#!/usr/bin/env python3

# Example .ipxe.json:
# {
#     "date": "Thu, 21 Jan 2021 06:42:21 +0000",
#     "variant": "efi",
#     "sha512": "b4d2e517c69224bf14f79e155(...)"
# }
# They don't version the ISO, so we use the file date on the mirror listing.

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'^(?:.*/)?ipxe\.'
                           r'(?P<variant>(iso|efi))$')
    _allowed_variants = ('iso', 'efi')
    _tpl_file = 'ipxe_grub.conf.j2'
    # I think this *technically* should be '%Y-%m-%d %H:%M %z' but it seems datetime cannot parse that if %z is empty.
    _datever_fmt = '%Y-%m-%d %H:%M'

    def __init__(self,
                 variant = 'iso',
                 dest_dir = '/boot/iso',  # Should be subdir of boot_dir
                 dest_file = 'ipxe.iso',
                 ver_file = '.ipxe.json',
                 lock_path = '/tmp/.ipxe.lck',
                 dl_base = 'https://boot.ipxe.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_ipxe',
                 # check_gpg = True,  # TODO: GPG sig checking, http://mirror.rit.edu/grml//gnupg-michael-prokop.txt
                 # hash_type = 'sha512'):
                 ):
        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()
        if self.variant == 'efi':
            dest_file = dest_file.replace('.iso', '.efi')
        super().__init__(dest_dir,
                         dest_file,
                         ver_file,
                         lock_path,
                         do_grub_cfg,
                         boot_dir,
                         grub_cfg,
                         hash_type = 'sha512')
        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
            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_hash = ver_info.get(self.hash_type)
        self.old_ver = datetime.datetime.strptime(ver_info['ver'], self._datever_fmt)
        self.variant = ver_info.get('variant', self.variant)
        # We do this to avoid the hash check in _base.BaseUpdater.download()
        self._new_hash = self.old_hash
        self.new_date = self.old_date
        self.new_ver = self.old_ver
        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):
        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'))
        # This is a little hacky.
        filelist = html.find('table')
        # Get the header, and the index for the proper columns.
        file_col = 0
        date_col = 0
        header = filelist.find('tr')
        # Icon, Name, Modified, Size, Description
        file_len = len(header.find_all('th'))
        if header is None:
            raise RuntimeError('Could not find header row')
        for idx, cell in enumerate(header.find_all('th')):
            link = cell.find('a')
            if link is None:
                continue
            # At least the header columns have predictable links (for sorting).
            if link['href'] == '?C=N;O=D':  # Name
                file_col = idx
                continue
            if link['href'] == '?C=M;O=A':  # Last Modified
                date_col = idx
        for idx, row in enumerate(filelist.find_all('tr')):
            if idx == 0:  # Header; skip.
                continue
            cells = row.find_all('td')
            if len(cells) != file_len:
                continue
            name_html = cells[file_col]
            date_html = cells[date_col]
            if not all((name_html, date_html)):
                continue
            date = datetime.datetime.strptime(date_html.text.strip(), self._datever_fmt)
            name_link = name_html.find('a')
            if name_link is None:
                continue
            name = name_link.text
            fname_r = self._fname_re.search(name)
            if not fname_r:
                continue
            f_variant = fname_r.groupdict()['variant']
            if f_variant != self.variant:
                continue
            self.new_ver = date
            self.iso_url = os.path.join(self.dl_base, name_link['href'].replace(self.dl_base, ''))
        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)
        return(None)

    def updateVer(self):
        if self.getRunning():
            return(None)
        if any((self.do_update, self.force_update)):
            self._new_hash = self.getISOHash()
        d = {'date': self.new_date.strftime(self._date_fmt),
             'variant': self.variant,
             'ver': self.new_ver.strftime(self._datever_fmt),
             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()