NotesScreen.kt

/**
 * A composable function that displays the main notes screen in the app.
 * This screen dynamically updates its content based on the UI state provided by the ViewModel.
 *
 * @param viewModel The ViewModel that provides the state and handles user interactions.
 */
@Composable
fun NotesScreen(
    viewModel: NoteViewModel
) {
    // Observes the UI state from the ViewModel using StateFlow and lifecycle-aware collection.
    val noteUiState = viewModel.notesViewState.collectAsStateWithLifecycle(
        lifecycleOwner = LocalLifecycleOwner.current
    )

    // Provides a title for the app bar.
    ProvideAppBarTitle {
        Text(
            modifier = Modifier
                .fillMaxWidth(),
            text = stringResource(id = R.string.app_name), // Displays the app name as the title.
            style = MaterialTheme.typography.displaySmall,
            color = MaterialTheme.colorScheme.onSecondaryContainer
        )
    }

    // Displays a loading indicator if the state indicates loading.
    if (noteUiState.value.isLoading) {
        LoadingItem()

    // Displays an empty screen message if there are no notes to show.
    } else if (noteUiState.value.notes.isEmpty()) {
        EmptyScreen()

    // Displays the list of notes if the state contains notes.
    } else {
        LazyVerticalStaggeredGrid(
            modifier = Modifier.padding(top = 10.dp, bottom = 10.dp, start = 12.dp, end = 12.dp),
            horizontalArrangement = Arrangement.spacedBy(16.dp),
            columns = StaggeredGridCells.Adaptive(minSize = 140.dp), // Dynamically adjusts columns based on screen size.
        ) {
            val notes = noteUiState.value.notes
            items(notes.size) {
                val note = notes[it]
                NoteItem(
                    note = note,
                    onNoteItemClicked = { viewModel.handleIntent(NoteIntent.OpenNoteClicked(it)) }, // Handles note click.
                    onNoteItemDeleted = { viewModel.handleIntent(NoteIntent.DeleteNote(it)) } // Handles note deletion.
                )
            }
        }
    }
}