![[tokkee]](http://tokkee.org/images/avatar.png){kind=avatar}
diff --git a/graph/graph.go b/graph/graph.go
--- /dev/null
+++ b/graph/graph.go
@@ -0,0 +1,128 @@
+//
+// Copyright (C) 2014-2015 Sebastian 'tokkee' Harl <sh@tokkee.org>
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+// 1. Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Package graph handles time-series data provided by SysDB. It supports
+// querying and post-processing of the data.
+package graph
+
+import (
+ "fmt"
+ "time"
+
+ "github.com/gonum/plot"
+ "github.com/gonum/plot/plotter"
+ "github.com/gonum/plot/plotutil"
+ "github.com/sysdb/go/client"
+ "github.com/sysdb/go/sysdb"
+)
+
+// A Graph represents a single graph. It may reference multiple time-series.
+type Graph struct {
+ // Time range of the graph.
+ Start, End time.Time
+
+ // Metrics: {<hostname>, <identifier>}
+ Metrics [][2]string
+}
+
+type pl struct {
+ *plot.Plot
+
+ ts int // Index of the current time-series.
+}
+
+func (p *pl) addTimeseries(c *client.Client, metric [2]string, start, end time.Time) error {
+ q, err := client.QueryString("TIMESERIES %s.%s START %s END %s", metric[0], metric[1], start, end)
+ if err != nil {
+ return fmt.Errorf("Failed to retrieve graph data: %v", err)
+ }
+ res, err := c.Query(q)
+ if err != nil {
+ return fmt.Errorf("Failed to retrieve graph data: %v", err)
+ }
+
+ ts, ok := res.(*sysdb.Timeseries)
+ if !ok {
+ return fmt.Errorf("TIMESERIES did not return a time-series but %T", res)
+ }
+
+ for name, data := range ts.Data {
+ pts := make(plotter.XYs, len(data))
+ for i, p := range data {
+ pts[i].X = float64(time.Time(p.Timestamp).UnixNano())
+ pts[i].Y = p.Value
+ }
+
+ l, err := plotter.NewLine(pts)
+ if err != nil {
+ return fmt.Errorf("Failed to create line plotter: %v", err)
+ }
+ l.LineStyle.Color = plotutil.DarkColors[p.ts%len(plotutil.DarkColors)]
+
+ p.Add(l)
+ p.Legend.Add(name, l)
+ p.ts++
+ }
+ return nil
+}
+
+// Plot fetches a graph's time-series data using the specified client and
+// plots it.
+func (g *Graph) Plot(c *client.Client) (*plot.Plot, error) {
+ var err error
+
+ p := &pl{}
+ p.Plot, err = plot.New()
+ if err != nil {
+ return nil, fmt.Errorf("Failed to create plot: %v", err)
+ }
+ p.Add(plotter.NewGrid())
+ p.X.Tick.Marker = dateTicks{}
+
+ for _, m := range g.Metrics {
+ if err := p.addTimeseries(c, m, g.Start, g.End); err != nil {
+ return nil, err
+ }
+ }
+ return p.Plot, nil
+}
+
+type dateTicks struct{}
+
+func (dateTicks) Ticks(min, max float64) []plot.Tick {
+ // TODO: this is surely not the best we can do
+ // but it'll distribute ticks evenly.
+ ticks := plot.DefaultTicks{}.Ticks(min, max)
+ for i, t := range ticks {
+ if t.Label == "" {
+ // Skip minor ticks.
+ continue
+ }
+ ticks[i].Label = time.Unix(0, int64(t.Value)).Format(time.RFC822)
+ }
+ return ticks
+}
+
+// vim: set tw=78 sw=4 sw=4 noexpandtab :