Implement "load more" feature for search screen

app/src/main/java/io/eelo/appinstaller/search/SearchFragment.kt

@@ -18,6 +18,7 @@ import android.view.ViewGroup
 import android.view.inputmethod.InputMethodManager
 import android.widget.LinearLayout
 import android.widget.ProgressBar
+import android.widget.RelativeLayout
 import android.widget.TextView
 import io.eelo.appinstaller.R
 import io.eelo.appinstaller.application.model.Application
@@ -36,6 +37,7 @@ class SearchFragment : Fragment(), SearchView.OnQueryTextListener, SearchView.On
     private lateinit var splashContainer: LinearLayout
     private var applicationList = ArrayList<Application>()
     private var applicationManager: ApplicationManager? = null
+    private var isLoadingMoreApplications = false
 
     fun initialise(applicationManager: ApplicationManager) {
         this.applicationManager = applicationManager
@@ -56,6 +58,7 @@ class SearchFragment : Fragment(), SearchView.OnQueryTextListener, SearchView.On
         splashContainer = view.findViewById(R.id.splash_container)
         val errorContainer = view.findViewById<LinearLayout>(R.id.error_container)
         val errorDescription = view.findViewById<TextView>(R.id.error_description)
+        val loadMoreContainer = view.findViewById<RelativeLayout>(R.id.load_more_container)
 
         searchViewModel.initialise(applicationManager!!)
         recyclerView.visibility = View.GONE
@@ -68,6 +71,7 @@ class SearchFragment : Fragment(), SearchView.OnQueryTextListener, SearchView.On
         }
         errorContainer.visibility = View.GONE
         view.findViewById<TextView>(R.id.error_resolve).setOnClickListener {
+            loadMoreContainer.visibility = View.GONE
             progressBar.visibility = View.VISIBLE
             onQueryTextSubmit(searchView.query.toString())
         }
@@ -83,10 +87,18 @@ class SearchFragment : Fragment(), SearchView.OnQueryTextListener, SearchView.On
         recyclerView.setHasFixedSize(true)
         recyclerView.layoutManager = LinearLayoutManager(context)
         recyclerView.adapter = ApplicationListAdapter(activity!!, applicationList)
+        loadMoreContainer.visibility = View.GONE
         recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
             override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                 if (!recyclerView.canScrollVertically(1)) {
-                    searchViewModel.loadMore(context!!)
+                    loadMoreContainer.visibility = View.VISIBLE
+                    recyclerView.scrollToPosition(applicationList.size - 1)
+                    if (!isLoadingMoreApplications) {
+                        isLoadingMoreApplications = true
+                        searchViewModel.loadMore(context!!)
+                    }
+                } else {
+                    loadMoreContainer.visibility = View.GONE
                 }
             }
         })
@@ -105,6 +117,8 @@ class SearchFragment : Fragment(), SearchView.OnQueryTextListener, SearchView.On
                 applicationList.addAll(it)
                 progressBar.visibility = View.GONE
                 recyclerView.adapter.notifyDataSetChanged()
+                loadMoreContainer.visibility = View.GONE
+                isLoadingMoreApplications = false
                 if (applicationList.isEmpty()) {
                     recyclerView.visibility = View.GONE
                 } else {
@@ -119,9 +133,11 @@ class SearchFragment : Fragment(), SearchView.OnQueryTextListener, SearchView.On
                 errorDescription.text = activity!!.getString(Common.getScreenErrorDescriptionId(it))
                 errorContainer.visibility = View.VISIBLE
                 progressBar.visibility = View.GONE
+                loadMoreContainer.visibility = View.GONE
             } else {
                 errorContainer.visibility = View.GONE
             }
+            isLoadingMoreApplications = false
         })
 
         // Handle suggestion clicks

app/src/main/java/io/eelo/appinstaller/search/model/SearchModel.kt

@@ -49,6 +49,8 @@ class SearchModel : SearchModelInterface {
         } else {
             if (pageNumber == 1) {
                 screenError.value = Error.NO_INTERNET
+            } else {
+                screenError.value = null
             }
         }
     }
@@ -64,10 +66,14 @@ class SearchModel : SearchModelInterface {
             }
             if (applicationList.isEmpty() && pageNumber == 1) {
                 screenError.value = Error.NO_RESULTS
+            } else {
+                screenError.value = null
             }
         } else {
             if (pageNumber == 1) {
                 screenError.value = error
+            } else {
+                screenError.value = null
             }
         }
     }

app/src/main/res/layout/fragment_search.xml

@@ -61,8 +61,21 @@
         android:id="@+id/app_list"
         android:layout_width="match_parent"
         android:layout_height="0dp"
-        android:scrollbars="none"
-        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintBottom_toTopOf="@id/load_more_container"
         app:layout_constraintTop_toBottomOf="@id/toolbar" />
 
+    <RelativeLayout
+        android:id="@+id/load_more_container"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:padding="@dimen/layout_padding_medium"
+        app:layout_constraintBottom_toBottomOf="parent">
+
+        <ProgressBar
+            android:layout_width="@dimen/load_more_progress_bar_size"
+            android:layout_height="@dimen/load_more_progress_bar_size"
+            android:layout_centerInParent="true" />
+
+    </RelativeLayout>
+
 </android.support.constraint.ConstraintLayout>
\ No newline at end of file