Publish Nerbus source snapshot and build documentation

lib/nerbus_status.js

@@ -0,0 +1,39 @@
+const http = require('http');
+const settings = require('./settings');
+const expected = settings.block_page.genesis_block;
+let state = {status:'offline',chain:'NRB',height:null};
+function rpc(method, params) {
+  return new Promise((resolve,reject)=>{
+    const data=JSON.stringify({id:'nerbus-health',method,params});
+    const r=http.request({host:settings.wallet.host,port:settings.wallet.port,method:'POST',
+      auth:settings.wallet.username+':'+settings.wallet.password,
+      headers:{'Content-Type':'application/json','Content-Length':Buffer.byteLength(data)}}, res=>{
+        let raw='';res.on('data',d=>raw+=d);res.on('end',()=>{
+          try { const v=JSON.parse(raw);if(v.error) reject(Error('RPC error'));else resolve(v.result); }
+          catch(e){reject(e);}
+        });
+      });
+    r.setTimeout(3000,()=>r.destroy(Error('RPC timeout')));
+    r.on('error',reject);r.end(data);
+  });
+}
+async function probe() {
+  try {
+    if(await rpc('getblockhash',[0])!==expected) {
+      state={status:'wrong-network',chain:'NRB',height:null};return;
+    }
+    state={status:'online',chain:'NRB',height:await rpc('getblockcount',[])};
+  } catch (_) { state={status:'offline',chain:'NRB',height:null}; }
+}
+module.exports=function(app) {
+  probe();setInterval(probe,10000).unref();
+  app.get('/healthz',(req,res)=>res.json({explorer:'Nerbus',...state}));
+  app.use((req,res,next)=>{res.locals.nerbusState=state;
+    if(state.status!=='online' && req.path==='/ext/getsummary')
+      return res.json({status:state.status,difficulty:'-',difficultyHybrid:'',supply:'-',hashrate:'-',
+        connections:'-',blockcount:'-',lastPrice:'0',lastUSDPrice:'0',marketcap:'0.00',usdMarketcap:'0.00'});
+    if(state.status!=='online' && req.path.startsWith('/api/'))
+      return res.status(503).json({error:'Nerbus node is offline; network launch pending'});
+    next();
+  });
+};