add notifications to android app

Signed-off-by: Christine Dodrill <me@christine.website>

app/src/main/java/website/christine/xesite/Application.kt

@@ -16,9 +16,37 @@
 package website.christine.xesite
 
 import android.app.Application
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.content.Context
+import android.os.Build
 
 class Application : Application() {
     override fun onCreate() {
         super.onCreate()
+
+        val ctx = this.applicationContext
+        createNotificationChannel(ctx)
+    }
+
+    private fun createNotificationChannel(ctx: Context) {
+        // Create the NotificationChannel, but only on API 26+ because
+        // the NotificationChannel class is new and not in the support library
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val name = NEW_POST_CHANNEL
+            val descriptionText = NEW_POST_CHANNEL_DESC
+            val importance = NotificationManager.IMPORTANCE_LOW
+            val channel = NotificationChannel(NEW_POST_CHANNEL, name, importance).apply {
+                description = descriptionText
+            }
+            // Register the channel with the system
+            val notificationManager: NotificationManager =
+                ctx.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            notificationManager.createNotificationChannel(channel)
+        }
     }
 }
+
+internal val NEW_POST_CHANNEL = "New Posts";
+internal val NEW_POST_CHANNEL_DESC = "New posts on christine.website";
+internal val notificationId = 1;

app/src/main/java/website/christine/xesite/LauncherActivity.kt

@@ -15,6 +15,7 @@
  */
 package website.christine.xesite
 
+import android.content.Context
 import android.net.Uri
 import com.google.androidbrowserhelper.trusted.LauncherActivity
 

app/src/main/java/website/christine/xesite/NewPostWidget.kt

@@ -1,10 +1,15 @@
 package website.christine.xesite
 
+import android.app.NotificationChannel
+import android.app.NotificationManager
 import android.appwidget.AppWidgetManager
 import android.appwidget.AppWidgetProvider
 import android.content.Context
+import android.os.Build
 import android.util.Log
 import android.widget.RemoteViews
+import androidx.core.app.NotificationCompat
+import androidx.core.app.NotificationManagerCompat
 import com.android.volley.RequestQueue
 import com.android.volley.Response
 import com.android.volley.toolbox.BasicNetwork
@@ -23,6 +28,18 @@ class NewPostWidget : AppWidgetProvider() {
         return ctx.packageName.plus("/").plus(pkgInfo.versionName)
     }
 
+    private fun notify(ctx: Context, newPost: NewPost) {
+        var builder = NotificationCompat.Builder(ctx, NEW_POST_CHANNEL)
+            .setSmallIcon(R.drawable.splash)
+            .setContentTitle(newPost.title)
+            .setContentText(newPost.summary)
+            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
+
+        NotificationManagerCompat.from(ctx).apply {
+            notify(notificationId, builder.build())
+        }
+    }
+
     override fun onUpdate(
         ctx: Context,
         appWidgetManager: AppWidgetManager,
@@ -38,6 +55,13 @@ class NewPostWidget : AppWidgetProvider() {
             NewPost::class.java,
             headers,
             Response.Listener<NewPost> { response ->
+                val oldURL = loadPref(ctx, "old_url", response.link)
+                if (response.link != oldURL) {
+                    // make notification?
+                    this.notify(ctx, response)
+                    savePref(ctx, "old_url", response.link)
+                }
+
                 Log.println(Log.INFO, "new_post", response.toString())
                 // There may be multiple widgets active, so update all of them
                 for (appWidgetId in appWidgetIds) {
@@ -75,6 +99,8 @@ class NewPostWidget : AppWidgetProvider() {
 
     override fun onEnabled(ctx: Context) {
         this.makeQueue(ctx)
+        //this.createNotificationChannel(ctx)
+        savePref(ctx, "old_url", "http://google.com")
     }
 
     override fun onDisabled(context: Context) {
@@ -103,3 +129,18 @@ class NewPostWidget : AppWidgetProvider() {
         appWidgetManager.updateAppWidget(appWidgetId, views)
     }
 }
+
+private const val PREFS_NAME = "website.christine.xesite.NewPostWidget"
+private const val PREF_PREFIX_KEY = "appwidget_"
+
+internal fun savePref(ctx: Context, key: String, value: String) {
+    val prefs = ctx.getSharedPreferences(PREFS_NAME, 0).edit()
+    prefs.putString(PREF_PREFIX_KEY + key, value)
+    prefs.apply()
+}
+
+internal fun loadPref(ctx: Context, key: String, default: String): String {
+    val prefs = ctx.getSharedPreferences(PREFS_NAME, 0)
+    val titleValue = prefs.getString(PREF_PREFIX_KEY + key, default)
+    return titleValue ?: default
+}