Device Availability Calculation (#11784)

* Device Availability Calculation

* Travis fix

* .

* schema corrections

* flexible duration

* travis

* .

* .

* .

* .

* remove not needed code

* line Text to RRD

* update humantime

* .

* only set up again if device was marked as down

* set RRD area transparency

* save uptime also, to keep last availability as good as possible

* file description correction

* look for outages even if uptime > duration

LibreNMS/Util/Time.php

@@ -83,4 +83,54 @@ class Time
 
         return $result;
     }
+
+
+    /*
+     * @param integer seconds of a time period
+     * @return string human readably time period
+     */
+    public static function humanTime($s)
+    {
+        $ret = [];
+
+        if ($s >= 86400) {
+            $d = floor($s / 86400);
+            $s -= $d * 86400;
+            if ($d == 1) {
+                $ret[] = $d . " day";
+            } else {
+                $ret[] = $d . " days";
+            }
+        }
+
+        if ($s >= 3600) {
+            $h = floor($s / 3600);
+            $s -= $h * 3600;
+            if ($h == 1) {
+                $ret[] = $h . " hour";
+            } else {
+                $ret[] = $h . " hours";
+            }
+        }
+
+        if ($s >= 60) {
+            $m = floor($s / 60);
+            $s -= $m * 60;
+            if ($m == 1) {
+                $ret[] = $m . " minute";
+            } else {
+                $ret[] = $m . " minutes";
+            }
+        }
+
+        if ($s > 0) {
+            if ($s == 1) {
+                $ret[] = $s . " second";
+            } else {
+                $ret[] = $s . " seconds";
+            }
+        }
+
+        return implode(' ,', $ret);
+    }
 }