Implement Jared Dillard suggestion to use rrd_info() array to get las…

…t updated time.

Better self documenting code with more explicit variable names.
Add logic to not use custom end within 1 minute of now.

Doesn't seem necessary to adjust the 'end' time reference anymore than last update time or '-1min'.  So for now just removing the endLookup array.

Without the datakeys code the time period is one resolution too long.  Maybe there is a way to correct for that, but for now just adding the datakeys code back in.

sysutils/pfSense-Status_Monitoring/files/usr/local/www/rrd_fetch_json.php

@@ -60,14 +60,6 @@
 
 $rrd_location = "/var/db/rrd/";
 
-//lookup end time based on resolution (ensure resolution interval)
-$endLookup = array(
-	"60"    => "-2min",
-	"300"   => "-5min",
-	"3600"  => "-1hour",
-	"86400" => "-1day"
-);
-
 //TODO security/validation checks
 $left = $_POST['left'];
 $right = $_POST['right'];
@@ -82,8 +74,17 @@
 $left_pieces = explode("-", $left);
 $right_pieces = explode("-", $right);
 
-if ($timePeriod === "custom") {
+// Get the last updated time of left and right axis RRD, or if not exist set to a very large value (decades into the future)
+$rrd_info_array = rrd_info($rrd_location . $left . ".rrd");
+$left_last_updated = ($rrd_info_array['last_update']) ? $rrd_info_array['last_update'] : 99999999999;
 
+$rrd_info_array = rrd_info($rrd_location . $right . ".rrd");
+$right_last_updated = ($rrd_info_array['last_update']) ? $rrd_info_array['last_update'] : 99999999999;
+
+// Use the earlier (smaller) of left or right last updated time
+$last_updated = ($left_last_updated < $right_last_updated) ? $left_last_updated : $right_last_updated;
+
+if ($timePeriod === "custom") {
 	//dates validation
 	if($end < $start) {
 		die ('{ "error" : "The start date must come before the end date." }');
@@ -95,14 +96,17 @@
 	$start = floor($start/$resolution) * $resolution;
 	$end = floor($end/$resolution) * $resolution;
 
-	$rrd_options = array( 'AVERAGE', '-r', $resolution, '-s', $start, '-e', $end );
-
+	// Don't use end that is later than the RRD last updated time, or that is within 1 minute of now, to prevent last value 0 (zero).
+	$end = ($end > $last_updated) ? $last_updated : ((time() - $end) < 60) ? $end : '-1min';
 } else {
-
-	$rrd_options = array( 'AVERAGE', '-r', $resolution, '-s', 'e'.$timePeriod, '-e', $endLookup[$resolution] );
-
+	// Use end time reference in 'start' to retain time period length.
+	$start = 'end' . $timePeriod;
+	// Use the RRD last updated time or '-1min' as end, to prevent last value 0 (zero).
+	$end = ($last_updated < 99999999999) ? $last_updated : '-1min';
 }
 
+$rrd_options = array( 'AVERAGE', '-r', $resolution, '-s', $start, '-e', $end );
+
 //Initialze
 $left_unit_acronym = $right_unit_acronym = "";
 
@@ -279,8 +283,12 @@
 
 			$data = array();
 
+			$dataKeys = array_keys($data_list);
+			$lastDataKey = array_pop($dataKeys);
 			foreach ($data_list as $time => $value) {
+				if($time != $lastDataKey) {
 					$data[] = array($time*1000, $value*$multiplier);
+				}
 			}
 
 			$obj[$ds_key_left_adjusted]['values'] = $data;
@@ -506,8 +514,12 @@
 
 			$data = array();
 
+			$dataKeys = array_keys($data_list);
+			$lastDataKey = array_pop($dataKeys);
 			foreach ($data_list as $time => $value) {
+				if($time != $lastDataKey) {
 					$data[] = array($time*1000, $value*$multiplier);
+				}
 			}
 
 			$obj[$ds_key_right_adjusted]['values'] = $data;