#!/usr/bin/env python
import subprocess
import os
import tempfile
import pprint
import json

from socket import getaddrinfo

# all changes mean we should regen the file
memcached_ips = []
rl = subprocess.Popen("relation-list",stdout=subprocess.PIPE)
for memcached_unit in rl.stdout:
    p = subprocess.Popen(["relation-get", "--format", "json", "-", memcached_unit.strip()],
            stdout=subprocess.PIPE, close_fds=True)
    settings = json.loads(p.stdout.read().strip())
    try:
        if 'private-address' in settings and 'port' in settings:
            memcached_ips.append("'%s:%d'" % getaddrinfo(settings['private-address'],int(settings['port']))[0][4][0:2])
    except KeyError:
        print memcached_unit + " has no settings. ["+str(settings)+"]"

rl.wait()

pprint.pprint(memcached_ips)

memcache_template = """<?php
$wgMainCacheType = CACHE_MEMCACHED;
$wgMemCachedServers = array(%s);
$wgSessionsInMemcached = true;
"""

with tempfile.NamedTemporaryFile(dir='/etc/mediawiki',delete=False) as settings:
    subprocess.call(["chmod","0644",settings.name])
    if len(memcached_ips):
        settings.write(memcache_template % ','.join(memcached_ips))
    else:
        settings.write("<?php\n#No Memcached Servers\n")

    try:
        os.unlink('/etc/mediawiki/memcached_settings.php.old')
    except:
        pass
    os.rename('/etc/mediawiki/memcached_settings.php','/etc/mediawiki/memcached_settings.php.old')
    os.rename(settings.name, '/etc/mediawiki/memcached_settings.php')