#!/usr/bin/env python

import datetime
import os
import re
import subprocess
import shutil
import sys
import urllib2

src_zip = os.path.join(os.getenv('HOME'), '__fab_src__.zip')
src_dir = os.path.join(os.getenv('HOME'), '__fab_src__')

# Check when this script was installed
my_date = datetime.datetime.fromtimestamp(os.path.getmtime(sys.argv[0]))

def get_date():
    '''Extracts the snapshot date from the kokompe downloads page.'''
    html = urllib2.urlopen('http://kokompe.cba.mit.edu/downloads.html').read()
    date = re.search('Snapshot from ([^\)]*)', html).group(1)
    return datetime.datetime.strptime(date, '%B %d, %Y, %I:%M%p')

def download():
    '''Downloads fab_src.zip, saving it in the user's home directory.'''
    if os.path.isfile(src_zip):
        print '''Error: Working file ~/__fab_src__.zip already exists.
Please delete it then rerun fab_update.'''
        sys.exit(1)
    zip = urllib2.urlopen('http://kokompe.cba.mit.edu/fab_src.zip')
    open(src_zip,'wb').write(zip.read())

def unzip():
    '''Unzips fab_src.zip then removes the zip file.'''
    if os.path.isdir(src_dir):
        print '''Error: Working directory ~/__fab_src__ already exists.
Please delete it then rerun fab_update'''
        sys.exit(1)
    os.mkdir(src_dir)
    os.chdir(src_dir)
    subprocess.call(['unzip', src_zip])
    os.remove(src_zip)

def print_help():
    print '''command line: fab_update [check|install]
   check will inform you if a newer version of the fab modules is available.
   install will install a newer version of the fab modules, if applicable.'''

if __name__ == '__main__':
    if len(sys.argv) == 1:
        print_help()
        sys.exit(1)

    # Check the date on the web to figure out if it is newer.
    web_date = get_date()
    date_info = '''  Your version was installed %s
  Online version is dated %s''' % (my_date.strftime('%B %d, %Y, %I:%M%p'),
                                   web_date.strftime('%B %d, %Y, %I:%M%p'))
    outdated = web_date > my_date

    # Check to see if the web version is newer than our version.
    if sys.argv[1] == 'check':
        web_date = get_date()
        if outdated:
            print 'Newer version is available:\n%s' % date_info
        else:
            print 'No newer version available:\n%s' % date_info

    # Download & install if the web version is newer than this version
    elif sys.argv[1] == 'install':
        web_date = get_date()
        if not outdated:
            print 'No newer version available:\n%s' % date_info
            sys.exit(0)
        print "Downloading source"
        download()
        print "Unzipping source"
        unzip()
        print "Installing"
        if subprocess.call(['make','fab']) != 0:
            print 'Build failed.  Please make sure your dependancies are up-to-date.'
            shutil.rmtree(src_dir)
            sys.exit(1)
        subprocess.call(['make','install'])
        shutil.rmtree(src_dir)

    # Invalid option
    else:
        print 'Invalid option "%s"' % ' '.join(sys.argv[1:])
        print_help()
        sys.exit(1)