import gpg
import os
import psutil
import gpg.errors

# http://files.au.adversary.org/crypto/GPGMEpythonHOWTOen.html
# https://www.gnupg.org/documentation/manuals/gpgme.pdf

class GPGHandler(object):
    def __init__(self, gnupg_homedir = None, key_id = None, keyservers = None):
        self.home = gnupg_homedir
        self.key_id = key_id
        self.keyservers = keyservers
        if self.home:
            self._prep_home()
        else:
            self._check_home()
        self.ctx = self.get_context(home_dir = self.home)

    def _check_home(self, home = None):
        if not home:
            home = self.home
        if not home:
            self.home = os.environ.get('GNUPGHOME', '~/.gnupg')
            home = self.home
        self._prep_home(home)
        return()

    def _prep_home(self, home = None):
        if not home:
            home = self.home
        if not home:
            self.home = os.environ.get('GNUPGHOME', '~/.gnupg')
        self.home = os.path.abspath(os.path.expanduser(self.home))
        if os.path.isdir(self.home):
            _exists = True
        else:
            _exists = False
        _uid = os.getuid()
        _gid = os.getgid()
        try:
            os.makedirs(self.home, exist_ok = True)
            os.chown(self.home, _uid, _gid)
            os.chmod(self.home, 0o700)
        except PermissionError:
            # It's alright; it's HOPEFULLY already created.
            if not _exists:
                raise PermissionError('We need a GnuPG home directory we can '
                                      'write to')
        return()

    def get_context(self, **kwargs):
        ctx = gpg.Context(**kwargs)
        return(ctx)

    def kill_stale_agent(self):
        _process_list = []
        # TODO: optimize; can I search by proc name?
        for p in psutil.process_iter():
            if (p.name() in ('gpg-agent', 'dirmngr') and \
                                                p.uids()[0] == os.getuid()):
                pd = psutil.Process(p.pid).as_dict()
                # TODO: convert these over
#                for d in (chrootdir, dlpath):
#                    if pd['cwd'].startswith('{0}'.format(d)):
#                        plst.append(p.pid)
#        if len(plst) >= 1:
#            for p in plst:
#                psutil.Process(p).terminate()

    def get_sigs(self, data_in):
        key_ids = []
        # Currently as of May 13, 2018 there's no way using the GPGME API to do
        # the equivalent of the CLI's --list-packets.
        # https://lists.gnupg.org/pipermail/gnupg-users/2018-January/
        #                                                           059708.html
        # https://lists.gnupg.org/pipermail/gnupg-users/2018-January/
        #                                                           059715.html
        # We use the "workaround in:
        # https://lists.gnupg.org/pipermail/gnupg-users/2018-January/
        #                                                           059711.html
        try:
            self.ctx.verify(data_in)
        except gpg.errors.BadSignatures as sig_except:
            for line in [i.strip() for i in str(sig_except).splitlines()]:
                l = [i.strip() for i in line.split(':')]
                key_ids.append(l[0])
        return(key_ids)