# Based on local.py (c) 2012, Michael DeHaan <michael.dehaan@gmail.com>
# (c) 2013, Maykel Moya <mmoya@speedyrails.com>
# (c) 2015, Toshio Kuratomi <tkuratomi@ansible.com>
#
# This file is part of Ansible
#
# Ansible 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 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or 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 Ansible.  If not, see <http://www.gnu.org/licenses/>.
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

import distutils.spawn
import os
import shlex
import subprocess
import traceback

from ansible import constants as C
from ansible.errors import AnsibleError
from ansible.plugins.connection import ConnectionBase
from ansible.module_utils.basic import is_executable
from ansible.utils.unicode import to_bytes


BUFSIZE = 65536


class Connection(ConnectionBase):
    ''' Local chroot based connections '''

    has_pipelining = True
    transport = 'chroot'
    # su currently has an undiagnosed issue with calculating the file
    # checksums (so copy, for instance, doesn't work right)
    # Have to look into that before re-enabling this
    become_methods = frozenset(C.BECOME_METHODS).difference(('su',))

    def __init__(self, play_context, new_stdin, *args, **kwargs):

        super(Connection, self).__init__(play_context, new_stdin, *args, **kwargs)

        self.chroot = self._play_context.remote_addr

        if os.geteuid() != 0:
            raise AnsibleError("chroot connection requires running as root")

        # we're running as root on the local system so do some
        # trivial checks for ensuring 'host' is actually a chroot'able dir
        if not os.path.isdir(self.chroot):
            raise AnsibleError("%s is not a directory" % self.chroot)

        chrootsh = os.path.join(self.chroot, 'bin/sh')
        if not is_executable(chrootsh):
            raise AnsibleError("%s does not look like a chrootable dir (/bin/sh missing)" % self.chroot)

        self.chroot_cmd = distutils.spawn.find_executable('chroot')
        if not self.chroot_cmd:
            raise AnsibleError("chroot command not found in PATH")

    def _connect(self):
        ''' connect to the chroot; nothing to do here '''
        super(Connection, self)._connect()
        self._display.vvv("THIS IS A LOCAL CHROOT DIR", host=self.chroot)

    def _generate_cmd(self, cmd, executable):
        # subprocess takes byte strings
        local_cmd = [self.chroot_cmd, self.chroot, executable, '-c']
        local_cmd.append(cmd)
        return local_cmd

    def _buffered_exec_command(self, cmd, in_data=None, sudoable=False, stdin=subprocess.PIPE):
        ''' run a command on the chroot.  This is only needed for implementing
        put_file() get_file() so that we don't have to read the whole file
        into memory.

        compared to exec_command() it looses some niceties like being able to
        return the process's exit code immediately.
        '''
        executable = C.DEFAULT_EXECUTABLE.split()[0] if C.DEFAULT_EXECUTABLE else '/bin/sh'
        local_cmd = self._generate_cmd(cmd, executable)

        self._display.vvv("EXEC %s" % (local_cmd), host=self.chroot)
        # FIXME: cwd= needs to be set to the basedir of the playbook, which
        #        should come from loader, but is not in the connection plugins
        p = subprocess.Popen(local_cmd, shell=False, stdin=stdin,
                stdout=subprocess.PIPE, stderr=subprocess.PIPE)

        return p

    def exec_command(self, cmd, in_data=None, sudoable=False):
        ''' run a command on the chroot '''
        super(Connection, self).exec_command(cmd, in_data=in_data, sudoable=sudoable)

        p = self._buffered_exec_command(cmd, in_data, sudoable)

        stdout, stderr = p.communicate(in_data)
        return (p.returncode, stdout, stderr)

    def put_file(self, in_path, out_path):
        ''' transfer a file from local to chroot '''
        super(Connection, self).put_file(in_path, out_path)

        self._display.vvv("PUT %s TO %s" % (in_path, out_path), host=self.chroot)

        try:
            with open(in_path, 'rb') as in_file:
                try:
                    p = self._buffered_exec_command('dd of=%s bs=%s' % (out_path, BUFSIZE), stdin=in_file)
                except OSError:
                    raise AnsibleError("chroot connection requires dd command in the chroot")
                try:
                    stdout, stderr = p.communicate()
                except:
                    traceback.print_exc()
                    raise AnsibleError("failed to transfer file %s to %s" % (in_path, out_path))
                if p.returncode != 0:
                    raise AnsibleError("failed to transfer file %s to %s:\n%s\n%s" % (in_path, out_path, stdout, stderr))
        except IOError:
            raise AnsibleError("file or module does not exist at: %s" % in_path)

    def fetch_file(self, in_path, out_path):
        ''' fetch a file from chroot to local '''
        super(Connection, self).fetch_file(in_path, out_path)

        self._display.vvv("FETCH %s TO %s" % (in_path, out_path), host=self.chroot)

        try:
            p = self._buffered_exec_command('dd if=%s bs=%s' % (in_path, BUFSIZE))
        except OSError:
            raise AnsibleError("chroot connection requires dd command in the chroot")

        with open(out_path, 'wb+') as out_file:
            try:
                chunk = p.stdout.read(BUFSIZE)
                while chunk:
                    out_file.write(chunk)
                    chunk = p.stdout.read(BUFSIZE)
            except:
                traceback.print_exc()
                raise AnsibleError("failed to transfer file %s to %s" % (in_path, out_path))
            stdout, stderr = p.communicate()
            if p.returncode != 0:
                raise AnsibleError("failed to transfer file %s to %s:\n%s\n%s" % (in_path, out_path, stdout, stderr))

    def close(self):
        ''' terminate the connection; nothing to do here '''
        pass