId = null, targetLanguageId = null))
+                            } else if (hadPairs) {
+                                updateConfig(exerciseConfig.copy(originLanguageId = null, targetLanguageId = null))
+                            }
+                        },
                         onOriginLanguageSelected = { language ->
+                            if (language?.nameResId == selectedOriginLanguage?.nameResId) {
+                                selectedOriginLanguage = null
+                                updateConfig(exerciseConfig.copy(originLanguageId = null))
+                            } else {
                                 selectedOriginLanguage = language
                                 if (selectedTargetLanguage?.nameResId == language?.nameResId) {
                                     selectedTargetLanguage = null
+                                    updateConfig(exerciseConfig.copy(targetLanguageId = null))
                                 }
                                 updateConfig(exerciseConfig.copy(originLanguageId = language?.nameResId))
+                            }
                         },
                         onTargetLanguageSelected = { language ->
+                            if (language?.nameResId == selectedTargetLanguage?.nameResId) {
+                                selectedTargetLanguage = null
+                                updateConfig(exerciseConfig.copy(targetLanguageId = null))
+                            } else {
                                 selectedTargetLanguage = language
                                 if (selectedOriginLanguage?.nameResId == language?.nameResId) {
                                     selectedOriginLanguage = null
+                                    updateConfig(exerciseConfig.copy(originLanguageId = null))
                                 }
                                 updateConfig(exerciseConfig.copy(targetLanguageId = language?.nameResId))
+                            }
                         },
+                        languageSelectionEnabled = true,
+                        selectedPairsCount = selectedLanguagePairs.size,
                         selectedOriginLanguage = selectedOriginLanguage,
                         selectedTargetLanguage = selectedTargetLanguage
                     )
@@ -249,6 +285,7 @@ fun TopBarSection(
     onShuffleCardsChanged: (Boolean) -> Unit,
     shuffleLanguages: Boolean,
     onShuffleLanguagesChanged: (Boolean) -> Unit,
+    shuffleLanguagesEnabled: Boolean,
     trainingMode: Boolean,
     onTrainingModeChanged: (Boolean) -> Unit
 ) {
@@ -306,6 +343,7 @@ fun TopBarSection(
             onShuffleCardsChanged = onShuffleCardsChanged,
             shuffleLanguages = shuffleLanguages,
             onShuffleLanguagesChanged = onShuffleLanguagesChanged,
+            shuffleLanguagesEnabled = shuffleLanguagesEnabled,
             trainingMode = trainingMode,
             onTrainingModeChanged = onTrainingModeChanged,
             onDismiss = {
@@ -348,9 +386,12 @@ fun SectionHeader(title: String, actionText: String? = null, onActionClick: () -
 @Composable
 fun LanguagePairSection(
     selectedPairs: List<Pair<Language, Language>>,
+    availableLanguageIds: Set<Int>,
     onPairsChanged: (List<Pair<Language, Language>>) -> Unit,
     onOriginLanguageSelected: (Language?) -> Unit,
     onTargetLanguageSelected: (Language?) -> Unit,
+    languageSelectionEnabled: Boolean,
+    selectedPairsCount: Int,
     selectedOriginLanguage: Language?,
     selectedTargetLanguage: Language?
 ) {
@@ -360,9 +401,8 @@ fun LanguagePairSection(
     val languagesPresent by vocabularyViewModel.languagesPresent.collectAsState(initial = emptySet())
     val allLanguages by languageViewModel.allLanguages.collectAsState(initial = emptyList())
 
-    val availableLanguages = remember(languagesPresent, allLanguages) {
+    val availableLanguages = remember(availableLanguageIds, allLanguages) {
-        val presentIds = languagesPresent.filterNotNull().toSet()
+        allLanguages.filter { it.nameResId in availableLanguageIds }
-        allLanguages.filter { it.nameResId in presentIds }
     }
 
     val allItems by vocabularyViewModel.vocabularyItems.collectAsState(initial = emptyList())
@@ -433,6 +473,14 @@ fun LanguagePairSection(
             style = MaterialTheme.typography.bodyMedium,
             color = MaterialTheme.colorScheme.onSurfaceVariant
         )
+        if (!languageSelectionEnabled && selectedPairsCount > 0) {
+            Spacer(modifier = Modifier.height(8.dp))
+            Text(
+                text = stringResource(R.string.text_language_direction_disabled_with_pairs),
+                style = MaterialTheme.typography.bodyMedium,
+                color = MaterialTheme.colorScheme.onSurfaceVariant
+            )
+        }
         Spacer(modifier = Modifier.height(12.dp))
         Row(
             horizontalArrangement = Arrangement.spacedBy(16.dp),
@@ -448,9 +496,15 @@ fun LanguagePairSection(
                     modifier = Modifier.fillMaxWidth(),
                     languageViewModel = languageViewModel,
                     selectedLanguage = selectedOriginLanguage,
-                    onLanguageSelected = onOriginLanguageSelected,
+                    onLanguageSelected = { language ->
+                        if (selectedTargetLanguage?.nameResId == language.nameResId) return@SingleLanguageDropDown
+                        onOriginLanguageSelected(language)
+                    },
                     showNoneOption = true,
-                    alternateLanguages = availableLanguages
+                    onNoneSelected = { onOriginLanguageSelected(null) },
+                    alternateLanguages = availableLanguages,
+                    restrictToAlternateLanguages = true,
+                    enabled = languageSelectionEnabled
                 )
             }
             Column(modifier = Modifier.weight(1f)) {
@@ -463,9 +517,15 @@ fun LanguagePairSection(
                     modifier = Modifier.fillMaxWidth(),
                     languageViewModel = languageViewModel,
                     selectedLanguage = selectedTargetLanguage,
-                    onLanguageSelected = onTargetLanguageSelected,
+                    onLanguageSelected = { language ->
+                        if (selectedOriginLanguage?.nameResId == language.nameResId) return@SingleLanguageDropDown
+                        onTargetLanguageSelected(language)
+                    },
                     showNoneOption = true,
-                    alternateLanguages = availableLanguages
+                    onNoneSelected = { onTargetLanguageSelected(null) },
+                    alternateLanguages = availableLanguages,
+                    restrictToAlternateLanguages = true,
+                    enabled = languageSelectionEnabled
                 )
             }
         }
@@ -807,6 +867,7 @@ private fun StartExerciseSettingsBottomSheet(
     onShuffleCardsChanged: (Boolean) -> Unit,
     shuffleLanguages: Boolean,
     onShuffleLanguagesChanged: (Boolean) -> Unit,
+    shuffleLanguagesEnabled: Boolean,
     trainingMode: Boolean,
     onTrainingModeChanged: (Boolean) -> Unit,
     onDismiss: () -> Unit
@@ -835,9 +896,22 @@ private fun StartExerciseSettingsBottomSheet(
             OptionItemSwitch(
                 title = stringResource(R.string.text_shuffle_languages),
                 description = stringResource(R.string.text_shuffle_languages_description),
-                checked = shuffleLanguages,
+                checked = shuffleLanguages && shuffleLanguagesEnabled,
-                onCheckedChange = onShuffleLanguagesChanged
+                onCheckedChange = { enabled ->
+                    if (shuffleLanguagesEnabled) {
+                        onShuffleLanguagesChanged(enabled)
+                    } else {
+                        onShuffleLanguagesChanged(false)
+                    }
+                }
             )
+            if (!shuffleLanguagesEnabled) {
+                Text(
+                    text = stringResource(R.string.text_shuffle_languages_disabled_by_direction),
+                    style = MaterialTheme.typography.bodySmall,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                )
+            }
             OptionItemSwitch(
                 title = stringResource(R.string.label_training_mode),
                 description = stringResource(R.string.text_training_mode_description),

app/src/main/res/values-de-rDE/strings.xml

@@ -680,6 +680,7 @@
     <string name="label_language_direction">Sprachenrichtung
 </string>
     <string name="text_language_direction_explanation">Du kannst eine optionale Einstellung vornehmen, welche Sprache zuerst oder zweit kommen soll.</string>
+    <string name="text_language_direction_disabled_with_pairs">Entferne die Sprachpaar-Auswahl, um eine Richtung zu wählen.</string>
     <string name="label_guessing_exercise">Raten</string>
     <string name="label_spelling_exercise">Rechtschreibung</string>
     <string name="label_multiple_choice_exercise">Multiple Choice</string>
@@ -687,6 +688,7 @@
     <string name="text_due_today_only_description">Nur Karten anzeigen, die heute fällig sind.</string>
     <string name="text_shuffle_card_order_description">Kartenmischung</string>
     <string name="text_shuffle_languages_description">Mische die Reihenfolge der Sprachen. Beeinflusst nicht deine Sprachrichtungs-Einstellungen.</string>
+    <string name="text_shuffle_languages_disabled_by_direction">Deaktiviere die Sprachrichtungs-Einstellung, um das Mischen zu aktivieren.</string>
     <string name="label_conjugation">Konjugation: %1$s</string>
     <string name="label_collapse">Einklappen</string>
     <string name="label_expand">Ausklappen</string>

app/src/main/res/values-pt-rBR/strings.xml

@@ -685,6 +685,7 @@
     <string name="text_due_today_only_description">Apenas perguntar cartas que estão a vencer hoje.</string>
     <string name="text_shuffle_card_order_description">Embaralhar Ordem das Cartas</string>
     <string name="text_shuffle_languages_description">Embaralhar qual idioma vem primeiro. Não afeta as preferências de direção do idioma.</string>
+    <string name="text_shuffle_languages_disabled_by_direction">Desative a preferência de direção do idioma para habilitar o embaralhamento.</string>
     <string name="label_conjugation">Conjugação: %1$s</string>
     <string name="label_collapse">Recolher</string>
     <string name="label_expand">Expandir</string>
@@ -844,6 +845,7 @@
     <string name="text_failed_to_fetch_manifest">Falha ao buscar informações de download sobre dicionários disponíveis: %1$s</string>
     <string name="text_translation_instructions">Defina o modelo para tradução e dê instruções opcionais sobre como traduzir.</string>
     <string name="text_language_direction_explanation">Você pode definir uma preferência opcional sobre qual idioma deve vir primeiro ou segundo.</string>
+    <string name="text_language_direction_disabled_with_pairs">Limpe a seleção de pares de idiomas para escolher uma direção.</string>
     <string name="label_all_categories">Todas as Categorias</string>
     <string name="text_description_dictionary_prompt">Defina um modelo para gerar conteúdo do dicionário e dê instruções opcionais.</string>
     <string name="hint_vocabulary_progress_hint_title">Acompanhamento de Progresso de Vocabulário</string>

app/src/main/res/values/strings.xml

@@ -824,6 +824,7 @@
     <string name="text_label_word">Enter a word\n</string>
     <string name="text_language_code">Language Code</string>
     <string name="text_language_direction_explanation">You can set an optional preference which language should come first or second.</string>
+    <string name="text_language_direction_disabled_with_pairs">Clear language pair selection to choose a direction.</string>
     <string name="text_language_options">Language Options</string>
     <string name="text_last_7_days">Last 7 Days</string>
     <string name="text_let_ai_find_vocabulary_for_you">Let AI find vocabulary for you!</string>
@@ -900,6 +901,7 @@
     <string name="text_shuffle_card_order_description">Shuffle Card Order</string>
     <string name="text_shuffle_languages">Shuffle Languages</string>
     <string name="text_shuffle_languages_description">Shuffle what language comes first. Does not affect language direction preferences.</string>
+    <string name="text_shuffle_languages_disabled_by_direction">Disable language direction preference to enable shuffling.</string>
     <string name="text_shuffle_questions">Shuffle questions</string>
     <string name="text_some_items_are_in_the_wrong_category">Some items are in the wrong category.</string>
     <string name="text_stage_2d">Stage %1$s</string>