From 1d15f3c11b241b24adfc91fa747accfebe569a2e Mon Sep 17 00:00:00 2001
From: Alexander Zobnin <alexanderzobnin@gmail.com>
Date: Tue, 22 Dec 2020 16:29:22 +0300
Subject: [PATCH] Fill trends with null values

---
 src/datasource-zabbix/datasource.ts | 16 ++++++++++++---
 src/datasource-zabbix/timeseries.ts | 30 +++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/src/datasource-zabbix/datasource.ts b/src/datasource-zabbix/datasource.ts
index 9e587a0..afc39d4 100644
--- a/src/datasource-zabbix/datasource.ts
+++ b/src/datasource-zabbix/datasource.ts
@@ -6,7 +6,7 @@ import * as utils from './utils';
 import * as migrations from './migrations';
 import * as metricFunctions from './metricFunctions';
 import * as c from './constants';
-import { align } from './timeseries';
+import { align, fillTrendsWithNulls } from './timeseries';
 import dataProcessor from './dataProcessor';
 import responseHandler from './responseHandler';
 import problemsHandler from './problemsHandler';
@@ -251,13 +251,16 @@ export class ZabbixDatasource extends DataSourceApi<ZabbixMetricsQuery, ZabbixDS
     let getHistoryPromise;
     options.valueType = this.getTrendValueType(target);
     options.consolidateBy = getConsolidateBy(target) || options.valueType;
+    const disableDataAlignment = this.disableDataAlignment || target.options?.disableDataAlignment;
 
     if (useTrends) {
-      getHistoryPromise = this.zabbix.getTrends(items, timeRange, options);
+      getHistoryPromise = this.zabbix.getTrends(items, timeRange, options)
+      .then(timeseries => {
+        return !disableDataAlignment ? this.fillTrendTimeSeriesWithNulls(timeseries) : timeseries;
+      });
     } else {
       getHistoryPromise = this.zabbix.getHistoryTS(items, timeRange, options)
       .then(timeseries => {
-        const disableDataAlignment = this.disableDataAlignment || target.options?.disableDataAlignment;
         return !disableDataAlignment ? this.alignTimeSeriesData(timeseries) : timeseries;
       });
     }
@@ -284,6 +287,13 @@ export class ZabbixDatasource extends DataSourceApi<ZabbixMetricsQuery, ZabbixDS
     return timeseries;
   }
 
+  fillTrendTimeSeriesWithNulls(timeseries: any[]) {
+    for (const ts of timeseries) {
+      ts.datapoints = fillTrendsWithNulls(ts.datapoints);
+    }
+    return timeseries;
+  }
+
   applyDataProcessingFunctions(timeseries_data, target) {
     const transformFunctions   = bindFunctionDefs(target.functions, 'Transform');
     const aggregationFunctions = bindFunctionDefs(target.functions, 'Aggregate');
diff --git a/src/datasource-zabbix/timeseries.ts b/src/datasource-zabbix/timeseries.ts
index 40f0623..4d56250 100644
--- a/src/datasource-zabbix/timeseries.ts
+++ b/src/datasource-zabbix/timeseries.ts
@@ -17,6 +17,8 @@ import { TimeSeriesPoints, TimeSeriesValue } from '@grafana/data';
 const POINT_VALUE = 0;
 const POINT_TIMESTAMP = 1;
 
+const HOUR_MS = 3600 * 1000;
+
 /**
  * Downsample time series by using given function (avg, min, max).
  */
@@ -118,6 +120,34 @@ function detectSeriesInterval(datapoints: TimeSeriesPoints): number {
   return intervalSec * 1000;
 }
 
+export function fillTrendsWithNulls(datapoints: TimeSeriesPoints): TimeSeriesPoints {
+  if (datapoints.length <= 1) {
+    return datapoints;
+  }
+
+  const interval = HOUR_MS;
+  const filled_ts: TimeSeriesPoints = [];
+  let frame_ts = datapoints[0][POINT_TIMESTAMP];
+  let point_frame_ts = frame_ts;
+  let point: TimeSeriesValue[];
+  for (let i = 0; i < datapoints.length; i++) {
+    point = datapoints[i];
+    point_frame_ts = point[POINT_TIMESTAMP];
+
+    if (point_frame_ts > frame_ts) {
+      // Move frame window to next non-empty interval and fill empty by null
+      while (frame_ts < point_frame_ts) {
+        filled_ts.push([null, frame_ts]);
+        frame_ts += interval;
+      }
+    }
+
+    filled_ts.push(point);
+    frame_ts += interval;
+  }
+  return filled_ts;
+}
+
 /**
  * Group points by given time interval
  * datapoints: [[<value>, <unixtime>], ...]