#!/usr/bin/env python3

# Example .grml.json:
# {
#     "date": "Thu, 21 Jan 2021 06:42:21 +0000",
#     "arch": "64",
#     "ver": 2020.06,
#     "sha512": "b4d2e517c69224bf14f79e155(...)"
# }

import datetime
import json
import os
import re
##
import requests
from bs4 import BeautifulSoup
##
import _base

try:
    import lxml
    _has_lxml = True
except ImportError:
    _has_lxml = False


class Updater(_base.BaseUpdater):
    _fname_re = re.compile(r'^(?:.*/)?grml(?P<arch>(32|64|96))-'
                           r'(?P<variant>(small|full))_'
                           r'(?P<version>[0-9]{4}\.[0-9]{2}).iso$')
    _def_hash = 'md5'
    _allowed_hashes = ('md5', 'sha1', 'sha256', 'sha512')
    _allowed_arches = ('32', '64', '96')  # 32-bit, 64-bit, both in one ISO
    _allowed_variants = ('small', 'full')
    _tpl_file = 'grml_grub.conf.j2'
    _datever_fmt = '%Y.%m'

    def __init__(self,
                 arch = '64',
                 variant = 'full',
                 dest_dir = '/boot/iso',  # Should be subdir of boot_dir
                 dest_file = 'grml.iso',
                 ver_file = '.grml.json',
                 lock_path = '/tmp/.grml.lck',
                 dl_base = 'https://download.grml.org/',
                 do_grub_cfg = True,
                 boot_dir = '/boot',  # ESP or boot partition mount; where GRUB files are installed *under*
                 grub_cfg = '/etc/grub.d/40_custom_grml',
                 # check_gpg = True,  # TODO: GPG sig checking, http://mirror.rit.edu/grml//gnupg-michael-prokop.txt
                 hash_type = 'sha512'):
        super().__init__(dest_dir, dest_file, ver_file, lock_path, do_grub_cfg, boot_dir, grub_cfg, hash_type)
        if arch.lower() not in self._allowed_arches:
            raise ValueError('arch must be one of: {0}'.format(', '.join(self._allowed_arches)))
        else:
            self.arch = arch.lower()
        if hash_type.lower() not in self._allowed_hashes:
            raise ValueError('hash_type must be one of: {0}'.format(', '.join(self._allowed_hashes)))
        else:
            self.hash_type = hash_type.lower()
        if variant not in self._allowed_variants:
            raise ValueError('variant must be one of: {0}'.format(', '.join(self._allowed_variants)))
        else:
            self.variant = variant.lower()
        self.dl_base = dl_base
        self._init_vars()

    def _init_vars(self):
        if self.getRunning():
            return(None)
        self.getCurVer()
        self.getNewVer()
        return(None)

    def getCurVer(self):
        if self.getRunning():
            return(None)
        if not os.path.isfile(self.dest_ver):
            self.do_update = True
            self.force_update = True
            self.old_ver = 0.00
            return(None)
        with open(self.dest_ver, 'rb') as fh:
            ver_info = json.load(fh)
        self.old_date = datetime.datetime.strptime(ver_info['date'], self._date_fmt)
        self.old_ver = ver_info['ver']
        self.old_hash = ver_info.get(self.hash_type, self._def_hash)
        self.variant = ver_info.get('variant', self.variant)
        self.new_hash = self.old_hash
        self.new_ver = self.old_ver
        self.new_date = self.old_date
        if ver_info.get('arch') != self.arch:
            self.do_update = True
            self.force_update = True
            return(None)
        if not os.path.isfile(self.dest_iso):
            self.do_update = True
            self.force_update = True
            return(None)
        realhash = self.getISOHash()
        if self.old_hash != realhash:
            self.do_update = True
            self.force_update = True
            return(None)
        return(None)

    def getNewVer(self):
        # We could do this a lot more reliably if the mirrors all had the same HTML.
        if self.getRunning():
            return(None)
        req = requests.get(self.dl_base, headers = {'User-Agent': 'curl/7.74.0'})
        if not req.ok:
            raise RuntimeError('Received non-200/30x {0} for {1}'.format(req.status_code, self.dl_base))
        html = BeautifulSoup(req.content.decode('utf-8'), ('lxml' if _has_lxml else 'html.parser'))
        # versions = dict of versions[ver]: (hash_url, iso_url)
        versions = {}
        for link in html.find_all('a'):
            fname_r = self._fname_re.search(link['href'])
            if not fname_r:
                continue
            ver_info = fname_r.groupdict()
            if ver_info['arch'] != self.arch:
                continue
            if ver_info['variant'] != self.variant:
                continue
            new_ver = float(ver_info.get('version', self.old_ver))
            iso_url = os.path.join(self.dl_base, link['href'].replace(self.dl_base, ''))
            hash_url = '{0}.{1}'.format(iso_url, self.hash_type)
            newver_info = (hash_url, iso_url)
            versions[new_ver] = newver_info
        self.new_ver = sorted(list(versions.keys()))[-1]
        if not all((self.old_ver, self.old_date)) or \
                    (self.new_ver > self.old_ver):
            self.do_update = True
            self.new_date = datetime.datetime.now(datetime.timezone.utc)
            hash_url, self.iso_url = versions[self.new_ver]
            req = requests.get(hash_url, headers = {'User-Agent': 'curl/7.74.0'})
            if not req.ok:
                raise RuntimeError('Received non-200/30x {0} for {1}'.format(req.status_code, hash_url))
            self.new_hash = req.content.decode('utf-8').lower().split()[0]
        return(None)

    def updateVer(self):
        if self.getRunning():
            return(None)
        d = {'date': self.new_date.strftime(self._date_fmt),
             'arch': self.arch,
             'ver': self.new_ver,
             'variant': self.variant,
             self.hash_type: self.new_hash}
        j = json.dumps(d, indent = 4)
        with open(self.dest_ver, 'w') as fh:
            fh.write(j)
            fh.write('\n')
        os.chmod(self.dest_ver, 0o0644)
        return(None)


if __name__ == '__main__':
    u = Updater()
    u.main()