feat: Converted three util classes to Kotlin (#2399)

* converted three util classes to kotlin

* converted util classes to kotlin

* format AuthUtil

* fixed authorisation to be nullable

android/app/src/main/java/org/fossasia/openevent/common/ConstantStrings.kt

@@ -0,0 +1,106 @@
+package org.fossasia.openevent.common
+
+object ConstantStrings {
+
+    const val TOKEN = "token"
+
+    const val USER_EMAIL = "user_email"
+
+    const val USER_FIRST_NAME = "user_first_name"
+
+    const val USER_LAST_NAME = "user_last_name"
+
+    const val TRACK = "TRACK"
+
+    const val TRACK_ID = "TRACK_ID"
+
+    const val SESSION = "SESSION"
+
+    const val SESSION_TIMING = "SESSION_TIMING"
+
+    const val EMAIL = "EMAIL"
+
+    const val APP_NAME = "APP_NAME"
+
+    const val IS_AUTH_ENABLED = "is_auth_enabled"
+
+    const val EVENT_ID = "eventId"
+
+    const val ORG_DESCRIPTION = "organizer_description"
+
+    const val TIMEZONE = "timezone"
+
+    const val BASE_API_URL = "BASE_API_URL"
+
+    const val ID = "ID"
+
+    const val YOUTUBE = "youtu.be"
+
+    const val YOUTUBE_URI_1 = "http://img.youtube.com/vi/"
+
+    const val YOUTUBE_URI_2 = "/0.jpg"
+
+    const val EVENT_DAY = "EVENT_DAY"
+
+    const val SPEAKERS = "speakers"
+
+    const val SESSIONS = "sessions"
+
+    const val TRACKS = "tracks"
+
+    const val SESSION_TYPES = "session_types"
+
+    const val FEED = "feed"
+
+    const val VERSION = "version"
+
+    const val EventDates = "eventDates"
+
+    const val MICROLOCATIONS = "microlocations"
+
+    const val SPONSORS = "sponsors"
+
+    const val EVENT = "event"
+
+    const val DATABASE_RECORDS_EXIST = "database_records_exist"
+
+    const val IS_DOWNLOAD_DONE = "isDownloadDone"
+
+    const val IS_MAP_FRAGMENT_FROM_MAIN_ACTIVITY = "isMapFragmenFromMainActivity"
+
+    const val LOCATION_NAME = "locationName"
+
+    const val SESSION_MAP_ID = "sessionMapId"
+
+    const val IMAGE_ZOOM_KEY = "imageZoom"
+
+    //Sort order
+
+    const val PREF_SORT_SCHEDULE = "schedule_sort_type"
+
+    const val PREF_SORT_SPEAKER = "speaker_sort_type"
+
+    const val PREF_SORT_ORDER = "sort_order"
+
+    const val FACEBOOK_PAGE_ID = "pageId"
+
+    const val FACEBOOK_PAGE_NAME = "fbPageName"
+
+    const val TWITTER_PAGE_NAME = "twitterPageName"
+
+    const val FACEBOOK_COMMENTS = "comments"
+
+    //Social link names
+
+    const val SOCIAL_LINK_GITHUB = "GitHub"
+
+    const val SOCIAL_LINK_TWITTER = "Twitter"
+
+    const val SOCIAL_LINK_FACEBOOK = "Facebook"
+
+    const val SOCIAL_LINK_LINKEDIN = "LinkedIn"
+
+    const val SOCIAL_LINK_YOUTUBE = "YouTube"
+
+    const val SOCIAL_LINK_GOOGLE = "Google"
+}

android/app/src/main/java/org/fossasia/openevent/common/notification/NotificationUtil.kt

@@ -0,0 +1,52 @@
+package org.fossasia.openevent.common.notification
+
+import android.app.AlarmManager
+import android.app.PendingIntent
+import android.content.Context
+import android.content.Intent
+
+import org.fossasia.openevent.common.ConstantStrings
+import org.fossasia.openevent.common.date.DateConverter
+import org.fossasia.openevent.data.Session
+import org.fossasia.openevent.common.utils.SharedPreferencesUtil
+import org.threeten.bp.ZonedDateTime
+
+import io.reactivex.Completable
+import timber.log.Timber
+
+object NotificationUtil {
+
+    private fun onSuccess(session: Session) {
+        Timber.d("Created notification for Session ${session.id} ${session.title} at time ${session.startsAt}")
+    }
+
+    private fun onError(throwable: Throwable, session: Session) {
+        Timber.e(throwable)
+        Timber.e("Error creating Date for Session ${session.id} ${session.title} at time ${session.startsAt}")
+    }
+
+    @JvmStatic
+    fun createNotification(session: Session, context: Context): Completable {
+        return Completable.fromAction {
+            val zonedDateTime = DateConverter.getDate(session.startsAt)
+
+            val prefResult = Integer.parseInt(SharedPreferencesUtil.getString("notification", "10 mins")?.substring(0, 2)?.trim { it <= ' ' })
+            when (prefResult) {
+                1 -> zonedDateTime.minusHours(-1)
+                12 -> zonedDateTime.minusHours(12)
+                else -> zonedDateTime.minusMinutes(10)
+            }
+            // Checking if the event time is after the current time
+            if (zonedDateTime.isAfter(ZonedDateTime.now())) {
+                val myIntent = Intent(context, NotificationAlarmReceiver::class.java)
+                myIntent.putExtra(ConstantStrings.SESSION, session.id)
+                val pendingIntent = PendingIntent.getBroadcast(context, 0, myIntent, PendingIntent.FLAG_UPDATE_CURRENT)
+
+                val alarmManager = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
+                alarmManager.set(AlarmManager.RTC, zonedDateTime.toInstant().toEpochMilli(), pendingIntent)
+            } else {
+                Timber.d("Session is finished. Skipping showing notification")
+            }
+        }.doOnComplete { onSuccess(session) }.doOnError { throwable -> onError(throwable, session) }
+    }
+}