show an activity over the lockscreen at Timer notification, if screen is off

app/src/main/AndroidManifest.xml

@@ -40,6 +40,8 @@
             android:name=".activities.MainActivity"
             android:launchMode="singleTask"/>
 
+        <activity android:name=".activities.ReminderActivity"/>
+
         <activity
             android:name=".activities.SettingsActivity"
             android:label="@string/settings"

app/src/main/kotlin/com/simplemobiletools/clock/activities/ReminderActivity.kt

@@ -0,0 +1,14 @@
+package com.simplemobiletools.clock.activities
+
+import android.os.Bundle
+import com.simplemobiletools.clock.R
+import com.simplemobiletools.clock.extensions.showOverLockscreen
+
+class ReminderActivity : SimpleActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_reminder)
+        showOverLockscreen()
+    }
+}

app/src/main/kotlin/com/simplemobiletools/clock/extensions/Activity.kt

@@ -0,0 +1,11 @@
+package com.simplemobiletools.clock.extensions
+
+import android.app.Activity
+import android.view.WindowManager
+
+fun Activity.showOverLockscreen() {
+    window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON or
+            WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD or
+            WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED or
+            WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON)
+}

app/src/main/kotlin/com/simplemobiletools/clock/extensions/Context.kt

@@ -9,6 +9,7 @@ import android.content.ComponentName
 import android.content.Context
 import android.content.Intent
 import android.media.RingtoneManager
+import android.os.PowerManager
 import android.provider.Settings
 import android.text.SpannableString
 import android.text.style.RelativeSizeSpan
@@ -217,3 +218,5 @@ fun Context.rescheduleEnabledAlarms() {
         scheduleNextAlarm(it, false)
     }
 }
+
+fun Context.isScreenOn() = (getSystemService(Context.POWER_SERVICE) as PowerManager).isScreenOn

app/src/main/kotlin/com/simplemobiletools/clock/fragments/TimerFragment.kt

@@ -19,6 +19,7 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import com.simplemobiletools.clock.R
+import com.simplemobiletools.clock.activities.ReminderActivity
 import com.simplemobiletools.clock.activities.SimpleActivity
 import com.simplemobiletools.clock.activities.SplashActivity
 import com.simplemobiletools.clock.dialogs.MyTimePickerDialogDialog
@@ -26,6 +27,7 @@ import com.simplemobiletools.clock.dialogs.SelectAlarmSoundDialog
 import com.simplemobiletools.clock.extensions.colorLeftDrawable
 import com.simplemobiletools.clock.extensions.config
 import com.simplemobiletools.clock.extensions.hideNotification
+import com.simplemobiletools.clock.extensions.isScreenOn
 import com.simplemobiletools.clock.helpers.OPEN_TAB
 import com.simplemobiletools.clock.helpers.TAB_TIMER
 import com.simplemobiletools.clock.helpers.TIMER_NOTIF_ID
@@ -35,6 +37,7 @@ import com.simplemobiletools.commons.helpers.isLollipopPlus
 import com.simplemobiletools.commons.helpers.isOreoPlus
 import kotlinx.android.synthetic.main.fragment_timer.view.*
 
+
 class TimerFragment : Fragment() {
     private val UPDATE_INTERVAL = 1000L
 
@@ -185,14 +188,20 @@ class TimerFragment : Fragment() {
 
         view.timer_time.text = formattedDuration
         if (diff == 0) {
-            val pendingIntent = getOpenAppIntent(context!!)
-            val notification = getNotification(context!!, pendingIntent)
-            val notificationManager = context!!.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
-            notificationManager.notify(TIMER_NOTIF_ID, notification)
+            if (context?.isScreenOn() == true) {
+                val pendingIntent = getOpenAppIntent(context!!)
+                val notification = getNotification(context!!, pendingIntent)
+                val notificationManager = context!!.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+                notificationManager.notify(TIMER_NOTIF_ID, notification)
 
-            Handler().postDelayed({
-                hideTimerNotification()
-            }, context?.config!!.timerMaxReminderSecs * 1000L)
+                Handler().postDelayed({
+                    hideTimerNotification()
+                }, context?.config!!.timerMaxReminderSecs * 1000L)
+            } else {
+                Intent(context, ReminderActivity::class.java).apply {
+                    activity?.startActivity(this)
+                }
+            }
         }
         return true
     }

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

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/reminder_holder"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+</RelativeLayout>