Explore FragmentStore changes.

Author: Laimiux

formula-android/src/main/java/com/instacart/formula/android/FragmentStore.kt

@@ -1,19 +1,18 @@
 package com.instacart.formula.android
 
-import com.instacart.formula.RuntimeConfig
 import com.instacart.formula.android.events.FragmentLifecycleEvent
 import com.instacart.formula.android.internal.FeatureComponent
 import com.instacart.formula.android.internal.Features
-import com.instacart.formula.android.internal.FragmentStoreFormula
 import com.instacart.formula.android.utils.MainThreadDispatcher
-import com.instacart.formula.rxjava3.toObservable
+import com.jakewharton.rxrelay3.PublishRelay
 import io.reactivex.rxjava3.core.Observable
+import io.reactivex.rxjava3.disposables.Disposable
 
 /**
  * A FragmentStore is responsible for managing the state of multiple [FragmentKey] instances.
  */
 class FragmentStore @PublishedApi internal constructor(
-    private val formula: FragmentStoreFormula,
+    private val featureComponent: FeatureComponent<*>,
 ) {
     companion object {
         val EMPTY = init {  }
@@ -37,23 +36,116 @@ class FragmentStore @PublishedApi internal constructor(
             features: Features<Component>
         ): FragmentStore {
             val featureComponent = FeatureComponent(component, features.bindings)
-            val formula = FragmentStoreFormula(featureComponent)
-            return FragmentStore(formula)
+            return FragmentStore(featureComponent)
         }
     }
 
+    @Volatile private var disposed = false
+    private val dispatcher = MainThreadDispatcher()
+    private val updateRelay = PublishRelay.create<Unit>()
+    private var state = FragmentState()
+    private var runningFeatures = mutableMapOf<FragmentId, Disposable>()
+
+    private lateinit var fragmentEnvironment: FragmentEnvironment
+
     internal fun onLifecycleEffect(event: FragmentLifecycleEvent) {
-        formula.onLifecycleEffect(event)
+        val fragmentId = event.fragmentId
+        when (event) {
+            is FragmentLifecycleEvent.Added -> handleNewFragment(fragmentId)
+            is FragmentLifecycleEvent.Removed -> handleRemoveFragment(fragmentId)
+        }
     }
 
     internal fun onVisibilityChanged(fragmentId: FragmentId, visible: Boolean) {
-        formula.onVisibilityChanged(fragmentId, visible)
+        dispatcher.dispatch {
+            val visibleIds = if (visible) {
+                state.visibleIds.plus(fragmentId)
+            } else {
+                state.visibleIds.minus(fragmentId)
+            }
+            state = state.copy(visibleIds = visibleIds)
+            updateRelay.accept(Unit)
+        }
     }
 
+    // TODO: should not be an observable.
     internal fun state(environment: FragmentEnvironment): Observable<FragmentState> {
-        val config = RuntimeConfig(
-            defaultDispatcher = MainThreadDispatcher(),
-        )
-        return formula.toObservable(environment, config)
+        // TODO: should be set differently
+        fragmentEnvironment = environment
+        return updateRelay.startWithItem(Unit).map { state }.distinctUntilChanged()
+    }
+
+    fun dispose() {
+        disposed = true
+
+        dispatcher.dispatch {
+            for (running in runningFeatures) {
+                running.value.dispose()
+            }
+
+            runningFeatures.clear()
+        }
+    }
+
+    private fun handleNewFragment(fragmentId: FragmentId) {
+        dispatcher.dispatch {
+            if (disposed) return@dispatch
+            if (state.activeIds.contains(fragmentId)) return@dispatch
+
+            val featureEvent = featureComponent.init(fragmentEnvironment, fragmentId)
+            state = state.copy(
+                activeIds = state.activeIds.plus(fragmentId),
+                features = state.features.plus(featureEvent.id to featureEvent)
+            )
+
+            runFeature(fragmentEnvironment, featureEvent)
+
+            updateRelay.accept(Unit)
+        }
+    }
+
+    private fun handleRemoveFragment(fragmentId: FragmentId) {
+        dispatcher.dispatch {
+            if (disposed) return@dispatch
+
+            runningFeatures.remove(fragmentId)?.dispose()
+
+            if (state.activeIds.contains(fragmentId)) {
+                state = state.copy(
+                    activeIds = state.activeIds.minus(fragmentId),
+                    features = state.features.minus(fragmentId),
+                    outputs = state.outputs.minus(fragmentId),
+                )
+                updateRelay.accept(Unit)
+            }
+        }
+    }
+
+    private fun runFeature(environment: FragmentEnvironment, event: FeatureEvent) {
+        val fragmentId = event.id
+        val feature = (event as? FeatureEvent.Init)?.feature
+        if (feature != null) {
+            val observable = feature.stateObservable.onErrorResumeNext {
+                environment.onScreenError(fragmentId.key, it)
+                Observable.empty()
+            }
+
+            runningFeatures[fragmentId] = observable.subscribe {
+                publishUpdate(fragmentId, it)
+            }
+        }
+    }
+
+    private fun publishUpdate(fragmentId: FragmentId, output: Any) {
+        dispatcher.dispatch {
+            if (!state.activeIds.contains(fragmentId)) {
+                return@dispatch
+            }
+
+            val keyState = FragmentOutput(fragmentId.key, output)
+            state = state.copy(outputs = state.outputs.plus(fragmentId to keyState))
+
+            updateRelay.accept(Unit)
+        }
     }
 }

formula-android/src/main/java/com/instacart/formula/android/internal/ActivityManager.kt

@@ -93,6 +93,7 @@ internal class ActivityManager<Activity : FragmentActivity>(
 
     fun dispose() {
         stateSubscription.dispose()
+        store.fragmentStore.dispose()
         store.onCleared?.invoke()
     }