#! /usr/bin/python3
#
# This script provides parallel remote execution of commands, while having
# some special knownledge of servers that should *not* be handled in parallel.
#
# It defers terminal-handling to tmux(1).
#
# It has some targeting capacities using keywords. Commas for 'OR' and slashes
# for 'AND', ex: ext/test,saas/test/passerelle will select all external test
# servers + all passerelle servers on the SaaS.
#
# It takes any shell command and has some builtin shortcuts such as apt.update
# and apt.upgrade.
#
# Requirements: libtmux and pyyaml.

import argparse
import configparser
import os
import random
import re
import sys
import time

import libtmux
import yaml

class Server:
    def __init__(self, servername, group=''):
        self.name = servername
        self.keywords = set(re.split(r'[-_ \.]', servername + ' ' + group))

    def __repr__(self):
        return '<Server %s %r>' % (self.name, self.keywords)

    def shell(self):
        return 'ssh %s' % self.name

    def cmd(self, cmd):
        return 'ssh %s "%s"' % (self.name, cmd)


servers = []

config = configparser.ConfigParser()
config.read(os.path.join(os.path.expanduser('~/.config/eoptasks.ini')))
servergroup = config.get('config', 'servergroups', fallback=None)
if servergroup is None:
    print("You need to create ~/.config/eoptasks.ini with such a content:\n"
          "\n"
          "  [config]\n"
          "  servergroups = /home/user/src/puppet/data/servergroups.yaml\n")
    sys.exit(1)

servergroups = yaml.load(open(servergroup))['servergroups']
for group in servergroups:
    for servername in servergroups[group]:
        servers.append(Server(servername, group))

parser = argparse.ArgumentParser()
parser.add_argument('-l', '--list-servers', action='store_true')
parser.add_argument('-k', dest='keywords', type=str)
parser.add_argument('cmd', type=str, nargs='?', default=None)

args = parser.parse_args()

selected_servers = []
if args.keywords:
    for keyword in args.keywords.split(','):
        keywords = set(keyword.split('/'))
        selected_servers.extend([
            x for x in servers
            if keywords.issubset(x.keywords) and not x in selected_servers])
    for keyword in args.keywords.split(','):
        if keyword.startswith('!') or keyword.startswith('-'):
            selected_servers = [x for x in selected_servers if keyword[1:] not in x.keywords]
else:
    selected_servers = servers

if args.list_servers:
    for server in sorted(selected_servers, key=lambda x: x.name):
        print(server.name)
    sys.exit(0)

if not selected_servers:
    sys.stderr.write('No matching servers\n')
    sys.exit(1)

if not args.cmd:
    sys.stderr.write('Missing command\n')
    sys.exit(1)

cmd = {
    'apt.update': 'sudo apt update',
    'apt.upgrade': 'sudo apt update && sudo apt upgrade -y',
    'collectstatic': '''sudo -u authentic-multitenant authentic2-multitenant-manage collectstatic --noinput;
                        sudo -u bijoe bijoe-manage collectstatic --noinput;
                        sudo -u chrono chrono-manage collectstatic --noinput;
                        sudo -u combo combo-manage collectstatic --noinput;
                        sudo -u corbo corbo-manage collectstatic --noinput;
                        sudo -u fargo fargo-manage collectstatic --noinput;
                        sudo -u hobo hobo-manage collectstatic --noinput;
                        sudo -u passerelle passerelle-manage collectstatic --noinput;
                        sudo -u wcs wcs-manage collectstatic;
                        /bin/true'''.replace('\n', ''),
}.get(args.cmd, args.cmd)

tmux_session_name = 's%s' % random.randrange(1000)
os.system('tmux new-session -s %s -d /bin/bash -c "sleep 2"' % tmux_session_name)
tmux = libtmux.Server()
session = tmux.find_where({'session_name': tmux_session_name})

pid = os.fork()
if pid:
    os.system('tmux attach-session -t %s' % tmux_session_name)
else:
    def cluster_name(server_name):
        return re.match(r'(.*?)(\d*)$', server_name).group(1).replace(
                '.rbx.', '.loc.').replace('.gra.', '.loc.').replace('.sbg.', '.loc.')

    random.shuffle(selected_servers)
    while selected_servers:
        current_clusters = [cluster_name(x.name) for x in session.list_windows()]
        for server in selected_servers[:]:
            if cluster_name(server.name) in current_clusters:
                continue
            selected_servers.remove(server)
            session.new_window(
                    attach=False,
                    window_name=server.name,
                    window_shell=server.cmd(cmd))
            break
        else:
            time.sleep(0.1)
            if len(session.list_windows()) == 1:
                # a single window remains but there are still unparallelizable
                # servers to process, create temporary tmux window to avoid tmux
                # being destroyed as the last window process is over.
                session.new_window(attach=False, window_name='sleep',
                        window_shell='/bin/bash -c "sleep 2"')
        while len(session.list_windows()) > 5:
            time.sleep(0.1)