fix: continuous event topic api calls

Author: iamanbansal

app/src/main/java/org/fossasia/openevent/general/event/EventDao.kt

@@ -6,6 +6,7 @@ import androidx.room.OnConflictStrategy.REPLACE
 import androidx.room.Query
 import io.reactivex.Flowable
 import io.reactivex.Single
+import org.fossasia.openevent.general.event.topic.EventTopic
 
 @Dao
 interface EventDao {
@@ -36,6 +37,9 @@ interface EventDao {
     @Query("SELECT id from Event WHERE favorite = 1 AND id in (:ids)")
     fun getFavoriteEventWithinIds(ids: List<Long>): Single<List<Long>>
 
-    @Query("SELECT * from Event WHERE eventTopic = :topicId")
-    fun getAllSimilarEvents(topicId: Long): Flowable<List<Event>>
+    @Query("SELECT * from Event WHERE eventTopic = :eventTopic")
+    fun getAllSimilarEvents(eventTopic: EventTopic): Flowable<List<Event>>
+
+    @Query("SELECT * FROM EventTopic WHERE id=:topicId")
+    fun getEventTopic(topicId: Long): Single<EventTopic>
 }

app/src/main/java/org/fossasia/openevent/general/event/EventService.kt

@@ -16,7 +16,6 @@ import org.fossasia.openevent.general.event.types.EventType
 import org.fossasia.openevent.general.event.types.EventTypesApi
 import org.fossasia.openevent.general.sessions.Session
 import org.fossasia.openevent.general.sessions.SessionApi
-import java.util.Locale.filter
 
 class EventService(
     private val eventApi: EventApi,
@@ -131,20 +130,24 @@ class EventService(
     }
 
     fun getSimilarEvents(id: Long): Flowable<List<Event>> {
-        val eventsFlowable = eventDao.getAllSimilarEvents(id)
-        return eventsFlowable.switchMap {
-            if (it.isNotEmpty())
-                eventsFlowable
-            else
-                eventTopicApi.getEventsUnderTopicId(id)
-                        .toFlowable()
-                        .map {
-                            eventDao.insertEvents(it)
+        val eventsFlowable = eventDao.getEventTopic(id)
+            .flatMapPublisher {
+                eventDao.getAllSimilarEvents(it)
+            }
+        return eventsFlowable
+            .switchMap {
+                if (it.isNotEmpty()) {
+                    eventsFlowable
+                } else {
+                    eventTopicApi.getEventsUnderTopicId(id)
+                        .map { list ->
+                            eventDao.insertEvents(list)
                         }
-                        .flatMap {
+                        .flatMapPublisher {
                             eventsFlowable
                         }
-        }
+                }
+            }
     }
 
     private fun buildQuery(eventIds: List<Long>): String {