Updated EventPageFragment.kt to have access to its own ViewModel and, by extension, its own reference to the database, which forgoes the need to transport data from EventFragment.kt through StudIPEventPageAdapter.kt to EventPageFragment.kt and allows for filtering for a specific day's items through the database rather than needing to iterate through the list via an extension function manually. Also implemented DiffUtil to perform individual updates rather than calling notifyDataSetChanged() every time a single item has been changed.

app/src/main/java/com/denizk0461/studip/adapter/StudIPEventItemAdapter.kt

@@ -3,7 +3,9 @@ package com.denizk0461.studip.adapter
 import android.content.res.ColorStateList
 import android.view.LayoutInflater
 import android.view.ViewGroup
+import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.RecyclerView
+import com.denizk0461.studip.data.AppDiffUtilCallback
 import com.google.android.material.R
 import com.denizk0461.studip.data.getThemedColor
 import com.denizk0461.studip.data.parseToMinutes
@@ -12,29 +14,30 @@ import com.denizk0461.studip.databinding.ItemEventBinding
 import java.util.*
 
 /**
- * Custom RecyclerView adapter that lays out the Stud.IP events of a given day.
+ * Custom RecyclerView adapter that lays out the Stud.IP events for a given day.
  *
- * @param events            list of all events (still not filtered by day at this point)
- * @param currentDay        current day that is used to show only events of a given day (0 = Monday,
+
+ * @param currentDay        current day that is used to show only a given day's events (0 = Monday,
  *                          4 = Friday)
  * @param onClickListener   used for listening to clicks and long presses
  */
 class StudIPEventItemAdapter(
-    events: List<StudIPEvent>,
     private val currentDay: Int,
     private val onClickListener: OnClickListener,
 ) : RecyclerView.Adapter<StudIPEventItemAdapter.EventViewHolder>() {
 
-    // Filter events to only show those of a given day
-    private val filteredEvents: List<StudIPEvent> = events.filter { it.day == currentDay }
+    /**
+     * List of all events (still not filtered by day at this point)
+     */
+    private var events: MutableList<StudIPEvent> = mutableListOf()
 
-    /*
+    /**
      * Retrieve an instance of Calendar to check whether the adapter's day matches the current day.
-     * TODO this can be optimised by checking in StudIPEventPageAdapter.kt and delivering a boolean
+     * TODO this can be optimised by checking in EventPageFragment.kt and delivering a boolean
      */
     private val currentCalendar = Calendar.getInstance()
 
-    /*
+    /**
      * Used to disallow highlighting more than one course at a time, since only a single course
      * could be coming up at a given time.
      */
@@ -58,12 +61,11 @@ class StudIPEventItemAdapter(
     }
 
     // Set the amount of items to the size of the filtered list, so only events of the current day
-    override fun getItemCount(): Int = filteredEvents.size
+    override fun getItemCount(): Int = events.size
 
-    // TODO inflate a view saying "no events" if none are available for a given day
     override fun onBindViewHolder(holder: EventViewHolder, position: Int) {
         // Retrieve item for current position
-        val currentItem = filteredEvents[position]
+        val currentItem = events[position]
 
         // Set up text fields with corresponding values
         holder.binding.textTitle.text = currentItem.title
@@ -117,6 +119,26 @@ class StudIPEventItemAdapter(
         }
     }
 
+    /**
+     * Updates the data and calculates the difference between the old dataset and the newly provided
+     * dataset.
+     *
+     * @param newData   new dataset to be displayed
+     */
+    fun setNewData(newData: List<StudIPEvent>) {
+        // Calculate the difference between the old list and the new list
+        val diffResult = DiffUtil.calculateDiff(AppDiffUtilCallback(events, newData))
+
+        // Remove all items from the list
+        events.clear()
+
+        // Add all items from the new list
+        events.addAll(newData)
+
+        // Tell the DiffUtil which items have changed between the two lists
+        diffResult.dispatchUpdatesTo(this)
+    }
+
     /**
      * Checks if a given course is the next course coming up. This is done by checking whether the
      * day of the course matches the current real world day, as well as by evaluating if the end
@@ -131,7 +153,6 @@ class StudIPEventItemAdapter(
         (calendar.get(Calendar.DAY_OF_WEEK) == this.day.toCalendarDay()) &&
                 ((calendar.get(Calendar.MINUTE) + calendar.get(Calendar.HOUR_OF_DAY) * 60) < this.timeslotEnd.parseToMinutes())
 
-    // Converts day as defined in StudIPEvent.kt to day from Calendar
     /**
      * Converts a numeric value as defined in StudIPEvent.kt to a calendar day. Used to convert from
      * American convention (where Sunday is the first day, 1 = Sunday, 2 = Monday, 7 = Saturday) to