#!/usr/bin/python3
# coding: utf-8

# aurbot - Archlinux User Repository Builder Bot
# Copyright © 2018 Sébastien Luttringer
#
# Started, October 30th 2011
#
# 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 2
# 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, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

from argparse import ArgumentParser
from configparser import ConfigParser
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.utils import formatdate
from json import load as jload, dump as jdump, loads as jloads
from logging import debug, warning, info, error, critical
from logging import StreamHandler, getLogger, Formatter, DEBUG, INFO
from os import chdir, environ, getcwd, mkdir, makedirs, geteuid, stat
from os.path import exists, join, abspath
from signal import signal, SIGHUP
from smtplib import SMTP, SMTP_SSL, SMTPException
from subprocess import Popen, check_call, DEVNULL, PIPE
from systemd.daemon import notify
from tarfile import open as tar
from tempfile import TemporaryDirectory
from time import sleep, time, strftime, localtime
from urllib.request import urlopen, Request

AUR_URL = 'https://aur.archlinux.org'
USER_AGENT = "aurbot"
XDG_DIRECTORY = "aurbot"

DEFAULT_CHECK_INTERVAL = 86400
DEFAULT_CONFIG_FILE = "/etc/aurbot.conf"
DEFAULT_DATA_DIR = "/var/lib/aurbot"

class Error(BaseException):
	"""Error handling"""
	ERR_USAGE = 1
	ERR_ABORT = 2
	ERR_CRITICAL = 3
	ERR_UNKNOWN = 4


class ABFormatter(Formatter):
	'''
	Customer logging formater
	'''
	def __init__(self, fmt="[%(levelname)s] %(msg)s"):
		Formatter.__init__(self, fmt)

	def format(self, record):
		format_orig = self._style._fmt
		if record.levelno == INFO and getLogger(record.name).getEffectiveLevel() != DEBUG:
			self._style._fmt =  "%(msg)s"
		result = Formatter.format(self, record)
		self._style._fmt = format_orig
		return result


class AURPackage(dict):
	'''
	Abstract AUR package action
	'''

	def __init__(self, name, timeout=None):
		self.name = name
		debug("getting %s aur infos" % self.name)
		url = "%s/rpc.php?type=info&arg=%s" % (AUR_URL, name)
		url_req = Request(url, headers={"User-Agent": USER_AGENT})
		debug("Requesting url: %s (timeout: %s)" % (url, timeout))
		url_fd = urlopen(url_req, timeout=timeout)
		d = jloads(url_fd.read().decode("utf-8"))
		if d["version"] != 1:
			raise Exception("Unknown AUR Backend version: %s" % d["version"])
		if len(d["results"]) == 0:
			raise Exception("No such package: %s" % name)
		if d["results"]["PackageBase"] != name:
			raise Exception("No such base package: %s" % name)
		self._info = d["results"]

	def __getattr__(self, name):
		for k, v in self._info.items():
			if name == k.lower():
				return v
		raise AttributeError()

	def __repr__(self):
		return "%s %s" % (self.name, self.version)

	def extract(self, path):
		'''
		Extract aur source tarball inside a directory path
		'''
		fo = urlopen('%s/%s' % (AUR_URL, self.urlpath))
		tarball = tar(mode='r|*', fileobj=fo)
		tarball.extractall(path)
		fo.close()


class LocalPackage(dict):
	'''Local package data abstraction'''

	def __init__(self, name):
		self.name = name
		self.path = join(environ.get("AURBOT_DATADIR", DEFAULT_DATA_DIR), name)
		debug("local path is: %s" % self.path)
		makedirs(self.path, exist_ok=True)

	@property
	def logdir(self):
		logdir = join(self.path, "log")
		if not exists(logdir):
			mkdir(logdir)
		return logdir

	def getlastX(self, X, cast=int, default=0):
		filepath = join(self.path, X)
		if not exists(filepath):
			return default
		try:
			return cast(open(filepath, "r").read())
		except Exception as exp:
			debug("Failed to load %s: %s" % (X, exp))
			return default

	def setlastX(self, X, value, cast=int):
		#try:
		open(join(self.path, X), "w").write("%s" % cast(value))
		#except Exception as exp:
		#	error("Failed to save %s: %s" % (X, exp))

	# store the moment where the build was done locally
	lastbuild = property(
		lambda x: LocalPackage.getlastX(x, "lastbuild"),
		lambda x, y: LocalPackage.setlastX(x, "lastbuild", y)
	)
	# store the aur lastmodified value of the last sucessful build
	lastsuccess = property(
		lambda x: LocalPackage.getlastX(x, "lastsuccess"),
		lambda x, y: LocalPackage.setlastX(x, "lastsuccess", y)
	)
	# store the aur lastmodified value of the last failed build
	lastfailed = property(
		lambda x: LocalPackage.getlastX(x, "lastfailed"),
		lambda x, y: LocalPackage.setlastX(x, "lastfailed", y)
	)
	# store the last time we check the aur
	lastchecked = property(
		lambda x: LocalPackage.getlastX(x, "lastchecked"),
		lambda x, y: LocalPackage.setlastX(x, "lastchecked", y)
	)
	# store the last maintainer for the package
	lastmaintainer = property(
		lambda x: LocalPackage.getlastX(x, "lastmaintainer", str, ""),
		lambda x, y: LocalPackage.setlastX(x, "lastmaintainer", y, str)
	)

class Aurbot(object):
	''' AUR Bot data and methods
	'''

	def __init__(self, path):
		''' initialize the bot
		'''
		self.init_config(abspath(path))
		self.parse_config()

	def init_config(self, path=None):
		''' default value for configured
		'''
		if path is not None:
			self.config_path = path
		self.config_mtime = 0
		self.config = ConfigParser()

	def parse_config(self):
		''' parse the config file
		'''
		# get the modification time of the config file
		try:
			mtime = stat(self.config_path).st_mtime
		except Exception as exp:
			self.init_config()
			debug("Unable to stat config file, empty one used: %s" % str(exp))
			return
		# reload only when file has been modified
		if mtime > self.config_mtime:
			self.config_mtime = mtime
			self.config = ConfigParser()
			try:
				self.config.read(self.config_path)
			except Exception as exp:
				self.init_config()
				debug("Unable to parse config file, empty one used: %s" % str(exp))
			info("Config file loaded %s" % self.config_path)

	def send_message(self, pkgconfig, msg):
		''' Send message to an smtp server
		'''
		info("Sending message to %s" % pkgconfig["notify"])
		# load smtp info
		try:
			smtp_host = pkgconfig["smtp_host"]
			smtp_port = pkgconfig["smtp_port"]
			smtp_login = pkgconfig.get("smtp_login", "")
			smtp_pass = pkgconfig.get("smtp_pass", "")
			smtp_security = pkgconfig.get("smtp_security", "")
		except:
			error("Unable to load smtp config")
			return
		# display message content when debug
		debug(msg)
		# prepare connection
		con = SMTP_SSL() if smtp_security == "ssl" else SMTP()
		if getLogger().isEnabledFor(DEBUG):
			con.set_debuglevel(True)
		con._host = smtp_host
		try:
			con.connect(smtp_host, smtp_port)
			if smtp_security == "starttls":
				con.starttls()
			if smtp_login != "" and smtp_pass != "":
				con.login(smtp_login, smtp_pass)
			# send it
			con.send_message(msg)
			# gentleman quit
			con.quit()
		except Exception as exp:
			error("Unable to send message via smtp: %s" % str(exp))

	def send_build_report(self, pkgconfig, localpkg, aurpkg, status, logfile):
		''' Send build notification
		'''
		info("Send build report")
		# generate message
		msg = MIMEMultipart()
		msg["Subject"] = "Build %s for %s %s" % (
			"successful" if status else "failure", localpkg.name, aurpkg.version)
		msg["From"] = pkgconfig.get("from", "Aurbot")
		msg["To"] = pkgconfig["notify"]
		msg["Date"] = formatdate(localtime=True)
		# attach logfile
		with open(logfile, "r") as fd:
			mt = MIMEText(fd.read())
		msg.attach(mt)
		self.send_message(pkgconfig, msg)

	def send_maintainer_report(self, pkgconfig, localpkg, aurpkg):
		''' Send email to notify invalid maintainer
		'''
		info("Send invalid maintainer report")
		# generate message
		msg = MIMEText(
			"Maintainer for package %s is invalid.\r\n" % localpkg.name +
			"He has probably changed. Check if the new one is trustworthy.\r\n"
			"\r\n"
			"Configured maintainer is %s.\r\n" % pkgconfig.get("maintainer") +
			"AUR maintainer is %s.\r\n" % aurpkg.maintainer +
			"\r\n"
			"Your aurbot configuration need to be updated!\r\n")
		msg["Subject"] = "Invalid maintainer for %s" % localpkg.name
		msg["From"] = pkgconfig.get("from", "Aurbot")
		msg["To"] = pkgconfig["notify"]
		msg["Date"] = formatdate(localtime=True)
		self.send_message(pkgconfig, msg)

	def build(self, pkgconfig, localpkg, aurpkg):
		''' Build a package
		'''
		# register the build
		localpkg.lastbuild = time()
		# log files
		fp = join(localpkg.logdir, strftime("build-%Y-%m-%d-%H-%M-%S.log", localtime(time())))
		debug("Build log file path: %s" % fp)
		# find build dir
		build_dir = TemporaryDirectory()
		debug("Build dir is %s" % build_dir.name)
		# extract tarball
		debug("Extracting aur tarball")
		aurpkg.extract(build_dir.name)
		with open(fp, "w") as fd:
			cwd = getcwd()
			try:
				chdir("%s/%s" % (build_dir.name, aurpkg.name))
				# build
				info("Starting build command")
				debug(pkgconfig["build_cmd"])
				fd.write("Build command: %s\n" % pkgconfig["build_cmd"])
				fd.flush()
				start_time = time()
				try:
					check_call(pkgconfig["build_cmd"], stdin=DEVNULL, stdout=fd,
						stderr=fd, shell=True, close_fds=True)
				except Exception as exp:
					raise Exception("Build failure: %s" % str(exp)) from exp
				end_time = time()
				info("Build duration: %.2fs" % (end_time - start_time))
				fd.write("Build duration: %.2fs\n" % (end_time - start_time))
				# commit
				if "commit_cmd" in pkgconfig:
					info("Starting commit command")
					debug(pkgconfig["commit_cmd"])
					fd.write("Commit command: %s\n" % pkgconfig["commit_cmd"])
					fd.flush()
					start_time = time()
					try:
						check_call(pkgconfig["commit_cmd"], stdin=DEVNULL,
						stdout=fd, stderr=fd, shell=True, close_fds=True)
					except Exception as exp:
						raise Exception("Commit failure: %s" % str(exp)) from exp
					end_time = time()
					info("Commit duration: %.2fs" % (end_time - start_time))
					fd.write("Commit duration: %.2fs\n" % (end_time - start_time))
				chdir(cwd)
				# we have to register after chdir in the original directory
				localpkg.lastsuccess = aurpkg.lastmodified
				status = True
			except Exception as exp:
				error("Update failure: %s" % exp)
				chdir(cwd)
				# we have to register after chdir in the original directory
				localpkg.lastfailed = aurpkg.lastmodified
				status = False
		if "notify" in pkgconfig:
			self.send_build_report(pkgconfig, localpkg, aurpkg, status, fp)

	def update(self, pkgconfig, localpkg, aurpkg):
		''' Update (build and commit) a package
		'''
		debug("Updating %s" % aurpkg.name)
		# for security, if the maintainer is incorrect we fail
		debug("Configured maintainer: %s" % pkgconfig.get("maintainer"))
		debug("AUR maintainer: %s" % aurpkg.maintainer)
		debug("Last maintainer: %s" % localpkg.lastmaintainer)
		# str is required to handle no maintainer as None string
		if pkgconfig.get("maintainer") != str(aurpkg.maintainer):
			# we notify by mail only once the maintainer is invalid
			if localpkg.lastmaintainer != str(aurpkg.maintainer):
				self.send_maintainer_report(pkgconfig, localpkg, aurpkg)
				localpkg.lastmaintainer = aurpkg.maintainer
			error("Invalid maintainer for package %s" % aurpkg.name)
			return
		localpkg.lastmaintainer = aurpkg.maintainer
		self.build(pkgconfig, localpkg, aurpkg)

	def start(self):
		''' start the bot loop
		'''
		while True:
			try:
				# reload package list
				self.parse_config()
				next_checks = set()
				for pkgname, pkgconfig in self.config.items():
					if pkgname == "DEFAULT":
						continue
					info("[%s]" % pkgname)
					if "build_cmd" not in pkgconfig:
						error("build_cmd is missing in config file")
						continue
					localpkg = LocalPackage(pkgname)
					check_interval = pkgconfig.getint("check_interval", DEFAULT_CHECK_INTERVAL)
					debug("Check interval is %ss" % check_interval)
					check_delta = int(localpkg.lastchecked - time() + check_interval)
					debug("Check delta is %ss" % check_delta)
					if check_delta > 0:
						# next check is in the future
						next_checks.add(check_delta)
						info("Next check is planned in %ss" % check_delta)
						continue
					next_checks.add(check_interval)
					# get remote data
					try:
						aurpkg = AURPackage(pkgname, pkgconfig.getint("timeout"))
						localpkg.lastchecked = int(time())
					except Exception as exp:
						error("Unable to get AUR package info: %s" % exp)
						continue
					# few debug printing
					debug("AUR last modified: %s" % aurpkg.lastmodified)
					debug("Local last success lastmodified: %s" % localpkg.lastbuild)
					debug("Local last failed lastmodified: %s" % localpkg.lastfailed)
					debug("Local last build time: %s" % localpkg.lastbuild)
					# check if package need to be updated
					if localpkg.lastsuccess >= aurpkg.lastmodified :
						if "force" in pkgconfig:
							info("Up to date, but force value is present.")
							if pkgconfig["force"].isdigit() is False:
								warning("Invalid force value, ignore it")
								continue
							# if lastbuild not exists, it will be equal to 0
							# too small to be > to time() even with big force time
							now = int(time())
							force = int(pkgconfig["force"])
							debug("Force is: %ss" % force)
							force_delta = localpkg.lastbuild - now + force
							debug("Force Delta is: %ss" % force_delta)
							if force_delta < 0:
								info("Forced update")
								self.update(pkgconfig, localpkg, aurpkg)
							else:
								info("Next forced update in %ss" % force_delta)
						else:
							info("Up to date, nothing to do.")
					elif localpkg.lastfailed >= aurpkg.lastmodified:
						warning("Last build has failed, skipping. Remove lastfailed file to retry.")
					else:
						info("New version available: %s" % aurpkg.version)
						self.update(pkgconfig, localpkg, aurpkg)
				# sleep until next check
				# len(next_checks) is 0 when there is no package configured
				timeout = min(next_checks) if len(next_checks) > 0 else DEFAULT_CHECK_INTERVAL
				debug("waiting for %ds" % timeout)
				sleep(timeout)
			except InterruptedError:
				pass


def sighup_handler(signum, frame):
	info("SIGHUP received")
	# since python 3.5 we need to raise an exception to prevent python to EINTR
	# see https://www.python.org/dev/peps/pep-0475/
	raise InterruptedError()

def parse_argv():
	'''Parse command line arguments'''
	# load parser
	parser = ArgumentParser()
	parser.add_argument("-c", "--config", help="config file path",
		default=environ.get("AURBOT_CONFIG", DEFAULT_CONFIG_FILE))
	parser.add_argument("-d", "--debug", action="store_true", help="debug mode")
	parser.epilog = "You could set $XDG_DATA_HOME to change the path of the local package cache."
	# parse it!
	args = parser.parse_args()
	# set global debug mode
	if args.debug:
		getLogger().setLevel(DEBUG)
	return args

def main():
	'''Program entry point'''
	try:
		# set logger config
		hdlr = StreamHandler()
		hdlr.setFormatter(ABFormatter())
		getLogger().addHandler(hdlr)
		# Early debugging mode
		getLogger().setLevel(DEBUG if "AURBOT_DEBUG" in environ else INFO)
		# do not run as root
		if geteuid() == 0:
			raise Error("Do not run as root")
		# use sighup to unblock sleep syscall
		signal(SIGHUP, sighup_handler)
		# parse command line
		args = parse_argv()
		# create the bot object
		bot = Aurbot(args.config)
		# tell to systemd we are ready
		notify("READY=1\n")
		# start the bot
		bot.start()
	except KeyboardInterrupt:
		exit(Error.ERR_ABORT)
	except Error as exp:
		critical(exp)
		exit(Error.ERR_CRITICAL)
	except Exception as exp:
		critical(exp)
		if getLogger().getEffectiveLevel() != DEBUG:
			error("Unknown error. Please report it with --debug.")
		else:
			raise
		exit(Error.ERR_UNKNOWN)

if __name__ == '__main__':
	main()