[5/n] Add more help text for slot remapping

app/src/main/java/im/angry/openeuicc/ui/SlotMappingFragment.kt

@@ -13,6 +13,7 @@ import android.widget.AdapterView.OnItemSelectedListener
 import android.widget.ArrayAdapter
 import android.widget.Spinner
 import android.widget.TextView
+import android.widget.Toast
 import androidx.appcompat.widget.Toolbar
 import androidx.appcompat.widget.Toolbar.OnMenuItemClickListener
 import androidx.fragment.app.DialogFragment
@@ -46,6 +47,7 @@ class SlotMappingFragment: DialogFragment(), OnMenuItemClickListener {
     private lateinit var toolbar: Toolbar
     private lateinit var recyclerView: RecyclerView
     private lateinit var adapter: SlotMappingAdapter
+    private lateinit var helpTextView: TextView
 
     override fun onCreateView(
         inflater: LayoutInflater,
@@ -58,6 +60,7 @@ class SlotMappingFragment: DialogFragment(), OnMenuItemClickListener {
         recyclerView = view.findViewById(R.id.mapping_list)
         recyclerView.layoutManager =
             LinearLayoutManager(view.context, LinearLayoutManager.VERTICAL, false)
+        helpTextView = view.findViewById(R.id.mapping_help)
         return view
     }
 
@@ -87,19 +90,56 @@ class SlotMappingFragment: DialogFragment(), OnMenuItemClickListener {
             recyclerView.adapter = adapter
             adapter.notifyDataSetChanged()
 
+            helpTextView.text = buildHelpText()
         }
     }
 
     private fun commit() {
         lifecycleScope.launch(Dispatchers.Main) {
-            withContext(Dispatchers.IO) {
-                tm.simSlotMapping = adapter.mappings
+            try {
+                withContext(Dispatchers.IO) {
+                    tm.simSlotMapping = adapter.mappings
+                }
+            } catch (e: Exception) {
+                Toast.makeText(requireContext(), R.string.slot_mapping_failure, Toast.LENGTH_LONG).show()
+                return@launch
             }
+            Toast.makeText(requireContext(), R.string.slot_mapping_completed, Toast.LENGTH_LONG).show()
             openEuiccApplication.euiccChannelManager.invalidate()
             requireActivity().finish()
         }
     }
 
+    private suspend fun buildHelpText() = withContext(Dispatchers.IO) {
+        var nLogicalSlots = adapter.mappings.size
+
+        val cards = openEuiccApplication.telephonyManager.uiccCardsInfoCompat
+
+        var nPhysicalSlots = cards.size
+        var idxMepCard = -1
+        var nMepPorts = 0
+
+        for (card in cards) {
+            if (card.isMultipleEnabledProfilesSupported) {
+                idxMepCard = card.physicalSlotIndex
+                nMepPorts = card.ports.size
+            }
+        }
+
+        val mayEnableDSDS =
+            openEuiccApplication.telephonyManager.supportsDSDS && !openEuiccApplication.telephonyManager.dsdsEnabled
+        val extraText =
+            if (nLogicalSlots == 1 && mayEnableDSDS) {
+                getString(R.string.slot_mapping_help_dsds)
+            } else if (idxMepCard != -1) {
+                getString(R.string.slot_mapping_help_mep, idxMepCard, nMepPorts)
+            } else {
+                ""
+            }
+
+        getString(R.string.slot_mapping_help, nLogicalSlots, nPhysicalSlots, extraText)
+    }
+
     override fun onMenuItemClick(item: MenuItem?): Boolean =
         when (item!!.itemId) {
             R.id.ok -> {

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

@@ -22,8 +22,24 @@
         android:layout_height="wrap_content"
         android:paddingTop="6dp"
         app:layout_constraintTop_toBottomOf="@id/toolbar"
-        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintBottom_toTopOf="@id/mapping_help"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintEnd_toEndOf="parent"/>
 
+    <TextView
+        android:id="@+id/mapping_help"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="6dp"
+        android:layout_marginBottom="10dp"
+        android:layout_marginHorizontal="24dp"
+        android:gravity="center"
+        android:textSize="12sp"
+        android:textColor="?attr/colorSecondary"
+        android:textStyle="italic"
+        app:layout_constraintTop_toBottomOf="@id/mapping_list"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>

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

@@ -9,4 +9,9 @@
     <string name="slot_mapping">Slot Mapping</string>
     <string name="slot_mapping_logical_slot">Logical slot %d:</string>
     <string name="slot_mapping_port">Slot %d Port %d</string>
+    <string name="slot_mapping_help">Your phone has %d logical and %d physical SIM slots.%s\n\nSelect which physical slot and/or "port" you want each logical slot to correspond to. Note that not all mapping modes may be supported by hardware.</string>
+    <string name="slot_mapping_help_mep">\n\nPhysical slot %d supports Multiple Enabled Profiles (MEP). To use this feature, associate its %d virtual "ports" to different logical slots shown above.</string>
+    <string name="slot_mapping_help_dsds">\nDual SIM mode is supported but disabled.</string>
+    <string name="slot_mapping_completed">Your new slot mapping has been set. Please wait until modem refreshes the slots.</string>
+    <string name="slot_mapping_failure">The specified mapping might be invalid or unsupported by hardware.</string>
 </resources>