#!/usr/local/bin/python

import sys, os
import re

import tempfile
import subprocess
import logging 
import time
import signal

from service_error import service_error

class ssh_emulab_segment:
    """
    Base class for segment starter classes that access their underlying testebd
    remotely using ssh.  It is promarily a code repository for commonly used
    ssh commands for moving code and logging in.
    """
    class ssh_cmd_timeout(RuntimeError): pass

    def __init__(self, log=None, keyfile=None, debug=False):
	"""
	log is the logging.log to print messages to, keyfile is the private key
	for ssh interactions and if debug is true, commands are not executed
	using ssh.
	"""
	self.log = log or logging.getLogger('fedd.access.ssh_emulab_segment')
	self.ssh_privkey_file = keyfile
	self.debug = debug
	self.ssh_exec="/usr/bin/ssh"
	self.scp_exec = "/usr/bin/scp"
	self.ssh_cmd_timeout = ssh_emulab_segment.ssh_cmd_timeout

    def scp_file(self, file, user, host, dest=""):
	"""
	scp a file to the remote host.  If debug is set the action is only
	logged.
	"""

	scp_cmd = [self.scp_exec, '-o', 'IdentitiesOnly yes', 
		'-o', 'StrictHostKeyChecking no', '-o', 'ForwardX11 no','-i', 
		self.ssh_privkey_file, file, 
		"%s@%s:%s" % (user, host, dest)]
	rv = 0

	try:
	    dnull = open("/dev/null", "w")
	except EnvironmentError:
	    self.log.debug("[ssh_file]: failed to open " + \
		    "/dev/null for redirect")
	    dnull = Null

	self.log.debug("[scp_file]: %s" % " ".join(scp_cmd))
	if not self.debug:
	    rv = subprocess.call(scp_cmd, stdout=dnull, 
		    stderr=dnull, close_fds=True)

	return rv == 0

    def scp_file_from(self, file, user, host, dest=""):
	"""
	scp a file to the remote host.  If debug is set the action is only
	logged.
	"""

	scp_cmd = [self.scp_exec, '-o', 'IdentitiesOnly yes',
		'-o', 'StrictHostKeyChecking no', '-o', 'ForwardX11 no','-i',
		self.ssh_privkey_file, "%s@%s:%s" % (user, host, file), dest]
	rv = 0

	try:
	    dnull = open("/dev/null", "w")
	except EnvironmentError:
	    self.log.debug("[ssh_file]: failed to open " + \
		    "/dev/null for redirect")
	    dnull = Null

	self.log.debug("[scp_file]: %s" % " ".join(scp_cmd))
	if not self.debug:
	    rv = subprocess.call(scp_cmd, stdout=dnull,
		    stderr=dnull, close_fds=True)

	return rv == 0

    def ssh_cmd(self, user, host, cmd, wname=None, timeout=None):
	"""
	Run a remote command on host as user.  If debug is set, the action
	is only logged.  Commands are run without stdin, to avoid stray
	SIGTTINs.
	"""
	sh_str = ("%s -n -o 'IdentitiesOnly yes' -o " + \
		"'StrictHostKeyChecking no' -o 'ForwardX11 no' " +
		"-i %s %s@%s %s") % \
		(self.ssh_exec, self.ssh_privkey_file, 
			user, host, cmd)

	try:
	    dnull = open("/dev/null", "w")
	except EnvironmentError:
	    self.log.debug("[ssh_cmd]: failed to open /dev/null " + \
		    "for redirect")
	    dnull = Null

	self.log.debug("[ssh_cmd]: %s" % sh_str)
	if not self.debug:
	    if dnull:
		sub = subprocess.Popen(sh_str, shell=True, stdout=dnull,
			stderr=dnull, close_fds=True)
	    else:
		sub = subprocess.Popen(sh_str, shell=True, close_fds=True)
	    if timeout:
		i = 0
		rv = sub.poll()
		while i < timeout:
		    if rv is not None: break
		    else:
			time.sleep(1)
			rv = sub.poll()
			i += 1
		else:
		    self.log.debug("Process exceeded runtime: %s" % sh_str)
		    os.kill(sub.pid, signal.SIGKILL)
		    raise self.ssh_cmd_timeout();
		return rv == 0
	    else:
		return sub.wait() == 0
	else:
	    if timeout == 0:
		self.log.debug("debug timeout raised on %s " % sh_str)
		raise self.ssh_cmd_timeout()
	    else:
		return True