#!/usr/bin/env python
# Copyright: (c) 2017, Ansible Project
# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
from __future__ import (absolute_import, division, print_function)

__metaclass__ = type


import fcntl
import hashlib
import io
import os
import pickle
import signal
import socket
import sys
import time
import traceback
import errno
import json

from contextlib import contextmanager

from ansible import constants as C
from ansible.cli.arguments import option_helpers as opt_help
from ansible.module_utils._text import to_bytes, to_text
from ansible.module_utils.connection import Connection, ConnectionError, send_data, recv_data
from ansible.module_utils.service import fork_process
from ansible.parsing.ajson import AnsibleJSONEncoder, AnsibleJSONDecoder
from ansible.playbook.play_context import PlayContext
from ansible.plugins.loader import connection_loader, init_plugin_loader
from ansible.utils.path import unfrackpath, makedirs_safe
from ansible.utils.display import Display
from ansible.utils.jsonrpc import JsonRpcServer

display = Display()


def read_stream(byte_stream):
    size = int(byte_stream.readline().strip())

    data = byte_stream.read(size)
    if len(data) < size:
        raise Exception("EOF found before data was complete")

    data_hash = to_text(byte_stream.readline().strip())
    if data_hash != hashlib.sha1(data).hexdigest():
        raise Exception("Read {0} bytes, but data did not match checksum".format(size))

    # restore escaped loose \r characters
    data = data.replace(br'\r', b'\r')

    return data


@contextmanager
def file_lock(lock_path):
    """
    Uses contextmanager to create and release a file lock based on the
    given path. This allows us to create locks using `with file_lock()`
    to prevent deadlocks related to failure to unlock properly.
    """

    lock_fd = os.open(lock_path, os.O_RDWR | os.O_CREAT, 0o600)
    fcntl.lockf(lock_fd, fcntl.LOCK_EX)
    yield
    fcntl.lockf(lock_fd, fcntl.LOCK_UN)
    os.close(lock_fd)


class ConnectionProcess(object):
    '''
    The connection process wraps around a Connection object that manages
    the connection to a remote device that persists over the playbook
    '''
    def __init__(self, fd, play_context, socket_path, original_path, task_uuid=None, ansible_playbook_pid=None):
        self.play_context = play_context
        self.socket_path = socket_path
        self.original_path = original_path
        self._task_uuid = task_uuid

        self.fd = fd
        self.exception = None

        self.srv = JsonRpcServer()
        self.sock = None

        self.connection = None
        self._ansible_playbook_pid = ansible_playbook_pid

    def start(self, options):
        messages = list()
        result = {}

        try:
            messages.append(('vvvv', 'control socket path is %s' % self.socket_path))

            # If this is a relative path (~ gets expanded later) then plug the
            # key's path on to the directory we originally came from, so we can
            # find it now that our cwd is /
            if self.play_context.private_key_file and self.play_context.private_key_file[0] not in '~/':
                self.play_context.private_key_file = os.path.join(self.original_path, self.play_context.private_key_file)
            self.connection = connection_loader.get(self.play_context.connection, self.play_context, '/dev/null',
                                                    task_uuid=self._task_uuid, ansible_playbook_pid=self._ansible_playbook_pid)
            try:
                self.connection.set_options(direct=options)
            except ConnectionError as exc:
                messages.append(('debug', to_text(exc)))
                raise ConnectionError('Unable to decode JSON from response set_options. See the debug log for more information.')

            self.connection._socket_path = self.socket_path
            self.srv.register(self.connection)
            messages.extend([('vvvv', msg) for msg in sys.stdout.getvalue().splitlines()])

            self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
            self.sock.bind(self.socket_path)
            self.sock.listen(1)
            messages.append(('vvvv', 'local domain socket listeners started successfully'))
        except Exception as exc:
            messages.extend(self.connection.pop_messages())
            result['error'] = to_text(exc)
            result['exception'] = traceback.format_exc()
        finally:
            result['messages'] = messages
            self.fd.write(json.dumps(result, cls=AnsibleJSONEncoder))
            self.fd.close()

    def run(self):
        try:
            log_messages = self.connection.get_option('persistent_log_messages')
            while not self.connection._conn_closed:
                signal.signal(signal.SIGALRM, self.connect_timeout)
                signal.signal(signal.SIGTERM, self.handler)
                signal.alarm(self.connection.get_option('persistent_connect_timeout'))

                self.exception = None
                (s, addr) = self.sock.accept()
                signal.alarm(0)
                signal.signal(signal.SIGALRM, self.command_timeout)
                while True:
                    data = recv_data(s)
                    if not data:
                        break

                    if log_messages:
                        display.display("jsonrpc request: %s" % data, log_only=True)

                    request = json.loads(to_text(data, errors='surrogate_or_strict'))
                    if request.get('method') == "exec_command" and not self.connection.connected:
                        self.connection._connect()

                    signal.alarm(self.connection.get_option('persistent_command_timeout'))

                    resp = self.srv.handle_request(data)
                    signal.alarm(0)

                    if log_messages:
                        display.display("jsonrpc response: %s" % resp, log_only=True)

                    send_data(s, to_bytes(resp))

                s.close()

        except Exception as e:
            # socket.accept() will raise EINTR if the socket.close() is called
            if hasattr(e, 'errno'):
                if e.errno != errno.EINTR:
                    self.exception = traceback.format_exc()
            else:
                self.exception = traceback.format_exc()

        finally:
            # allow time for any exception msg send over socket to receive at other end before shutting down
            time.sleep(0.1)

            # when done, close the connection properly and cleanup the socket file so it can be recreated
            self.shutdown()

    def connect_timeout(self, signum, frame):
        msg = 'persistent connection idle timeout triggered, timeout value is %s secs.\nSee the timeout setting options in the Network Debug and ' \
              'Troubleshooting Guide.' % self.connection.get_option('persistent_connect_timeout')
        display.display(msg, log_only=True)
        raise Exception(msg)

    def command_timeout(self, signum, frame):
        msg = 'command timeout triggered, timeout value is %s secs.\nSee the timeout setting options in the Network Debug and Troubleshooting Guide.'\
              % self.connection.get_option('persistent_command_timeout')
        display.display(msg, log_only=True)
        raise Exception(msg)

    def handler(self, signum, frame):
        msg = 'signal handler called with signal %s.' % signum
        display.display(msg, log_only=True)
        raise Exception(msg)

    def shutdown(self):
        """ Shuts down the local domain socket
        """
        lock_path = unfrackpath("%s/.ansible_pc_lock_%s" % os.path.split(self.socket_path))
        if os.path.exists(self.socket_path):
            try:
                if self.sock:
                    self.sock.close()
                if self.connection:
                    self.connection.close()
                    if self.connection.get_option("persistent_log_messages"):
                        for _level, message in self.connection.pop_messages():
                            display.display(message, log_only=True)
            except Exception:
                pass
            finally:
                if os.path.exists(self.socket_path):
                    os.remove(self.socket_path)
                    setattr(self.connection, '_socket_path', None)
                    setattr(self.connection, '_connected', False)

        if os.path.exists(lock_path):
            os.remove(lock_path)

        display.display('shutdown complete', log_only=True)


def main(args=None):
    """ Called to initiate the connect to the remote device
    """

    parser = opt_help.create_base_parser(prog='ansible-connection')
    opt_help.add_verbosity_options(parser)
    parser.add_argument('playbook_pid')
    parser.add_argument('task_uuid')
    args = parser.parse_args(args[1:] if args is not None else args)
    init_plugin_loader()

    # initialize verbosity
    display.verbosity = args.verbosity

    rc = 0
    result = {}
    messages = list()
    socket_path = None

    # Need stdin as a byte stream
    stdin = sys.stdin.buffer

    # Note: update the below log capture code after Display.display() is refactored.
    saved_stdout = sys.stdout
    sys.stdout = io.StringIO()

    try:
        # read the play context data via stdin, which means depickling it
        opts_data = read_stream(stdin)
        init_data = read_stream(stdin)

        pc_data = pickle.loads(init_data, encoding='bytes')
        options = pickle.loads(opts_data, encoding='bytes')

        play_context = PlayContext()
        play_context.deserialize(pc_data)

    except Exception as e:
        rc = 1
        result.update({
            'error': to_text(e),
            'exception': traceback.format_exc()
        })

    if rc == 0:
        ssh = connection_loader.get('ssh', class_only=True)
        ansible_playbook_pid = args.playbook_pid
        task_uuid = args.task_uuid
        cp = ssh._create_control_path(play_context.remote_addr, play_context.port, play_context.remote_user, play_context.connection, ansible_playbook_pid)
        # create the persistent connection dir if need be and create the paths
        # which we will be using later
        tmp_path = unfrackpath(C.PERSISTENT_CONTROL_PATH_DIR)
        makedirs_safe(tmp_path)

        socket_path = unfrackpath(cp % dict(directory=tmp_path))
        lock_path = unfrackpath("%s/.ansible_pc_lock_%s" % os.path.split(socket_path))

        with file_lock(lock_path):
            if not os.path.exists(socket_path):
                messages.append(('vvvv', 'local domain socket does not exist, starting it'))
                original_path = os.getcwd()
                r, w = os.pipe()
                pid = fork_process()

                if pid == 0:
                    try:
                        os.close(r)
                        wfd = os.fdopen(w, 'w')
                        process = ConnectionProcess(wfd, play_context, socket_path, original_path, task_uuid, ansible_playbook_pid)
                        process.start(options)
                    except Exception:
                        messages.append(('error', traceback.format_exc()))
                        rc = 1

                    if rc == 0:
                        process.run()
                    else:
                        process.shutdown()

                    sys.exit(rc)

                else:
                    os.close(w)
                    rfd = os.fdopen(r, 'r')
                    data = json.loads(rfd.read(), cls=AnsibleJSONDecoder)
                    messages.extend(data.pop('messages'))
                    result.update(data)

            else:
                messages.append(('vvvv', 'found existing local domain socket, using it!'))
                conn = Connection(socket_path)
                try:
                    conn.set_options(direct=options)
                except ConnectionError as exc:
                    messages.append(('debug', to_text(exc)))
                    raise ConnectionError('Unable to decode JSON from response set_options. See the debug log for more information.')
                pc_data = to_text(init_data)
                try:
                    conn.update_play_context(pc_data)
                    conn.set_check_prompt(task_uuid)
                except Exception as exc:
                    # Only network_cli has update_play context and set_check_prompt, so missing this is
                    # not fatal e.g. netconf
                    if isinstance(exc, ConnectionError) and getattr(exc, 'code', None) == -32601:
                        pass
                    else:
                        result.update({
                            'error': to_text(exc),
                            'exception': traceback.format_exc()
                        })

    if os.path.exists(socket_path):
        messages.extend(Connection(socket_path).pop_messages())
    messages.append(('vvvv', sys.stdout.getvalue()))
    result.update({
        'messages': messages,
        'socket_path': socket_path
    })

    sys.stdout = saved_stdout
    if 'exception' in result:
        rc = 1
        sys.stderr.write(json.dumps(result, cls=AnsibleJSONEncoder))
    else:
        rc = 0
        sys.stdout.write(json.dumps(result, cls=AnsibleJSONEncoder))

    sys.exit(rc)


if __name__ == '__main__':
    main()
