Adds support for known 0 hopsAway (#1295)

app/src/main/java/com/geeksville/mesh/database/entity/NodeEntity.kt

@@ -48,7 +48,7 @@ data class NodeEntity(
     var viaMqtt: Boolean = false,
 
     @ColumnInfo(name = "hops_away")
-    var hopsAway: Int = 0,
+    var hopsAway: Int = -1,
 
     @ColumnInfo(name = "is_favorite")
     var isFavorite: Boolean = false,

app/src/main/java/com/geeksville/mesh/service/MeshService.kt

@@ -1101,8 +1101,10 @@ class MeshService : Service(), Logging {
                 it.rssi = packet.rxRssi
 
                 // Generate our own hopsAway, comparing hopStart to hopLimit.
-                if (packet.hopStart != 0 && packet.hopLimit <= packet.hopStart) {
-                    it.hopsAway = packet.hopStart - packet.hopLimit
+                it.hopsAway = if (packet.hopStart == 0 || packet.hopLimit < packet.hopStart) {
+                    -1
+                } else {
+                    packet.hopStart - packet.hopLimit
                 }
             }
             handleReceivedData(packet)
@@ -1407,7 +1409,13 @@ class MeshService : Service(), Logging {
 
             it.channel = info.channel
             it.viaMqtt = info.viaMqtt
-            it.hopsAway = info.hopsAway
+
+            // hopsAway should be nullable/optional from the proto, but explicitly checking it's existence first
+            it.hopsAway = if (info.hasHopsAway()) {
+                info.hopsAway
+            } else {
+                -1
+            }
             it.isFavorite = info.isFavorite
         }
     }

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

@@ -13,6 +13,9 @@ import com.geeksville.mesh.database.entity.NodeEntity
 import com.geeksville.mesh.ui.preview.NodeEntityPreviewParameterProvider
 import com.geeksville.mesh.ui.theme.AppTheme
 
+const val MAX_VALID_SNR = 100F
+const val MAX_VALID_RSSI = 0
+
 @Composable
 fun signalInfo(
     modifier: Modifier = Modifier,
@@ -26,15 +29,24 @@ fun signalInfo(
         )
     } else {
         buildList {
-            if (node.channel > 0) add("ch:${node.channel}")
-            if (node.hopsAway == 0) {
-                if (node.snr < 100F && node.rssi < 0) {
+            val hopsString = "%s: %s".format(
+                stringResource(R.string.hops_away),
+                if (node.hopsAway == -1) {
+                    stringResource(R.string.unknown)
+                } else {
+                    node.hopsAway.toString()
+                }
+            )
+            if (node.channel > 0) {
+                add("ch:${node.channel}")
+            }
+            if (node.hopsAway <= 0) {
+                if (node.snr < MAX_VALID_SNR && node.rssi < MAX_VALID_RSSI) {
                     add("RSSI: %d SNR: %.1f".format(node.rssi, node.snr))
                 }
-            } else {
-                add("%s: %d".format(stringResource(R.string.hops_away), node.hopsAway))
             }
-        }.joinToString(" ")
+            add(hopsString)
+        }.joinToString(" | ")
     }
     return if (text.isNotEmpty()) {
         Text(