Implemented Base for fetching Deck Meta Data

AnkiDroid/build.gradle

@@ -328,5 +328,8 @@ dependencies {
     androidTestImplementation 'androidx.test.espresso:espresso-contrib:3.4.0'
     androidTestImplementation 'androidx.test.ext:junit:1.1.3'
     androidTestImplementation 'androidx.test:rules:1.4.0'
+
+    // GSON
+    implementation 'com.google.code.gson:gson:2.9.0'
 }
 apply from: "./kotlinMigration.gradle"

AnkiDroid/src/main/AndroidManifest.xml

@@ -377,6 +377,11 @@
 
         <!-- Service to perform web API queries -->
         <service android:name="com.ichi2.widget.AnkiDroidWidgetSmall$UpdateService" />
+        <service
+            android:enabled="true"
+            android:name=".services.DeckMetaDataService"
+            android:exported="false"/>
+
 
         <!-- small widget -->
         <receiver

AnkiDroid/src/main/java/com/ichi2/anki/DeckMetaDataPreference.kt

@@ -0,0 +1,42 @@
+package com.ichi2.anki
+
+import android.content.Context
+import android.content.SharedPreferences
+import com.google.gson.Gson
+import com.ichi2.anki.services.DeckMetaDataService
+import timber.log.Timber
+
+class DeckMetaDataPreference(context: Context) {
+
+    private val sharedPreferences: SharedPreferences =
+        context.getSharedPreferences("DeckMetaData", Context.MODE_PRIVATE)
+
+    fun setString(key: String, value: String) {
+        sharedPreferences.edit()
+            .putString(key, value)
+            .apply()
+    }
+
+    fun getString(key: String, default: String): String {
+        return sharedPreferences.getString(key, default)!!
+    }
+
+    fun setMetaData(key: String, value: DeckMetaDataService.Meta) {
+        val json: String = Gson().toJson(value)
+        sharedPreferences.edit()
+            .putString(key, json)
+            .apply()
+        Timber.tag("META").e(json)
+    }
+
+    fun getMetaData(key: String): DeckMetaDataService.Meta? {
+        val jsonData = sharedPreferences
+            .getString(key, null)
+
+        return if (jsonData == null) {
+            null
+        } else {
+            Gson().fromJson(jsonData, DeckMetaDataService.Meta::class.java)
+        }
+    }
+}

AnkiDroid/src/main/java/com/ichi2/anki/IntentHandler.kt

@@ -27,6 +27,7 @@ import com.ichi2.anki.UIUtils.showThemedToast
 import com.ichi2.anki.dialogs.DialogHandler
 import com.ichi2.anki.dialogs.DialogHandler.Companion.storeMessage
 import com.ichi2.anki.servicelayer.ScopedStorageService
+import com.ichi2.anki.services.DeckMetaDataService
 import com.ichi2.anki.services.ReminderService
 import com.ichi2.themes.Themes.disableXiaomiForceDarkMode
 import com.ichi2.utils.ImportUtils.handleFileImport
@@ -48,6 +49,7 @@ class IntentHandler : Activity() {
         Timber.d("onCreate()")
         super.onCreate(savedInstanceState)
         disableXiaomiForceDarkMode(this)
+        launchDeckMetaDataService()
         setContentView(R.layout.progress_bar)
         val intent = intent
         Timber.v(intent.toString())
@@ -136,6 +138,16 @@ class IntentHandler : Activity() {
         finish()
     }
 
+    private fun launchDeckMetaDataService() {
+        Timber.tag("META").e("Launching deck meta data service...")
+        val intent = Intent(this, DeckMetaDataService::class.java)
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            startForegroundService(intent)
+        } else {
+            startService(intent)
+        }
+    }
+
     // COULD_BE_BETTER: Also extract the parameters into here to reduce coupling
     @VisibleForTesting
     enum class LaunchType {

AnkiDroid/src/main/java/com/ichi2/anki/services/DeckMetaDataService.kt

@@ -0,0 +1,127 @@
+package com.ichi2.anki.services
+
+import android.annotation.SuppressLint
+import android.app.AlarmManager
+import android.app.Notification
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Intent
+import android.os.IBinder
+import androidx.core.app.NotificationCompat
+import androidx.core.app.NotificationCompat.*
+import com.ichi2.anki.CollectionHelper
+import com.ichi2.anki.DeckMetaDataPreference
+import com.ichi2.anki.NotificationChannels
+import com.ichi2.anki.R
+import com.ichi2.libanki.sched.Counts
+import com.ichi2.libanki.utils.Time
+import timber.log.Timber
+import java.util.*
+
+class DeckMetaDataService : Service() {
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+
+        Timber.tag("META").e("On Service start command...")
+
+        /**
+         * It sets the notification till the service is completed.
+         * */
+        val notification = NotificationCompat.Builder(this, NotificationChannels.getId(NotificationChannels.Channel.GENERAL))
+            .setOngoing(true)
+            .setContentTitle("Anki")
+            .setContentText("Ankidroid is syncing deck data.")
+            .setSmallIcon(R.mipmap.ic_launcher)
+            .setPriority(PRIORITY_LOW)
+            .setSilent(true)
+            .setCategory(Notification.CATEGORY_SERVICE)
+            .build()
+
+        startForeground(FOREGROUND_SERVICE_ID, notification)
+
+        // Update the data of Deck Metadata from HERE
+        val col = CollectionHelper.getInstance().getCol(this)
+        val deckList = col.sched.deckDueList()
+
+        deckList.forEach {
+            val new = it?.newCount ?: -1
+            val lrn = it?.lrnCount ?: -1
+            val rev = it?.revCount ?: -1
+            val data = Meta(
+                it?.did ?: -1,
+                it?.fullDeckName ?: "Deck Name",
+                new,
+                lrn,
+                rev,
+                col.sched.eta(Counts(new, lrn, rev), false)
+            )
+            storeInPreference(data)
+        }
+
+        updateLastFetch()
+
+        stopSelf() // Stops the current running service.
+        return START_NOT_STICKY
+    }
+
+    private fun updateLastFetch() {
+        val metaPreference = DeckMetaDataPreference(this)
+        metaPreference.setString(LAST_FETCH_TIME, System.currentTimeMillis().toString())
+    }
+
+    /**
+     * It is used to store the data in the DeckMetaData Shared Preference.
+     * */
+    private fun storeInPreference(list: Meta) {
+        val metaPreference = DeckMetaDataPreference(this)
+        metaPreference.setMetaData(list.did.toString(), list)
+    }
+
+    /**
+     * Does Nothing
+     * */
+    override fun onBind(intent: Intent?): IBinder? {
+        // Kept Intentionally
+        return null
+    }
+
+    override fun onDestroy() {
+        Timber.tag("META").e("Deck meta data Service on Destroy...")
+        scheduleNextAlarm(Long.MAX_VALUE) // Temp
+    }
+
+    /**
+     * It is used to schedule the next alarm which helps in starting this service again.
+     **/
+    @SuppressLint("UnspecifiedImmutableFlag")
+    private fun scheduleNextAlarm(interval: Long) {
+
+        val intent = Intent(this, DeckMetaDataService::class.java)
+        val pendingIntent = PendingIntent.getService(
+            this.applicationContext, SERVICE_PENDING_INTENT_ID, intent, 0
+        )
+
+        val alarmManager = getSystemService(ALARM_SERVICE) as AlarmManager
+        alarmManager.set(
+            AlarmManager.RTC_WAKEUP,
+            System.currentTimeMillis() + interval,
+            pendingIntent
+        )
+        Timber.tag("META").e("Service will start again at %s", (Time.calendar(System.currentTimeMillis() + interval).time))
+    }
+
+    data class Meta(
+        val did: Long,
+        val deckName: String,
+        val new: Int,
+        val lrn: Int,
+        val rev: Int,
+        val eta: Int
+    )
+
+    companion object {
+        const val FOREGROUND_SERVICE_ID = 10001
+        const val SERVICE_PENDING_INTENT_ID = 10002
+        const val LAST_FETCH_TIME = "LAST_FETCH"
+    }
+}