#!/usr/bin/env python3

config_file = '/etc/minecraft.conf'
manifest_url = 'https://launchermeta.mojang.com/mc/game/version_manifest.json'

import configparser, os, os.path, zipfile, io, json, sys
import requests

cparser = configparser.ConfigParser()
with open(config_file) as f:
    # ConfigParser needs INI-style config with at least one section
    cparser.read_string('[a]\n' + f.read())

mc_dir = cparser['a']['srvdir']
build_type = cparser['a']['build_type']

mc_jar = os.path.join(mc_dir, 'server.jar')
with zipfile.ZipFile(mc_jar) as z:
    with z.open('version.json') as f:
        mc_ver_local = json.load(io.TextIOWrapper(f, 'utf-8'))['id']

all_manifest = requests.get(manifest_url).json()
mc_ver_remote = all_manifest['latest'][build_type]

if mc_ver_local != mc_ver_remote:
    print('upgrade from', mc_ver_local, 'to', mc_ver_remote)
    new_manifest_url = [x['url'] for x in all_manifest['versions'] if x['id'] == mc_ver_remote][0]
    new_manifest = requests.get(new_manifest_url).json()
    download_url = new_manifest['downloads']['server']['url']
    download_file = os.path.join('versions', mc_ver_remote + '.jar')
    download_file_full = os.path.join(mc_dir, download_file)
    resp = requests.get(download_url, stream=True)
    if resp.ok:
        with open(download_file_full, 'wb') as f:
            for chunk in resp.iter_content(None):
                f.write(chunk)
        mc_jar_new = os.path.join(mc_dir, 'server.jar.new')
        os.symlink(download_file, mc_jar_new)
        os.rename(mc_jar_new, mc_jar)
    else:
        print('download failed:', resp.status_code, file=sys.stderr)
        exit(1)