Fix for showing accurate next enabled alarm

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

@@ -33,6 +33,9 @@ import com.simplemobiletools.clock.receivers.HideTimerReceiver
 import com.simplemobiletools.clock.services.SnoozeService
 import com.simplemobiletools.commons.extensions.*
 import com.simplemobiletools.commons.helpers.*
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import java.text.SimpleDateFormat
 import java.util.*
 import kotlin.math.pow
 
@@ -266,6 +269,44 @@ fun Context.getNextAlarm(): String {
     return "$dayOfWeek $formatted"
 }
 
+suspend fun Context.getClosestEnabledAlarmString(): String = withContext(Dispatchers.IO) {
+    val enabledAlarms = dbHelper.getEnabledAlarms()
+    val nextAlarmList = enabledAlarms
+        .mapNotNull { getTimeUntilNextAlarm(it.timeInMinutes, it.days) }
+
+    if (nextAlarmList.isEmpty()) {
+        return@withContext ""
+    }
+
+    var closestAlarmTime = Int.MAX_VALUE
+    nextAlarmList.forEach { time ->
+        if (time < closestAlarmTime) {
+            closestAlarmTime = time
+        }
+    }
+
+    if (closestAlarmTime == Int.MAX_VALUE) {
+        return@withContext ""
+    }
+
+    val calendar = Calendar.getInstance().apply { firstDayOfWeek = Calendar.MONDAY }
+    calendar.add(Calendar.MINUTE, closestAlarmTime)
+    var dayOfWeekIndex = calendar.get(Calendar.DAY_OF_WEEK) - Calendar.MONDAY
+    if (dayOfWeekIndex < 0) {  // Adjust for Calendar.MONDAY being 2
+        dayOfWeekIndex += 7
+    }
+
+    val dayOfWeek = resources.getStringArray(R.array.week_days_short)[dayOfWeekIndex]
+    val pattern = if (DateFormat.is24HourFormat(this@getClosestEnabledAlarmString)) {
+        "HH:mm"
+    } else {
+        "h:mm a"
+    }
+
+    val formattedTime = SimpleDateFormat(pattern, Locale.getDefault()).format(calendar.time)
+    return@withContext "$dayOfWeek $formattedTime"
+}
+
 fun Context.rescheduleEnabledAlarms() {
     dbHelper.getEnabledAlarms().forEach {
         if (it.days != TODAY_BIT || it.timeInMinutes > getCurrentDayMinutes()) {

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

@@ -7,6 +7,7 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
+import androidx.lifecycle.lifecycleScope
 import com.simplemobiletools.clock.R
 import com.simplemobiletools.clock.activities.SimpleActivity
 import com.simplemobiletools.clock.adapters.TimeZonesAdapter
@@ -20,6 +21,8 @@ import com.simplemobiletools.commons.extensions.getProperTextColor
 import com.simplemobiletools.commons.extensions.updateTextColors
 import kotlinx.android.synthetic.main.fragment_clock.*
 import kotlinx.android.synthetic.main.fragment_clock.view.*
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.launch
 import java.util.*
 
 class ClockFragment : Fragment() {
@@ -113,10 +116,12 @@ class ClockFragment : Fragment() {
 
     fun updateAlarm() {
         view.apply {
-            val nextAlarm = requireContext().getNextAlarm()
-            clock_alarm.beVisibleIf(nextAlarm.isNotEmpty())
-            clock_alarm.text = nextAlarm
-            clock_alarm.colorCompoundDrawable(requireContext().getProperTextColor())
+            lifecycleScope.launch {
+                val nextAlarm = requireContext().getClosestEnabledAlarmString()
+                clock_alarm.beVisibleIf(nextAlarm.isNotEmpty())
+                clock_alarm.text = nextAlarm
+                clock_alarm.colorCompoundDrawable(requireContext().getProperTextColor())
+            }
         }
     }
 

app/src/main/kotlin/com/simplemobiletools/clock/helpers/Constants.kt

@@ -193,3 +193,43 @@ fun getAllTimeZones() = arrayListOf(
     MyTimeZone(88, "GMT+13:00 Auckland", "Pacific/Auckland"),
     MyTimeZone(89, "GMT+13:00 Tongatapu", "Pacific/Tongatapu")
 )
+
+fun getTimeUntilNextAlarm(alarmTimeInMinutes: Int, days: Int): Int? {
+    val calendar = Calendar.getInstance()
+    calendar.firstDayOfWeek = Calendar.MONDAY
+    val currentTimeInMinutes = calendar.get(Calendar.HOUR_OF_DAY) * 60 + calendar.get(Calendar.MINUTE)
+    val currentDayOfWeek = calendar.get(Calendar.DAY_OF_WEEK) - Calendar.MONDAY
+
+    var minTimeDifferenceInMinutes = Int.MAX_VALUE
+
+    for (i in 0..6) {
+        val alarmDayOfWeek = (currentDayOfWeek + i) % 7
+        if (isAlarmEnabledForDay(alarmDayOfWeek, days)) {
+            val timeDifferenceInMinutes = getTimeDifferenceInMinutes(currentTimeInMinutes, alarmTimeInMinutes, i)
+            if (timeDifferenceInMinutes < minTimeDifferenceInMinutes) {
+                minTimeDifferenceInMinutes = timeDifferenceInMinutes
+            }
+        }
+    }
+
+    return if (minTimeDifferenceInMinutes != Int.MAX_VALUE) {
+        minTimeDifferenceInMinutes
+    } else {
+        null
+    }
+}
+
+fun isAlarmEnabledForDay(day: Int, alarmDays: Int): Boolean {
+    return ((alarmDays shr day) and 1) == 1
+}
+
+fun getTimeDifferenceInMinutes(currentTimeInMinutes: Int, alarmTimeInMinutes: Int, daysUntilAlarm: Int): Int {
+    val minutesInADay = 24 * 60
+    val minutesUntilAlarm = daysUntilAlarm * minutesInADay + alarmTimeInMinutes
+    return if (minutesUntilAlarm > currentTimeInMinutes) {
+        minutesUntilAlarm - currentTimeInMinutes
+    } else {
+        minutesInADay - (currentTimeInMinutes - minutesUntilAlarm)
+    }
+}
+