# Copyright © 2015-2016 Nick Bowler
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY of FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>

import time
import email.utils
import logging
import contextlib

import portage
from portage import os
from portage.util import writemsg_level
from portage.process import spawn
from portage.sync.syncbase import NewBase

# Determine snapshot date.  While timestamps from snapshots indicate
# early in the day (UTC), filenames indicate the previous day (snapshot
# at end of day).  Simply subtract 4 hours before calculating the day
# to accomodate this difference, assuming snapshot generation is faster
# than that.
def repo_date(repo):
    with open(repo.sync_uri + '/metadata/timestamp.chk', 'r') as f:
        timestamp = f.readline()
    repotime  = email.utils.mktime_tz(email.utils.parsedate_tz(timestamp))
    return time.strftime("%Y%m%d", time.gmtime(repotime - 4*3600))

def repo_filename(repo):
    opts = repo.module_specific_options
    return '%s/%s-%s.sqfs' % (opts['squash-cache-location'],
                              repo.name, repo_date(repo))

class SquashMirror(NewBase):
    def __init__(self):
        NewBase.__init__(self, 'mksquashfs', 'sys-fs/squashfs-tools')

    def msg(self, msg, level=0, noiselevel=0):
        self.logger(self.xterm_titles, msg)
        writemsg_level(msg + "\n", level, noiselevel)

    def err(self, msg, level=0, noiselevel=0):
        self.msg("!!! " + msg, level=logging.ERROR, noiselevel=-1)

    def exists(self, **kwargs):
        if kwargs:
            self._kwargs(kwargs)
        elif not self.repo:
            return False
        if not os.path.exists(repo_filename(self.repo)):
            return False
        return True;

    def new(self, **kwargs):
        opts = self.repo.module_specific_options
        filename = repo_filename(self.repo)
        self.msg("Creating squashfs image " + filename)

        args = [self.bin_command]
        args.extend([self.repo.sync_uri, filename])
        args.extend(['-no-xattrs'])
        args.extend(['-force-uid', 'portage', '-force-gid', 'portage'])
        args.extend(['-comp', opts['squash-compression']])
        args.extend(opts['squash-extra-opts'].split())

        rc = spawn(args, **self.spawn_kwargs)
        if rc != os.EX_OK:
            self.err("command failed: %s" % " ".join(args))
            return (rc, False)

        symlink = "%s/%s-current.sqfs" % (opts['squash-cache-location'],
                                          self.repo.name)

        with contextlib.suppress(FileNotFoundError):
            os.remove(symlink)
        os.symlink(os.path.basename(filename), symlink)
        return (0, True)

    def update(self, **kwargs):
        filename = repo_filename(self.repo)
        self.err("%s already exists; exiting." % filename);
        return (1, False)