From 31ed6230bac023331328a531e325cb2f778c38f3 Mon Sep 17 00:00:00 2001
From: Arty Bishop <bishop.arty@gmail.com>
Date: Wed, 17 Mar 2021 20:47:24 +0000
Subject: [PATCH] Swapped Entries StateFlow for SharedFlow

---
 .../rtbishop/look4sat/ui/SharedViewModel.kt   | 34 +++++++------------
 .../ui/entriesScreen/EntriesFragment.kt       | 18 ++++++----
 2 files changed, 24 insertions(+), 28 deletions(-)

diff --git a/app/src/main/java/com/rtbishop/look4sat/ui/SharedViewModel.kt b/app/src/main/java/com/rtbishop/look4sat/ui/SharedViewModel.kt
index fa3c076a..8d44adb9 100644
--- a/app/src/main/java/com/rtbishop/look4sat/ui/SharedViewModel.kt
+++ b/app/src/main/java/com/rtbishop/look4sat/ui/SharedViewModel.kt
@@ -29,68 +29,58 @@ import com.rtbishop.look4sat.repository.SatelliteRepo
 import com.rtbishop.look4sat.utility.getPredictor
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.delay
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.collect
-import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.*
 import kotlinx.coroutines.launch
 import timber.log.Timber
 import java.util.*
 import javax.inject.Inject
 import kotlin.system.measureTimeMillis
 
+@FlowPreview
 @HiltViewModel
 class SharedViewModel @Inject constructor(
     private val prefsRepo: PrefsRepo,
     private val satelliteRepo: SatelliteRepo,
 ) : ViewModel() {
 
-    private val _satData = MutableStateFlow<Result<List<SatItem>>>(Result.InProgress)
+    private val satDataState = MutableSharedFlow<Result<List<SatItem>>>(replay = 0)
+    private val satDataFlow = satelliteRepo.satDataFlow.map { Result.Success(it) }
+    val satData = flowOf(satDataState, satDataFlow).flattenMerge().asLiveData()
+
     private val _passes = MutableStateFlow<Result<MutableList<SatPass>>>(Result.InProgress)
     val passes: LiveData<Result<MutableList<SatPass>>> = _passes.asLiveData()
-    val satData = _satData.asLiveData(viewModelScope.coroutineContext)
 
     init {
         if (prefsRepo.isFirstLaunch()) {
             updateSatDataFromSources()
             prefsRepo.setFirstLaunchDone()
         }
-        loadSatData()
         calculatePasses()
     }
 
-    private fun loadSatData() {
-        viewModelScope.launch {
-            delay(8)
-            satelliteRepo.satDataFlow.map { Result.Success(it) }.collect {
-                _satData.value = it
-            }
-        }
-    }
-
     fun updateSatDataFromFile(uri: Uri) {
-        _satData.value = Result.InProgress
         viewModelScope.launch {
+            satDataState.emit(Result.InProgress)
             try {
                 satelliteRepo.updateSatDataFromFile(uri)
             } catch (exception: Exception) {
-                _satData.value = Result.Error(exception)
+                satDataState.emit(Result.Error(exception))
             }
-            loadSatData()
         }
     }
 
     fun updateSatDataFromSources(sources: List<TleSource> = prefsRepo.loadTleSources()) {
-        _satData.value = Result.InProgress
         viewModelScope.launch {
+            satDataState.emit(Result.InProgress)
             val updateMillis = measureTimeMillis {
                 try {
-                    prefsRepo.saveTleSources(sources)
                     satelliteRepo.updateSatDataFromWeb(sources)
+                    prefsRepo.saveTleSources(sources)
                 } catch (exception: Exception) {
-                    _satData.value = Result.Error(exception)
+                    satDataState.emit(Result.Error(exception))
                 }
-                loadSatData()
             }
             Timber.d("Update from WEB took $updateMillis ms")
         }
diff --git a/app/src/main/java/com/rtbishop/look4sat/ui/entriesScreen/EntriesFragment.kt b/app/src/main/java/com/rtbishop/look4sat/ui/entriesScreen/EntriesFragment.kt
index 89cdae8b..5f3bc20e 100644
--- a/app/src/main/java/com/rtbishop/look4sat/ui/entriesScreen/EntriesFragment.kt
+++ b/app/src/main/java/com/rtbishop/look4sat/ui/entriesScreen/EntriesFragment.kt
@@ -34,7 +34,9 @@ import com.rtbishop.look4sat.utility.RecyclerDivider
 import com.rtbishop.look4sat.utility.navigateSafe
 import dagger.hilt.android.AndroidEntryPoint
 import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.FlowPreview
 
+@FlowPreview
 @AndroidEntryPoint
 class EntriesFragment : Fragment(R.layout.fragment_entries) {
 
@@ -77,8 +79,12 @@ class EntriesFragment : Fragment(R.layout.fragment_entries) {
         viewModel.satData.observe(viewLifecycleOwner, { result ->
             when (result) {
                 is Result.Success -> {
-                    entriesAdapter?.setItems(result.data)
-                    setLoaded()
+                    if (result.data.isEmpty()) {
+                        setEmpty()
+                    } else {
+                        entriesAdapter?.setItems(result.data)
+                        setLoaded()
+                    }
                 }
                 is Result.InProgress -> {
                     setLoading()
@@ -88,7 +94,7 @@ class EntriesFragment : Fragment(R.layout.fragment_entries) {
                     Snackbar.make(requireView(), errorMsg, Snackbar.LENGTH_SHORT).show()
                     entriesAdapter?.let { adapter ->
                         if (adapter.getItems().isEmpty()) {
-                            setError()
+                            setEmpty()
                         } else {
                             setLoaded()
                         }
@@ -109,16 +115,16 @@ class EntriesFragment : Fragment(R.layout.fragment_entries) {
     private fun setLoading() {
         binding?.apply {
             entriesError.visibility = View.INVISIBLE
-            entriesRecycler.visibility = View.INVISIBLE
             entriesProgress.visibility = View.VISIBLE
+            entriesRecycler.visibility = View.INVISIBLE
         }
     }
 
-    private fun setError() {
+    private fun setEmpty() {
         binding?.apply {
+            entriesError.visibility = View.VISIBLE
             entriesProgress.visibility = View.INVISIBLE
             entriesRecycler.visibility = View.INVISIBLE
-            entriesError.visibility = View.VISIBLE
         }
     }