show channel suffix per https://github.com/meshtastic/Meshtastic-device/issues/269

app/src/main/java/com/geeksville/mesh/model/Channel.kt

@@ -8,6 +8,7 @@ import com.google.zxing.BarcodeFormat
 import com.google.zxing.MultiFormatWriter
 import com.journeyapps.barcodescanner.BarcodeEncoder
 import java.net.MalformedURLException
+import kotlin.experimental.xor
 
 /** Utility function to make it easy to declare byte arrays - FIXME move someplace better */
 fun byteArrayOfInts(vararg ints: Int) = ByteArray(ints.size) { pos -> ints[pos].toByte() }
@@ -52,6 +53,17 @@ data class Channel(
     val name: String get() = settings.name
     val modemConfig: MeshProtos.ChannelSettings.ModemConfig get() = settings.modemConfig
 
+    /**
+     * Return a name that is formatted as #channename-suffix
+     *
+     * Where suffix indicates the hash of the PSK
+     */
+    val humanName: String
+        get() {
+            val code = settings.psk.fold(0.toByte(), { acc, x -> acc xor x })
+            return "#${settings.name}-${'A' + (code % 26)}"
+        }
+
     /// Can this channel be changed right now?
     var editable = false
 

app/src/main/java/com/geeksville/mesh/ui/ChannelFragment.kt

@@ -77,7 +77,7 @@ class ChannelFragment : ScreenFragment("Channel"), Logging {
         if (channel != null) {
             qrView.visibility = View.VISIBLE
             channelNameEdit.visibility = View.VISIBLE
-            channelNameEdit.setText(channel.name)
+            channelNameEdit.setText(channel.humanName)
 
             // For now, we only let the user edit/save channels while the radio is awake - because the service
             // doesn't cache radioconfig writes.
@@ -134,7 +134,12 @@ class ChannelFragment : ScreenFragment("Channel"), Logging {
         }
 
         editableCheckbox.setOnCheckedChangeListener { _, checked ->
-            if (!checked) {
+            if (checked) {
+                // User just unlocked for editing - remove the # goo around the channel name
+                UIViewModel.getChannel(model.radioConfig.value)?.let { channel ->
+                    channelNameEdit.setText(channel.name)
+                }
+            } else {
                 // User just locked it, we should warn and then apply changes to radio
                 MaterialAlertDialogBuilder(requireContext())
                     .setTitle(R.string.change_channel)
@@ -177,7 +182,7 @@ class ChannelFragment : ScreenFragment("Channel"), Logging {
                                 // Since we are writing to radioconfig, that will trigger the rest of the GUI update (QR code etc)
                             } catch (ex: RemoteException) {
                                 errormsg("ignoring channel problem", ex)
-                                
+
                                 setGUIfromModel() // Throw away user edits
 
                                 // Tell the user to try again