Offset function added (#638)

* Shift function added

* Remane shift function to offset

src/datasource-zabbix/dataProcessor.js

@@ -9,6 +9,7 @@ let sumSeries = ts.sumSeries;
 let delta = ts.delta;
 let rate = ts.rate;
 let scale = (factor, datapoints) => ts.scale_perf(datapoints, factor);
+let offset = (factor, datapoints) => ts.offset(datapoints, delta);
 let simpleMovingAverage = (n, datapoints) => ts.simpleMovingAverage(datapoints, n);
 let expMovingAverage = (a, datapoints) => ts.expMovingAverage(datapoints, a);
 
@@ -117,6 +118,7 @@ function unShiftTimeSeries(interval, datapoints) {
 let metricFunctions = {
   groupBy: groupByWrapper,
   scale: scale,
+  offset: offset,
   delta: delta,
   rate: rate,
   movingAverage: simpleMovingAverage,

src/datasource-zabbix/metricFunctions.js

@@ -44,6 +44,15 @@ addFuncDef({
   defaultParams: [100],
 });
 
+addFuncDef({
+  name: 'offset',
+  category: 'Transform',
+  params: [
+    { name: 'delta', type: 'float', options: [-100, 100]}
+  ],
+  defaultParams: [100],
+});
+
 addFuncDef({
   name: 'delta',
   category: 'Transform',

src/datasource-zabbix/specs/timeseries.spec.js

@@ -30,5 +30,15 @@ describe('timeseries processing functions', () => {
       expect(result).toEqual(expected);
       done();
     });
+
+    it('should properly offset metric', (done) => {
+      let points = [[1, 1], [-4, 2], [2, 3]];
+
+      let expected = [[101, 1], [96, 2], [102, 3]];
+
+      let result = ts.offset(points, 100);
+      expect(result).toEqual(expected);
+      done();
+    });
   });
 });

src/datasource-zabbix/timeseries.js

@@ -191,6 +191,17 @@ function scale_perf(datapoints, factor) {
   return datapoints;
 }
 
+function offset(datapoints, delta) {
+  for (let i = 0; i < datapoints.length; i++) {
+    datapoints[i] = [
+      datapoints[i][POINT_VALUE] + delta,
+      datapoints[i][POINT_TIMESTAMP]
+    ];
+  }
+
+  return datapoints;
+}
+
 /**
  * Simple delta. Calculate value delta between points.
  * @param {*} datapoints
@@ -477,6 +488,7 @@ const exportedFunctions = {
   groupBy_perf,
   sumSeries,
   scale,
+  offset,
   scale_perf,
   delta,
   rate,