Ask AddCrossing for sidewalk and crossing ways

app/src/main/java/de/westnordost/streetcomplete/quests/AListQuestForm.kt

@@ -19,6 +19,8 @@ abstract class AListQuestForm<T> : AbstractOsmQuestForm<T>() {
 
     private val radioButtonIds = HashMap<Int, TextItem<T>>()
 
+    val checkedItem get() = radioButtonIds[binding.radioButtonGroup.checkedRadioButtonId]
+
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
         for (item in items) {
@@ -38,7 +40,7 @@ abstract class AListQuestForm<T> : AbstractOsmQuestForm<T>() {
     }
 
     override fun onClickOk() {
-        applyAnswer(radioButtonIds.getValue(binding.radioButtonGroup.checkedRadioButtonId).value)
+        applyAnswer(checkedItem!!.value)
     }
 
     override fun isFormComplete() = binding.radioButtonGroup.checkedRadioButtonId != -1

app/src/main/java/de/westnordost/streetcomplete/quests/crossing/AddCrossing.kt

@@ -25,16 +25,10 @@ class AddCrossing : OsmElementQuestType<CrossingAnswer> {
     private val footwaysFilter by lazy { """
         ways with
           (highway ~ footway|steps or highway ~ path|cycleway and foot ~ designated|yes)
-          and footway !~ sidewalk|crossing
           and area != yes
           and access !~ private|no
     """.toElementFilterExpression() }
 
-    /* It is neither asked for sidewalks nor crossings (=separately mapped sidewalk infrastructure)
-    *  because a "no" answer would require to also delete/adapt the crossing ways, rather than just
-    *  tagging crossing=no on the vertex.
-    *  See https://github.com/streetcomplete/StreetComplete/pull/2999#discussion_r681516203 */
-
     override val changesetComment = "Specify whether there are crossings at intersections of paths and roads"
     override val wikiLink = "Tag:highway=crossing"
     override val icon = R.drawable.ic_quest_pedestrian

app/src/main/java/de/westnordost/streetcomplete/quests/crossing/AddCrossingForm.kt

@@ -1,15 +1,48 @@
 package de.westnordost.streetcomplete.quests.crossing
 
+import androidx.appcompat.app.AlertDialog
 import de.westnordost.streetcomplete.R
+import de.westnordost.streetcomplete.data.osm.edits.MapDataWithEditsSource
 import de.westnordost.streetcomplete.quests.AListQuestForm
 import de.westnordost.streetcomplete.quests.TextItem
 import de.westnordost.streetcomplete.quests.crossing.CrossingAnswer.*
+import org.koin.android.ext.android.inject
 
 class AddCrossingForm : AListQuestForm<CrossingAnswer>() {
+    private val mapDataSource: MapDataWithEditsSource by inject()
 
     override val items = listOf(
         TextItem(YES, R.string.quest_crossing_yes),
         TextItem(NO, R.string.quest_crossing_no),
         TextItem(PROHIBITED, R.string.quest_crossing_prohibited),
     )
+
+    /*  PROHIBITED is not possible for sidewalks or crossings (=separately mapped sidewalk
+        infrastructure) because if the crossing does not exist, it would require to also
+        delete/adapt the crossing ways, rather than just tagging crossing=no on the vertex.
+
+        This situation needs to be solved in a different editor, so we ask the user to leave a note.
+        See https://github.com/streetcomplete/StreetComplete/pull/2999#discussion_r681516203
+        and https://github.com/streetcomplete/StreetComplete/issues/5160
+
+        NO on the other hand would be okay because crossing=informal would not require deleting
+        the crossing ways (I would say... it is in edge case...)
+        */
+    override fun onClickOk() {
+        if (checkedItem?.value == PROHIBITED && isOnSidewalkOrCrossing()) {
+            AlertDialog.Builder(requireContext())
+                .setMessage(R.string.quest_leave_new_note_as_answer)
+                .setPositiveButton(R.string.quest_leave_new_note_yes) { _, _ -> composeNote() }
+                .setNegativeButton(android.R.string.cancel, null)
+                .show()
+        } else {
+            super.onClickOk()
+        }
+    }
+
+    private fun isOnSidewalkOrCrossing(): Boolean =
+        mapDataSource.getWaysForNode(element.id).any {
+            val footway = it.tags["footway"]
+            footway == "sidewalk" || footway == "crossing"
+        }
 }

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

@@ -131,6 +131,8 @@ The info you enter is directly added to OpenStreetMap in your name, without the
     <string name="quest_leave_new_note_description">"You can leave a public note for other mappers to resolve at this location, or hide this quest for yourself only"</string>
     <string name="quest_leave_new_note_yes">"Leave note"</string>
     <string name="quest_leave_new_note_no">"Hide"</string>
+    <string name="quest_leave_new_note_as_answer">In this case, you need to leave a note in which you explain the situation.</string>
+
 
     <string name="quest_generic_otherAnswers">"Other answers…"</string>
     <!-- aka "not applicable", "not answerable" -->