feature: add meta deltas support to FullSignalK (#597)

Author: sbender9

src/fullsignalk.js

@@ -105,7 +105,12 @@ FullSignalK.prototype.addUpdate = function(context, contextPath, update) {
   } else {
     console.error("No source in delta update:" + JSON.stringify(update));
   }
-  addValues(context, contextPath, update.source || update['$source'], update.timestamp, update.values);
+  if ( update.values ) {
+    addValues(context, contextPath, update.source || update['$source'], update.timestamp, update.values);
+  }
+  if ( update.meta ) {
+    addMetas(context, contextPath, update.source || update['$source'], update.timestamp, update.meta);
+  }
 }
 
 FullSignalK.prototype.updateDollarSource = function(context, dollarSource, timestamp) {
@@ -198,17 +203,13 @@ function addValue(context, contextPath, source, timestamp, pathValue) {
         if (!previous[pathPart]) {
           previous[pathPart] = {};
         }
-        if ( i === splitPath.length-1 && typeof previous[pathPart].value === 'undefined' ) {
-          let meta = signalkSchema.getMetadata(contextPath + '.' + pathValue.path)
-          if (meta ) {
-            //ignore properties from keyswithmetadata.json
-            meta = JSON.parse(JSON.stringify(meta))
-            delete meta.properties
-
+      if ( i === splitPath.length-1 && typeof previous[pathPart].value === 'undefined' ) {
+          let meta = signalkSchema.internalGetMetadata(contextPath + '.' + pathValue.path)
+          if (meta) {
             _.assign(meta, previous[pathPart].meta)
-            previous[pathPart].meta = meta            
+            previous[pathPart].meta = meta
           }
-      }
+        }
       return previous[pathPart];
     }, context);
   }
@@ -267,5 +268,17 @@ function setMessage(leaf, source) {
   }
 }
 
+function addMetas(context, contextPath, source, timestamp, metas) {
+  metas.forEach(metaPathValue => addMeta(context, contextPath, source, timestamp, metaPathValue))
+}
+
+function addMeta(context, contextPath, source, timestamp, pathValue) {
+  if (_.isUndefined(pathValue.path) || _.isUndefined(pathValue.value)) {
+    console.error("Illegal value in delta:" + JSON.stringify(pathValue));
+    return;
+  }
+  signalkSchema.addMetaData(contextPath, pathValue.path, pathValue.value)
+}
+
 
 module.exports = FullSignalK;

src/index.js

@@ -346,7 +346,55 @@ module.exports.getMetadata = function (path) {
   const result = metadataByRegex.find(entry =>
     entry.regexp.test('/' + path.replace(/\./g, '/'))
   )
-  return result ? result.metadata : undefined
+
+  return result && Object.keys(result.metadata).length > 0  ? result.metadata : undefined
+}
+
+module.exports.internalGetMetadata = function (path) {
+  const result = metadataByRegex.find(entry =>
+    entry.regexp.test('/' + path.replace(/\./g, '/'))
+  )
+
+  let meta = result ? result.metadata : undefined
+  const parts = path.split('.')
+  const key = `/${parts[0]}/*/` + parts.slice(2).join('/')
+  if ( !module.exports.metadata[key] ) {
+    meta = result ? JSON.parse(JSON.stringify(result.metadata)) : {}
+    module.exports.metadata[key] = meta
+    const regexpKey =
+          '^' + key.replace(/\*/g, '.*').replace(/RegExp/g, '.*') + '$'
+    metadataByRegex.unshift({
+      regexp: new RegExp(regexpKey),
+      metadata: meta
+    })
+  }
+  
+  return meta
+}
+
+module.exports.addMetaData = function(context, path, meta) {
+  const root = context.split('.')[0]
+  const key = `/${root}/*/${path.replace(/\./g, '/')}`
+  let existing = module.exports.metadata[key]
+  if ( existing ) {
+    _.merge(existing, meta)
+  } else {
+    let regexMeta = module.exports.getMetadata(context + '.' + path)
+    if ( regexMeta ) {
+      let newMeta = JSON.parse(JSON.stringify(regexMeta))
+      _.merge(newMeta, meta)
+      meta = newMeta
+    }
+       
+    module.exports.metadata[key] = meta
+    
+    const regexpKey =
+          '^' + key.replace(/\*/g, '.*').replace(/RegExp/g, '.*') + '$'
+    metadataByRegex.unshift({
+      regexp: new RegExp(regexpKey),
+      metadata: meta
+    })
+  }
 }
 
 module.exports.getAISShipTypeName = function(id) {