Time to full: estimated charge-completion row in the details table (#124)

app/src/main/java/com/almothafar/simplebatterynotifier/service/BatteryRateTracker.java

@@ -411,6 +411,45 @@ public static String formatCurrentValue(final Context context, final int signedM
 		return context.getString(R.string.battery_current_value, sign + Math.abs(signedMilliAmps));
 	}
 
+	/**
+	 * Estimated minutes until full from the smoothed charge rate (#124): a capacity-free linear projection,
+	 * {@code (100 − level) / ratePercentPerHour} hours, so it works even where the charge counter is
+	 * unreliable (Kirin). Deliberately simple — it does <b>not</b> model the charge-curve taper above ~80%,
+	 * so it overshoots near full; precision is a non-goal (the OS owns the accurate figure). Callers gate on
+	 * charging + a trustworthy rate + a level below the taper top before showing it. Pure so it is testable.
+	 *
+	 * @param level              current battery level (0-100)
+	 * @param ratePercentPerHour smoothed charge-rate magnitude in %/h
+	 *
+	 * @return estimated minutes to full, or 0 when not computable (non-positive rate, or already at/above full)
+	 */
+	public static int estimateMinutesToFull(final int level, final int ratePercentPerHour) {
+		if (ratePercentPerHour <= 0 || level >= 100) {
+			return 0;
+		}
+		final int remaining = 100 - level;
+		return (int) Math.round(remaining * 60.0 / ratePercentPerHour);
+	}
+
+	/**
+	 * Formats a time-to-full estimate as a compact {@code "~1h 20m"} / {@code "~45m"}, with Western digits
+	 * in every locale (#96). The units stay Latin (h/m), matching {@code battery_rate_value} and
+	 * {@code design_capacity_value}.
+	 *
+	 * @param context      Application context
+	 * @param totalMinutes estimated minutes to full (from {@link #estimateMinutesToFull}); must be &gt; 0
+	 *
+	 * @return the formatted duration string
+	 */
+	public static String formatTimeToFull(final Context context, final int totalMinutes) {
+		final int hours = totalMinutes / 60;
+		final int minutes = totalMinutes % 60;
+		if (hours > 0) {
+			return context.getString(R.string.time_to_full_value_hm, String.valueOf(hours), String.valueOf(minutes));
+		}
+		return context.getString(R.string.time_to_full_value_m, String.valueOf(minutes));
+	}
+
 	/**
 	 * Serializes a window to a compact string ("t:level:currentUa" joined by ';'). Pure and testable.
 	 *

app/src/main/java/com/almothafar/simplebatterynotifier/ui/fragment/BatteryDetailsFragment.java

@@ -383,12 +383,40 @@ private void addRateRows(final View view) {
 			valuesMap.put(rateLabel, BatteryRateTracker.formatRateValue(view.getContext(), rate.percentPerHour()));
 			rateValueColor = rateColor(view.getContext(), rate);
 		}
+		addTimeToFullRow(view, rate);
 		if (rate.hasCurrent()) {
 			valuesMap.put(getResources().getString(R.string.battery_current),
 					BatteryRateTracker.formatCurrentValue(view.getContext(), rate.currentMilliAmps()));
 		}
 	}
 
+	/**
+	 * Adds the estimated time-to-full row directly below the charge rate it is derived from (#124). Shown
+	 * only while charging, with a trustworthy rate, and below the taper top (level < 99%) — hidden
+	 * otherwise, so the user never sees a garbage "0m" or a wildly optimistic figure right as the charge
+	 * tapers. The estimate is a rough linear projection (see
+	 * {@link BatteryRateTracker#estimateMinutesToFull}); precision is a non-goal — the OS owns the accurate
+	 * number. Reuses the already-computed {@code rate}; only the level is read here.
+	 *
+	 * @param view The fragment view
+	 * @param rate The already-computed rate for this refresh
+	 */
+	private void addTimeToFullRow(final View view, final BatteryRateTracker.BatteryRate rate) {
+		if (!rate.charging() || !rate.hasRate()) {
+			return;
+		}
+		final int level = Math.round(batteryDO.getBatteryPercentage());
+		if (level >= 99) {
+			return;
+		}
+		final int minutes = BatteryRateTracker.estimateMinutesToFull(level, rate.percentPerHour());
+		if (minutes <= 0) {
+			return;
+		}
+		valuesMap.put(getResources().getString(R.string.time_to_full),
+				BatteryRateTracker.formatTimeToFull(view.getContext(), minutes));
+	}
+
 	/**
 	 * The colour for the drain-rate value: red at/above the user's limit, amber as it approaches (derived
 	 * just below the limit), otherwise the default. Charging is left uncoloured in v1 — its context traps

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

@@ -30,6 +30,8 @@
     <string name="drain_rate">معدل الاستهلاك</string>
     <string name="charge_rate">معدل الشحن</string>
     <string name="battery_current">التيار</string>
+    <!-- #124: الوقت المقدّر حتى اكتمال الشحن -->
+    <string name="time_to_full">الوقت حتى الاكتمال</string>
 
     <string name="battery">على البطارية</string>
     <string name="charger_ac">مقبس طاقة</string>
@@ -154,6 +156,9 @@
     <!-- معدل الشحن/الاستهلاك (#108) -->
     <string name="battery_rate_value">%1$s%%/h</string>
     <string name="battery_current_value">%1$s mA</string>
+    <!-- #124: الوحدات h/m تبقى لاتينية كبقية قيم المعدل -->
+    <string name="time_to_full_value_hm">~%1$sh %2$sm</string>
+    <string name="time_to_full_value_m">~%1$sm</string>
     <string name="pref_cat_title_drain">استهلاك البطارية</string>
     <string name="show_rate_in_notification">إظهار المعدل في إشعار الحالة</string>
     <string name="show_rate_in_notification_summary_on">يعرض الإشعار المستمر معدل الشحن/الاستهلاك المباشر بجانب الحالة</string>

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

@@ -32,6 +32,8 @@
     <string name="drain_rate">Drain rate</string>
     <string name="charge_rate">Charge rate</string>
     <string name="battery_current">Current</string>
+    <!-- #124: estimated time to full, shown below the charge rate while charging -->
+    <string name="time_to_full">Time to full</string>
 
     <string name="battery">On Battery</string>
     <string name="charger_ac">AC Charger</string>
@@ -162,6 +164,10 @@
     <string name="battery_rate_value">%1$s%%/h</string>
     <!-- %1$s is a signed Western-digit number, e.g. "+900" or "−450" -->
     <string name="battery_current_value">%1$s mA</string>
+    <!-- #124: time-to-full duration. %1$s hours, %2$s minutes — Western-digit numbers (String.valueOf);
+         the h/m units stay Latin like the other rate values (#96). -->
+    <string name="time_to_full_value_hm">~%1$sh %2$sm</string>
+    <string name="time_to_full_value_m">~%1$sm</string>
     <string name="pref_cat_title_drain">Battery Drain</string>
     <string name="show_rate_in_notification">Show rate in status notification</string>
     <string name="show_rate_in_notification_summary_on">The ongoing notification shows the live drain/charge rate next to the status</string>

app/src/test/java/com/almothafar/simplebatterynotifier/service/BatteryRateTrackerTest.java

@@ -1,17 +1,23 @@
 package com.almothafar.simplebatterynotifier.service;
 
+import android.content.Context;
 import android.os.BatteryManager;
 
+import androidx.test.core.app.ApplicationProvider;
+
 import com.almothafar.simplebatterynotifier.model.BatteryDO;
 import com.almothafar.simplebatterynotifier.service.BatteryRateTracker.BatteryRate;
 import com.almothafar.simplebatterynotifier.service.BatteryRateTracker.Sample;
 
+import org.junit.Before;
 import org.junit.Test;
 import org.junit.experimental.runners.Enclosed;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
 import org.junit.runners.Parameterized.Parameter;
 import org.junit.runners.Parameterized.Parameters;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
 
 import java.util.Arrays;
 import java.util.Collection;
@@ -252,6 +258,78 @@ public void matchesExpected() {
 		}
 	}
 
+	/**
+	 * {@link BatteryRateTracker#estimateMinutesToFull}: the capacity-free linear projection (#124) and its
+	 * not-computable guards. Boundaries: the taper-top levels (99/100), a zero/negative rate, and rounding.
+	 */
+	@RunWith(Parameterized.class)
+	public static class EstimateMinutesToFull {
+
+		@Parameter(0) public String label;
+		@Parameter(1) public int level;
+		@Parameter(2) public int ratePercentPerHour;
+		@Parameter(3) public int expectedMinutes;
+
+		@Parameters(name = "{0}")
+		public static Collection<Object[]> data() {
+			return Arrays.asList(new Object[][]{
+					{"50% at 30%/h -> 100m", 50, 30, 100},        // 50/30 h = 1h40m
+					{"80% at 60%/h -> 20m", 80, 60, 20},          // 20/60 h
+					{"20% at 10%/h -> 480m", 20, 10, 480},        // 80/10 h = 8h
+					{"rounds to nearest minute", 55, 40, 68},     // 45/40 h = 67.5m -> 68
+					{"one point left at 60%/h -> 1m", 99, 60, 1}, // helper allows; the UI gates level >= 99
+					{"zero rate not computable", 50, 0, 0},
+					{"negative rate not computable", 50, -5, 0},
+					{"already full not computable", 100, 30, 0},
+			});
+		}
+
+		@Test
+		public void matchesExpected() {
+			assertEquals(label, expectedMinutes, BatteryRateTracker.estimateMinutesToFull(level, ratePercentPerHour));
+		}
+	}
+
+	/**
+	 * {@link BatteryRateTracker#formatTimeToFull}: the "~1h 20m" / "~45m" rendering and its Western-digit
+	 * guarantee (#96). Context-dependent (string resources), so it runs under Robolectric — unlike the pure
+	 * math above; mirrors how the other Context-backed formatters would be exercised.
+	 */
+	@RunWith(RobolectricTestRunner.class)
+	@Config(sdk = 34)
+	public static class FormatTimeToFull {
+
+		private Context context;
+
+		@Before
+		public void setUp() {
+			context = ApplicationProvider.getApplicationContext();
+		}
+
+		@Test
+		public void hoursAndMinutes() {
+			assertEquals("~1h 20m", BatteryRateTracker.formatTimeToFull(context, 80));
+		}
+
+		@Test
+		public void minutesOnly() {
+			assertEquals("~45m", BatteryRateTracker.formatTimeToFull(context, 45));
+		}
+
+		@Test
+		public void wholeHoursStillShowMinutes() {
+			assertEquals("~2h 0m", BatteryRateTracker.formatTimeToFull(context, 120));
+		}
+
+		@Test
+		@Config(qualifiers = "ar")
+		public void keepsWesternDigitsUnderArabicLocale() {
+			// values-ar keeps the "~%1$sh %2$sm" shape and String.valueOf keeps the digits 0-9 (#96), so the
+			// Arabic render is identical — a regression to %d here would surface Arabic-Indic digits.
+			assertEquals("~1h 20m", BatteryRateTracker.formatTimeToFull(context, 80));
+		}
+	}
+
 	/**
 	 * {@link BatteryRateTracker#isChargingDirection}: charging and full map to the charging direction.
 	 */