#! /usr/bin/env python

'''Emulate the mail-sending portion of the unix Mail program.'''

#
#  Do imports with care in case we are loaded as a module.
#

import getopt
_getopt = getopt
del getopt

import smtplib
_smtplib = smtplib
del smtplib

import socket
_socket = socket
del socket

import sys

import time
_time = time
del time


def send_message (subject, recipients, msgbody):
	'''Send e-mail message.'''

	envelope_from = "d0-release-mgr@fnal.gov"
	envelope_to = recipients.split (",")

	# Construct the message.
	msg = _format_msg (subject, recipients, msgbody)

	# Send the message.
	_send_message_via_smtp (envelope_from, envelope_to, msg)


def _usage (msg):
	'''Command line help.'''
	sys.exit (sys.argv[0] + ": usage: " + msg)


def _main ():
	'''Command line executive.'''

	envelope_from = "d0-release-mgr@fnal.gov"

	# Get the command line options and arguments.
	try: (opts, args) = _getopt.getopt (sys.argv[1:], "s:")
	except (_getopt.error), msg: _usage (msg)

	# The -s option specifies the optional subject.
	subject = ""
	for (opt, arg) in opts:
		if opt == "-s": subject = arg

	# There must be exactly one argument which is the recipient list.
	if not args: _usage ("you must specify at least one recipient!")
	if len (args) > 1: _usage ("only one argument expected!")

	# Process the recipient list.
	recipients = args[0]
	envelope_to = recipients.split (",")

	# Get the message body from stdin.
	msgbody = ""
	for line in sys.stdin.xreadlines ():
		msgbody = msgbody + line

	# Construct the message.
	msg = _format_msg (subject, recipients, msgbody)

	# Send the message.
	_send_message_via_smtp (envelope_from, envelope_to, msg)


def _format_msg (subject, recipients, msgbody):
	'''Add a RFC822 header to the message.'''

	# Get the current date in the RFC822 format.
	curtime = _time.time ()
	localtime = _time.localtime (curtime)
	daylight = localtime[8]
	gmtime = _time.gmtime (curtime)
	if daylight:
		tz = -_time.altzone
		tzname = _time.tzname[1]
	else:
		tz = -_time.timezone
		tzname = _time.tzname[0]
	tz_hr = tz / 3600
	tz_mn = tz % 3600
	tz_mn = tz_mn / 60
	curdate = _time.strftime ("%a, %d %b %Y %H:%M:%S ", localtime)
	curdate = curdate + "%+03d%02d (%s)" % (tz_hr, tz_mn, tzname)

	# Makeup a message id using the current time and the hostname.
	hostname = _socket.gethostname ()
	if hostname.find (".") == -1:
		(prim_name, alias_names, ipaddrs) = _socket.gethostbyaddr (hostname)
		if not hostname:
			hostname = prim_name
		if prim_name.find (".") != -1:
			hostname = prim_name
		else:
			for alias in alias_names:
				if alias.find (".") != -1:
					hostname = alias
					break
	msgid = "<%08x@%s>" % (curtime, hostname)
				
	# Ok, we can make the message header now.
        msg = ""
	msg = msg + "Date: %s\n" % (curdate,)
	msg = msg + "From: D0 Release Manager <d0-release-mgr@fnal.gov>\n"
	msg = msg + "Subject: %s\n" % (subject,)
	msg = msg + "To: %s\n" % (recipients,)
	msg = msg + "Errors-to: d0-release-mgr-owner@fnal.gov\n"
	msg = msg + "Message-id: %s\n" % (msgid,)
	msg = msg + "Organization: Fermi National Accelerator Laboratory\n"
	msg = msg + "X-Mailer: PyMail v1.0\n"
	msg = msg + "MIME-version: 1.0\n"
	msg = msg + "Content-type: text/plain; charset=us-ascii\n"
	msg = msg + "Content-transfer-encoding: 7bit\n"
	msg = msg + "X-Accept-Language: en\n"
	msg = msg + "\n"
	msg = msg + msgbody

	return msg


def _send_message_via_smtp (envelope_from, envelope_to, msg):
	'''Send and e-mail message via SMTP.'''

	server = _smtplib.SMTP ()
#	server.set_debuglevel (1)
	server.connect ("smtp.fnal.gov")
	server.sendmail (envelope_from, envelope_to, msg)
	server.quit ()
	return 0


if __name__ == "__main__":
	# We have been called as a script.
	_main ()
	sys.exit (0)
else:
	# We are loading as a module.
	pass