# Authors:
#   Petr Viktorin <pviktori@redhat.com>
#
# Copyright (C) 2013  Red Hat
# see file 'COPYING' for use and warranty information
#
# This program 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.
#
# This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

"""Host class for integration testing"""

import os
import socket
import threading
import subprocess
from contextlib import contextmanager
import errno

import paramiko

from ipapython.ipaldap import IPAdmin
from ipapython import ipautil
from ipapython.ipa_log_manager import log_mgr


class RemoteCommand(object):
    """A Popen-style object representing a remote command

    Unlike subprocess.Popen, this does not run the given command; instead
    it only starts a shell. The command must be written to stdin manually.

    The standard error and output are handled by this class. They're not
    available for file-like reading. They are logged by default.
    To make sure reading doesn't stall after one buffer fills up, they are read
    in parallel using threads.

    After calling wait(), stdout_text and stderr_text attributes will be
    strings containing the output, and returncode will contain the
    exit code.

    :param host: The Host on which the command is run
    :param argv: The command that will be run (for logging only)
    :param index: An identification number added to the logs
    :param log_stdout: If false, stdout will not be logged
    """
    def __init__(self, host, argv, index, log_stdout=True):
        self.returncode = None
        self.host = host
        self.argv = argv
        self._stdout_lines = []
        self._stderr_lines = []
        self.running_threads = set()

        self.logger_name = '%s.cmd%s' % (self.host.logger_name, index)
        self.log = log_mgr.get_logger(self.logger_name)

        self.log.info('RUN %s', argv)

        self._ssh = host.transport.open_channel('session')

        self._ssh.invoke_shell()
        stdin = self.stdin = self._ssh.makefile('wb')
        stdout = self._ssh.makefile('rb')
        stderr = self._ssh.makefile_stderr('rb')

        self._start_pipe_thread(self._stdout_lines, stdout, 'out', log_stdout)
        self._start_pipe_thread(self._stderr_lines, stderr, 'err', True)

        self._done = False

    def wait(self, raiseonerr=True):
        """Wait for the remote process to exit

        Raises an excption if the exit code is not 0.
        """
        if self._done:
            return self.returncode

        self._ssh.shutdown_write()
        while self.running_threads:
            self.running_threads.pop().join()

        self.stdout_text = ''.join(self._stdout_lines)
        self.stderr_text = ''.join(self._stderr_lines)
        self.returncode = self._ssh.recv_exit_status()
        self._ssh.close()

        self._done = True

        if raiseonerr and self.returncode:
            self.log.error('Exit code: %s', self.returncode)
            raise subprocess.CalledProcessError(self.returncode, self.argv)
        else:
            self.log.debug('Exit code: %s', self.returncode)
        return self.returncode

    def _start_pipe_thread(self, result_list, stream, name, do_log=True):
        log = log_mgr.get_logger('%s.%s' % (self.logger_name, name))

        def read_stream():
            for line in stream:
                if do_log:
                    log.debug(line.rstrip('\n'))
                result_list.append(line)

        thread = threading.Thread(target=read_stream)
        self.running_threads.add(thread)
        thread.start()
        return thread


@contextmanager
def sftp_open(sftp, filename, mode='r'):
    """Context manager that provides a file-like object over a SFTP channel

    This provides compatibility with older Paramiko versions.
    (In Paramiko 1.10+, file objects from `sftp.open` are directly usable as
    context managers).
    """
    file = sftp.open(filename, mode)
    try:
        yield file
    finally:
        file.close()


class Host(object):
    """Representation of a remote IPA host"""
    def __init__(self, domain, hostname, role, index, ip=None):
        self.domain = domain
        self.role = role
        self.index = index

        shortname, dot, ext_domain = hostname.partition('.')
        self.shortname = shortname
        self.hostname = shortname + '.' + self.domain.name
        self.external_hostname = hostname

        self.logger_name = '%s.%s.%s' % (
            self.__module__, type(self).__name__, shortname)
        self.log = log_mgr.get_logger(self.logger_name)

        if ip:
            self.ip = ip
        else:
            if self.config.ipv6:
                # $(dig +short $M $rrtype|tail -1)
                stdout, stderr, returncode = ipautil.run(
                    ['dig', '+short', self.external_hostname, 'AAAA'])
                self.ip = stdout.splitlines()[-1].strip()
            else:
                try:
                    self.ip = socket.gethostbyname(self.external_hostname)
                except socket.gaierror:
                    self.ip = None

            if not self.ip:
                raise RuntimeError('Could not determine IP address of %s' %
                                   self.external_hostname)

        self.root_password = self.config.root_password
        self.root_ssh_key_filename = self.config.root_ssh_key_filename
        self.host_key = None
        self.ssh_port = 22

        self.env_sh_path = os.path.join(domain.config.test_dir, 'env.sh')

        self._command_index = 0

        self.log_collectors = []

    def __str__(self):
        template = ('<{s.__class__.__name__} {s.hostname} ({s.role})>')
        return template.format(s=self)

    def __repr__(self):
        template = ('<{s.__module__}.{s.__class__.__name__} '
                    '{s.hostname} ({s.role})>')
        return template.format(s=self)

    def add_log_collector(self, collector):
        """Register a log collector for this host"""
        self.log_collectors.append(collector)

    def remove_log_collector(self, collector):
        """Unregister a log collector"""
        self.log_collectors.remove(collector)

    @classmethod
    def from_env(cls, env, domain, hostname, role, index):
        ip = env.get('BEAKER%s%s_IP_env%s' %
                        (role.upper(), index, domain.index), None)
        self = cls(domain, hostname, role, index, ip)
        return self

    @property
    def config(self):
        return self.domain.config

    def to_env(self, **kwargs):
        """Return environment variables specific to this host"""
        env = self.domain.to_env(**kwargs)

        role = self.role.upper()
        if self.role != 'master':
            role += str(self.index)

        env['MYHOSTNAME'] = self.hostname
        env['MYBEAKERHOSTNAME'] = self.external_hostname
        env['MYIP'] = self.ip

        env['MYROLE'] = '%s%s' % (role, self.domain._env)
        env['MYENV'] = str(self.domain.index)

        return env

    def run_command(self, argv, set_env=True, stdin_text=None,
                    log_stdout=True, raiseonerr=True,
                    cwd=None):
        """Run the given command on this host

        Returns a RemoteCommand instance. The command will have already run
        when this method returns, so its stdout_text, stderr_text, and
        returncode attributes will be available.

        :param argv: Command to run, as either a Popen-style list, or a string
                     containing a shell script
        :param set_env: If true, env.sh exporting configuration variables will
                        be sourced before running the command.
        :param stdin_text: If given, will be written to the command's stdin
        :param log_stdout: If false, standard output will not be logged
                           (but will still be available as cmd.stdout_text)
        :param raiseonerr: If true, an exception will be raised if the command
                           does not exit with return code 0
        """
        assert self.transport

        self._command_index += 1
        command = RemoteCommand(self, argv, index=self._command_index,
                                log_stdout=log_stdout)

        if cwd is None:
            cwd = self.config.test_dir
        command.stdin.write('cd %s\n' % ipautil.shell_quote(cwd))

        if set_env:
            command.stdin.write('. %s\n' %
                                ipautil.shell_quote(self.env_sh_path))
        command.stdin.write('set -e\n')

        if isinstance(argv, basestring):
            command.stdin.write('(')
            command.stdin.write(argv)
            command.stdin.write(')')
        else:
            for arg in argv:
                command.stdin.write(ipautil.shell_quote(arg))
                command.stdin.write(' ')
        command.stdin.write(';exit\n')
        if stdin_text:
            command.stdin.write(stdin_text)
        command.stdin.flush()

        command.wait(raiseonerr=raiseonerr)
        return command

    @property
    def transport(self):
        """Paramiko Transport connected to this host"""
        try:
            return self._transport
        except AttributeError:
            sock = socket.create_connection((self.external_hostname,
                                             self.ssh_port))
            self._transport = transport = paramiko.Transport(sock)
            transport.connect(hostkey=self.host_key)
            if self.root_ssh_key_filename:
                self.log.debug('Authenticating with private RSA key')
                filename = os.path.expanduser(self.root_ssh_key_filename)
                key = paramiko.RSAKey.from_private_key_file(filename)
                transport.auth_publickey(username='root', key=key)
            elif self.root_password:
                self.log.debug('Authenticating with password')
                transport.auth_password(username='root',
                                        password=self.root_password)
            else:
                self.log.critical('No SSH credentials configured')
                raise RuntimeError('No SSH credentials configured')
            return transport

    @property
    def sftp(self):
        """Paramiko SFTPClient connected to this host"""
        try:
            return self._sftp
        except AttributeError:
            transport = self.transport
            self._sftp = paramiko.SFTPClient.from_transport(transport)
            return self._sftp

    def ldap_connect(self):
        """Return an LDAPClient authenticated to this host as directory manager
        """
        ldap = IPAdmin(self.external_hostname)
        ldap.do_simple_bind(self.config.dirman_dn,
                            self.config.dirman_password)
        return ldap

    def mkdir_recursive(self, path):
        """`mkdir -p` on the remote host"""
        try:
            self.sftp.chdir(path or '/')
        except IOError as e:
            if not path or path == '/':
                raise
            self.mkdir_recursive(os.path.dirname(path))
            self.sftp.mkdir(path)
            self.sftp.chdir(path)

    def get_file_contents(self, filename):
        """Read the named remote file and return the contents as a string"""
        self.log.debug('READ %s', filename)
        with sftp_open(self.sftp, filename) as f:
            return f.read()

    def put_file_contents(self, filename, contents):
        """Write the given string to the named remote file"""
        self.log.info('WRITE %s', filename)
        with sftp_open(self.sftp, filename, 'w') as f:
            f.write(contents)

    def file_exists(self, filename):
        """Return true if the named remote file exists"""
        self.log.debug('STAT %s', filename)
        try:
            self.sftp.stat(filename)
        except IOError, e:
            if e.errno == errno.ENOENT:
                return False
            else:
                raise
        return True

    def get_file(self, remotepath, localpath):
        self.log.debug('GET %s', remotepath)
        self.sftp.get(remotepath, localpath)

    def put_file(self, localpath, remotepath):
        self.log.info('PUT %s', remotepath)
        self.sftp.put(localpath, remotepath)

    def collect_log(self, filename):
        for collector in self.log_collectors:
            collector(self, filename)