[Catalyst] Migrate "Dark theme" settings

Bug: 375132235
Flag: com.android.settings.flags.catalyst_dark_ui_mode
Test: Manual
Change-Id: I40f305fe8d89feac84e2316c7a90c6eeb2b4a5fa

aconfig/catalyst/display.aconfig

@@ -14,3 +14,11 @@ flag {
   description: "Flag for Screen Timeout settings"
   bug: "323791114"
 }
+
+flag {
+  name: "catalyst_dark_ui_mode"
+  namespace: "android_settings"
+  description: "Flag for Dark theme"
+  bug: "323791114"
+}
+

src/com/android/settings/display/DarkUIPreferenceController.java

@@ -34,6 +34,7 @@ import com.android.settingslib.core.lifecycle.LifecycleObserver;
 import com.android.settingslib.core.lifecycle.events.OnStart;
 import com.android.settingslib.core.lifecycle.events.OnStop;
 
+// LINT.IfChange
 public class DarkUIPreferenceController extends TogglePreferenceController implements
         LifecycleObserver, OnStart, OnStop {
 
@@ -123,3 +124,4 @@ public class DarkUIPreferenceController extends TogglePreferenceController imple
         return AVAILABLE;
     }
 }
+// LINT.ThenChange(darkmode/DarkModeScreen.kt)

src/com/android/settings/display/DisplayScreen.kt

@@ -18,6 +18,7 @@ package com.android.settings.display
 import android.content.Context
 import com.android.settings.DisplaySettings
 import com.android.settings.R
+import com.android.settings.display.darkmode.DarkModeScreen
 import com.android.settings.flags.Flags
 import com.android.settingslib.metadata.PreferenceAvailabilityProvider
 import com.android.settingslib.metadata.PreferenceIconProvider
@@ -46,7 +47,9 @@ class DisplayScreen :
 
     override fun fragmentClass() = DisplaySettings::class.java
 
-    override fun getPreferenceHierarchy(context: Context) = preferenceHierarchy(this) {}
+    override fun getPreferenceHierarchy(context: Context) = preferenceHierarchy(this) {
+        +DarkModeScreen.KEY
+    }
 
     override fun isAvailable(context: Context) =
         context.resources.getBoolean(R.bool.config_show_top_level_display)

src/com/android/settings/display/darkmode/DarkModeScreen.kt

@@ -0,0 +1,171 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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 com.android.settings.display.darkmode
+
+import android.app.UiModeManager
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.content.IntentFilter
+import android.content.res.Configuration
+import android.os.PowerManager
+import androidx.preference.Preference
+import com.android.settings.R
+import com.android.settings.flags.Flags
+import com.android.settingslib.PrimarySwitchPreference
+import com.android.settingslib.datastore.KeyValueStore
+import com.android.settingslib.datastore.NoOpKeyedObservable
+import com.android.settingslib.metadata.BooleanValue
+import com.android.settingslib.metadata.PersistentPreference
+import com.android.settingslib.metadata.PreferenceLifecycleContext
+import com.android.settingslib.metadata.PreferenceLifecycleProvider
+import com.android.settingslib.metadata.PreferenceMetadata
+import com.android.settingslib.metadata.PreferenceSummaryProvider
+import com.android.settingslib.metadata.ProvidePreferenceScreen
+import com.android.settingslib.metadata.preferenceHierarchy
+import com.android.settingslib.preference.PreferenceScreenBinding
+import com.android.settingslib.preference.PreferenceScreenCreator
+import java.util.WeakHashMap
+
+// LINT.IfChange
+@ProvidePreferenceScreen
+class DarkModeScreen :
+    PreferenceScreenCreator,
+    PreferenceScreenBinding,
+    PersistentPreference<Boolean>,
+    BooleanValue,
+    PreferenceSummaryProvider,
+    PreferenceLifecycleProvider {
+
+    /**
+     * States for different screens.
+     *
+     * The "Dark mode" appears in several screens. And in Android split-screen mode, more than one
+     * "Dark mode" settings could be displayed at the same time. As [PreferenceScreenCreator] works
+     * like singleton, we need to register different broadcast receivers for different screens.
+     */
+    private val fragmentStates = WeakHashMap<PreferenceLifecycleContext, FragmentState>()
+
+    override val key: String
+        get() = KEY
+
+    override val title: Int
+        get() = R.string.dark_ui_mode
+
+    override val keywords: Int
+        get() = R.string.keywords_dark_ui_mode
+
+    override fun isFlagEnabled(context: Context) = Flags.catalystDarkUiMode()
+
+    override fun fragmentClass() = DarkModeSettingsFragment::class.java
+
+    override fun hasCompleteHierarchy() = false
+
+    override fun getPreferenceHierarchy(context: Context) = preferenceHierarchy(this) {}
+
+    override fun storage(context: Context): KeyValueStore = DarkModeStorage(context)
+
+    override fun createWidget(context: Context) = PrimarySwitchPreference(context)
+
+    override fun bind(preference: Preference, metadata: PreferenceMetadata) {
+        super.bind(preference, metadata)
+        if (preference is DarkModePreference) preference.setCatalystEnabled(true)
+        val context = preference.context
+        val primarySwitchPreference = preference as PrimarySwitchPreference
+        primarySwitchPreference.isSwitchEnabled = !context.isPowerSaveMode()
+        primarySwitchPreference.isChecked = context.isDarkMode()
+    }
+
+    override fun isEnabled(context: Context) = !context.isPowerSaveMode()
+
+    override fun getSummary(context: Context): CharSequence? {
+        val active = context.isDarkMode()
+        return when {
+            !context.isPowerSaveMode() -> AutoDarkTheme.getStatus(context, active)
+            active -> context.getString(R.string.dark_ui_mode_disabled_summary_dark_theme_on)
+            else -> context.getString(R.string.dark_ui_mode_disabled_summary_dark_theme_off)
+        }
+    }
+
+    override fun onStart(context: PreferenceLifecycleContext) {
+        val broadcastReceiver =
+            object : BroadcastReceiver() {
+                override fun onReceive(receiverContext: Context, intent: Intent) {
+                    context.notifyPreferenceChange(this@DarkModeScreen)
+                }
+            }
+        context.registerReceiver(
+            broadcastReceiver,
+            IntentFilter(PowerManager.ACTION_POWER_SAVE_MODE_CHANGED),
+        )
+
+        val darkModeObserver = DarkModeObserver(context)
+        darkModeObserver.subscribe { context.notifyPreferenceChange(this@DarkModeScreen) }
+
+        fragmentStates[context] = FragmentState(broadcastReceiver, darkModeObserver)
+    }
+
+    override fun onStop(context: PreferenceLifecycleContext) {
+        fragmentStates.remove(context)?.run {
+            context.unregisterReceiver(broadcastReceiver)
+            darkModeObserver.unsubscribe()
+        }
+    }
+
+    private class FragmentState(
+        val broadcastReceiver: BroadcastReceiver,
+        val darkModeObserver: DarkModeObserver,
+    )
+
+    /**
+     * Abstract storage for dark mode settings.
+     *
+     * The underlying storage is manipulated by [UiModeManager] but we do not need to worry about
+     * the details. Additionally, the observer is for UI purpose only right now, so use
+     * [NoOpKeyedObservable].
+     */
+    @Suppress("UNCHECKED_CAST")
+    private class DarkModeStorage(private val context: Context) :
+        NoOpKeyedObservable<String>(), KeyValueStore {
+
+        override fun contains(key: String) = key == KEY
+
+        override fun <T : Any> getValue(key: String, valueType: Class<T>) =
+            when {
+                key == KEY && valueType == Boolean::class.javaObjectType ->
+                    context.isDarkMode() as T
+                else -> null
+            }
+
+        override fun <T : Any> setValue(key: String, valueType: Class<T>, value: T?) {
+            if (key == KEY && value is Boolean) {
+                context.getSystemService(UiModeManager::class.java)?.setNightModeActivated(value)
+            }
+        }
+    }
+
+    companion object {
+        const val KEY = "dark_ui_mode"
+
+        private fun Context.isPowerSaveMode() =
+            getSystemService(PowerManager::class.java)?.isPowerSaveMode == true
+
+        private fun Context.isDarkMode() =
+            (resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_YES) != 0
+    }
+}
+// LINT.ThenChange(../DarkUIPreferenceController.java)