feat(widget): using work to refresh widget

app/src/main/kotlin/com/zjutjh/ijh/widget/ScheduleWidget.kt

@@ -1,6 +1,7 @@
 package com.zjutjh.ijh.widget
 
 import android.content.Context
+import android.util.Log
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
@@ -20,6 +21,7 @@ import androidx.glance.appwidget.cornerRadius
 import androidx.glance.appwidget.lazy.LazyColumn
 import androidx.glance.appwidget.lazy.items
 import androidx.glance.appwidget.provideContent
+import androidx.glance.appwidget.updateAll
 import androidx.glance.background
 import androidx.glance.layout.Alignment
 import androidx.glance.layout.Box
@@ -51,13 +53,16 @@ import java.time.format.DateTimeFormatter
 class ScheduleWidget : GlanceAppWidget() {
     @OptIn(ExperimentalCoroutinesApi::class)
     override suspend fun provideGlance(context: Context, id: GlanceId) {
+        Log.d("ScheduleWidget", "provideGlance called.")
+
         val entryPoint =
             EntryPointAccessors.fromApplication<ScheduleWidgetReceiver.Repositories>(context)
 
         val dayStateFlow = entryPoint.weJhInfoRepository.infoStream
             .map { it?.toTermDayState() }
         val coursesFlow = dayStateFlow.flatMapLatest {
             it ?: return@flatMapLatest flowOf(null)
+
             entryPoint.courseRepository
                 .getCourses(it.year, it.term, it.week, it.dayOfWeek)
         }
@@ -68,6 +73,9 @@ class ScheduleWidget : GlanceAppWidget() {
                 DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(it.withZoneSameInstant(ZoneId.systemDefault()))
             }
 
+        // Force update, or the widget will not show data when it is first created
+        updateAll(context)
+
         provideContent {
             val termDay by dayStateFlow.collectAsState(initial = null)
             val courses by coursesFlow.collectAsState(initial = null)

app/src/main/kotlin/com/zjutjh/ijh/widget/ScheduleWidgetReceiver.kt

@@ -10,6 +10,7 @@ import androidx.work.WorkManager
 import com.zjutjh.ijh.data.repository.CourseRepository
 import com.zjutjh.ijh.data.repository.WeJhInfoRepository
 import com.zjutjh.ijh.work.ScheduleWidgetUpdater
+import com.zjutjh.ijh.work.WidgetRefreshWorker
 import dagger.hilt.EntryPoint
 import dagger.hilt.InstallIn
 import dagger.hilt.components.SingletonComponent
@@ -46,6 +47,8 @@ class ScheduleWidgetReceiver : GlanceAppWidgetReceiver() {
             request
         )
 
+        WidgetRefreshWorker.enqueue<ScheduleWidget>(context)
+
         Log.i("ScheduleWidget", "Updater enqueued.")
     }
 
@@ -54,6 +57,9 @@ class ScheduleWidgetReceiver : GlanceAppWidgetReceiver() {
         // Enter relevant functionality for when the last widget is disabled
         val manager = WorkManager.getInstance(context)
         manager.cancelUniqueWork(ScheduleWidgetUpdater.PERIODIC_UNIQUE_NAME)
+
+        WidgetRefreshWorker.cancel<ScheduleWidget>(context)
+
         Log.i("ScheduleWidget", "Updater canceled.")
     }
 }

app/src/main/kotlin/com/zjutjh/ijh/work/WidgetRefreshWorker.kt

@@ -1,20 +1,80 @@
 package com.zjutjh.ijh.work
 
 import android.content.Context
+import android.util.Log
+import androidx.glance.appwidget.GlanceAppWidget
+import androidx.glance.appwidget.updateAll
+import androidx.work.Constraints
 import androidx.work.CoroutineWorker
+import androidx.work.ExistingPeriodicWorkPolicy
+import androidx.work.PeriodicWorkRequestBuilder
+import androidx.work.WorkManager
 import androidx.work.WorkerParameters
+import androidx.work.workDataOf
+import java.time.Duration
 
+/**
+ * This worker is used to refresh the widget periodically.
+ */
 class WidgetRefreshWorker(
     private val context: Context,
     workerParameters: WorkerParameters
 ) : CoroutineWorker(context, workerParameters) {
 
-    override suspend fun doWork(): Result =
-        try {
-            // TODO
+    companion object {
+        const val INPUT_CLASS_NAME = "className"
+
+        inline fun <reified T : GlanceAppWidget> getUniqueWorkName() =
+            WidgetRefreshWorker::class.java.simpleName + "_" + T::class.java.simpleName
+
+        /**
+         * Enqueue a [WidgetRefreshWorker] for the given [GlanceAppWidget].
+         * Do nothing if the worker is already enqueued.
+         * Default refresh interval is 20 minutes.
+         */
+        inline fun <reified T : GlanceAppWidget> enqueue(context: Context) {
+            val manager = WorkManager.getInstance(context)
+            val request = PeriodicWorkRequestBuilder<WidgetRefreshWorker>(
+                Duration.ofMinutes(20), Duration.ofMinutes(5)
+            ).setConstraints(
+                Constraints(requiresBatteryNotLow = true, requiresDeviceIdle = true)
+            ).setInputData(
+                workDataOf(INPUT_CLASS_NAME to T::class.java.name)
+            ).build()
+
+            manager.enqueueUniquePeriodicWork(
+                getUniqueWorkName<T>(),
+                ExistingPeriodicWorkPolicy.KEEP,
+                request
+            )
+        }
+
+        inline fun <reified T : GlanceAppWidget> cancel(context: Context) {
+            val manager = WorkManager.getInstance(context)
+            manager.cancelUniqueWork(getUniqueWorkName<T>())
+        }
+    }
+
+    /**
+     * Using reflection to get the class name of the widget, then update it.
+     */
+    override suspend fun doWork(): Result {
+        return try {
+            val className = inputData.getString(INPUT_CLASS_NAME) ?: return Result.failure()
+            val clazz = Class.forName(className)
+
+            // check if clazz is a subclass of GlanceAppWidget
+            if (!GlanceAppWidget::class.java.isAssignableFrom(clazz)) return Result.failure()
+
+            val obj = clazz.getConstructor().newInstance() as GlanceAppWidget
+
+            obj.updateAll(context)
+
             Result.success()
         } catch (e: Exception) {
+            Log.e("WidgetRefreshWorker", "Error when refreshing widget.", e)
             Result.failure()
         }
+    }
 
 }

app/src/main/res/xml/app_widget_schedule.xml

@@ -12,6 +12,6 @@
     android:resizeMode="horizontal|vertical"
     android:targetCellWidth="3"
     android:targetCellHeight="3"
-    android:updatePeriodMillis="1800000"
+    android:updatePeriodMillis="0"
     android:widgetCategory="home_screen"
     tools:targetApi="s" />