import os
import shutil
import socket
import tempfile

from .git import GitRepo

from tftp.backend import IWriter
from twisted.python import log
from zope.interface import implementer


@implementer(IWriter)
class GitWriter(object):
    def __init__(self, file_path, repo, remote):
        file_dir = file_path.parent()
        if not file_dir.exists():
            file_dir.makedirs()

        self.file_path = file_path
        self.temp_destination = tempfile.TemporaryFile()
        self.repo = os.path.abspath(repo)
        self.remote = remote
        self.state = 'active'

    def _get_hostname(self, remote):
        try:
            flags = socket.NI_DGRAM | socket.NI_NOFQDN | socket.NI_NAMEREQD
            (host, _) = socket.getnameinfo(remote, flags)
        except:
            (host, _) = remote
        return host

    def _do_git_commit(self):
        git_repo = GitRepo(self.repo)
        git_repo.stage([self.file_path.path])

        if not git_repo.has_changed():
            return

        msg = 'Automatic commit after tftp upload'
        if self.remote is not None:
            msg += ' from %s' % self._get_hostname(self.remote)
        committer = 'Backup Server <backup@spline.inf.fu-berlin.de>'
        git_repo.commit(msg, committer)
        git_repo.push('origin')

    def write(self, data):
        self.temp_destination.write(data)

    def finish(self):
        if self.state not in ('finished', 'cancelled'):
            self.destination_file = self.file_path.open('w')
            self.temp_destination.seek(0)
            shutil.copyfileobj(self.temp_destination, self.destination_file)
            self.temp_destination.close()
            self.destination_file.close()

            self._do_git_commit()
            self.state = 'finished'

    def cancel(self):
        if self.state not in ('finished', 'cancelled'):
            self.temp_destination.close()
            self.state = 'cancelled'