#!/usr/local/bin/python -tt
#
# graph-weight.py: A CGI-like script for using gnuplot to draw a plot of
# weights pulled from SQL.

import cgitb; cgitb.enable()
import datetime
import os
import sys
import time
import pg

# When executed as a CGI, HOME isn't set.  But we need it for a temp
# directory.
if not os.environ.has_key('HOME'):
    os.environ['HOME'] = 'XXX' # TODO: replace

def getWeightHistory(conn):
    weights_by_date = {}
   
    sql = "SELECT date, weight FROM fitness_weight"
    r = conn.query(sql)
    for result in r.getresult():
        dateStr = result[0]
        dateTime = time.strptime(dateStr, '%Y-%m-%d')
        date = datetime.date(dateTime.tm_year, dateTime.tm_mon, dateTime.tm_mday)
        weight = result[1]
        weights_by_date[date] = weight

    return weights_by_date 

def isPlotOutOfDate(plot_file):
    if not os.path.exists(plot_file):
        return True

    mtime = os.path.getmtime(plot_file)
    now = time.time()

    # If file is less than 15 minutes old, we'll keep it
    if (now - mtime < 60 * 15):
        return False

    return True

def generatePlot(weight_history, plot_file):
    weight_dates = weight_history.keys()
    weight_dates.sort()

    first_date = weight_dates[0]
    last_date = weight_dates[-1]

    f = os.popen('gnuplot', 'w')
    try:
        print >>f, "set terminal png medium transparent size 960,400"
        print >>f, "set out '%s'" % (plot_file)
        print >>f, "set grid"
        print >>f, "set xdata time"
        print >>f, "set timefmt \"%Y-%m-%d\""
        print >>f, "set xrange [\"%s\":\"%s\"]" % (first_date, last_date)
        print >>f, "set xlabel 'Date'"
        print >>f, "set ylabel 'Weight'"
        print >>f, "plot '-' using 1:2 title 'Weight' with points, '-' using 1:2 title 'Smoothed Weight' with lines lw 3 smooth bezier"
        for date in weight_dates:
            print >>f, "%s %s" % (date, weight_history[date])
        print >>f, "e"

        for date in weight_dates:
            print >>f, "%s %s" % (date, weight_history[date])
        print >>f, "e"
    finally:
        f.close()

plot_file_name = '%s/.weight.png' % os.environ['HOME']
if isPlotOutOfDate(plot_file_name):
    conn = pg.DB(dbname='XXX', host='XXX', user='XXX') # TODO: Fill in these values
    weight_history = getWeightHistory(conn)
    generatePlot(weight_history, plot_file_name)

plot_file = file(plot_file_name, 'rb')

# After this point, we've already committed to sending the web page,
# so try really hard not to generate any errors.
print 'Content-Type: image/png'
print
sys.stdout.write(plot_file.read())