--- a/server/ts.py	Tue Jun 12 00:35:23 2012 +0800
+++ b/server/ts.py	Tue Jun 12 23:27:53 2012 +0800
@@ -110,7 +110,7 @@
     return int(next_wake)
 
 def send_results(lines):
-    enc_lines = binascii.b2a_base64('\n'.join(lines))
+    enc_lines = binascii.b2a_base64(zlib.compress('\n'.join(lines)))
     hmac.new(config.HMAC_KEY, enc_lines).hexdigest()
 
     url_data = urllib.url_encode( ('lines', enc_lines), ('hmac', mac) )

--- a/web/config.py	Tue Jun 12 00:35:23 2012 +0800
+++ b/web/config.py	Tue Jun 12 23:27:53 2012 +0800
@@ -3,3 +3,10 @@
 
 HMAC_KEY = 'a hmac key'
 
+GRAPH_WIDTH = 800
+
+LINE_WIDTH = 2
+
+SENSOR_NAMES = {}
+
+SENSOR_COLOURS = {}

--- a/web/index.py	Tue Jun 12 00:35:23 2012 +0800
+++ b/web/index.py	Tue Jun 12 23:27:53 2012 +0800
@@ -2,6 +2,7 @@
 
 import binascii
 import hmac
+import zlib
 
 import bottle
 from bottle import route, request
@@ -17,7 +18,7 @@
     if hmac.new(config.HMAC_KEY, enc_lines).hexdigest() != mac:
         raise HTTPError(code = 403, output = "Bad key")
 
-    lines = binascii.a2b_base64(enc_lines).split('\n')
+    lines = zlib.decompress(binascii.a2b_base64(enc_lines)).split('\n')
 
     log.parse(lines)
 

--- a/web/log.py	Tue Jun 12 00:35:23 2012 +0800
+++ b/web/log.py	Tue Jun 12 23:27:53 2012 +0800
@@ -1,17 +1,58 @@
 import rrdtool
 import os
+import os.path
 import sys
+import glob
+from colorsys import hls_to_rgb
 
 import config
 
 def sensor_rrd_path(s):
     return '%s/sensor_%s.rrd' % (config.DATA_PATH, s)
 
+# returns (path, sensor_name) tuples
+def all_sensors():
+    return [(r, os.path.basename(r[:-4])) 
+        for r in glob.glob('%s/*.rrd' % config.DATA_PATH)]
+
 def create_rrd(sensor_id):
     rrdtool.create(sensor_rrd_path(sensor_id), '-s', '300',
                 'DS:temp:GAUGE:600:-10:100',
                 'RRA:AVERAGE:0.5:1:1051200')
 
+
+# stolen from viewmtn, stolen from monotone-viz
+def colour_from_string(str):
+    def f(off):
+        return ord(hashval[off]) / 256.0
+    hashval = sha.new(str).digest()
+    hue = f(5)
+    li = f(1) * 0.15 + 0.55
+    sat = f(2) * 0.5 + .5
+    return ''.join(["%.2x" % int(x * 256) for x in hls_to_rgb(hue, li, sat)])
+
+def graph_png(start, length):
+    rrds = all_sensors()
+
+    graph_args = []
+    for n, (rrdfile, sensor) in enumerate(rrds):
+        vname = 'temp%d' % n
+        graph_args.append('DEF:%(vname)s=%(rrdfile)s:temp:AVERAGE' % locals())
+        width = config.LINE_WIDTH
+        legend = config.SENSOR_NAMES.get(sensor, sensor)
+        colour = config.SENSOR_COLOURS.get(legend, colour_from_string(r))
+        graph_args.append('LINE%(width)f:%(vname)s#%(colour)s:%(legend)s' % locals())
+
+    tempf = tempfile.NamedTemporaryFile()
+    args = [tempf.name, '-s', str(start),
+        '-e', str(start+length),
+        '-w', config.GRAPH_WIDTH,
+        '--slope-mode',
+        '--imgformat', 'PNG']
+        + graph_args
+    rrdtool.graph(*args)
+    return tempf.read()
+
 def sensor_update(sensor_id, measurements, first_real_time, time_step):
     try:
         open(sensor_rrd_path(sensor_id))

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/test.py	Tue Jun 12 23:27:53 2012 +0800
@@ -0,0 +1,5 @@
+#!/usr/bin/env python
+import log
+import time
+
+log.sensor_update("test1", [22,22,22.1,22.4,22.5], time.time() - 10, 300)