Added jq filter to convert new format to old format

This makes it easily possible to continue using the legacy ffmap-d3
front end with the new backend while migrating.

README.md

@@ -79,6 +79,21 @@ will prefix `sudo` where necessary.
 - online
 - gateway
 
+## Old data format
+
+If you want to still use the old [ffmap-d3](https://github.com/ffnord/ffmap-d3)
+front end, you can use the file `ffmap-d3.jq` to convert the new output to the
+old one:
+
+```
+jq -n -f ffmap-d3.jq \
+    --argfile nodes nodedb/nodes.json \
+    --argfile graph nodedb/graph.json \
+    > nodedb/ffmap-d3.json
+```
+
+Then point your ffmap-d3 instance to the `ffmap-d3.json` file.
+
 # Removing owner information
 
 If you'd like to redact information about the node owner from `nodes.json`,

ffmap-d3.jq

@@ -0,0 +1,52 @@
+{
+    "meta": {
+        "timestamp": $nodes.timestamp
+    },
+    "nodes": (
+        $graph.batadv.nodes
+        | map(
+            if has("node_id") and .node_id
+            then (
+                $nodes.nodes[.node_id] as $node
+                | {
+                    "id": .id,
+                    "uptime": $node.statistics.uptime,
+                    "flags": ($node.flags + {"client": false}),
+                    "name": $node.nodeinfo.hostname,
+                    "clientcount": (if $node.statistics.clients >= 0 then $node.statistics.clients else 0 end),
+                    "hardware": $node.nodeinfo.hardware.model,
+                    "firmware": $node.nodeinfo.software.firmware.release,
+                    "geo": (if $node.nodeinfo.location then [$node.nodeinfo.location.latitude, $node.nodeinfo.location.longitude] else null end),
+                    #"lastseen": $node.lastseen,
+                    "network": $node.nodeinfo.network
+                }
+            )
+            else
+                {
+                    "flags": {},
+                    "id": .id,
+                    "geo": null,
+                    "clientcount": 0
+                }
+            end
+        )
+    ),
+    "links": (
+        $graph.batadv.links
+        | map(
+            $graph.batadv.nodes[.source].node_id as $source_id
+            | $graph.batadv.nodes[.target].node_id as $target_id
+            | select(
+                $source_id and $target_id and
+                ($nodes.nodes | (has($source_id) and has($target_id)))
+            )
+            | {
+                "target": .target,
+                "source": .source,
+                "quality": "\(.tq), \(.tq)",
+                "id": ($source_id + "-" + $target_id),
+                "type": (if .vpn then "vpn" else null end)
+            }
+        )
+    )
+}