feat: Add pagination in search (#2072)

Details:
- Add pagination in search
- Split adapter class between FavoriteFragment and SearchResultsFragment
- Split ViewModel between SearchFragment and SearchResultsFragment

Fixes: #2013

Author: anhanh11001

app/src/main/java/org/fossasia/openevent/general/di/Modules.kt

@@ -84,6 +84,7 @@ import org.fossasia.openevent.general.feedback.FeedbackViewModel
 import org.fossasia.openevent.general.feedback.Feedback
 import org.fossasia.openevent.general.feedback.FeedbackService
 import org.fossasia.openevent.general.feedback.FeedbackApi
+import org.fossasia.openevent.general.search.SearchResultsViewModel
 import org.fossasia.openevent.general.speakercall.SpeakersCall
 import org.fossasia.openevent.general.sessions.SessionViewModel
 import org.fossasia.openevent.general.sessions.microlocation.MicroLocation
@@ -120,7 +121,7 @@ val commonModule = module {
     single { Preference() }
     single { Network() }
     single { Resource() }
-    single { MutableConnectionLiveData() }
+    factory { MutableConnectionLiveData() }
     factory<LocationService> { LocationServiceImpl(androidContext()) }
 }
 
@@ -216,7 +217,8 @@ val viewModelModule = module {
     viewModel { SignUpViewModel(get(), get(), get()) }
     viewModel { EventDetailsViewModel(get(), get(), get(), get(), get(), get(), get(), get(), get(), get()) }
     viewModel { SessionViewModel(get(), get(), get()) }
-    viewModel { SearchViewModel(get(), get(), get(), get()) }
+    viewModel { SearchViewModel(get(), get()) }
+    viewModel { SearchResultsViewModel(get(), get(), get(), get(), get()) }
     viewModel { AttendeeViewModel(get(), get(), get(), get(), get(), get(), get()) }
     viewModel { SearchLocationViewModel(get(), get()) }
     viewModel { SearchTimeViewModel(get()) }

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

@@ -8,9 +8,6 @@ import retrofit2.http.Query
 
 interface EventApi {
 
-    @GET("events?include=event-topic")
-    fun getEvents(): Single<List<Event>>
-
     @GET("events?include=event-sub-topic,event-topic,event-type,speakers-call")
     fun searchEvents(@Query("sort") sort: String, @Query("filter") eventName: String): Single<List<Event>>
 

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

@@ -46,8 +46,8 @@ class EventService(
         return eventTypesApi.getEventTypes()
     }
 
-    fun getSearchEvents(eventName: String, sortBy: String): Flowable<List<Event>> {
-        return eventApi.searchEvents(sortBy, eventName).flatMapPublisher { eventsList ->
+    fun getSearchEventsPaged(filter: String, sortBy: String, page: Int): Flowable<List<Event>> {
+        return eventApi.searchEventsPaged(sortBy, filter, page).flatMapPublisher { eventsList ->
             eventsList.forEach {
                 it.speakersCall?.let { sc -> speakersCallDao.insertSpeakerCall(sc) }
             }

app/src/main/java/org/fossasia/openevent/general/favorite/FavoriteEventsRecyclerAdapter.kt renamed to app/src/main/java/org/fossasia/openevent/general/favorite/FavoriteEventsListAdapter.kt

@@ -17,7 +17,7 @@ import org.fossasia.openevent.general.databinding.ItemCardFavoriteEventBinding
  * @property onFavFabClick The callback to be invoked when the favorite FAB is clicked
  * @property onShareFabClick The callback to be invoked when the share FAB is clicked
  */
-class FavoriteEventsRecyclerAdapter : ListAdapter<Event, FavoriteEventViewHolder>(EventsDiffCallback()) {
+class FavoriteEventsListAdapter : ListAdapter<Event, FavoriteEventViewHolder>(EventsDiffCallback()) {
 
     var onEventClick: EventClickListener? = null
     var onFavFabClick: FavoriteFabClickListener? = null

app/src/main/java/org/fossasia/openevent/general/favorite/FavoriteFragment.kt

@@ -45,7 +45,7 @@ import org.jetbrains.anko.design.snackbar
 class FavoriteFragment : Fragment(), BottomIconDoubleClick {
     private val favoriteEventViewModel by viewModel<FavoriteEventsViewModel>()
     private lateinit var rootView: View
-    private val favoriteEventsRecyclerAdapter = FavoriteEventsRecyclerAdapter()
+    private val favoriteEventsRecyclerAdapter = FavoriteEventsListAdapter()
 
     override fun onCreateView(
         inflater: LayoutInflater,

app/src/main/java/org/fossasia/openevent/general/search/SearchEventsDataSource.kt

@@ -0,0 +1,48 @@
+package org.fossasia.openevent.general.search
+
+import androidx.lifecycle.MutableLiveData
+import androidx.paging.PageKeyedDataSource
+import io.reactivex.disposables.CompositeDisposable
+import io.reactivex.rxkotlin.plusAssign
+import org.fossasia.openevent.general.event.Event
+import org.fossasia.openevent.general.event.EventService
+import org.fossasia.openevent.general.utils.extensions.withDefaultSchedulers
+import timber.log.Timber
+
+class SearchEventsDataSource(
+    private val eventService: EventService,
+    private val compositeDisposable: CompositeDisposable,
+    private val query: String,
+    private val sortBy: String,
+    private val mutableProgress: MutableLiveData<Boolean>
+) : PageKeyedDataSource<Int, Event>() {
+
+    override fun loadInitial(params: LoadInitialParams<Int>, callback: LoadInitialCallback<Int, Event>) {
+        compositeDisposable += eventService.getSearchEventsPaged(query, sortBy, 1)
+            .take(1)
+            .withDefaultSchedulers()
+            .subscribe({ response ->
+                if (response.isEmpty())
+                    mutableProgress.value = false
+                callback.onResult(response, null, 2)
+            }, { error ->
+                Timber.e(error, "Fail on fetching page of events")
+            })
+    }
+
+    override fun loadAfter(params: LoadParams<Int>, callback: LoadCallback<Int, Event>) {
+        compositeDisposable += eventService.getSearchEventsPaged(query, sortBy, params.key)
+            .take(1)
+            .withDefaultSchedulers()
+            .subscribe({ response ->
+                if (response.isEmpty())
+                    mutableProgress.value = false
+                callback.onResult(response, params.key + 1)
+            }, { error ->
+                Timber.e(error, "Fail on fetching page of events")
+            })
+    }
+
+    override fun loadBefore(params: LoadParams<Int>, callback: LoadCallback<Int, Event>) {
+    }
+}

app/src/main/java/org/fossasia/openevent/general/search/SearchEventsDataSourceFactory.kt

@@ -0,0 +1,25 @@
+package org.fossasia.openevent.general.search
+
+import androidx.lifecycle.MutableLiveData
+import androidx.paging.DataSource
+import io.reactivex.disposables.CompositeDisposable
+import org.fossasia.openevent.general.event.Event
+import org.fossasia.openevent.general.event.EventService
+
+data class SearchEventsDataSourceFactory(
+    private val compositeDisposable: CompositeDisposable,
+    private val eventService: EventService,
+    private val query: String,
+    private val sortBy: String,
+    private val mutableProgress: MutableLiveData<Boolean>
+) : DataSource.Factory<Int, Event>() {
+    override fun create(): DataSource<Int, Event> {
+        return SearchEventsDataSource(
+            eventService,
+            compositeDisposable,
+            query,
+            sortBy,
+            mutableProgress
+        )
+    }
+}

app/src/main/java/org/fossasia/openevent/general/search/SearchPagedListAdapter.kt

@@ -0,0 +1,38 @@
+package org.fossasia.openevent.general.search
+
+import org.fossasia.openevent.general.favorite.FavoriteEventViewHolder
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import androidx.paging.PagedListAdapter
+import org.fossasia.openevent.general.event.Event
+import org.fossasia.openevent.general.common.EventClickListener
+import org.fossasia.openevent.general.common.EventsDiffCallback
+import org.fossasia.openevent.general.common.FavoriteFabClickListener
+import org.fossasia.openevent.general.databinding.ItemCardFavoriteEventBinding
+
+class SearchPagedListAdapter : PagedListAdapter<Event, FavoriteEventViewHolder>(EventsDiffCallback()) {
+
+    var onEventClick: EventClickListener? = null
+    var onFavFabClick: FavoriteFabClickListener? = null
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FavoriteEventViewHolder {
+        val binding = ItemCardFavoriteEventBinding.inflate(LayoutInflater.from(parent.context), parent, false)
+        return FavoriteEventViewHolder(binding)
+    }
+
+    override fun onBindViewHolder(holder: FavoriteEventViewHolder, position: Int) {
+        val event = getItem(position)
+        if (event != null) {
+            holder.apply {
+                bind(event, position)
+                eventClickListener = onEventClick
+                favFabClickListener = onFavFabClick
+            }
+        }
+    }
+
+    fun clear() {
+        this.submitList(null)
+    }
+}