fix(about): reflect battery-optimization state; fix stale unresponsive item

The 'Ignore battery optimizations' item was only shown while the app was still
optimized, and its result callback recreated the list only on RESULT_OK. But Android's
ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS dialog returns RESULT_CANCELED even when the
user grants the exemption, so the item never refreshed: it stayed visible and a second
tap did nothing (already exempt -> the request dialog is a no-op).

Now:
- always show the item, with subtext reflecting state (Enabled / Disabled);
- when already exempt, tapping opens ACTION_IGNORE_BATTERY_OPTIMIZATION_SETTINGS so the
  user can toggle it back off (the request dialog can't);
- refresh the list via refreshMaterialAboutList() regardless of result code so the
  subtext updates immediately on return.

Author: hawkff

app/src/main/java/io/nekohasekai/sagernet/ui/AboutFragment.kt

@@ -1,6 +1,5 @@
 package io.nekohasekai.sagernet.ui
 
-import android.app.Activity
 import android.content.Context
 import android.content.Intent
 import android.net.Uri
@@ -10,8 +9,6 @@ import android.os.PowerManager
 import android.provider.Settings
 import android.view.View
 import android.widget.Toast
-import androidx.activity.result.component1
-import androidx.activity.result.component2
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.core.view.ViewCompat
 import androidx.recyclerview.widget.RecyclerView
@@ -51,12 +48,11 @@ class AboutFragment : ToolbarFragment(R.layout.layout_about) {
 
         val requestIgnoreBatteryOptimizations = registerForActivityResult(
             ActivityResultContracts.StartActivityForResult()
-        ) { (resultCode, _) ->
-            if (resultCode == Activity.RESULT_OK) {
-                parentFragmentManager.beginTransaction()
-                    .replace(R.id.about_fragment_holder, AboutContent())
-                    .commitAllowingStateLoss()
-            }
+        ) {
+            // The battery-optimization request/settings screen returns RESULT_CANCELED even
+            // when the user actually granted the exemption, so don't gate on the result code
+            // — just rebuild the list so the item's on/off subtext reflects the new state.
+            refreshMaterialAboutList()
         }
 
         override fun getMaterialAboutList(activityContext: Context): MaterialAboutList {
@@ -131,22 +127,32 @@ class AboutFragment : ToolbarFragment(R.layout.layout_about) {
                         .apply {
                             if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                                 val pm = app.getSystemService(Context.POWER_SERVICE) as PowerManager
-                                if (!pm.isIgnoringBatteryOptimizations(app.packageName)) {
-                                    addItem(
-                                        MaterialAboutActionItem.Builder()
-                                            .icon(R.drawable.ic_baseline_running_with_errors_24)
-                                            .text(R.string.ignore_battery_optimizations)
-                                            .subText(R.string.ignore_battery_optimizations_sum)
-                                            .setOnClickAction {
-                                                requestIgnoreBatteryOptimizations.launch(
-                                                    Intent(
-                                                        Settings.ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS,
-                                                        "package:${app.packageName}".toUri()
-                                                    )
+                                val ignoring = pm.isIgnoringBatteryOptimizations(app.packageName)
+                                addItem(
+                                    MaterialAboutActionItem.Builder()
+                                        .icon(R.drawable.ic_baseline_running_with_errors_24)
+                                        .text(R.string.ignore_battery_optimizations)
+                                        .subText(
+                                            if (ignoring) R.string.battery_optimization_enabled
+                                            else R.string.battery_optimization_disabled
+                                        )
+                                        .setOnClickAction {
+                                            // The ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS
+                                            // dialog only appears while the app is still
+                                            // optimized; once exempt it is a no-op. So when
+                                            // already exempt, send the user to the battery
+                                            // settings screen where they can toggle it back off.
+                                            val intent = if (ignoring) {
+                                                Intent(Settings.ACTION_IGNORE_BATTERY_OPTIMIZATION_SETTINGS)
+                                            } else {
+                                                Intent(
+                                                    Settings.ACTION_REQUEST_IGNORE_BATTERY_OPTIMIZATIONS,
+                                                    "package:${app.packageName}".toUri()
                                                 )
                                             }
-                                            .build())
-                                }
+                                            requestIgnoreBatteryOptimizations.launch(intent)
+                                        }
+                                        .build())
                             }
                         }
                         .build())

app/src/main/res/values/strings.xml

@@ -309,6 +309,8 @@
     <string name="donate_info">I love money</string>
     <string name="ignore_battery_optimizations">Ignore battery optimizations</string>
     <string name="ignore_battery_optimizations_sum">Remove some restrictions</string>
+    <string name="battery_optimization_enabled">Enabled — the app can run unrestricted in the background</string>
+    <string name="battery_optimization_disabled">Disabled — tap to allow background activity</string>
     <!-- plugin -->
     <string name="plugin">Plugin</string>
     <string name="plugin_configure">Configure…</string>