Fixes #127: Add architecture classes

app/build.gradle

@@ -65,12 +65,23 @@ android.applicationVariants.all { variant ->
     println("Version code: " + variant.mergedFlavor.versionCode)
 }
 
+androidExtensions {
+    experimental = true
+}
+
 dependencies {
     implementation fileTree(dir: 'libs', include: ['*.jar'])
     implementation Deps.kotlin_stdlib
     implementation Deps.androidx_appcompat
     implementation Deps.androidx_constraintlayout
 
+    implementation Deps.rxAndroid
+    implementation Deps.rxKotlin
+    implementation Deps.anko_commons
+    implementation Deps.anko_sdk
+    implementation Deps.anko_appcompat
+    implementation Deps.anko_constraintlayout
+
     implementation Deps.mozilla_concept_engine
     implementation Deps.mozilla_concept_storage
     implementation Deps.mozilla_concept_toolbar

app/src/main/java/org/mozilla/fenix/home/HomeFragment.kt

@@ -9,15 +9,15 @@ import android.transition.TransitionInflater
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
-
 import androidx.core.view.ViewCompat
 import androidx.fragment.app.Fragment
 import androidx.navigation.Navigation
 import androidx.navigation.fragment.FragmentNavigator
-import androidx.recyclerview.widget.LinearLayoutManager
 import kotlinx.android.synthetic.main.fragment_home.*
 import org.mozilla.fenix.R
-import org.mozilla.fenix.home.sessions.SessionsAdapter
+import org.mozilla.fenix.home.sessions.SessionsComponent
+import org.mozilla.fenix.home.sessions.layoutComponents
+import org.mozilla.fenix.mvi.ActionBusFactory
 
 class HomeFragment : Fragment() {
     override fun onCreateView(
@@ -27,8 +27,6 @@ class HomeFragment : Fragment() {
         return inflater.inflate(R.layout.fragment_home, container, false)
     }
 
-    private lateinit var sessionsAdapter: SessionsAdapter
-
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
 
@@ -36,8 +34,6 @@ class HomeFragment : Fragment() {
         menuButton.visibility = View.GONE
         privateBrowsingButton.visibility = View.GONE
 
-        sessionsAdapter = SessionsAdapter()
-
         toolbar_wrapper.clipToOutline = false
         toolbar.setOnClickListener { it ->
             val extras = FragmentNavigator.Extras.Builder().addSharedElement(
@@ -46,11 +42,8 @@ class HomeFragment : Fragment() {
             Navigation.findNavController(it).navigate(R.id.action_homeFragment_to_searchFragment, null, null, extras)
         }
 
-        session_list.apply {
-            adapter = sessionsAdapter
-            layoutManager = LinearLayoutManager(requireContext())
-            setHasFixedSize(true)
-        }
+        SessionsComponent(homeLayout, ActionBusFactory.get(this)).setup()
+        layoutComponents(homeLayout)
     }
 
     override fun onCreate(savedInstanceState: Bundle?) {

app/src/main/java/org/mozilla/fenix/home/sessions/SessionsComponent.kt

@@ -0,0 +1,40 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+   License, v. 2.0. If a copy of the MPL was not distributed with this
+   file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.home.sessions
+
+import android.annotation.SuppressLint
+import android.view.ViewGroup
+import mozilla.components.browser.session.Session
+import org.mozilla.fenix.mvi.*
+
+class SessionsComponent(private val container: ViewGroup, override val bus: ActionBusFactory) :
+    UIComponent<SessionsState, SessionsAction, SessionsChange>(bus) {
+
+    override var initialState: SessionsState = SessionsState(emptyList())
+
+    override val reducer : (SessionsState, SessionsChange) -> SessionsState = { state, change ->
+        when (change) {
+            is SessionsChange.SessionsChanged -> state // copy state with changes here
+        }
+    }
+
+    override fun initView() = SessionsUIView(container, bus)
+
+    @SuppressLint("CheckResult")
+    fun setup(): SessionsComponent {
+        render(reducer)
+        return this
+    }
+}
+
+data class SessionsState(val sessions: List<Session>) : ViewState
+
+sealed class SessionsAction : Action {
+    object Select : SessionsAction()
+}
+
+sealed class SessionsChange : Change {
+    object SessionsChanged : SessionsChange()
+}

app/src/main/java/org/mozilla/fenix/home/sessions/SessionsLayouts.kt

@@ -0,0 +1,25 @@
+package org.mozilla.fenix.home.sessions
+
+import androidx.constraintlayout.widget.ConstraintLayout
+import androidx.constraintlayout.widget.ConstraintLayout.LayoutParams.PARENT_ID
+import kotlinx.android.synthetic.main.component_sessions.*
+import kotlinx.android.synthetic.main.fragment_home.*
+import org.jetbrains.anko.constraint.layout.ConstraintSetBuilder.Side.BOTTOM
+import org.jetbrains.anko.constraint.layout.ConstraintSetBuilder.Side.TOP
+import org.jetbrains.anko.constraint.layout.ConstraintSetBuilder.Side.START
+import org.jetbrains.anko.constraint.layout.ConstraintSetBuilder.Side.END
+import org.jetbrains.anko.constraint.layout.applyConstraintSet
+import org.mozilla.fenix.home.HomeFragment
+
+fun HomeFragment.layoutComponents(layout: ConstraintLayout) {
+    layout.applyConstraintSet {
+        session_list {
+            connect(
+                BOTTOM to BOTTOM of PARENT_ID,
+                START to START of PARENT_ID,
+                END to END of PARENT_ID,
+                TOP to BOTTOM of toolbar_wrapper
+            )
+        }
+    }
+}

app/src/main/java/org/mozilla/fenix/home/sessions/SessionsUIView.kt

@@ -0,0 +1,39 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+   License, v. 2.0. If a copy of the MPL was not distributed with this
+   file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.home.sessions
+
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.constraintlayout.widget.ConstraintLayout
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import io.reactivex.functions.Consumer
+import kotlinx.android.synthetic.main.component_sessions.*
+import kotlinx.android.synthetic.main.fragment_home.*
+import org.mozilla.fenix.R
+import org.mozilla.fenix.mvi.ActionBusFactory
+import org.mozilla.fenix.mvi.UIView
+
+class SessionsUIView(container: ViewGroup, bus: ActionBusFactory) : UIView<SessionsState>(container, bus) {
+
+    val view: ConstraintLayout = LayoutInflater.from(container.context)
+        .inflate(R.layout.component_sessions, container, true) as ConstraintLayout
+
+    private var sessionAdapter = SessionsAdapter()
+
+    init {
+        session_list.apply {
+            layoutManager = LinearLayoutManager(view.context)
+            adapter = sessionAdapter
+            setHasFixedSize(true)
+        }
+    }
+
+    override fun updateView() = Consumer<SessionsState> {
+        
+    }
+
+}

app/src/main/java/org/mozilla/fenix/mvi/ActionBusFactory.kt

@@ -0,0 +1,157 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+   License, v. 2.0. If a copy of the MPL was not distributed with this
+   file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Copyright (C) 2018 Netflix, Inc.
+ *
+ * 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.
+ *
+ * Created by Juliano Moraes, Rohan Dhruva, Emmanuel Boudrant.
+ */
+package org.mozilla.fenix.mvi
+
+import androidx.annotation.VisibleForTesting
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleObserver
+import androidx.lifecycle.LifecycleOwner
+import androidx.lifecycle.OnLifecycleEvent
+import io.reactivex.Observable
+import io.reactivex.rxkotlin.merge
+import io.reactivex.subjects.PublishSubject
+import io.reactivex.subjects.Subject
+
+/**
+ * It implements a Factory pattern generating Rx Subjects based on Event Types.
+ * It maintain a map of Rx Subjects, one per type per instance of ActionBusFactory.
+ *
+ * @param owner is a LifecycleOwner used to auto dispose based on destroy observable
+ */
+class ActionBusFactory private constructor(val owner: LifecycleOwner) {
+
+    companion object {
+
+        private val buses = mutableMapOf<LifecycleOwner, ActionBusFactory>()
+
+        /**
+         * Return the [ActionBusFactory] associated to the [LifecycleOwner]. It there is no bus it will create one.
+         * If the [LifecycleOwner] used is a fragment it use [Fragment#getViewLifecycleOwner()]
+         */
+        @JvmStatic
+        fun get(lifecycleOwner: LifecycleOwner): ActionBusFactory {
+            return with(lifecycleOwner) {
+                var bus = buses[lifecycleOwner]
+                if (bus == null) {
+                    bus = ActionBusFactory(lifecycleOwner)
+                    buses[lifecycleOwner] = bus
+                    // LifecycleOwner
+                    lifecycleOwner.lifecycle.addObserver(bus.observer)
+                }
+                bus
+            }
+        }
+    }
+
+    @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
+    val map = HashMap<Class<*>, Subject<*>>()
+
+    internal val observer = object : LifecycleObserver {
+
+        @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
+        fun onDestroy() {
+            map.forEach { entry -> entry.value.onComplete() }
+            buses.remove(owner)
+        }
+    }
+
+    private fun <T> create(clazz: Class<T>): Subject<T> {
+        val subject = PublishSubject.create<T>().toSerialized()
+        map[clazz] = subject
+        return subject
+    }
+
+    /**
+     * emit will create (if needed) or use the existing Rx Subject to send events.
+     *
+     * @param clazz is the Event Class
+     * @param event is the instance of the Event to be sent
+     */
+    fun <T : Action> emit(clazz: Class<T>, event: T) {
+        val subject = if (map[clazz] != null) map[clazz] else create(clazz)
+        (subject as Subject<T>).onNext(event)
+    }
+
+    /**x
+     * getSafeManagedObservable returns an Rx Observable which is
+     *  *Safe* against reentrant events as it is serialized and
+     *  *Managed* since it disposes itself based on the lifecycle
+     *
+     *  @param clazz is the class of the event type used by this observable
+     */
+    fun <T : Action> getSafeManagedObservable(clazz: Class<T>): Observable<T> {
+        return if (map[clazz] != null) map[clazz] as Observable<T> else create(clazz)
+    }
+
+    fun logMergedObservables() {
+        // TODO make this observe new items in the map and combine them
+        map.values.merge().compose(logState()).subscribe()
+    }
+
+    /**
+     * getDestroyObservable observes to Lifecycle owner and fires when
+     * lifecycle.currentState == Lifecycle.State.DESTROYED
+     */
+    fun getDestroyObservable(): Observable<Unit> {
+        return owner.createDestroyObservable()
+    }
+}
+
+/**
+ * Extension on [LifecycleOwner] used to emit an event.
+ */
+inline fun <reified T : Action> LifecycleOwner.emit(event: T) =
+    kotlin.with(ActionBusFactory.get(this)) {
+        getSafeManagedObservable(T::class.java)
+        emit(T::class.java, event)
+    }
+
+/**
+ * Extension on [LifecycleOwner] used used to get the state observable.
+ */
+inline fun <reified T : Action> LifecycleOwner.getSafeManagedObservable(): Observable<T> =
+    ActionBusFactory.get(this).getSafeManagedObservable(T::class.java)
+
+/**
+ * This method returns a destroy observable that can be passed to [org.mozilla.fenix.mvi.UIView]s as needed.
+ * This is deliberately scoped to the attached [LifecycleOwner]'s [Lifecycle.Event.ON_DESTROY]
+ * because a viewholder can be reused across adapter destroys.
+ */
+inline fun LifecycleOwner?.createDestroyObservable(): Observable<Unit> {
+    return Observable.create { emitter ->
+        if (this == null || this.lifecycle.currentState == Lifecycle.State.DESTROYED) {
+            emitter.onNext(kotlin.Unit)
+            emitter.onComplete()
+            return@create
+        }
+        this.lifecycle.addObserver(object : LifecycleObserver {
+            @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
+            fun emitDestroy() {
+                if (emitter.isDisposed) {
+                    emitter.onNext(kotlin.Unit)
+                    emitter.onComplete()
+                }
+            }
+        })
+    }
+}
+

app/src/main/java/org/mozilla/fenix/mvi/Concepts.kt

@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+   License, v. 2.0. If a copy of the MPL was not distributed with this
+   file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.mvi
+
+import io.reactivex.ObservableTransformer
+import io.reactivex.subjects.Subject
+import mozilla.components.support.base.log.logger.Logger
+import org.mozilla.fenix.BuildConfig
+
+/**
+ * An action is a command or intent the user performed
+ */
+interface Action
+
+/**
+ * A Change is a change to the view coming from the model
+ * (Extending action so we can reuse the ActionBusFactory)
+ */
+interface Change : Action
+
+/**
+ * A ViewState is a model reflecting the current state of the view
+ */
+interface ViewState
+
+/**
+ * A Reducer applies changes to the ViewState
+ */
+typealias Reducer<S, C> = (S, C) -> S
+
+/**
+ * Simple logger for tracking ViewState changes
+ */
+fun <S> logState(): ObservableTransformer<S, S> = ObservableTransformer { observable ->
+    observable.doOnNext {
+        if (BuildConfig.DEBUG) Logger("State").debug(it.toString())
+    }
+}
+
+/**
+ * For capturing state to a Subject for testing
+ */
+fun <S> captureState(subject: Subject<S>):
+        ObservableTransformer<S, S> = ObservableTransformer { observable ->
+    observable.doOnNext {
+        subject.onNext(it)
+    }
+}

app/src/main/java/org/mozilla/fenix/mvi/UIComponent.kt

@@ -0,0 +1,32 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+   License, v. 2.0. If a copy of the MPL was not distributed with this
+   file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.mvi
+
+import io.reactivex.Observable
+import io.reactivex.android.schedulers.AndroidSchedulers
+import io.reactivex.disposables.Disposable
+import io.reactivex.schedulers.Schedulers
+
+abstract class UIComponent<S: ViewState, A: Action, C: Change>(open val bus: ActionBusFactory) {
+    abstract var initialState: S
+    abstract val reducer: Reducer<S, C>
+    val uiView: UIView<S> by lazy { initView() }
+
+    abstract fun initView(): UIView<S>
+    open fun getContainerId() = uiView.containerId
+    inline fun <reified A: Action> getUserInteractionEvents(): Observable<A> = bus.getSafeManagedObservable(A::class.java)
+    inline fun <reified C: Change> getModelChangeEvents(): Observable<C> = bus.getSafeManagedObservable(C::class.java)
+
+    /**
+     * Render the ViewState to the View through the Reducer
+     */
+    inline fun <reified C : Change> render(noinline reducer: Reducer<S, C>): Disposable =
+        bus.getSafeManagedObservable(C::class.java)
+            .scan(initialState, reducer)
+            .distinctUntilChanged()
+            .subscribeOn(Schedulers.io())
+            .observeOn(AndroidSchedulers.mainThread())
+            .subscribe(uiView.updateView())
+}

app/src/main/java/org/mozilla/fenix/mvi/UIView.kt

@@ -0,0 +1,43 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+   License, v. 2.0. If a copy of the MPL was not distributed with this
+   file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.mvi
+
+import android.view.View
+import android.view.ViewGroup
+import androidx.annotation.IdRes
+import io.reactivex.functions.Consumer
+import kotlinx.android.extensions.LayoutContainer
+
+abstract class UIView<S : ViewState>(
+    private val container: ViewGroup, val bus: ActionBusFactory
+) : LayoutContainer {
+    /**
+     * Get the XML id for the UIView
+     */
+    @get:IdRes
+    val containerId: Int
+        get() = container.id
+
+    /**
+     * Provides container to empower Kotlin Android Extensions
+     */
+    override val containerView: View?
+        get() = container
+
+    /**
+     * Show the UIView
+     */
+    open fun show() { container.visibility = View.VISIBLE }
+
+    /**
+     * Hide the UIView
+     */
+    open fun hide() { container.visibility = View.GONE }
+
+    /**
+     * Update the view from the ViewState
+     */
+    abstract fun updateView(): Consumer<S>
+}

app/src/main/res/layout/component_sessions.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.recyclerview.widget.RecyclerView
+        xmlns:android="http://schemas.android.com/apk/res/android"
+        android:id="@+id/session_list"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
+        android:layout_margin="16dp"/>

app/src/main/res/layout/fragment_home.xml

@@ -71,14 +71,4 @@
             android:transitionName="firstTransitionName" />
     </FrameLayout>
 
-    <androidx.recyclerview.widget.RecyclerView
-        android:id="@+id/session_list"
-        android:layout_width="0dp"
-        android:layout_height="0dp"
-        android:layout_margin="16dp"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@id/toolbar_wrapper" />
-
 </androidx.constraintlayout.motion.widget.MotionLayout>

buildSrc/src/main/java/Dependencies.kt

@@ -6,6 +6,9 @@ private object Versions {
     const val kotlin = "1.3.11"
     const val android_gradle_plugin = "3.2.1"
     const val geckoNightly = "66.0.20190128092811"
+    const val rxAndroid = "2.1.0"
+    const val rxKotlin = "2.3.0"
+    const val anko = "0.10.8"
 
     const val androidx_appcompat = "1.0.2"
     const val androidx_constraint_layout = "2.0.0-alpha3"
@@ -26,6 +29,14 @@ object Deps {
     const val tools_kotlingradle = "org.jetbrains.kotlin:kotlin-gradle-plugin:${Versions.kotlin}"
     const val kotlin_stdlib = "org.jetbrains.kotlin:kotlin-stdlib-jdk7:${Versions.kotlin}"
 
+    const val rxKotlin = "io.reactivex.rxjava2:rxkotlin:${Versions.rxKotlin}"
+    const val rxAndroid = "io.reactivex.rxjava2:rxandroid:${Versions.rxAndroid}"
+
+    const val anko_commons = "org.jetbrains.anko:anko-commons:${Versions.anko}"
+    const val anko_sdk = "org.jetbrains.anko:anko-sdk25:${Versions.anko}"
+    const val anko_appcompat = "org.jetbrains.anko:anko-appcompat-v7:${Versions.anko}"
+    const val anko_constraintlayout = "org.jetbrains.anko:anko-constraint-layout:${Versions.anko}"
+
     const val geckoview_nightly_arm = "org.mozilla.geckoview:geckoview-nightly-armeabi-v7a:${Versions.geckoNightly}"
     const val geckoview_nightly_x86 = "org.mozilla.geckoview:geckoview-nightly-x86:${Versions.geckoNightly}"