Comparing target and user location using Flow in ViewModel

vector/src/main/java/im/vector/app/features/location/LocationSharingAction.kt

@@ -21,4 +21,5 @@ import im.vector.app.core.platform.VectorViewModelAction
 sealed class LocationSharingAction : VectorViewModelAction {
     object CurrentUserLocationSharingAction : LocationSharingAction()
     data class PinnedLocationSharingAction(val locationData: LocationData?) : LocationSharingAction()
+    data class LocationTargetChangeAction(val locationData: LocationData) : LocationSharingAction()
 }

vector/src/main/java/im/vector/app/features/location/LocationSharingFragment.kt

@@ -45,7 +45,7 @@ class LocationSharingFragment @Inject constructor(
         private val urlMapProvider: UrlMapProvider,
         private val avatarRenderer: AvatarRenderer,
         private val matrixItemColorProvider: MatrixItemColorProvider
-) : VectorBaseFragment<FragmentLocationSharingBinding>() {
+) : VectorBaseFragment<FragmentLocationSharingBinding>(), LocationTargetChangeListener {
 
     private val viewModel: LocationSharingViewModel by fragmentViewModel()
 
@@ -66,7 +66,10 @@ class LocationSharingFragment @Inject constructor(
         views.mapView.onCreate(savedInstanceState)
 
         lifecycleScope.launchWhenCreated {
-            views.mapView.initialize(urlMapProvider.getMapUrl())
+            views.mapView.initialize(
+                    url = urlMapProvider.getMapUrl(),
+                    locationTargetChangeListener = this@LocationSharingFragment
+            )
         }
 
         initOptionsPicker()
@@ -115,6 +118,10 @@ class LocationSharingFragment @Inject constructor(
         super.onDestroy()
     }
 
+    override fun onLocationTargetChange(target: LocationData) {
+        viewModel.handle(LocationSharingAction.LocationTargetChangeAction(target))
+    }
+
     override fun invalidate() = withState(viewModel) { state ->
         updateMap(state)
         updateUserAvatar(state.userItem)
@@ -138,17 +145,18 @@ class LocationSharingFragment @Inject constructor(
 
     private fun initOptionsPicker() {
         // TODO
-        //  move pin creation into the Fragment
-        //  create a useCase to compare pinnedLocation and userLocation
+        //  create a useCase to compare 2 locations
+        //  update options menu dynamically
         //  change the pin dynamically depending on the current chosen location: cf. LocationPinProvider
+        //  move pin creation into the Fragment? => need to ask other's opinions
         //  reset map to user location when clicking on reset icon
         //  need changes in the event sent when this is a pin drop location?
         //  need changes in the parsing of events when receiving pin drop location?: should it be shown with user avatar or with pin?
         // set no option at start
         views.shareLocationOptionsPicker.render()
         views.shareLocationOptionsPicker.optionPinned.debouncedClicks {
-            val selectedLocation = views.mapView.getLocationOfMapCenter()
-            viewModel.handle(LocationSharingAction.PinnedLocationSharingAction(selectedLocation))
+            val targetLocation = views.mapView.getLocationOfMapCenter()
+            viewModel.handle(LocationSharingAction.PinnedLocationSharingAction(targetLocation))
         }
         views.shareLocationOptionsPicker.optionUserCurrent.debouncedClicks {
             viewModel.handle(LocationSharingAction.CurrentUserLocationSharingAction)
@@ -160,9 +168,7 @@ class LocationSharingFragment @Inject constructor(
 
     private fun updateMap(state: LocationSharingViewState) {
         // first, update the options view
-        // TODO compute distance between userLocation and location at center of map
-        val isUserLocation = true
-        if (isUserLocation) {
+        if (state.areTargetAndUserLocationEqual) {
             // TODO activate USER_LIVE option when implemented
             views.shareLocationOptionsPicker.render(
                     LocationSharingOption.USER_CURRENT

vector/src/main/java/im/vector/app/features/location/LocationSharingViewModel.kt

@@ -25,18 +25,31 @@ import im.vector.app.core.di.hiltMavericksViewModelFactory
 import im.vector.app.core.extensions.exhaustive
 import im.vector.app.core.platform.VectorViewModel
 import im.vector.app.features.home.room.detail.timeline.helper.LocationPinProvider
+import im.vector.app.features.location.domain.usecase.CompareLocationsUseCase
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.flow.sample
+import kotlinx.coroutines.launch
 import org.matrix.android.sdk.api.session.Session
 import org.matrix.android.sdk.api.util.toMatrixItem
 
+private const val TARGET_LOCATION_CHANGE_SAMPLING_PERIOD_IN_MS = 100L
+
 class LocationSharingViewModel @AssistedInject constructor(
         @Assisted private val initialState: LocationSharingViewState,
         private val locationTracker: LocationTracker,
         private val locationPinProvider: LocationPinProvider,
-        private val session: Session
+        private val session: Session,
+        private val compareLocationsUseCase: CompareLocationsUseCase
 ) : VectorViewModel<LocationSharingViewState, LocationSharingAction, LocationSharingViewEvents>(initialState), LocationTracker.Callback {
 
     private val room = session.getRoom(initialState.roomId)!!
 
+    private val locationTargetFlow = MutableSharedFlow<LocationData>()
+
     @AssistedFactory
     interface Factory : MavericksAssistedViewModelFactory<LocationSharingViewModel, LocationSharingViewState> {
         override fun create(initialState: LocationSharingViewState): LocationSharingViewModel
@@ -48,6 +61,7 @@ class LocationSharingViewModel @AssistedInject constructor(
         locationTracker.start(this)
         setUserItem()
         createPin()
+        compareTargetAndUserLocation()
     }
 
     private fun setUserItem() {
@@ -64,6 +78,21 @@ class LocationSharingViewModel @AssistedInject constructor(
         }
     }
 
+    private fun compareTargetAndUserLocation() {
+        locationTargetFlow
+                .sample(TARGET_LOCATION_CHANGE_SAMPLING_PERIOD_IN_MS)
+                .map { compareTargetLocation(it) }
+                .distinctUntilChanged()
+                .onEach { setState { copy(areTargetAndUserLocationEqual = it) } }
+                .launchIn(viewModelScope)
+    }
+
+    private suspend fun compareTargetLocation(targetLocation: LocationData): Boolean {
+        return awaitState().lastKnownUserLocation
+                ?.let { userLocation -> compareLocationsUseCase.execute(userLocation, targetLocation) }
+                ?: false
+    }
+
     override fun onCleared() {
         super.onCleared()
         locationTracker.stop()
@@ -73,6 +102,7 @@ class LocationSharingViewModel @AssistedInject constructor(
         when (action) {
             LocationSharingAction.CurrentUserLocationSharingAction -> handleCurrentUserLocationSharingAction()
             is LocationSharingAction.PinnedLocationSharingAction   -> handlePinnedLocationSharingAction(action)
+            is LocationSharingAction.LocationTargetChangeAction    -> handleLocationTargetChangeAction(action)
         }.exhaustive
     }
 
@@ -98,6 +128,12 @@ class LocationSharingViewModel @AssistedInject constructor(
         }
     }
 
+    private fun handleLocationTargetChangeAction(action: LocationSharingAction.LocationTargetChangeAction) {
+        viewModelScope.launch {
+            locationTargetFlow.emit(action.locationData)
+        }
+    }
+
     override fun onLocationUpdate(locationData: LocationData) {
         setState {
             copy(lastKnownUserLocation = locationData)

vector/src/main/java/im/vector/app/features/location/LocationSharingViewState.kt

@@ -31,6 +31,8 @@ data class LocationSharingViewState(
         val roomId: String,
         val mode: LocationSharingMode,
         val userItem: MatrixItem.UserItem? = null,
+        // TODO declare as nullable when we cannot compare?
+        val areTargetAndUserLocationEqual: Boolean = true,
         val lastKnownUserLocation: LocationData? = null,
         // TODO move pin drawable creation into the view?
         val pinDrawable: Drawable? = null

vector/src/main/java/im/vector/app/features/location/LocationTargetChangeListener.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2022 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package im.vector.app.features.location
+
+interface LocationTargetChangeListener {
+    fun onLocationTargetChange(target: LocationData)
+}

vector/src/main/java/im/vector/app/features/location/MapTilerMapView.kt

@@ -48,18 +48,36 @@ class MapTilerMapView @JvmOverloads constructor(
     /**
      * For location fragments
      */
-    fun initialize(url: String) {
+    fun initialize(url: String, locationTargetChangeListener: LocationTargetChangeListener? = null) {
         Timber.d("## Location: initialize")
         getMapAsync { map ->
-            map.setStyle(url) { style ->
-                mapRefs = MapRefs(
-                        map,
-                        SymbolManager(this, map, style),
-                        style
-                )
-                pendingState?.let { render(it) }
-                pendingState = null
-            }
+            initMapStyle(map, url)
+            notifyLocationOfMapCenter(locationTargetChangeListener)
+            listenCameraMove(map, locationTargetChangeListener)
+        }
+    }
+
+    private fun initMapStyle(map: MapboxMap, url: String) {
+        map.setStyle(url) { style ->
+            mapRefs = MapRefs(
+                    map,
+                    SymbolManager(this, map, style),
+                    style
+            )
+            pendingState?.let { render(it) }
+            pendingState = null
+        }
+    }
+
+    private fun listenCameraMove(map: MapboxMap, locationTargetChangeListener: LocationTargetChangeListener?) {
+        map.addOnCameraMoveListener {
+            notifyLocationOfMapCenter(locationTargetChangeListener)
+        }
+    }
+
+    private fun notifyLocationOfMapCenter(locationTargetChangeListener: LocationTargetChangeListener?) {
+        getLocationOfMapCenter()?.let { target ->
+            locationTargetChangeListener?.onLocationTargetChange(target)
         }
     }
 

vector/src/main/java/im/vector/app/features/location/domain/usecase/CompareLocationsUseCase.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2022 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package im.vector.app.features.location.domain.usecase
+
+import im.vector.app.features.location.LocationData
+import kotlinx.coroutines.withContext
+import org.matrix.android.sdk.api.session.Session
+import javax.inject.Inject
+
+/**
+ * Use case to check if 2 locations can be considered as equal.
+ */
+class CompareLocationsUseCase @Inject constructor(
+        private val session: Session
+) {
+
+    // TODO unit test
+    /**
+     * Compare the 2 given locations.
+     * @return true when they are really close and could be considered as the same location, false otherwise
+     */
+    suspend fun execute(location1: LocationData, location2: LocationData): Boolean =
+            withContext(session.coroutineDispatchers.io) {
+                // TODO implement real comparison
+                location1 == location2
+            }
+}