#!/usr/bin/env python
# -*- coding: UTF-8 -*-

from os import popen2
from os.path import getmtime, isfile, expanduser
from time import gmtime, strftime, time

FREQUENCY = 60
CACHE_FILE = expanduser('~/sandbox/uptime.dat')
LOG_FILE = expanduser('~/sandbox/uptime.log')
ENABLE_LOG = True

def getprocessoutput(e):
    """
    Executes e and returns its output.
    """
    return popen2(e)[1].read().rstrip()

# So, um, why do people put everything in a main() function?
def main():
    now = time()
    if isfile(CACHE_FILE):
        fresh = False
        fh = open(CACHE_FILE, 'r')
        uptime, servername = [line.rstrip() for line in fh.readlines()]
        fh.close()
        if getmtime(CACHE_FILE) <= (now - FREQUENCY):
            fresh = True
            uptime = getprocessoutput('/usr/bin/uptime')

            # I do not know how to only open the file once. :|
            fh = open(CACHE_FILE, 'w')
            fh.write(uptime + '\n' + servername)
            fh.close()

    else:
        fresh = True

        uptime = getprocessoutput('/usr/bin/uptime')
        hostname = getprocessoutput('/bin/hostname')
        domainname = getprocessoutput('/bin/dnsdomainname')

        # Is that even possible?
        if hostname in ('','localhost'):
            servername = 'this server'

        else:
            if domainname in ('','localdomain'):
                servername = hostname
            else:
                servername = hostname + '.' + domainname

        # The file could probably be screwed up if the script is accessed twice
        # at the exact same time...
        cfh = open(CACHE_FILE, 'w')
        cfh.write(uptime + '\n' + servername)
        cfh.close()

    mtime = getmtime(CACHE_FILE) # That getmtime() is called up in the if and here..

    print 'Content-Type: text/plain;charset=us-ascii'
    print 'Cache-Control: max-age=' + str(FREQUENCY) + ', must-revalidate, private, ' \
          'proxy-revalidate, s-maxage=' + str(FREQUENCY)
    print 'Expires: ' + strftime('%a, %d %b %Y %H:%M:%S GMT', gmtime(now + FREQUENCY))
    print 'Last-Modified: ' + strftime('%a, %d %b %Y %H:%M:%S GMT', gmtime(mtime))
    print

    print '/usr/bin/uptime output on', servername, 'as of',

    if fresh:
        # The bit of code below is simply not being executed. I can make the if
        # check for a nonexistant variable if I want to, and I won't get an
        # error. If I put invalid syntax here, I get an error, so Python knows
        # it exists (how could it not?). The code messing with cfh above works,
        # but I can put a print or whatever I want in or around it, and it won't
        # be executed. Is my sleepy brain missing something, or is Python
        # completely insane?

        if ENABLE_LOG:
            lfh = open(LOG_FILE, 'a')
            lfh.write(strftime('%Y-%m-%d %H:%M:%S: ') + uptime + '\n')
            lfh.close()

        print 'right now:\n'

    else:
        timediff = int(now - mtime)
        print timediff,
        if timediff == 1:
            print 'second ago:\n'
        else:
            print 'seconds ago:\n'
    print uptime

if __name__ == '__main__':
    main()