StudIPParser.kt now stops fetching items that don't provide full information, and tells the user how many items were skipped

app/src/main/java/com/denizk0461/studip/activity/FetcherActivity.kt

@@ -102,11 +102,17 @@ class FetcherActivity : FragmentActivity() {
                 ) { p0 ->
                     try {
                         // Decode HTML and parse it into a list of StudIPEvent.kt
-                        // TODO add a tutorial for the user to know what to do
+                        val elementsNotFetched = viewModel.parse(URLDecoder.decode(p0, "UTF-8"))
-                        viewModel.parse(URLDecoder.decode(p0, "UTF-8"))
 
-                        // Notify the user that the fetch was successful
+                        /*
-                        showToast(this, getString(R.string.toast_fetch_finished))
+                         * Notify the user that the fetch was successful, and tell the user how many
+                         * items could not be fetched.
+                         */
+                        showToast(this, when (elementsNotFetched) {
+                            0 -> getString(R.string.toast_fetch_finished_zero)
+                            1 -> getString(R.string.toast_fetch_finished_one)
+                            else -> getString(R.string.toast_fetch_finished_other, elementsNotFetched)
+                        })
 
                         // Close the activity
                         finish()

app/src/main/java/com/denizk0461/studip/data/Extensions.kt

@@ -23,15 +23,17 @@ import kotlin.jvm.Throws
  */
 
 /**
- * Converts a time stamp string to its numeric value in minutes.
+ * Converts a time stamp string to its numeric value in minutes. Returns 0 on error.
  * Example: 13:20. (20 minutes) + (13 hours * 60 minutes) = 800 minutes.
  *
  * @return  minute value of the string
  */
-fun String.parseToMinutes(): Int {
+fun String.parseToMinutes(): Int = try {
-    val parts = split(":")
+        val parts = split(":")
-    return (parts[0].toInt() * 60) + parts[1].toInt()
+        (parts[0].toInt() * 60) + parts[1].toInt()
-}
+    } catch (e: IndexOutOfBoundsException) {
+        0
+    }
 
 /**
  * Retrieves a specified colour customised to the currently applied theme.

app/src/main/java/com/denizk0461/studip/data/StudIPParser.kt

@@ -17,16 +17,20 @@ class StudIPParser(application: Application) {
     private val repo: AppRepository = AppRepository.getRepositoryInstance(application)
 
     /**
-     * Parse a given HTML string. HTML must be of a Stud.IP timetable.
+     * Parse a given HTML string. HTML must be of a Stud.IP timetable. May skip elements that don't
+     * provide full information on an event (title, timeslot, lecturers, room).
      *
      * @param html          website content of the Stud.IP timetable
      * @throws IOException  when an error in fetching or the database transaction occurs
      */
     @Throws(IOException::class)
-    fun parse(html: String) {
+    fun parse(html: String): Int {
         // Primary key value to uniquely identify entries in the database
         var id = 0
 
+        // Counts how many elements could not be successfully fetched
+        var elementsNotFetched = 0
+
         // Parse the HTML using Jsoup to traverse the document
         val doc = Jsoup.parse(html)
 
@@ -43,7 +47,7 @@ class StudIPParser(application: Application) {
         doc.getDateIndices().forEach { (index, element) ->
 
             // Iterate through all events scheduled for a given day
-            element.getElementsByClass("schedule_entry").forEach { entry ->
+            element.getElementsByClass("schedule_entry").forEach loop@{ entry ->
                 /*
                  * Retrieve the event's header. This will contain the event's title as well as the
                  * lecturers holding the event.
@@ -57,10 +61,21 @@ class StudIPParser(application: Application) {
                 val delimiter = entryHeader.lastIndexOf('(')
 
                 // Retrieve the title of the event from the header string
-                val parsedTitle = entryHeader.substring(0 until delimiter).trim()
+                val parsedTitle = try {
+                    entryHeader.substring(0 until delimiter).trim()
+                } catch (e: StringIndexOutOfBoundsException) {
+                    elementsNotFetched += 1
+                    return@loop
+                }
 
                 // Retrieve the lecturer name(s) from the header string
-                val parsedLecturers = entryHeader.substring(delimiter + 1 until entryHeader.length - 1).trim()
+                val parsedLecturers = try {
+                    entryHeader
+                        .substring(delimiter + 1 until entryHeader.length - 1).trim()
+                } catch (e: StringIndexOutOfBoundsException) {
+                    elementsNotFetched += 1
+                    return@loop
+                }
 
                 /*
                  * Retrieve further event information. This will contain both the time slot the
@@ -72,18 +87,18 @@ class StudIPParser(application: Application) {
                 // Retrieve the time slot and split it into start and end time stamps
                 val timeSlot = entryInfo[0].split(" - ")
 
-                // Time the event starts at
+                // Time the course starts at
-                val eventStart = timeSlot[0]
+                val eventStart = timeSlot.getOrQuestionMark(0)
 
                 // Construct the newly scraped Stud.IP event
                 val event = StudIPEvent(
                     eventId = id,
                     title = parsedTitle,
                     lecturer = parsedLecturers,
-                    room = entryInfo[1],
+                    room = entryInfo.getOrQuestionMark(1),
                     day = index,
                     timeslotStart = eventStart,
-                    timeslotEnd = timeSlot[1],
+                    timeslotEnd = timeSlot.getOrQuestionMark(1),
                     timeslotId = eventStart.parseToMinutes(),
                 )
 
@@ -100,6 +115,9 @@ class StudIPParser(application: Application) {
 
         // After fetching has finished, save the list of new items into persistent storage
         repo.insertEvents(newEvents)
+
+        // Return the count of elements that were not able to be fetched
+        return elementsNotFetched
     }
 
     /**
@@ -141,6 +159,11 @@ class StudIPParser(application: Application) {
             // Add the days found to the list
             list.add(Pair(
                 dayIndex,
+                /*
+                 * The index of the columns doesn't seem to depend on the other elements in the
+                 * table. Friday will always have the index 4 ("calendar_view_1_column_4") even if
+                 * Monday through Thursday are hidden from the schedule.
+                 */
                 getElementById("calendar_view_1_column_${dayIndex}") ?: continue,
             ))
         }
@@ -148,4 +171,10 @@ class StudIPParser(application: Application) {
         // Return the list of columns
         return list
     }
+
+    private fun List<String>.getOrQuestionMark(index: Int): String = try {
+        get(index)
+    } catch (e: IndexOutOfBoundsException) {
+        "?"
+    }
 }

app/src/main/java/com/denizk0461/studip/viewmodel/FetcherViewModel.kt

@@ -23,9 +23,9 @@ class FetcherViewModel(app: Application) : AppViewModel(app) {
      * @param html  source code of the schedule website
      */
     @Throws(IOException::class)
-    fun parse(html: String) {
+    fun parse(html: String): Int =
-        doAsync {
+        returnBlocking {
             parser.parse(html)
         }
-    }
+
 }

app/src/main/res/values-de/strings.xml

@@ -23,6 +23,11 @@
     <string name="fetch_error_webpage_snack">Du musst deinen Stundenplan öffnen!</string>
     <string name="canteen_fetch_error">Mensaplan konnte nicht heruntergeladen werden!</string>
 
+    <!-- plurals string resource cannot be used here because Android doesn't treat 0 differently from 2 -->
+    <string name="toast_fetch_finished_zero">Dein Stundenplan wurde aktualisiert!</string>
+    <string name="toast_fetch_finished_one">Dein Stundenplan wurde aktualisiert, doch eine Veranstaltung konnte nicht heruntergeladen werden.</string>
+    <string name="toast_fetch_finished_other">Dein Stundenplan wurde aktualisiert, doch %d Veranstaltungen konnten nicht heruntergeladen werden.</string>
+
     <string name="fetch_bar_close_title">Schließen</string>
     <string name="fetch_bar_close_desc">Schließe die Webseite, ohne etwas zu speichern</string>
     <string name="fetch_bar_refresh_title">Aktualisieren</string>
@@ -134,8 +139,6 @@
     <string name="nav_food">Mensa</string>
     <string name="nav_settings">Einstellungen</string>
 
-    <string name="toast_fetch_finished">Dein Stundenplan wurde aktualisiert!</string>
-
     <string name="settings_general">Allgemein</string>
     <string name="settings_schedule">Stud.IP-Stundenplan</string>
     <string name="settings_canteen">Mensenangebote</string>

app/src/main/res/values/strings.xml

@@ -23,6 +23,11 @@
     <string name="fetch_error_webpage_snack">You must navigate to your schedule!</string>
     <string name="canteen_fetch_error">Couldn\'t retrieve the canteen plan!</string>
 
+    <!-- plurals resource cannot be used here; view German translation for details -->
+    <string name="toast_fetch_finished_zero">Your schedule has been refreshed!</string>
+    <string name="toast_fetch_finished_one">Your schedule has been refreshed, but one item could not be saved.</string>
+    <string name="toast_fetch_finished_other">Your schedule has been refreshed, but %d items could not be saved.</string>
+
     <string name="fetch_bar_close_title">Close</string>
     <string name="fetch_bar_close_desc">Close the website without saving anything</string>
     <string name="fetch_bar_refresh_title">Refresh</string>
@@ -138,8 +143,6 @@
     <string name="nav_food">Canteens</string>
     <string name="nav_settings">Settings</string>
 
-    <string name="toast_fetch_finished">Your schedule has been refreshed!</string>
-
     <string name="settings_general">General</string>
     <string name="settings_schedule">Stud.IP Schedule</string>
     <string name="settings_canteen">Canteen Offers</string>