# -*- coding: utf-8 -*-
# -----------------------------------------------------------------------------
# Project   : Cuisine - Functions to write Fabric recipies
# -----------------------------------------------------------------------------
# Author    : Sebastien Pierre                            <sebastien@ffctn.com>
# Author    : Thierry Stiegler   (gentoo port)     <thierry.stiegler@gmail.com>
# Author    : Jim McCoy (distro checks and rpm port)      <jim.mccoy@gmail.com>
# License   : Revised BSD License
# -----------------------------------------------------------------------------
# Creation  : 26-Apr-2010
# Last mod  : 06-Feb-2012
# -----------------------------------------------------------------------------

"""
`cuisine` makes it easy to write automatic server installation
and configuration recipies by wrapping common administrative tasks
(installing packages, creating users and groups) in Python
functions.

`cuisine` is designed to work with Fabric and provide all you
need for getting your new server up and running in minutes.

Note, that right now, Cuisine only supports Debian-based Linux
systems.

See also:

- Deploying Django with Fabric
  <http://lethain.com/entry/2008/nov/04/deploying-django-with-fabric>

- Notes on Python Fabric 0.9b1
  <http://www.saltycrane.com/blog/2009/10/notes-python-fabric-09b1>`_

- EC2, fabric, and "err: stdin: is not a tty"
  <http://blog.markfeeney.com/2009/12/ec2-fabric-and-err-stdin-is-not-tty.html>`_

:copyright: (c) 2011 by Sébastien Pierre, see AUTHORS for more details.
:license:   BSD, see LICENSE for more details.
"""

import base64, bz2, crypt, hashlib, os, random, sys, re, string, tempfile, subprocess, types
import fabric, fabric.api, fabric.operations, fabric.context_managers

VERSION     = "0.2.1"

RE_SPACES   = re.compile("[\s\t]+")
MAC_EOL     = "\n"
UNIX_EOL    = "\n"
WINDOWS_EOL = "\r\n"
# FIXME: MODE should be in the fabric env, as this is definitely not thread-safe
MODE_USER   = "user"
MODE_LOCAL  = False
MODE_SUDO   = "sudo"
MODE        = MODE_USER
DEFAULT_OPTIONS = dict(
	package="apt"
)

# context managers and wrappers around fabric's run/sudo; used to
# either execute cuisine functions with sudo or as current user:
#
# with mode_sudo():
#     pass

def mode_local():
	"""Sets Cuisine into local mode, where run/sudo won't go through
	Fabric's API, but directly through a popen. This allows you to
	easily test your Cuisine scripts without using Fabric"""
	global MODE_LOCAL
	if MODE_LOCAL is False:
		def custom_run( cmd ):
			global MODE
			if MODE == "sudo":
				return os.popen(cmd).read()[:-1]
			else:
				return os.popen("sudo " + cmd).read()[:-1]
		def custom_sudo( cmd ):
			return os.popen("sudo " + cmd).read()[:-1]
		module   = sys.modules[__name__]
		old_run  = getattr(module, "run")
		old_sudo = getattr(module, "sudo")
		setattr(module, "run",  custom_run)
		setattr(module, "sudo", custom_sudo)
		MODE_LOCAL = (old_run, old_sudo)
		return True
	else:
		return False

def mode_remote():
	"""Comes back to Fabric's API for run/sudo. This basically reverts
	the effect of calling `mode_local()`."""
	global MODE_LOCAL
	if not (MODE_LOCAL is False):
		setattr(module, "run",  MODE_LOCAL[0])
		setattr(module, "sudo", MODE_LOCAL[1])
		MODE_LOCAL = False
		return True
	else:
		return False


class mode_user(object):
	"""Cuisine functions will be executed as the current user."""

	def __init__(self):
		global MODE
		self._old_mode = MODE
		MODE = MODE_USER

	def __enter__(self):
		pass

	def __exit__(self, *args, **kws):
		global MODE
		MODE = self._old_mode

class mode_sudo(object):
	"""Cuisine functions will be executed with sudo."""

	def __init__(self):
		global MODE
		self._old_mode = MODE
		MODE = MODE_SUDO

	def __enter__(self):
		pass

	def __exit__(self, *args, **kws):
		global MODE
		MODE = self._old_mode

# =============================================================================
#
# OPTIONS
#
# =============================================================================

def select_package( option=None ):
	supported = ["apt"]
	if not (option is None):
		assert option in supported, "Option must be one of: %s"  % (supported)
		fabric.api.env["option_package"] = option
	return (fabric.api.env["option_package"], supported)


# =============================================================================
#
# RUN/SUDO METHODS
#
# =============================================================================

def run(*args, **kwargs):
	"""A wrapper to Fabric's run/sudo commands, using the
	'cuisine.MODE' global to tell wether the command should be run as
	regular user or sudo."""
	if MODE == MODE_SUDO:
		return fabric.api.sudo(*args, **kwargs)
	else:
		return fabric.api.run(*args, **kwargs)

def run_local(command):
	"""A wrapper around subprocess"""
	pipe = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE).stdout
	res = pipe.read()
	# FIXME: Should stream the pipe, and only print it if fabric's properties allow it
	print res
	return pipe

def sudo(*args, **kwargs):
	"""A wrapper to Fabric's run/sudo commands, using the
	'cuisine.MODE' global to tell wether the command should be run as
	regular user or sudo."""
	return fabric.api.sudo(*args, **kwargs)

# =============================================================================
#
# DECORATORS
#
# =============================================================================

def dispatch(function):
	"""Dispatches the current function to specific implementation. For instance
	@dispatch("package_ensure", select="package_system").
	"""
	def wrapper(*args, **kwargs):
		function_name = function.__name__
		prefix        = function_name.split("_")[0]
		select        = fabric.api.env.get("option_" + prefix)
		assert select, "No option defined for: %s, call select_%s(<YOUR OPTION>) to set it" % (prefix, prefix)
		function_name = function.__name__ + "_" + select
		specific      = eval(function_name)
		if specific:
			if type(specific) == types.FunctionType:
				return specific(*args, **kwargs)
			else:
				raise Exception("Function expected for: " + function_name)
		else:
			raise Exception("Function variant not defined: " + function_name)
	# We copy name and docstring
	wrapper.__name__ = function.__name__
	wrapper.__doc__  = function.__doc__
	return wrapper

# =============================================================================
#
# TEXT PROCESSING
#
# =============================================================================

def text_detect_eol(text):
	# FIXME: Should look at the first line
	if text.find("\r\n") != -1:
		return WINDOWS_EOL
	elif text.find("\n") != -1:
		return UNIX_EOL
	elif text.find("\r") != -1:
		return MAC_EOL
	else:
		return "\n"

def text_get_line(text, predicate):
	"""Returns the first line that matches the given predicate."""
	for line in text.split("\n"):
		if predicate(line):
			return line
	return ""

def text_normalize(text):
	"""Converts tabs and spaces to single space and strips the text."""
	return RE_SPACES.sub(" ", text).strip()

def text_nospace(text):
	"""Converts tabs and spaces to single space and strips the text."""
	return RE_SPACES.sub("", text).strip()

def text_replace_line(text, old, new, find=lambda old, new: old == new, process=lambda _: _):
	"""Replaces lines equal to 'old' with 'new', returning the new
	text and the count of replacements."""
	res = []
	replaced = 0
	eol = text_detect_eol(text)
	for line in text.split(eol):
		if find(process(line), process(old)):
			res.append(new)
			replaced += 1
		else:
			res.append(line)
	return eol.join(res), replaced

def text_ensure_line(text, *lines):
	"""Ensures that the given lines are present in the given text,
	otherwise appends the lines that are not already in the text at
	the end of it."""
	eol = text_detect_eol(text)
	res = list(text.split(eol))
	for line in lines:
		assert line.find(eol) == -1, "No EOL allowed in lines parameter: " + repr(line)
		found = False
		for l in res:
			if l == line:
				found = True
				break
		if not found:
			res.append(line)
	return eol.join(res)

def text_strip_margin(text, margin="|"):
	res = []
	eol = text_detect_eol(text)
	for line in text.split(eol):
		l = line.split(margin, 1)
		if len(l) == 2:
			_, line = l
			res.append(line)
	return eol.join(res)

def text_template(text, variables):
	"""Substitutes '${PLACEHOLDER}'s within the text with the
	corresponding values from variables."""
	template = string.Template(text)
	return template.safe_substitute(variables)

# =============================================================================
#
# FILE OPERATIONS
#
# =============================================================================

def file_local_read(location):
	"""Reads a *local* file from the given location, expanding '~' and
	shell variables."""
	p = os.path.expandvars(os.path.expanduser(location))
	f = file(p, 'rb')
	t = f.read()
	f.close()
	return t

def file_read(location):
	"""Reads the *remote* file at the given location."""
	# NOTE: We use base64 here to be sure to preserve the encoding (UNIX/DOC/MAC) of EOLs
	return base64.b64decode(run('cat "%s" | base64' % (location)))

def file_exists(location):
	"""Tests if there is a *remote* file at the given location."""
	return run('test -e "%s" && echo OK ; true' % (location)) == "OK"

def file_is_file(location):
	return run("test -f '%s' && echo OK ; true" % (location)) == "OK"

def file_is_dir(location):
	return run("test -d '%s' && echo OK ; true" % (location)) == "OK"

def file_is_link(location):
	return run("test -L '%s' && echo OK ; true" % (location)) == "OK"

def file_attribs(location, mode=None, owner=None, group=None, recursive=False):
	"""Updates the mode/owner/group for the remote file at the given
	location."""
	recursive = recursive and "-R " or ""
	if mode:
		run('chmod %s %s "%s"' % (recursive, mode,  location))
	if owner:
		run('chown %s %s "%s"' % (recursive, owner, location))
	if group:
		run('chgrp %s %s "%s"' % (recursive, group, location))

def file_attribs_get(location):
	"""Return mode, owner, and group for remote path.
	Return mode, owner, and group if remote path exists, 'None'
	otherwise.
	"""
	if file_exists(location):
		fs_check = run('stat %s %s' % (location, '--format="%a %U %G"'))
		(mode, owner, group) = fs_check.split(' ')
		return {'mode': mode, 'owner': owner, 'group': group}
	else:
		return None

def file_write(location, content, mode=None, owner=None, group=None):
	"""Writes the given content to the file at the given remote
	location, optionally setting mode/owner/group."""
	# FIXME: Big files are never transferred properly!
	# Gets the content signature and write it to a secure tempfile
	sig            = hashlib.sha256(content).hexdigest()
	fd, local_path = tempfile.mkstemp()
	os.write(fd, content)
	# Upload the content if necessary
	if not file_exists(location) or sig != file_sha256(location):
		fabric.operations.put(local_path, location, use_sudo=(mode == MODE_SUDO))
	# Remove the local temp file
	os.close(fd)
	os.unlink(local_path)
	# Ensure that the signature matches
	assert sig == file_sha256(location)

def file_ensure(location, mode=None, owner=None, group=None, recursive=False):
	"""Updates the mode/owner/group for the remote file at the given
	location."""
	if file_exists(location):
		file_attribs(location,mode=mode,owner=owner,group=group)
	else:
		file_write(location,"",mode=mode,owner=owner,group=group)

def file_upload(remote, local):
	"""Uploads the local file to the remote location only if the remote location does not
	exists or the content are different."""
	# FIXME: Big files are never transferred properly!
	f       = file(local, 'rb')
	content = f.read()
	f.close()
	sig     = hashlib.sha256(content).hexdigest()
	if not file_exists(remote) or sig != file_sha256(remote):
		fabric.operations.put(local, remote, use_sudo=(MODE == MODE_SUDO))

def file_update(location, updater=lambda x: x):
	"""Updates the content of the given by passing the existing
	content of the remote file at the given location to the 'updater'
	function.

	For instance, if you'd like to convert an existing file to all
	uppercase, simply do:

	>   file_update("/etc/myfile", lambda _:_.upper())
	"""
	assert file_exists(location), "File does not exists: " + location
	new_content = updater(file_read(location))
	# assert type(new_content) in (str, unicode, fabric.operations._AttributeString), "Updater must be like (string)->string, got: %s() = %s" %  (updater, type(new_content))
	run('echo "%s" | base64 -d > "%s"' %
		(base64.b64encode(new_content), location))

def file_append(location, content, mode=None, owner=None, group=None):
	"""Appends the given content to the remote file at the given
	location, optionally updating its mode/owner/group."""
	run('echo "%s" | base64 -d >> "%s"' %
		(base64.b64encode(content), location))
	file_attribs(location, mode, owner, group)

def file_unlink(path):
	if file_exists(path):
		run("unlink '%s'" % (path))

def file_link(source, destination, symbolic=True, mode=None, owner=None, group=None):
	"""Creates a (symbolic) link between source and destination on the remote host,
	optionally setting its mode/owner/group."""
	if file_exists(destination) and (not file_is_link(destination)):
		raise Exception("Destination already exists and is not a link: %s" % (destination))
	if file_is_link(destination):
		file_unlink(destination)
	if symbolic:
		run('ln -sf "%s" "%s"' % (source, destination))
	else:
		run('ln -f "%s" "%s"' % (source, destination))
	file_attribs(destination, mode, owner, group)

def file_sha256(location):
	"""Returns the SHA-256 sum (as a hex string) for the remote file at the given location"""
	return run('sha256sum "%s" | cut -d" " -f1' % (location))

# TODO: From McCoy's version, consider merging
# def file_append( location, content, use_sudo=False, partial=False, escape=True):
#       """Wrapper for fabric.contrib.files.append."""
#       fabric.contrib.files.append(location, content, use_sudo, partial, escape)

# =============================================================================
#
# DIRECTOR OPERATIONS
#
# =============================================================================

def dir_attribs(location, mode=None, owner=None, group=None, recursive=False):
	"""Updates the mode/owner/group for the given remote directory."""
	file_attribs(location, mode, owner, group, recursive)

def dir_exists(location):
	"""Tells if there is a remote directory at the given location."""
	return run('test -d "%s" && echo OK ; true' % (location)).endswith("OK")

def dir_ensure(location, recursive=False, mode=None, owner=None, group=None):
	"""Ensures that there is a remote directory at the given location,
	optionnaly updating its mode/owner/group.

	If we are not updating the owner/group then this can be done as a single
	ssh call, so use that method, otherwise set owner/group after creation."""
	if mode:
		mode_arg = "-m %s" % (mode)
	else:
		mode_arg = ""
	run('test -d "%s" || mkdir %s %s "%s" && echo OK ; true' %
		(location, recursive and "-p" or "", mode_arg, location))
	if owner or group:
		dir_attribs(location, owner=owner, group=group)

# =============================================================================
#
# PACKAGE OPERATIONS
#
# =============================================================================

@dispatch
def package_update(package=None):
	"""Updates the package database (when no argument) or update the package
	or list of packages given as argument."""

@dispatch
def package_install(package, update=False):
	"""Installs the given package/list of package, optionnaly updating
	the package database."""

@dispatch
def package_ensure(package):
	"""Tests if the given package is installed, and installes it in
	case it's not already there."""

# -----------------------------------------------------------------------------
# APT PACKAGE (DEBIAN/UBUNTU)
# -----------------------------------------------------------------------------

def package_update_apt(package=None):
	if package == None:
		sudo("apt-get --yes update")
	else:
		if type(package) in (list, tuple):
			package = " ".join(package)
		sudo("apt-get --yes upgrade " + package)

def package_install_apt(package, update=False):
	if update:
		sudo("apt-get --yes update")
	if type(package) in (list, tuple):
		package = " ".join(package)
	sudo("apt-get --yes install %s" % (package))


def package_ensure_apt(package):
	status = run("dpkg-query -W -f='${Status}' %s ; true" % package)
	if status.find("not-installed") != -1 or status.find("installed") == -1:
		package_install(package)
		return False
	else:
		return True

# =============================================================================
#
# SHELL COMMANDS
#
# =============================================================================

def command_check(command):
	"""Tests if the given command is available on the system."""
	return run("which '%s' >& /dev/null && echo OK ; true" % command).endswith("OK")


def command_ensure(command, package=None):
	"""Ensures that the given command is present, if not installs the
	package with the given name, which is the same as the command by
	default."""
	if package is None:
		package = command
	if not command_check(command):
		package_install(package)
	assert command_check(command), \
		"Command was not installed, check for errors: %s" % (command)

# =============================================================================
#
# USER OPERATIONS
#
# =============================================================================

def user_create(name, passwd=None, home=None, uid=None, gid=None, shell=None,
				uid_min=None, uid_max=None):
	"""Creates the user with the given name, optionally giving a
	specific password/home/uid/gid/shell."""
	options = ["-m"]
	if passwd:
		method = 6
		saltchars = string.ascii_letters + string.digits + './'
		salt = ''.join([random.choice(saltchars) for x in range(8)])
		passwd_crypted = crypt.crypt(passwd, '$%s$%s' % (method, salt))
		options.append("-p '%s'" % (passwd_crypted))
	if home:
		options.append("-d '%s'" % (home))
	if uid:
		options.append("-u '%s'" % (uid))
	if gid:
		options.append("-g '%s'" % (gid))
	if shell:
		options.append("-s '%s'" % (shell))
	if uid_min:
		options.append("-K UID_MIN='%s'" % (uid_min))
	if uid_max:
		options.append("-K UID_MAX='%s'" % (uid_max))
	sudo("useradd %s '%s'" % (" ".join(options), name))

def user_check(name):
	"""Checks if there is a user defined with the given name,
	returning its information as a
	'{"name":<str>,"uid":<str>,"gid":<str>,"home":<str>,"shell":<str>}'
	or 'None' if the user does not exists."""
	d = sudo("cat /etc/passwd | egrep '^%s:' ; true" % (name))
	s = sudo("cat /etc/shadow | egrep '^%s:' | awk -F':' '{print $2}'" % (name))
	results = {}
	if d:
		d = d.split(":")
		results = dict(name=d[0], uid=d[2], gid=d[3], home=d[5], shell=d[6])
	if s:
		results['passwd'] = s
	if results:
		return results
	else:
		return None

def user_ensure(name, passwd=None, home=None, uid=None, gid=None, shell=None):
	"""Ensures that the given users exists, optionally updating their
	passwd/home/uid/gid/shell."""
	d = user_check(name)
	if not d:
		user_create(name, passwd, home, uid, gid, shell)
	else:
		options = []
		if passwd != None and d.get('passwd') != None:
			method, salt = d.get('passwd').split('$')[1:3]
			passwd_crypted = crypt.crypt(passwd, '$%s$%s' % (method, salt))
			if passwd_crypted != d.get('passwd'):
				options.append("-p '%s'" % (passwd_crypted))
		if passwd != None and d.get('passwd') is None:
			# user doesn't have passwd
			method = 6
			saltchars = string.ascii_letters + string.digits + './'
			salt = ''.join([random.choice(saltchars) for x in range(8)])
			passwd_crypted = crypt.crypt(passwd, '$%s$%s' % (method, salt))
			options.append("-p '%s'" % (passwd_crypted))
		if home != None and d.get("home") != home:
			options.append("-d '%s'" % (home))
		if uid != None and d.get("uid") != uid:
			options.append("-u '%s'" % (uid))
		if gid != None and d.get("gid") != gid:
			options.append("-g '%s'" % (gid))
		if shell != None and d.get("shell") != shell:
			options.append("-s '%s'" % (shell))
		if options:
			sudo("usermod %s '%s'" % (" ".join(options), name))

# =============================================================================
#
# GROUP OPERATIONS
#
# =============================================================================

def group_create(name, gid=None):
	"""Creates a group with the given name, and optionally given gid."""
	options = []
	if gid:
		options.append("-g '%s'" % (gid))
	sudo("groupadd %s '%s'" % (" ".join(options), name))

def group_check(name):
	"""Checks if there is a group defined with the given name,
	returning its information as a
	'{"name":<str>,"gid":<str>,"members":<list[str]>}' or 'None' if
	the group does not exists."""
	group_data = run("cat /etc/group | egrep '^%s:' ; true" % (name))
	if group_data:
		name, _, gid, members = group_data.split(":", 4)
		return dict(name=name, gid=gid,
					members=tuple(m.strip() for m in members.split(",")))
	else:
		return None

def group_ensure(name, gid=None):
	"""Ensures that the group with the given name (and optional gid)
	exists."""
	d = group_check(name)
	if not d:
		group_create(name, gid)
	else:
		if gid != None and d.get("gid") != gid:
			sudo("groupmod -g %s '%s'" % (gid, name))

def group_user_check(group, user):
	"""Checks if the given user is a member of the given group. It
	will return 'False' if the group does not exist."""
	d = group_check(group)
	if d is None:
		return False
	else:
		return user in d["members"]

def group_user_add(group, user):
	"""Adds the given user/list of users to the given group/groups."""
	assert group_check(group), "Group does not exist: %s" % (group)
	if not group_user_check(group, user):
		sudo("usermod -a -G '%s' '%s'" % (group, user))

def group_user_ensure(group, user):
	"""Ensure that a given user is a member of a given group."""
	d = group_check(group)
	if user not in d["members"]:
		group_user_add(group, user)

### ssh_<operation> functions

def ssh_keygen(user, keytype="dsa"):
	"""Generates a pair of ssh keys in the user's home .ssh directory."""
	d = user_check(user)
	assert d, "User does not exist: %s" % (user)
	home = d["home"]
	key_file = home + "/.ssh/id_%s.pub" % keytype
	if not file_exists(key_file):
		dir_ensure(home + "/.ssh", mode="0700", owner=user, group=user)
		run("ssh-keygen -q -t %s -f '%s/.ssh/id_%s' -N ''" %
			(keytype, home, keytype))
		file_attribs(home + "/.ssh/id_%s" % keytype, owner=user, group=user)
		file_attribs(home + "/.ssh/id_%s.pub" % keytype, owner=user, group=user)
		return key_file
	else:
		return key_file

# =============================================================================
#
# MISC
#
# =============================================================================

def ssh_authorize(user, key):
	"""Adds the given key to the '.ssh/authorized_keys' for the given
	user."""
	d = user_check(user)
	keyf = d["home"] + "/.ssh/authorized_keys"
	if key[-1] != "\n":
		key += "\n"
	if file_exists(keyf):
		d = file_read(keyf)
		if file_read(keyf).find(key[:-1]) == -1:
			file_append(keyf, key)
			return False
		else:
			return True
	else:
		file_write(keyf, key)
		return False


def upstart_ensure(name):
	"""Ensures that the given upstart service is running, restarting
	it if necessary"""
	status = sudo("service %s status" % name)
	if status.find("is running") >= 0 or status.find("/running") >= 0:
		sudo("service %s restart" % name)
	else:
		sudo("service %s start" % name)

def system_uuid_alias_add():
	"""Adds system UUID alias to /etc/hosts.
	Some tools/processes rely/want the hostname as an alias in
	/etc/hosts e.g. `127.0.0.1 localhost <hostname>`.
	"""
	with mode_sudo():
		old = "127.0.0.1 localhost"
		new = old + " " + system_uuid()
		file_update('/etc/hosts', lambda x: text_replace_line(x, old, new)[0])

def system_uuid():
	"""Gets a machines UUID (Universally Unique Identifier)."""
	return sudo('dmidecode -s system-uuid | tr "[A-Z]" "[a-z]"')

# Sets up the default options so that @dispatch'ed functions work
for option, value in DEFAULT_OPTIONS.items():
	eval("select_" + option)(value)

# EOF - vim: ts=4 sw=4 noet
