Swapped SingleLiveEvent for MutableStateFlow

app/src/main/java/com/rtbishop/look4sat/data/Event.kt

@@ -1,34 +0,0 @@
-/*
- * Look4Sat. Amateur radio satellite tracker and pass predictor.
- * Copyright (C) 2019-2021 Arty Bishop (bishop.arty@gmail.com)
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-package com.rtbishop.look4sat.data
-
-class Event<out T>(private val content: T) {
-
-    private var hasBeenHandled = false
-
-    fun getContentIfNotHandled(): T? {
-        return if (hasBeenHandled) {
-            null
-        } else {
-            hasBeenHandled = true
-            content
-        }
-    }
-
-    fun peekContent(): T = content
-}

app/src/main/java/com/rtbishop/look4sat/ui/SharedViewModel.kt

@@ -20,13 +20,18 @@ package com.rtbishop.look4sat.ui
 import android.net.Uri
 import androidx.lifecycle.*
 import com.github.amsacode.predict4java.Satellite
-import com.rtbishop.look4sat.data.*
+import com.rtbishop.look4sat.data.Result
+import com.rtbishop.look4sat.data.SatItem
+import com.rtbishop.look4sat.data.SatPass
+import com.rtbishop.look4sat.data.TleSource
 import com.rtbishop.look4sat.repository.PrefsRepo
 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.delay
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.launch
 import java.util.*
 import javax.inject.Inject
@@ -37,18 +42,21 @@ class SharedViewModel @Inject constructor(
     private val satelliteRepo: SatelliteRepo,
 ) : ViewModel() {
     
-    private val _passes = MutableLiveData<Result<MutableList<SatPass>>>()
-    private val _appEvent = MutableLiveData<Event<Int>>()
+    private val _passes = MutableStateFlow<Result<MutableList<SatPass>>>(Result.InProgress)
+    val passes: LiveData<Result<MutableList<SatPass>>> = _passes.asLiveData()
+    
+    private val _satData = MutableStateFlow<Result<List<SatItem>>>(Result.InProgress)
+    val satData: LiveData<Result<List<SatItem>>> = _satData.asLiveData()
     
     init {
         if (prefsRepo.isFirstLaunch()) {
             updateDefaultSourcesAndEntries()
             prefsRepo.setFirstLaunchDone()
         }
+        loadDataFromDb()
         calculatePasses()
     }
     
-    fun getAppEvent(): LiveData<Event<Int>> = _appEvent
     fun getAppTimer() = liveData {
         while (true) {
             emit(System.currentTimeMillis())
@@ -57,10 +65,7 @@ class SharedViewModel @Inject constructor(
     }
     
     fun getSources() = prefsRepo.loadTleSources()
-    fun getSatItems() = satelliteRepo.getSatItems().asLiveData()
-    fun getPasses(): LiveData<Result<MutableList<SatPass>>> = _passes
-    fun getTransmittersForSat(satId: Int) =
-        satelliteRepo.getTransmittersForSat(satId).asLiveData()
+    fun getTransmittersForSat(satId: Int) = satelliteRepo.getTransmittersForSat(satId).asLiveData()
     
     fun calculatePasses(dateNow: Date = Date(System.currentTimeMillis())) {
         _passes.value = Result.InProgress
@@ -70,30 +75,30 @@ class SharedViewModel @Inject constructor(
                 passes.addAll(getPasses(satellite, dateNow))
             }
             val filteredPasses = sortList(passes, dateNow)
-            _passes.postValue(Result.Success(filteredPasses))
+            _passes.value = Result.Success(filteredPasses)
         }
     }
-
+    
     fun updateEntriesFromFile(uri: Uri) {
-        postAppEvent(Event(0))
+        _satData.value = Result.InProgress
         viewModelScope.launch {
             try {
                 satelliteRepo.updateEntriesFromFile(uri)
             } catch (exception: Exception) {
-                postAppEvent(Event(1))
+                _satData.value = Result.Error(exception)
             }
         }
     }
-
-    fun updateEntriesFromSources(sources: List<TleSource>) {
-        postAppEvent(Event(0))
+    
+    fun updateEntriesFromSources(sources: List<TleSource> = prefsRepo.loadTleSources()) {
+        _satData.value = Result.InProgress
         viewModelScope.launch {
             try {
                 prefsRepo.saveTleSources(sources)
                 satelliteRepo.updateEntriesFromWeb(sources)
                 satelliteRepo.updateTransmitters()
             } catch (exception: Exception) {
-                postAppEvent(Event(1))
+                _satData.value = Result.Error(exception)
             }
         }
     }
@@ -107,10 +112,6 @@ class SharedViewModel @Inject constructor(
         }
     }
     
-    private fun postAppEvent(event: Event<Int>) {
-        _appEvent.value = event
-    }
-    
     private fun getPasses(satellite: Satellite, dateNow: Date): MutableList<SatPass> {
         val predictor = satellite.getPredictor(prefsRepo.getStationPosition())
         val passes = predictor.getPasses(dateNow, prefsRepo.getHoursAhead(), true)
@@ -130,8 +131,19 @@ class SharedViewModel @Inject constructor(
         passes.sortBy { it.pass.startTime }
         return passes
     }
-
+    
+    private fun loadDataFromDb() {
+        _satData.value = Result.InProgress
+        viewModelScope.launch {
+            satelliteRepo.getSatItems().collect { satItems: List<SatItem> ->
+                if (satItems.isNotEmpty()) {
+                    _satData.value = Result.Success(satItems)
+                }
+            }
+        }
+    }
+    
     private fun updateDefaultSourcesAndEntries() {
-        updateEntriesFromSources(prefsRepo.loadTleSources())
+        updateEntriesFromSources()
     }
 }

app/src/main/java/com/rtbishop/look4sat/ui/entriesScreen/EntriesFragment.kt

@@ -27,6 +27,7 @@ import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.LinearLayoutManager
 import com.google.android.material.snackbar.Snackbar
 import com.rtbishop.look4sat.R
+import com.rtbishop.look4sat.data.Result
 import com.rtbishop.look4sat.databinding.FragmentEntriesBinding
 import com.rtbishop.look4sat.ui.SharedViewModel
 import com.rtbishop.look4sat.utility.RecyclerDivider
@@ -70,19 +71,16 @@ class EntriesFragment : Fragment(R.layout.fragment_entries) {
     }
     
     private fun setupObservers() {
-        setLoading()
-        viewModel.getSatItems().observe(viewLifecycleOwner, { satItems ->
-            if (satItems.isNullOrEmpty()) {
-                setError()
-            } else {
-                entriesAdapter?.setItems(satItems)
-                setLoaded()
-            }
-        })
-        viewModel.getAppEvent().observe(viewLifecycleOwner, { event ->
-            event.getContentIfNotHandled()?.let { content ->
-                if (content == 0) setLoading()
-                else if (content == 1) {
+        viewModel.satData.observe(viewLifecycleOwner, { result ->
+            when (result) {
+                is Result.Success -> {
+                    entriesAdapter?.setItems(result.data)
+                    setLoaded()
+                }
+                is Result.InProgress -> {
+                    setLoading()
+                }
+                is Result.Error -> {
                     val errorMsg = getString(R.string.entries_update_error)
                     Snackbar.make(requireView(), errorMsg, Snackbar.LENGTH_SHORT).show()
                     entriesAdapter?.let { adapter ->

app/src/main/java/com/rtbishop/look4sat/ui/mapScreen/MapFragment.kt

@@ -83,7 +83,7 @@ class MapFragment : Fragment(R.layout.fragment_map) {
 
     private fun setupObservers() {
         mapViewModel.getGSP().observe(viewLifecycleOwner, { setupPosOverlay(it) })
-        sharedViewModel.getPasses().observe(viewLifecycleOwner, {
+        sharedViewModel.passes.observe(viewLifecycleOwner, {
             if (it is Result.Success && it.data.isNotEmpty()) {
                 mapViewModel.setPasses(it.data)
                 binding.fabPrev.setOnClickListener { mapViewModel.scrollSelection(true) }

app/src/main/java/com/rtbishop/look4sat/ui/passesScreen/PassesFragment.kt

@@ -54,7 +54,7 @@ class PassesFragment : Fragment(R.layout.fragment_passes) {
     }
 
     private fun setupObservers() {
-        viewModel.getPasses().observe(viewLifecycleOwner, { result ->
+        viewModel.passes.observe(viewLifecycleOwner, { result ->
             if (result is Result.Success) {
                 if (result.data.isEmpty()) {
                     binding?.apply {

app/src/main/java/com/rtbishop/look4sat/ui/polarScreen/PolarFragment.kt

@@ -97,7 +97,7 @@ class PolarFragment : Fragment(R.layout.fragment_polar), SensorEventListener {
     }
 
     private fun observePasses() {
-        viewModel.getPasses().observe(viewLifecycleOwner, { result ->
+        viewModel.passes.observe(viewLifecycleOwner, { result ->
             if (result is Result.Success) {
                 satPass = result.data[requireArguments().getInt("index")]
                 polarView = PolarView(requireContext()).apply { setPass(satPass) }

build.gradle

@@ -5,7 +5,7 @@ buildscript {
         material_version = '1.3.0'
         constraint_layout_version = '2.0.4'
         lifecycle_version = '2.3.0'
-        navigation_version = '2.3.3'
+        navigation_version = '2.3.4'
         preference_version = '1.1.1'
         room_version = '2.2.6'
         hilt_version = '2.33-beta'