app/src/main/java/cz/fel/barysole/ackeetesttask/MainActivity.kt

@@ -14,9 +14,7 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.saveable.rememberSaveable
-import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.tooling.preview.Preview
 import androidx.core.splashscreen.SplashScreen.Companion.installSplashScreen
 import androidx.navigation.NavController
 import androidx.navigation.NavDestination.Companion.hierarchy
@@ -39,6 +37,8 @@ class MainActivity : ComponentActivity() {
         val splashScreen = installSplashScreen()
         super.onCreate(savedInstanceState)
         setContent {
+            //Main screen contains the TopAppBar and other functions, which are experimental and are likely to change or to be removed in the future.
+            //But in the small test app it looks nice, i guess.
             MainScreen()
         }
     }
@@ -46,7 +46,7 @@ class MainActivity : ComponentActivity() {
 
 }
 
-// Main handler for screens changing. Perform every (!) screen change operation in the app.
+// Main handler for navigation performing. Perform every (!) navigation operation in the app.
 // todo: split into separate navigation methods
 fun navigate(
     navController: NavController,
@@ -70,49 +70,64 @@ fun navigate(
         } else if (nextScreen == Screen.Previous) {
             navController.navigateUp()
         }
-
     }
 }
 
 @Composable
 fun MainScreen() {
-    val navController = rememberNavController()
-    val navBackStackEntry by navController.currentBackStackEntryAsState()
-    val currentDestination = navBackStackEntry?.destination
-    val selectedScreen = remember {
-        // the initial screen
-        mutableStateOf(appScreenList.find { item -> currentDestination?.hierarchy?.first()?.route == item.route }
-            ?: Screen.Characters)
-    }
-    val snackbarHostState = remember { SnackbarHostState() }
-    val actionFlow = MutableSharedFlow<ScreenAction>(extraBufferCapacity = 1)
-    val onActionClick = { action: ScreenAction ->
-        actionFlow.tryEmit(action)
-    }
-    var topBarTitle: String by rememberSaveable {
+    // Top bar settings block
+    // Top bar will set the topBarTitle if current screen doesn't have title
+    val topBarTitle = rememberSaveable {
         mutableStateOf("")
     }
-    var isFavoriteIconActive by rememberSaveable {
+    // Favorite icon state for the detail screen
+    val isFavoriteIconActive = rememberSaveable {
         mutableStateOf(false)
     }
-    val onTopBarTitleChangeFun = { newBarTitle: String -> topBarTitle = newBarTitle }
-    val onTopBarFavoriteIconChangeFun =
-        { isFavoriteActive: Boolean -> isFavoriteIconActive = isFavoriteActive }
+    val onTopBarTitleChange =
+        remember { { newBarTitle: String -> topBarTitle.value = newBarTitle } }
+    val onTopBarFavoriteIconStateChange =
+        remember { { isFavoriteActive: Boolean -> isFavoriteIconActive.value = isFavoriteActive } }
     val isSearchBarShowing = rememberSaveable {
         mutableStateOf(false)
     }
+    // Top bar action flow
+    val actionFlow = remember { MutableSharedFlow<ScreenAction>(extraBufferCapacity = 1) }
+    val onActionClick = remember {
+        { action: ScreenAction ->
+            actionFlow.tryEmit(action)
+        }
+    }
 
+    // Navigation block.
+    val navController = rememberNavController()
+    val navBackStackEntry by navController.currentBackStackEntryAsState()
+    // Current screen.
+    val selectedScreen = remember {
+        // The initial screen.
+        mutableStateOf(appScreenList.find { item -> navBackStackEntry?.destination?.hierarchy?.first()?.route == item.route }
+            ?: Screen.Characters)
+    }
+    // Changes selectedScreen when the route changes
     navController.addOnDestinationChangedListener { _, destination, _ ->
-        // Close search bar when navigation was performed
-        isSearchBarShowing.value = false
+        if (selectedScreen.value == Screen.CharacterDetail) {
+            onTopBarTitleChange("")
+        }
         // Take current screen from the the top of the current navigation stack after navigation
         selectedScreen.value =
             appScreenList.find { item -> destination.hierarchy.first().route == item.route }
                 ?: Screen.Characters
     }
-    val onScreenSelected = { screen: Screen, args: List<Any>? ->
-        navigate(navController, selectedScreen, screen, args)
+    // onScreenSelected perform all navigation in the app
+    val onSelectScreen = remember {
+        { screen: Screen, args: List<Any>? ->
+            navigate(navController, selectedScreen, screen, args)
+        }
     }
+
+    // Snackbar
+    val snackbarHostState = remember { SnackbarHostState() }
+
     // Main content
     AckeeTestTaskTheme {
         Scaffold(
@@ -120,33 +135,30 @@ fun MainScreen() {
             snackbarHost = { SnackbarHost(snackbarHostState) },
             topBar = {
                 MyTopAppBar(
-                    selectedScreen,
-                    { action -> onActionClick(action) },
-                    barTitle = topBarTitle,
-                    isFavoriteIconEnabled = isFavoriteIconActive,
+                    selectedScreen = selectedScreen.value,
+                    onActionClick = { action -> onActionClick(action) },
+                    barTitle = topBarTitle.value,
+                    isFavoriteIconEnabled = isFavoriteIconActive.value,
                     isSearchBarShowing = isSearchBarShowing,
-                    onScreenSelected = onScreenSelected
+                    onSelectScreen = onSelectScreen
                 )
             },
             content = { innerPadding ->
                 MyNavHost(
-                    navController,
-                    snackbarHostState,
-                    Modifier.padding(innerPadding),
-                    actionFlow,
-                    onTopBarTitleChange = onTopBarTitleChangeFun,
-                    onTopBarFavoriteIconChange = onTopBarFavoriteIconChangeFun,
-                    onScreenSelected = onScreenSelected
+                    navController = navController,
+                    snackbarHostState = snackbarHostState,
+                    modifier = Modifier.padding(innerPadding),
+                    screenActionFlow = actionFlow,
+                    onTopBarTitleChange = onTopBarTitleChange,
+                    onTopBarFavoriteIconChange = onTopBarFavoriteIconStateChange,
+                    onSelectScreen = onSelectScreen
                 )
             },
             bottomBar = {
-                MyNavigationBar(selectedScreen, onScreenSelected)
+                MyNavigationBar(
+                    selectedScreen = selectedScreen.value,
+                    onSelectScreen = onSelectScreen
+                )
             })
     }
-}
-
-@Preview
-@Composable
-fun MainScreenPreview() {
-    MainScreen()
 }
\ No newline at end of file

app/src/main/java/cz/fel/barysole/ackeetesttask/MyNavHost.kt

@@ -24,7 +24,7 @@ fun MyNavHost(
     screenActionFlow: Flow<ScreenAction>,
     onTopBarTitleChange: (String) -> Unit,
     onTopBarFavoriteIconChange: (Boolean) -> Unit,
-    onScreenSelected: (Screen, List<Any>?) -> Unit
+    onSelectScreen: (Screen, List<Any>?) -> Unit
 ) {
     NavHost(
         navController,
@@ -32,28 +32,28 @@ fun MyNavHost(
         modifier = modifier
     ) {
         composable(Screen.Characters.route) {
-            CustomBackHandler(onScreenSelected)
+            CustomBackHandler(onSelectScreen)
             CharacterListScreen(
                 snackbarHostState,
-                onItemSelected = { characterId ->
-                    onScreenSelected(Screen.CharacterDetail, listOf(characterId))
+                onSelectItem = { characterId ->
+                    onSelectScreen(Screen.CharacterDetail, listOf(characterId))
                 }
             )
         }
         composable(Screen.Favorite.route) {
-            CustomBackHandler(onScreenSelected)
+            CustomBackHandler(onSelectScreen)
             FavoriteCharacterListScreen(
-                    onItemSelected = { characterId ->
-                        onScreenSelected(Screen.CharacterDetail, listOf(characterId))
-            })
+                onSelectItem = { characterId ->
+                    onSelectScreen(Screen.CharacterDetail, listOf(characterId))
+                })
         }
         composable(
             Screen.CharacterDetail.route,
             arguments = listOf(navArgument("characterId") { type = NavType.LongType })
         ) { backStackEntry ->
-            CustomBackHandler(onScreenSelected)
+            CustomBackHandler(onSelectScreen)
             CharacterDetailScreen(
-                backStackEntry.arguments?.getLong("characterId"),
+                characterId = backStackEntry.arguments?.getLong("characterId"),
                 screenActionFlow,
                 onTopBarTitleChange,
                 onTopBarFavoriteIconChange
@@ -63,9 +63,9 @@ fun MyNavHost(
 }
 
 @Composable
-fun CustomBackHandler(onScreenSelected: (Screen, List<Any>?) -> Unit) {
+fun CustomBackHandler(onSelectScreen: (Screen, List<Any>?) -> Unit) {
     BackHandler(true) {
-        onScreenSelected(Screen.Previous, null)
+        onSelectScreen(Screen.Previous, null)
     }
 }
 

app/src/main/java/cz/fel/barysole/ackeetesttask/db/room/dao/PaginationDao.kt

 package cz.fel.barysole.ackeetesttask.db.room.dao
 
-import androidx.paging.PagingSource
 import androidx.room.Dao
 import androidx.room.Insert
 import androidx.room.OnConflictStrategy

app/src/main/java/cz/fel/barysole/ackeetesttask/model/CharacterInfo.kt

@@ -5,9 +5,6 @@ import androidx.room.Entity
 import androidx.room.PrimaryKey
 import com.google.gson.annotations.SerializedName
 
-/**
- * Immutable model class for the Retrofit and the Room.
- */
 @Entity(tableName = "CharacterInfo")
 data class CharacterInfo(
     @PrimaryKey @field:SerializedName("id") val id: Long,

app/src/main/java/cz/fel/barysole/ackeetesttask/repository/RepositoryResult.kt

-package cz.fel.barysole.ackeetesttask.repository
-
-class RepositoryResult {
-}
\ No newline at end of file

app/src/main/java/cz/fel/barysole/ackeetesttask/repository/characters/CharacterRemoteMediator.kt

@@ -37,7 +37,7 @@ class CharacterRemoteMediator(
         // compute required page index
         val requiredPage = when (loadType) {
             LoadType.REFRESH -> {
-                STARTING_PAGE_NUMBER
+                state.anchorPosition ?: STARTING_PAGE_NUMBER
             }
             // REFRESH will always load the first page in the list, so prepend is no longer needed.
             LoadType.PREPEND -> {

app/src/main/java/cz/fel/barysole/ackeetesttask/repository/characters/CharacterRepositoryImpl.kt

@@ -19,14 +19,19 @@ class CharacterRepositoryImpl @Inject constructor(
     private val appDatabase: AppDatabase
 ) : CharacterRepository {
 
-    // Find chracters by name query. Works without DB.
+    // Find characters by name query. Works without DB.
     override fun getCharactersByNameFlow(characterNameQuery: String): Flow<PagingData<CharacterInfo>> {
         return Pager(
             config = PagingConfig(
                 pageSize = NETWORK_PAGE_SIZE,
                 enablePlaceholders = false
             ),
-            pagingSourceFactory = { CharactersSearchPagingSource(rickAndMortyApi, characterNameQuery) }
+            pagingSourceFactory = {
+                CharactersSearchPagingSource(
+                    rickAndMortyApi,
+                    characterNameQuery
+                )
+            }
         ).flow
     }
 
@@ -53,11 +58,11 @@ class CharacterRepositoryImpl @Inject constructor(
     }
 
     override suspend fun getCharacter(characterId: Long): CharacterInfo? {
-            val response = rickAndMortyApi.getCharacterById(characterId)
-            appDatabase.withTransaction {
-                insertCharacterItems(listOf(response), appDatabase.characterDao())
-            }
-            return appDatabase.characterDao().getById(characterId)
+        val response = rickAndMortyApi.getCharacterById(characterId)
+        appDatabase.withTransaction {
+            insertCharacterItems(listOf(response), appDatabase.characterDao())
+        }
+        return appDatabase.characterDao().getById(characterId)
     }
 
     override suspend fun changeCharacterFavoriteStatus(characterId: Long) {

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/screen/Screen.kt

 package cz.fel.barysole.ackeetesttask.ui.screen
 
 import androidx.annotation.DrawableRes
+import androidx.annotation.StringRes
 import cz.fel.barysole.ackeetesttask.R
 
 sealed class Screen(
     val route: String = "",
-    val nameResId: Int? = null,
+    @StringRes val nameResId: Int? = null,
     @DrawableRes val iconResId: Int? = null,
     val routeWithoutArgument: String? = null,
     val isBackButtonShowing: Boolean = false,
@@ -46,10 +47,4 @@ val appScreenList = listOf(
     Screen.Characters,
     Screen.Favorite,
     Screen.CharacterDetail
-)
-
-val screenWithTopAppBarList = listOf(
-    Screen.Characters,
-    Screen.Favorite,
-    Screen.CharacterDetail
 )
\ No newline at end of file

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/screen/characterdetail/CharacterDetailScreen.kt

@@ -21,7 +21,12 @@ fun CharacterDetailScreen(
     onTopBarFavoriteIconChange: (Boolean) -> Unit,
     viewModel: CharacterDetailViewModel = hiltViewModel()
 ) {
-    viewModel.initialize(characterId, onTopBarTitleChange, onTopBarFavoriteIconChange, screenActionFlow)
+    viewModel.initialize(
+        characterId,
+        onTopBarTitleChange,
+        onTopBarFavoriteIconChange,
+        screenActionFlow
+    )
     val characterDetailScreenState by viewModel.uiState.collectAsState()
     Surface(
         shape = MaterialTheme.shapes.large,

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/screen/characterdetail/CharacterDetailViewModel.kt

@@ -6,12 +6,14 @@ import cz.fel.barysole.ackeetesttask.model.CharacterInfo
 import cz.fel.barysole.ackeetesttask.repository.characters.CharacterRepository
 import cz.fel.barysole.ackeetesttask.ui.screen.ScreenAction
 import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import javax.inject.Inject
 
 @HiltViewModel
@@ -20,13 +22,19 @@ class CharacterDetailViewModel @Inject constructor(
 ) : ViewModel() {
 
     private var isInit: Boolean = false
+
     // The UI state
     private val _uiState = MutableStateFlow(UiState())
     val uiState: StateFlow<UiState> = _uiState.asStateFlow()
     var onTopBarTitleChange: (String) -> Unit = {}
     var onTopBarFavoriteIconChange: (Boolean) -> Unit = {}
 
-    fun initialize(characterId: Long?, onTopBarTitleChange: (String) -> Unit = {}, onTopBarFavoriteIconChange: (Boolean) -> Unit = {}, screenFlow: Flow<ScreenAction>? = null) {
+    fun initialize(
+        characterId: Long?,
+        onTopBarTitleChange: (String) -> Unit = {},
+        onTopBarFavoriteIconChange: (Boolean) -> Unit = {},
+        screenFlow: Flow<ScreenAction>? = null
+    ) {
         if (!isInit) {
             this.onTopBarTitleChange = onTopBarTitleChange
             this.onTopBarFavoriteIconChange = onTopBarFavoriteIconChange
@@ -46,9 +54,11 @@ class CharacterDetailViewModel @Inject constructor(
         showLoadingError(false)
         characterId?.let {
             viewModelScope.launch {
-                val characterInfo = characterRepository.getCharacter(
-                    characterId
-                )
+                val characterInfo = withContext(Dispatchers.IO) {
+                    characterRepository.getCharacter(
+                        characterId
+                    )
+                }
                 onTopBarTitleChange(characterInfo?.name ?: "")
                 onTopBarFavoriteIconChange(characterInfo?.isFavorite ?: false)
                 _uiState.update { state ->

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/screen/characterdetail/CharacterInfo.kt

@@ -15,6 +15,7 @@ import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
+import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.tooling.preview.Preview
@@ -22,6 +23,7 @@ import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import com.bumptech.glide.integration.compose.ExperimentalGlideComposeApi
 import com.bumptech.glide.integration.compose.GlideImage
+import cz.fel.barysole.ackeetesttask.R
 import cz.fel.barysole.ackeetesttask.model.CharacterInfo
 import cz.fel.barysole.ackeetesttask.model.Location
 import cz.fel.barysole.ackeetesttask.model.Origin
@@ -43,7 +45,7 @@ fun CharacterInfo(
             character.image?.let {
                 GlideImage(
                     model = it,
-                    contentDescription = "Character image",
+                    contentDescription = stringResource(R.string.character_image_description),
                     modifier = Modifier
                         .padding(top = topPaddingForElements, start = startPaddingForElements)
                         .size(128.dp)
@@ -57,7 +59,7 @@ fun CharacterInfo(
                 )
             ) {
                 Text(
-                    text = "Name",
+                    text = stringResource(R.string.name_field_title),
                     style = MaterialTheme.typography.bodyLarge,
                     color = MaterialTheme.colorScheme.secondary,
                     maxLines = 1,
@@ -80,7 +82,7 @@ fun CharacterInfo(
         Row(modifier = Modifier.padding(start = startPaddingForElements)) {
             Column {
                 Text(
-                    text = "Status",
+                    text = stringResource(R.string.status_field_title),
                     style = MaterialTheme.typography.bodyMedium,
                     color = MaterialTheme.colorScheme.secondary,
                     maxLines = 1,
@@ -97,7 +99,7 @@ fun CharacterInfo(
                 )
                 Spacer(modifier = Modifier.height(itemSpaceSize))
                 Text(
-                    text = "Type",
+                    text = stringResource(R.string.type_field_title),
                     style = MaterialTheme.typography.bodyMedium,
                     color = MaterialTheme.colorScheme.secondary,
                     maxLines = 1,
@@ -114,7 +116,7 @@ fun CharacterInfo(
                 )
                 Spacer(modifier = Modifier.height(itemSpaceSize))
                 Text(
-                    text = "Gender",
+                    text = stringResource(R.string.gender_field_title),
                     style = MaterialTheme.typography.bodyMedium,
                     color = MaterialTheme.colorScheme.secondary,
                     maxLines = 1,
@@ -131,7 +133,7 @@ fun CharacterInfo(
                 )
                 Spacer(modifier = Modifier.height(itemSpaceSize))
                 Text(
-                    text = "Origin",
+                    text = stringResource(R.string.origin_field_title),
                     style = MaterialTheme.typography.bodyMedium,
                     color = MaterialTheme.colorScheme.secondary,
                     maxLines = 1,
@@ -148,7 +150,7 @@ fun CharacterInfo(
                 )
                 Spacer(modifier = Modifier.height(itemSpaceSize))
                 Text(
-                    text = "Location",
+                    text = stringResource(R.string.location_field_title),
                     style = MaterialTheme.typography.bodyMedium,
                     color = MaterialTheme.colorScheme.secondary,
                     maxLines = 1,
@@ -181,7 +183,7 @@ fun CharacterInfoPreview() {
             gender = "Male",
             origin = Origin("Earth"),
             location = Location("Earth"),
-            image = "https://rickandmortyapi.com/api/character/avatar/2.jpeg"
+            image = null
         )
     )
 }
\ No newline at end of file

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/screen/characterlist/CharacterListScreen.kt

@@ -14,21 +14,23 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.paging.LoadState
 import androidx.paging.compose.collectAsLazyPagingItems
+import cz.fel.barysole.ackeetesttask.R
 import cz.fel.barysole.ackeetesttask.ui.uielement.character.CharacterList
 
 @Composable
 fun CharacterListScreen(
-    snackbar: SnackbarHostState,
-    onItemSelected: (id: Long) -> Unit,
+    snackbarHostState: SnackbarHostState,
+    onSelectItem: (id: Long) -> Unit,
     characterListViewModel: CharacterListViewModel = hiltViewModel()
 ) {
     Surface(
         color = MaterialTheme.colorScheme.background
     ) {
-        characterListViewModel.pagingDataFlow.collectAsLazyPagingItems().let {
+        characterListViewModel.charactersPDFlow.collectAsLazyPagingItems().let {
             if (it.loadState.mediator?.refresh is LoadState.Error || it.loadState.mediator?.append is LoadState.Error) {
                 characterListViewModel.showLoadingError(true)
             } else {
@@ -36,44 +38,35 @@ fun CharacterListScreen(
             }
             // If the UI state contains an error, show snackbar
             if (characterListViewModel.uiState.value.showError) {
-                LaunchedEffect(snackbar) {
-                    snackbar.showSnackbar(
-                        message = "Data cannot be loaded!"
+                val errorMessage = stringResource(R.string.data_cannot_be_loaded_error)
+                LaunchedEffect(snackbarHostState) {
+                    snackbarHostState.showSnackbar(
+                        message = errorMessage
                     )
                 }
             }
-            // todo: there is no pullToRefresh in MD3 at this moment :c Add it later.
-            if (it.itemCount == 0) {
+            // todo: there is no pullToRefresh in MD3 at this moment. Add it later. :c
+            if (it.itemCount == 0 && it.loadState.refresh != LoadState.Loading) {
                 Column(
-                    modifier = Modifier.fillMaxWidth().fillMaxHeight(),
+                    modifier = Modifier
+                        .fillMaxWidth()
+                        .fillMaxHeight(),
                     verticalArrangement = Arrangement.Center,
                     horizontalAlignment = Alignment.CenterHorizontally
                 ) {
                     Button(
                         onClick = { characterListViewModel.refreshList() },
-                        colors = ButtonDefaults.buttonColors(containerColor = MaterialTheme.colorScheme.surface, contentColor = MaterialTheme.colorScheme.primary)
+                        colors = ButtonDefaults.buttonColors(
+                            containerColor = MaterialTheme.colorScheme.surface,
+                            contentColor = MaterialTheme.colorScheme.primary
+                        )
                     ) {
-                        Text("Reload")
+                        Text(stringResource(R.string.reload_text))
                     }
                 }
             } else {
-                CharacterList(it, onItemSelected)
+                CharacterList(it, onSelectItem)
             }
         }
     }
-}
-
-/*
-@Preview
-@Composable
-fun CharacterListPreview() {
-    CharacterList(
-        (
-            CharacterInfo(
-                "1",
-                "Rick Sanchez",
-                "Alive"
-            ), CharacterInfo("2", "Morty", "Alive")
-        )
-    )
-}*/
+}
\ No newline at end of file

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/screen/characterlist/CharacterListViewModel.kt

@@ -6,8 +6,8 @@ import androidx.paging.PagingData
 import androidx.paging.cachedIn
 import cz.fel.barysole.ackeetesttask.model.CharacterInfo
 import cz.fel.barysole.ackeetesttask.repository.characters.CharacterRepository
-import cz.fel.barysole.ackeetesttask.ui.uielement.main.UiState
 import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
@@ -17,6 +17,7 @@ import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import javax.inject.Inject
 
 @OptIn(ExperimentalCoroutinesApi::class)
@@ -28,14 +29,18 @@ class CharacterListViewModel @Inject constructor(
     // The UI state
     private val _uiState = MutableStateFlow(UiState())
     val uiState: StateFlow<UiState> = _uiState.asStateFlow()
-    val pagingDataFlow: Flow<PagingData<CharacterInfo>>
+    val charactersPDFlow: Flow<PagingData<CharacterInfo>>
 
     private val getAllCharacters = MutableSharedFlow<Unit>()
 
     init {
-        pagingDataFlow = getAllCharacters
+        charactersPDFlow = getAllCharacters
             .onStart { emit(Unit) }
-            .flatMapLatest { getCharactersPagingData() }
+            .flatMapLatest {
+                withContext(Dispatchers.IO) {
+                    characterRepository.getCharactersFlow()
+                }
+            }
             .cachedIn(viewModelScope)
     }
 
@@ -44,13 +49,12 @@ class CharacterListViewModel @Inject constructor(
     }
 
     fun refreshList() {
-        showLoadingError(false)
-        viewModelScope.launch { getAllCharacters.emit(Unit) }
+        viewModelScope.launch {
+            showLoadingError(false)
+            getAllCharacters.emit(Unit)
+        }
     }
 
-    private fun getCharactersPagingData(): Flow<PagingData<CharacterInfo>> =
-        characterRepository.getCharactersFlow()
-
     data class UiState(
         val showError: Boolean = false
     )

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/screen/favorite/FavoriteCharacterListScreen.kt

@@ -4,26 +4,26 @@ import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxHeight
 import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.material3.Button
-import androidx.compose.material3.ButtonDefaults
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.paging.compose.collectAsLazyPagingItems
+import cz.fel.barysole.ackeetesttask.R
 import cz.fel.barysole.ackeetesttask.ui.uielement.character.CharacterList
 
 @Composable
 fun FavoriteCharacterListScreen(
-    onItemSelected: (id: Long) -> Unit,
+    onSelectItem: (id: Long) -> Unit,
     favoriteCharacterListViewModel: FavoriteCharacterListViewModel = hiltViewModel()
 ) {
     favoriteCharacterListViewModel.refreshList()
     val favoriteCharacters =
-        favoriteCharacterListViewModel.pagingDataFlow.collectAsLazyPagingItems()
+        favoriteCharacterListViewModel.favoriteCharactersPDFlow.collectAsLazyPagingItems()
     Surface(
         color = MaterialTheme.colorScheme.background
     ) {
@@ -35,10 +35,10 @@ fun FavoriteCharacterListScreen(
                 verticalArrangement = Arrangement.Center,
                 horizontalAlignment = Alignment.CenterHorizontally
             ) {
-                    Text("There is no favorite characters yet.")
+                Text(stringResource(R.string.no_favorite_characters_text))
             }
         } else {
-            CharacterList(favoriteCharacters, onItemSelected)
+            CharacterList(favoriteCharacters, onSelectItem)
         }
     }
 }
\ No newline at end of file

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/screen/favorite/FavoriteCharacterListViewModel.kt

@@ -4,40 +4,37 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import androidx.paging.PagingData
 import androidx.paging.cachedIn
-import androidx.room.withTransaction
-import cz.fel.barysole.ackeetesttask.db.room.AppDatabase
 import cz.fel.barysole.ackeetesttask.model.CharacterInfo
 import cz.fel.barysole.ackeetesttask.repository.characters.CharacterRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import javax.inject.Inject
 
 @OptIn(ExperimentalCoroutinesApi::class)
 @HiltViewModel
 class FavoriteCharacterListViewModel @Inject constructor(
-    private val characterRepository: CharacterRepository,
-    private val appDatabase: AppDatabase
+    private val characterRepository: CharacterRepository
 ) : ViewModel() {
 
-    // The UI state
-    private val _uiState = MutableStateFlow(UiState())
-    val uiState: StateFlow<UiState> = _uiState.asStateFlow()
-    val pagingDataFlow: Flow<PagingData<CharacterInfo>>
+    val favoriteCharactersPDFlow: Flow<PagingData<CharacterInfo>>
 
     private val getFavoriteCharacters = MutableSharedFlow<Unit>()
 
     init {
-        pagingDataFlow = getFavoriteCharacters
+        favoriteCharactersPDFlow = getFavoriteCharacters
             .onStart { emit(Unit) }
-            .flatMapLatest { characterRepository.getFavoriteCharactersFlow() }
+            .flatMapLatest {
+                withContext(Dispatchers.IO) {
+                    characterRepository.getFavoriteCharactersFlow()
+                }
+            }
             .cachedIn(viewModelScope)
     }
 
@@ -45,12 +42,4 @@ class FavoriteCharacterListViewModel @Inject constructor(
         viewModelScope.launch { getFavoriteCharacters.emit(Unit) }
     }
 
-    fun showLoadingError(hasError: Boolean) {
-        _uiState.value = UiState(showError = hasError)
-    }
-
-    data class UiState(
-        val showError: Boolean = false
-    )
-
 }
\ No newline at end of file

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/uielement/character/CharacterList.kt

@@ -12,7 +12,7 @@ import cz.fel.barysole.ackeetesttask.model.CharacterInfo
 @Composable
 fun CharacterList(
     characterList: LazyPagingItems<CharacterInfo>,
-    onItemSelected: (id: Long) -> Unit
+    onSelectItem: (id: Long) -> Unit
 ) {
     LazyColumn(modifier = Modifier.padding(vertical = 4.dp)) {
         items(
@@ -20,7 +20,7 @@ fun CharacterList(
             contentType = { if (characterList[it] == null) 1 else 0 }
         ) { index ->
             characterList[index]?.let {
-                CharacterListItem(it, onItemSelected)
+                CharacterListItem(it, onSelectItem)
             }
         }
     }

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/uielement/character/CharacterListItem.kt

@@ -19,25 +19,28 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import com.bumptech.glide.integration.compose.ExperimentalGlideComposeApi
 import com.bumptech.glide.integration.compose.GlideImage
 import cz.fel.barysole.ackeetesttask.R
 import cz.fel.barysole.ackeetesttask.model.CharacterInfo
-import cz.fel.barysole.ackeetesttask.ui.screen.Screen
+import cz.fel.barysole.ackeetesttask.model.Location
+import cz.fel.barysole.ackeetesttask.model.Origin
 
 @OptIn(ExperimentalGlideComposeApi::class)
 @Composable
-fun CharacterListItem(character: CharacterInfo, onItemSelected: (id: Long) -> Unit) {
+fun CharacterListItem(character: CharacterInfo, onSelectItem: (id: Long) -> Unit) {
     Surface(
         shape = MaterialTheme.shapes.large,
         color = MaterialTheme.colorScheme.surface,
         shadowElevation = 4.dp,
         modifier = Modifier
             .padding(horizontal = 8.dp, vertical = 4.dp)
-            .clickable { onItemSelected(character.id) }
+            .clickable { onSelectItem(character.id) }
     ) {
         Row(
             modifier = Modifier
@@ -48,7 +51,7 @@ fun CharacterListItem(character: CharacterInfo, onItemSelected: (id: Long) -> Un
             character.image?.let {
                 GlideImage(
                     model = it,
-                    contentDescription = "Character image",
+                    contentDescription = stringResource(R.string.character_image_description),
                     modifier = Modifier
                         .size(48.dp)
                         .clip(MaterialTheme.shapes.small)
@@ -56,7 +59,7 @@ fun CharacterListItem(character: CharacterInfo, onItemSelected: (id: Long) -> Un
             }
             Spacer(modifier = Modifier.width(12.dp))
             Column {
-                Row (verticalAlignment = Alignment.CenterVertically) {
+                Row(verticalAlignment = Alignment.CenterVertically) {
                     Text(
                         text = "${character.name}",
                         style = MaterialTheme.typography.titleMedium,
@@ -71,7 +74,7 @@ fun CharacterListItem(character: CharacterInfo, onItemSelected: (id: Long) -> Un
                                 .padding(horizontal = 8.dp)
                                 .size(16.dp),
                             tint = Color.Blue,
-                            contentDescription = "Arrow back icon"
+                            contentDescription = stringResource(R.string.arrow_back_icon_description)
                         )
                     }
                 }
@@ -88,4 +91,22 @@ fun CharacterListItem(character: CharacterInfo, onItemSelected: (id: Long) -> Un
             }
         }
     }
+}
+
+@Preview
+@Composable
+fun CharacterInfoPreview() {
+    CharacterListItem(
+        character = CharacterInfo(
+            id = 2,
+            name = "Morty Smith",
+            status = "Alive",
+            species = "Human",
+            type = "",
+            gender = "Male",
+            origin = Origin("Earth"),
+            location = Location("Earth"),
+            image = null
+        )
+    ) {}
 }
\ No newline at end of file

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/uielement/main/CharacterSearchViewModel.kt → app/src/main/java/cz/fel/barysole/ackeetesttask/ui/uielement/charactersearch/CharacterSearchViewModel.kt

-package cz.fel.barysole.ackeetesttask.ui.uielement.main
+package cz.fel.barysole.ackeetesttask.ui.uielement.charactersearch
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
@@ -7,6 +7,7 @@ import androidx.paging.cachedIn
 import cz.fel.barysole.ackeetesttask.model.CharacterInfo
 import cz.fel.barysole.ackeetesttask.repository.characters.CharacterRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableSharedFlow
@@ -18,6 +19,7 @@ import kotlinx.coroutines.flow.filterNot
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import javax.inject.Inject
 
 @OptIn(ExperimentalCoroutinesApi::class)
@@ -37,21 +39,20 @@ constructor(
     init {
         pagingDataFlow = searchCharacterByName
             .distinctUntilChanged()
-            .onEach { name ->
-                _uiState.value = UiState(query = name)
+            .onEach { characterName ->
+                _uiState.value = UiState(query = characterName)
             }
-            .filterNot { name -> name.isBlank() }
-            .flatMapLatest { name ->
-                searchCharacter(characterName = name)
+            .filterNot { characterName -> characterName.isBlank() }
+            .flatMapLatest { characterName ->
+                withContext(Dispatchers.IO) {
+                    characterRepository.getCharactersByNameFlow(characterName)
+                }
             }
             .cachedIn(viewModelScope)
     }
 
-    private fun searchCharacter(characterName: String): Flow<PagingData<CharacterInfo>> =
-        characterRepository.getCharactersByNameFlow(characterName)
-
     fun onCharacterSearch(characterName: String) {
-        viewModelScope.launch { searchCharacterByName.emit(characterName) };
+        viewModelScope.launch { searchCharacterByName.emit(characterName) }
     }
 
     fun onFieldClean() {

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/uielement/main/MySearchBar.kt → app/src/main/java/cz/fel/barysole/ackeetesttask/ui/uielement/charactersearch/MySearchBar.kt

-package cz.fel.barysole.ackeetesttask.ui.uielement.main
+package cz.fel.barysole.ackeetesttask.ui.uielement.charactersearch
 
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Box
-import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.material3.ExperimentalMaterial3Api
@@ -10,18 +9,17 @@ import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.SearchBar
 import androidx.compose.material3.SearchBarDefaults
-import androidx.compose.material3.SnackbarHostState
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.MutableState
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.saveable.rememberSaveable
 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.hilt.navigation.compose.hiltViewModel
@@ -30,13 +28,12 @@ import androidx.paging.compose.collectAsLazyPagingItems
 import cz.fel.barysole.ackeetesttask.R
 import cz.fel.barysole.ackeetesttask.ui.screen.Screen
 import cz.fel.barysole.ackeetesttask.ui.uielement.character.CharacterList
-import kotlinx.coroutines.launch
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
 fun MySearchBar(
     isSearchBarShowing: MutableState<Boolean>,
-    onScreenSelected: (Screen, List<Any>?) -> Unit,
+    onSelectScreen: (Screen, List<Any>?) -> Unit,
     characterSearchViewModel: CharacterSearchViewModel = hiltViewModel()
 ) {
     val isSearchBarIsActive = rememberSaveable {
@@ -55,19 +52,19 @@ fun MySearchBar(
         active = isSearchBarIsActive.value,
         onActiveChange = { isSearchBarIsActive.value = it },
         placeholder = {
-            Text(text = "Start enter a name...")
+            Text(text = stringResource(R.string.search_bar_placeholder))
         },
         leadingIcon = {
             Icon(
                 painterResource(R.drawable.baseline_arrow_back_ios_new_24),
                 modifier = Modifier.clickable { isSearchBarShowing.value = false },
-                contentDescription = "Arrow back icon"
+                contentDescription = stringResource(R.string.arrow_back_icon_description)
             )
         },
         trailingIcon = {
             Icon(
                 painterResource(R.drawable.baseline_close_24),
-                contentDescription = "Close icon",
+                contentDescription = stringResource(R.string.close_icon_description),
                 modifier = Modifier.clickable {
                     if (searchBarState.query.isNotBlank()) {
                         characterSearchViewModel.onFieldClean()
@@ -84,12 +81,21 @@ fun MySearchBar(
             // do not show elements when the query is empty
             if (searchBarState.query.isNotBlank()) {
                 if (it.loadState.refresh is LoadState.Error) {
-                    Box (modifier = Modifier.fillMaxWidth(1f).padding(vertical = 64.dp), contentAlignment = Alignment.Center) {
-                        Text("Data cannot be loaded!", style = MaterialTheme.typography.titleMedium, textAlign = TextAlign.Center)
+                    Box(
+                        modifier = Modifier
+                            .fillMaxWidth(1f)
+                            .padding(vertical = 64.dp),
+                        contentAlignment = Alignment.Center
+                    ) {
+                        Text(
+                            stringResource(R.string.data_cannot_be_loaded_error),
+                            style = MaterialTheme.typography.titleMedium,
+                            textAlign = TextAlign.Center
+                        )
                     }
                 } else {
                     CharacterList(it) { characterId ->
-                        onScreenSelected(
+                        onSelectScreen(
                             Screen.CharacterDetail,
                             listOf(characterId)
                         )
@@ -98,4 +104,4 @@ fun MySearchBar(
             }
         }
     }
-}
+}
\ No newline at end of file

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/uielement/main/MyNavigationBar.kt

@@ -5,29 +5,33 @@ import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.NavigationBar
 import androidx.compose.material3.NavigationBarItem
+import androidx.compose.material3.NavigationBarItemDefaults
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.shadow
+import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
-import androidx.navigation.NavController
 import cz.fel.barysole.ackeetesttask.R
 import cz.fel.barysole.ackeetesttask.ui.screen.Screen
 
 
 @Composable
 fun MyNavigationBar(
-    selectedScreen: MutableState<Screen>,
-    onScreenSelected: (Screen, List<Any>?) -> Unit
+    selectedScreen: Screen,
+    onSelectScreen: (Screen, List<Any>?) -> Unit
 ) {
-    val navBarItems = listOf(
-        Screen.Characters,
-        Screen.Favorite
-    )
-    if (selectedScreen.value.showBottomBar == true) {
+    val navBarItems = remember {
+        listOf(
+            Screen.Characters,
+            Screen.Favorite
+        )
+    }
+    if (selectedScreen.showBottomBar) {
         NavigationBar(
             modifier = Modifier.shadow(8.dp),
             containerColor = MaterialTheme.colorScheme.surface,
@@ -39,18 +43,29 @@ fun MyNavigationBar(
                         if (screen.iconResId != null) {
                             Icon(
                                 painterResource(screen.iconResId),
-                                contentDescription = stringResource(screen.nameResId?: R.string.empty_string),
+                                contentDescription = stringResource(
+                                    screen.nameResId ?: R.string.empty_string
+                                ),
                                 modifier = Modifier.size(24.dp)
                             )
                         }
                     },
-                    label = { Text(stringResource(screen.nameResId?: R.string.empty_string)) },
-                    selected = selectedScreen.value == screen,
+                    colors = NavigationBarItemDefaults.colors(selectedIconColor = Color.Blue),
+                    label = { Text(stringResource(screen.nameResId ?: R.string.empty_string)) },
+                    selected = selectedScreen == screen,
                     onClick = {
-                        onScreenSelected(screen, null)
+                        onSelectScreen(screen, null)
                     }
                 )
             }
         }
     }
+}
+
+@Preview
+@Composable
+fun MyNavigationBarPreview() {
+    MyNavigationBar(
+        Screen.Characters
+    ) { _, _ -> }
 }
\ No newline at end of file