Added NotificationUtils to build and manage notifications

The `TermuxPreferenceConstants` classes has been updated to `v0.5.0`. Check its Changelog sections for info on changes.

app/src/main/java/com/termux/app/settings/preferences/TermuxAppSharedPreferences.java

@@ -122,6 +122,16 @@ public class TermuxAppSharedPreferences {
 
 
 
+    public int getLastNotificationId() {
+        return SharedPreferenceUtils.getInt(mSharedPreferences, TERMUX_APP.KEY_LAST_NOTIFICATION_ID, TERMUX_APP.DEFAULT_VALUE_KEY_LAST_NOTIFICATION_ID);
+    }
+
+    public void setLastNotificationId(int notificationId) {
+        SharedPreferenceUtils.setInt(mSharedPreferences, TERMUX_APP.KEY_LAST_NOTIFICATION_ID, notificationId, false);
+    }
+
+
+
     public boolean getTerminalViewKeyLoggingEnabled() {
         return SharedPreferenceUtils.getBoolean(mSharedPreferences, TERMUX_APP.KEY_TERMINAL_VIEW_KEY_LOGGING_ENABLED, TERMUX_APP.DEFAULT_VALUE_TERMINAL_VIEW_KEY_LOGGING_ENABLED);
     }

app/src/main/java/com/termux/app/settings/preferences/TermuxPreferenceConstants.java

@@ -1,7 +1,7 @@
 package com.termux.app.settings.preferences;
 
 /*
- * Version: v0.4.0
+ * Version: v0.5.0
  *
  * Changelog
  *
@@ -9,19 +9,23 @@ package com.termux.app.settings.preferences;
  *      - Initial Release.
  *
  * - 0.2.0 (2021-03-13)
- *      - Added `KEY_LOG_LEVEL` and `KEY_TERMINAL_VIEW_LOGGING_ENABLED`
+ *      - Added `KEY_LOG_LEVEL` and `KEY_TERMINAL_VIEW_LOGGING_ENABLED`.
- * 
+ *
  * - 0.3.0 (2021-03-16)
  *      - Changed to per app scoping of variables so that the same file can store all constants of
  *          Termux app and its plugins. This will allow {@link com.termux.app.TermuxSettings} to
  *          manage preferences of plugins as well if they don't have launcher activity themselves
  *          and also allow plugin apps to make changes to preferences from background.
  *      - Added following to `TERMUX_TASKER_APP`:
-     *      `KEY_LOG_LEVEL`.
+ *           `KEY_LOG_LEVEL`.
  *
  * - 0.4.0 (2021-03-13)
  *      - Added following to `TERMUX_APP`:
  *          `KEY_PLUGIN_ERROR_NOTIFICATIONS_ENABLED` and `DEFAULT_VALUE_PLUGIN_ERROR_NOTIFICATIONS_ENABLED`.
+ *
+ * - 0.5.0 (2021-03-24)
+ *      - Added following to `TERMUX_APP`:
+ *          `KEY_LAST_NOTIFICATION_ID` and `DEFAULT_VALUE_KEY_LAST_NOTIFICATION_ID`.
  */
 
 /**
@@ -70,6 +74,13 @@ public final class TermuxPreferenceConstants {
         public static final String KEY_LOG_LEVEL = "log_level";
 
 
+        /**
+         * Defines the key for last used notification id
+         */
+        public static final String KEY_LAST_NOTIFICATION_ID = "last_notification_id";
+        public static final int DEFAULT_VALUE_KEY_LAST_NOTIFICATION_ID = 0;
+
+
         /**
          * Defines the key for whether termux terminal view key logging is enabled or not
          */

app/src/main/java/com/termux/app/utils/NotificationUtils.java

@@ -0,0 +1,166 @@
+package com.termux.app.utils;
+
+import android.app.Notification;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.Context;
+import android.os.Build;
+
+import androidx.annotation.Nullable;
+
+import com.termux.app.RunCommandService;
+import com.termux.app.TermuxService;
+import com.termux.app.settings.preferences.TermuxAppSharedPreferences;
+import com.termux.app.settings.preferences.TermuxPreferenceConstants;
+
+public class NotificationUtils {
+
+    /** Do not show notification */
+    public static final int NOTIFICATION_MODE_NONE = 0;
+    /** Show notification without sound, vibration or lights */
+    public static final int NOTIFICATION_MODE_SILENT = 1;
+    /** Show notification with sound */
+    public static final int NOTIFICATION_MODE_SOUND = 2;
+    /** Show notification with vibration */
+    public static final int NOTIFICATION_MODE_VIBRATE = 3;
+    /** Show notification with lights */
+    public static final int NOTIFICATION_MODE_LIGHTS = 4;
+    /** Show notification with sound and vibration */
+    public static final int NOTIFICATION_MODE_SOUND_AND_VIBRATE = 5;
+    /** Show notification with sound and lights */
+    public static final int NOTIFICATION_MODE_SOUND_AND_LIGHTS = 6;
+    /** Show notification with vibration and lights */
+    public static final int NOTIFICATION_MODE_VIBRATE_AND_LIGHTS = 7;
+    /** Show notification with sound, vibration and lights */
+    public static final int NOTIFICATION_MODE_ALL = 8;
+
+    private static final String LOG_TAG = "NotificationUtils";
+
+    /**
+     * Get the {@link NotificationManager}.
+     *
+     * @param context The {@link Context} for operations.
+     * @return Returns the {@link NotificationManager}.
+     */
+    @Nullable
+    public static NotificationManager getNotificationManager(final Context context) {
+        if(context == null) return null;
+        return (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
+    }
+
+    /**
+     * Try to get the next unique notification id that isn't already being used by the app.
+     *
+     * @param context The {@link Context} for operations.
+     * @return Returns the notification id that should be safe to use.
+     */
+    public synchronized static int getNextNotificationId(final Context context) {
+        if(context == null) return TermuxPreferenceConstants.TERMUX_APP.DEFAULT_VALUE_KEY_LAST_NOTIFICATION_ID;
+
+        TermuxAppSharedPreferences preferences = new TermuxAppSharedPreferences(context);
+        int lastNotificationId = preferences.getLastNotificationId();
+
+        int nextNotificationId = lastNotificationId + 1;
+        while(nextNotificationId == TermuxService.NOTIFICATION_ID || nextNotificationId == RunCommandService.NOTIFICATION_ID) {
+            nextNotificationId++;
+        }
+
+        if(nextNotificationId == Integer.MAX_VALUE || nextNotificationId < 0)
+            nextNotificationId = TermuxPreferenceConstants.TERMUX_APP.DEFAULT_VALUE_KEY_LAST_NOTIFICATION_ID;
+
+        preferences.setLastNotificationId(nextNotificationId);
+        return nextNotificationId;
+    }
+
+    /**
+     * Get {@link Notification.Builder}.
+     *
+     * @param context The {@link Context} for operations.
+     * @param title The title for the notification.
+     * @param notifiationText The second line text of the notification.
+     * @param notificationBigText The full text of the notification that may optionally be styled.
+     * @param pendingIntent The {@link PendingIntent} which should be sent when notification is clicked.
+     * @param notificationMode The notification mode. It must be one of {@code NotificationUtils.NOTIFICATION_MODE_*}.
+     *                         The builder returned will be {@code null} if {@link #NOTIFICATION_MODE_NONE}
+     *                         is passed. That case should ideally be handled before calling this function.
+     * @return Returns the {@link Notification.Builder}.
+     */
+    @Nullable
+    public static Notification.Builder geNotificationBuilder(final Context context, final String channelId, final int priority, final CharSequence title, final CharSequence notifiationText, final CharSequence notificationBigText, final PendingIntent pendingIntent, final int notificationMode) {
+        if(context == null) return null;
+        Notification.Builder builder = new Notification.Builder(context);
+        builder.setContentTitle(title);
+        builder.setContentText(notifiationText);
+        builder.setStyle(new Notification.BigTextStyle().bigText(notificationBigText));
+        builder.setContentIntent(pendingIntent);
+
+        builder.setPriority(priority);
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
+            builder.setChannelId(channelId);
+
+        builder = setNotificationDefaults(builder, notificationMode);
+
+        return builder;
+    }
+
+    /**
+     * Setup the notification channel if Android version is greater than or equal to
+     * {@link Build.VERSION_CODES#O}.
+     *
+     * @param context The {@link Context} for operations.
+     * @param channelId The id of the channel. Must be unique per package.
+     * @param channelName The user visible name of the channel.
+     * @param importance The importance of the channel. This controls how interruptive notifications
+     *                   posted to this channel are.
+     */
+    public static void setupNotificationChannel(final Context context, final String channelId, final CharSequence channelName, final int importance) {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) return;
+
+        NotificationChannel channel = new NotificationChannel(channelId, channelName, importance);
+
+        NotificationManager notificationManager = getNotificationManager(context);
+        if(notificationManager != null)
+            notificationManager.createNotificationChannel(channel);
+    }
+
+    public static Notification.Builder setNotificationDefaults(Notification.Builder builder, final int notificationMode) {
+
+        // TODO: setDefaults() is deprecated and should also implement setting notification mode via notification channel
+        switch (notificationMode) {
+            case NOTIFICATION_MODE_NONE:
+                Logger.logWarn(LOG_TAG, "The NOTIFICATION_MODE_NONE passed to setNotificationDefaults(), force setting builder to null.");
+                return null; // return null since notification is not supposed to be shown
+            case NOTIFICATION_MODE_SILENT:
+                break;
+            case NOTIFICATION_MODE_SOUND:
+                builder.setDefaults(Notification.DEFAULT_SOUND);
+                break;
+            case NOTIFICATION_MODE_VIBRATE:
+                builder.setDefaults(Notification.DEFAULT_VIBRATE);
+                break;
+            case NOTIFICATION_MODE_LIGHTS:
+                builder.setDefaults(Notification.DEFAULT_LIGHTS);
+                break;
+            case NOTIFICATION_MODE_SOUND_AND_VIBRATE:
+                builder.setDefaults(Notification.DEFAULT_SOUND | Notification.DEFAULT_VIBRATE);
+                break;
+            case NOTIFICATION_MODE_SOUND_AND_LIGHTS:
+                builder.setDefaults(Notification.DEFAULT_SOUND | Notification.DEFAULT_LIGHTS);
+                break;
+            case NOTIFICATION_MODE_VIBRATE_AND_LIGHTS:
+                builder.setDefaults(Notification.DEFAULT_VIBRATE | Notification.DEFAULT_LIGHTS);
+                break;
+            case NOTIFICATION_MODE_ALL:
+                builder.setDefaults(Notification.DEFAULT_ALL);
+                break;
+            default:
+                Logger.logError(LOG_TAG, "Invalid notificationMode: \"" + notificationMode + "\" passed to setNotificationDefaults()");
+                break;
+        }
+
+        return builder;
+    }
+
+}