#!/usr/bin/env python
# Count messages per month in a mailbox and produce a gnuplot graph.
# Adam Sampson <ats@offog.org>

import sys, rfc822, time, os, math

PERIOD_LENGTH = 60 * 60 * 24

def readposts(times):
	while 1:
		while 1:
			l = sys.stdin.readline()
			if l == "": return
			if l.startswith("From "): break
		while 1:
			l = sys.stdin.readline()
			if l == "": return
			if l.lower().startswith("date: "):
				date = l[6:].strip()
				dt = rfc822.parsedate(date)
				if dt is None:
					print "failed to parse", date
				else:
					times.append(time.mktime(dt))
			if l == "\n": break

def period_of(t):
	return int(t / PERIOD_LENGTH) * PERIOD_LENGTH

def main():
	times = []
	readposts(times)
	times.sort()

	periods = {}
	for i in xrange(times[0], times[-1] + PERIOD_LENGTH, PERIOD_LENGTH):
		periods[period_of(i)] = []
	for t in times:
		periods[period_of(t)].append(t)

	ps = periods.keys()
	ps.sort()
	# Discard first and last data points, since they'll be incomplete.
	ps = ps[1:-2]

	fn = "/tmp/mboxcount.data"
	fmt = "%Y-%m-%dT%H:%M:%S"
	f = open(fn, "w")
	for p in ps:
		t = time.strftime(fmt, time.gmtime(p))
		v = len(periods[p])
		print >>f, "%s\t%f" % (t, v)
	f.close()

	f = os.popen("gnuplot", "w")
#	print >>f, "set terminal postscript eps color solid"
#	print >>f, "set output \"out.ps\""
	print >>f, "set terminal png small size 800,600 xffffff x000000 x000000 xee7777 x000077"
	print >>f, "set output \"out.png\""
	print >>f, "set xdata time"
	print >>f, "set data style lines"
	print >>f, "set timefmt \"" + fmt + "\""
	print >>f, "set format x \"%Y-%m\""
	print >>f, "set xlabel \"Date\""
	print >>f, "set ylabel \"Number of posts per %dh\"" % (PERIOD_LENGTH / (60 * 60),)
	print >>f, "plot \"" + fn + "\" using 1:2 title 'Counts', \"" + fn + "\" using 1:2 smooth bezier title 'Smoothed'"
	f.close()
	os.unlink(fn)

if __name__ == "__main__":
	main()