"""High level ssh library.

Usage examples:

Execute command and get output:

    ssh = sshclient.SSH("root", "example.com", port=33)
    status, stdout, stderr = ssh.execute("ps ax")
    if status:
        raise Exception("Command failed with non-zero status.")
    print(stdout.splitlines())

Execute command with huge output:

    class PseudoFile(io.RawIOBase):
        def write(chunk):
            if "error" in chunk:
                email_admin(chunk)

    ssh = SSH("root", "example.com")
    with PseudoFile() as p:
        ssh.run("tail -f /var/log/syslog", stdout=p, timeout=False)

Execute local script on remote side:

    ssh = sshclient.SSH("user", "example.com")

    with open("~/myscript.sh", "r") as stdin_file:
        status, out, err = ssh.execute('/bin/sh -s "arg1" "arg2"',
                                       stdin=stdin_file)

Upload file:

    ssh = SSH("user", "example.com")
    # use rb for binary files
    with open("/store/file.gz", "rb") as stdin_file:
        ssh.run("cat > ~/upload/file.gz", stdin=stdin_file)

"""
from __future__ import print_function
#import io
import logging
import os
import re
import select
import socket
import time

import paramiko
#from oslo_utils import encodeutils
from scp import SCPClient
import six

NON_NONE_DEFAULT = object()

def try_int(s, *args):
    """Convert to integer if possible."""
    #pylint: disable=invalid-name
    try:
        return int(s)
    except (TypeError, ValueError):
        return args[0] if args else s

class SSH():
    """Represent ssh connection."""
    #pylint: disable=no-member

    SSH_PORT = paramiko.config.SSH_PORT
    DEFAULT_WAIT_TIMEOUT = 120

    @staticmethod
    def gen_keys(key_filename, bit_count=2048):
        """
        Generate Keys
        """
        rsa_key = paramiko.RSAKey.generate(bits=bit_count, progress_func=None)
        rsa_key.write_private_key_file(key_filename)
        print("Writing %s ..." % key_filename)
        with open('.'.join([key_filename, "pub"]), "w") as pubkey_file:
            pubkey_file.write(rsa_key.get_name())
            pubkey_file.write(' ')
            pubkey_file.write(rsa_key.get_base64())
            pubkey_file.write('\n')

    @staticmethod
    def get_class():
        """
        Get Class object
        """
        # must return static class name, anything else
        # refers to the calling class
        # i.e. the subclass, not the superclass
        return SSH

    @classmethod
    def get_arg_key_map(cls):
        """
        Get Key Map
        """
        return {
            'user': ('user', NON_NONE_DEFAULT),
            'host': ('ip', NON_NONE_DEFAULT),
            'port': ('ssh_port', cls.SSH_PORT),
            'pkey': ('pkey', None),
            'key_filename': ('key_filename', None),
            'password': ('password', None),
            'name': ('name', None),
        }

    #pylint: disable=too-many-arguments
    def __init__(self, user, host, port=None, pkey=None,
                 key_filename=None, password=None, name=None):
        """Initialize SSH client.
        :param user: ssh username
        :param host: hostname or ip address of remote ssh server
        :param port: remote ssh port
        :param pkey: RSA or DSS private key (not supported)
        :param key_filename: private key filename
        :param password: password
        """
        self.name = name
        if name:
            self.log = logging.getLogger(__name__ + '.' + self.name)
        else:
            self.log = logging.getLogger(__name__)

        self.wait_timeout = self.DEFAULT_WAIT_TIMEOUT
        self.user = user
        self.host = host
        # everybody wants to debug this in the caller, do it here instead
        self.log.debug("user:%s host:%s", user, host)

        # we may get text port from YAML, convert to int
        self.port = try_int(port, self.SSH_PORT)
        self.pkey = pkey
        self.password = password
        self.key_filename = key_filename
        self._client = False
        # paramiko loglevel debug will output ssh protocl debug
        # we don't ever really want that unless we are debugging paramiko
        # ssh issues
        if os.environ.get("PARAMIKO_DEBUG", "").lower() == "true":
            logging.getLogger("paramiko").setLevel(logging.DEBUG)
        else:
            logging.getLogger("paramiko").setLevel(logging.WARN)

    @property
    def is_connected(self):
        """
        Return true if connected
        """
        return bool(self._client)

    def _get_client(self):
        """
        Get Client object
        """
        if self.is_connected:
            return self._client
        try:
            self._client = paramiko.SSHClient()
            self._client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
            self._client.connect(self.host, username=self.user,
                                 port=self.port, pkey=self.pkey,
                                 key_filename=self.key_filename,
                                 password=self.password,
                                 allow_agent=False, look_for_keys=False,
                                 timeout=1)
            return self._client
        except (paramiko.BadHostKeyException,
                paramiko.AuthenticationException,
                paramiko.ChannelException,
                paramiko.SSHException,
                socket.error) as error:
            message = ("Exception %(exception_type)s was raised "
                       "during connect. Exception value is: %(exception)r" %
                       {"exception": error, "exception_type": type(error)})
            self._client = False
            print(message)

    def close(self):
        """
        Close connection
        """
        if self._client:
            self._client.close()
            self._client = False

    #pylint: disable=too-many-arguments
    def run(self, cmd, stdin=None, stdout=None, stderr=None,
            raise_on_error=True, timeout=3600,
            keep_stdin_open=False, pty=False):
        """Execute specified command on the server.

        :param cmd:             Command to be executed.
        :type cmd:              str
        :param stdin:           Open file or string to pass to stdin.
        :param stdout:          Open file to connect to stdout.
        :param stderr:          Open file to connect to stderr.
        :param raise_on_error:  If False then exit code will be return. If True
                                then exception will be raized if non-zero code.
        :param timeout:         Timeout in seconds for command execution.
                                Default 1 hour. No timeout if set to 0.
        :param keep_stdin_open: don't close stdin on empty reads
        :type keep_stdin_open:  bool
        :param pty:             Request a pseudo terminal for this connection.
                                This allows passing control characters.
                                Default False.
        :type pty:              bool
        """

        client = self._get_client()

        if isinstance(stdin, six.string_types):
            stdin = six.moves.StringIO(stdin)

        return self._run(client, cmd, stdin=stdin, stdout=stdout,
                         stderr=stderr, raise_on_error=raise_on_error,
                         timeout=timeout,
                         keep_stdin_open=keep_stdin_open, pty=pty)

    #pylint: disable=too-many-arguments,too-many-nested-blocks
    def _run(self, client, cmd, stdin=None, stdout=None, stderr=None,
             raise_on_error=True, timeout=3600,
             keep_stdin_open=False, pty=False):
        """
        Actual Run function (internal)
        """

        transport = client.get_transport()
        session = transport.open_session()
        if pty:
            session.get_pty()
        session.exec_command(cmd)
        start_time = time.time()

        # encode on transmit, decode on receive
        #data_to_send = encodeutils.safe_encode("", incoming='utf-8')
        data_to_send = "".encode('utf-8', 'strict')
        stderr_data = None

        # If we have data to be sent to stdin then `select' should also
        # check for stdin availability.
        if stdin and not stdin.closed:
            writes = [session]
        else:
            writes = []

        while True:
            # Block until data can be read/write.
            expe = select.select([session], writes, [session], 1)[2]

            if session.recv_ready():
                #data = encodeutils.safe_decode(session.recv(4096), 'utf-8')
                data = session.recv(8192).decode('utf-8', 'strict')
                self.log.debug("stdout: %r", data)
                if stdout is not None:
                    stdout.write(data)
                continue

            if session.recv_stderr_ready():
                #stderr_data = encodeutils.safe_decode(
                #    session.recv_stderr(4096), 'utf-8')
                stderr_data = session.recv_stderr(4096).decode(
                    'utf=8', 'strict')
                self.log.debug("stderr: %r", stderr_data)
                if stderr is not None:
                    stderr.write(stderr_data)
                continue

            if session.send_ready():
                if stdin is not None and not stdin.closed:
                    if not data_to_send:
                        stdin_txt = stdin.read(4096)
                        if stdin_txt is None:
                            stdin_txt = ''
                        #data_to_send = encodeutils.safe_encode(
                        #    stdin_txt, incoming='utf-8')
                        data_to_send = stdin_txt.encode('utf-8', 'strict')
                        if not data_to_send:
                            # we may need to keep stdin open
                            if not keep_stdin_open:
                                stdin.close()
                                session.shutdown_write()
                                writes = []
                    if data_to_send:
                        sent_bytes = session.send(data_to_send)
                        # LOG.debug("sent: %s" % data_to_send[:sent_bytes])
                        data_to_send = data_to_send[sent_bytes:]

            if session.exit_status_ready():
                break

            if timeout and (time.time() - timeout) > start_time:
                message = ('Timeout executing command %(cmd)s on host %(host)s'
                           % {"cmd": cmd, "host": self.host})
                raise socket.timeout(message)
            if expe:
                raise paramiko.SSHException('Socket error')

        exit_status = session.recv_exit_status()
        if exit_status != 0 and raise_on_error:
            fmt = "Command '%(cmd)s' failed with exit_status %(status)d."
            details = fmt % {"cmd": cmd, "status": exit_status}
            if stderr_data:
                details += " Last stderr data: '%s'." % stderr_data
            raise paramiko.SSHException(details)
        return exit_status

    def execute(self, cmd, stdin=None, timeout=3600, raise_on_error=False):
        """Execute the specified command on the server.

        :param cmd: (str)             Command to be executed.
        :param stdin: (StringIO)      Open file to be sent on process stdin.
        :param timeout: (int)         Timeout for execution of the command.
        :param raise_on_error: (bool) If True, then an SSHError will be raised
                                      when non-zero exit code.

        :returns: tuple (exit_status, stdout, stderr)
        """
        stdout = six.moves.StringIO()
        stderr = six.moves.StringIO()

        exit_status = self.run(cmd, stderr=stderr,
                               stdout=stdout, stdin=stdin,
                               timeout=timeout, raise_on_error=raise_on_error)
        stdout.seek(0)
        stderr.seek(0)
        return exit_status, stdout.read(), stderr.read()


    def put(self, files, remote_path=b'.', recursive=False):
        """
        Push Files to remote
        """
        client = self._get_client()

        with SCPClient(client.get_transport()) as scp:
            scp.put(files, remote_path, recursive)

    def get(self, remote_path, local_path='/tmp/', recursive=True):
        """
        Get Files from remote
        """
        client = self._get_client()

        with SCPClient(client.get_transport()) as scp:
            scp.get(remote_path, local_path, recursive)

    # keep shell running in the background, e.g. screen
    def send_command(self, command):
        """
        Execute in Background
        """
        client = self._get_client()
        client.exec_command(command, get_pty=True)

    def _put_file_sftp(self, localpath, remotepath, mode=None):
        """
        Transfer file (internal)
        """
        client = self._get_client()

        with client.open_sftp() as sftp:
            sftp.put(localpath, remotepath)
            if mode is None:
                mode = 0o777 & os.stat(localpath).st_mode
            sftp.chmod(remotepath, mode)

    TILDE_EXPANSIONS_RE = re.compile("(^~[^/]*/)?(.*)")

    def _put_file_shell(self, localpath, remotepath, mode=None):
        # quote to stop wordpslit
        """
        Transfer file (Internal) by ssh
        """
        tilde, remotepath = self.TILDE_EXPANSIONS_RE.match(remotepath).groups()
        if not tilde:
            tilde = ''
        cmd = ['cat > %s"%s"' % (tilde, remotepath)]
        if mode is not None:
            # use -- so no options
            cmd.append('chmod -- 0%o %s"%s"' % (mode, tilde, remotepath))

        with open(localpath, "rb") as localfile:
            # only chmod on successful cat
            self.run("&& ".join(cmd), stdin=localfile)

    def put_file(self, localpath, remotepath, mode=None):
        """Copy specified local file to the server.

        :param localpath:   Local filename.
        :param remotepath:  Remote filename.
        :param mode:        Permissions to set after upload
        """
        try:
            self._put_file_sftp(localpath, remotepath, mode=mode)
        except (paramiko.SSHException, socket.error):
            self._put_file_shell(localpath, remotepath, mode=mode)

    def put_file_obj(self, file_obj, remotepath, mode=None):
        """
        CHange file permission
        """
        client = self._get_client()

        with client.open_sftp() as sftp:
            sftp.putfo(file_obj, remotepath)
            if mode is not None:
                sftp.chmod(remotepath, mode)

    def get_file_obj(self, remotepath, file_obj):
        """
        Get File Object
        """
        client = self._get_client()

        with client.open_sftp() as sftp:
            sftp.getfo(remotepath, file_obj)