From 91b4e1a21cbd25bcc3c72ddc278ccfeb2943a0e1 Mon Sep 17 00:00:00 2001
From: Knut Ahlers <knut@ahlers.me>
Date: Fri, 10 Jul 2015 20:28:55 +0200
Subject: [PATCH] Display only 60 items in graph

The decision is left to the template so template designers can easily change this behavior by removing the lastNItems filter in the template itself. Also the value can be changed easily.

fixes #4
---
 filters/filter.go        | 16 ++++++++++++++++
 main.go                  |  1 +
 structs.go               | 26 ++++++++++----------------
 templates/dashboard.html | 10 ++++------
 4 files changed, 31 insertions(+), 22 deletions(-)
 create mode 100644 filters/filter.go

diff --git a/filters/filter.go b/filters/filter.go
new file mode 100644
index 0000000..5bd67bb
--- /dev/null
+++ b/filters/filter.go
@@ -0,0 +1,16 @@
+package filters
+
+import "github.com/flosch/pongo2"
+
+func init() {
+	pongo2.RegisterFilter("lastNItems", filterLastNItems)
+}
+
+func filterLastNItems(in *pongo2.Value, param *pongo2.Value) (*pongo2.Value, *pongo2.Error) {
+	if !in.CanSlice() {
+		return in, nil
+	}
+
+	from := in.Len() - param.Integer()
+	return in.Slice(from, in.Len()), nil
+}
diff --git a/main.go b/main.go
index f0da838..c2a301a 100644
--- a/main.go
+++ b/main.go
@@ -13,6 +13,7 @@ import (
 	"github.com/flosch/pongo2"
 	"github.com/gorilla/mux"
 
+	_ "github.com/Luzifer/mondash/filters"
 	_ "github.com/flosch/pongo2-addons"
 )
 
diff --git a/structs.go b/structs.go
index 353873b..d9aa5a1 100644
--- a/structs.go
+++ b/structs.go
@@ -166,27 +166,21 @@ func (dm *dashboardMetric) StatisticalStatus() string {
 	return "OK"
 }
 
-func (dm *dashboardMetric) LabelHistory() string {
-	s := "["
-	for i, v := range dm.HistoricalData {
-		if i != 0 {
-			s = s + ", "
-		}
-		s = s + "" + strconv.Itoa(int(v.Time.Unix())) + ""
+func (dm *dashboardMetric) LabelHistory() []string {
+	s := []string{}
+	for _, v := range dm.HistoricalData[len(dm.HistoricalData)-60:] {
+		s = append(s, strconv.Itoa(int(v.Time.Unix())))
 	}
-	s = s + "]"
+
 	return s
 }
 
-func (dm *dashboardMetric) DataHistory() string {
-	s := "["
-	for i, v := range dm.HistoricalData {
-		if i != 0 {
-			s = s + ", "
-		}
-		s = s + strconv.FormatFloat(v.Value, 'g', 4, 64)
+func (dm *dashboardMetric) DataHistory() []string {
+	s := []string{}
+	for _, v := range dm.HistoricalData[len(dm.HistoricalData)-60:] {
+		s = append(s, strconv.FormatFloat(v.Value, 'g', 4, 64))
 	}
-	s = s + "]"
+
 	return s
 }
 
diff --git a/templates/dashboard.html b/templates/dashboard.html
index 675e8c1..127a2eb 100644
--- a/templates/dashboard.html
+++ b/templates/dashboard.html
@@ -11,8 +11,8 @@
     <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap-theme.min.css">
 
 	<!-- Chartist Library -->
-	<link rel="stylesheet" href="//cdn.jsdelivr.net/chartist.js/latest/chartist.min.css">
-    <script src="//cdn.jsdelivr.net/chartist.js/latest/chartist.min.js"></script>
+  <link rel="stylesheet" href="//cdn.jsdelivr.net/chartist.js/latest/chartist.min.css">
+  <script src="//cdn.jsdelivr.net/chartist.js/latest/chartist.min.js"></script>
 	<script>
 	function timeConverter(UNIX_timestamp){
 	  var a = new Date(UNIX_timestamp*1000);
@@ -110,11 +110,9 @@
 			<script>
 				    var data = {
 				        // A labels array that can contain any sort of values
-				        labels: {{ metric.LabelHistory }},
+				        labels: [{{ metric.LabelHistory|lastNItems:"60"|join:"," }}],
 				        // Our series array that contains series objects or in this case series data arrays
-				        series: [
-				            {{ metric.DataHistory }}
-				        ]
+				        series: [[{{ metric.DataHistory|lastNItems:"60"|join:"," }}]]
 				    };
 
 					for (var i = 0; i < data.labels.length; i++) {