#! /usr/bin/env python

# set interfaces in hv_kvp_daemon style
import fileinput
import sys
import errno
import os
import shutil
import tempfile
import subprocess

if_filename="/etc/network/interfaces"

'''Get quiet'''
sys.stdout = open(os.devnull, 'w')
sys.stderr = open(os.devnull, 'w')

try:
	if_file=open(if_filename,"r+")
except IOError as e:
	exit(e.errno)
else:
	if_file.close()


def kvp_dict(file):
	return dict(line.strip().split("=") for line in file)


#setting the hwaddress to something azure is not expecting is fatal networking 

if len(sys.argv) != 2 :
	exit(errno.EINVAL)

kvp=dict(line.strip().split("=") for line in fileinput.input())

if not "HWADDR" in kvp :
	exit(errno.EPROTO)

if not "DEVICE" in kvp :
	exit(1)

output=[]
basename=kvp["DEVICE"]

if "DHCP" in kvp and kvp["DHCP"]=="yes" :
	output += ["auto " + basename]
	output += ["iface " + basename  + " inet dhcp"]
	output += [""]
else:
	''' Matchup the interface specific lines '''

	'''DNS entries will go with the first interface
	and there can be a max of three'''
	autolist=[]
	dns=[]
	if "DNS1" in kvp :
		dns+=[kvp["DNS1"]]
		if "DNS2" in kvp :
			dns+=[kvp["DNS2"]]
			if "DNS3" in kvp :
				dns+=[kvp["DNS3"]]


	'''
	    No real max for the number of interface + aliases ... 
	    only required is the address (but mate everything up that comes in. '''

	'''ipv4 first'''

	v4names=[name for name in kvp.keys() if name.startswith("IPADDR")]
	v4names.sort()

	v6names=[name for name in kvp.keys() if name.startswith("IPV6ADDR")]
	v6names.sort()

	'''IPV6 requires a netmask'''
	'''If an ipv6 exists, you'll want to turn off /proc/sys/net/ipv6/conf/all/autoconf with
	up echo 0 > /proc/sys/net/ipv6/conf/all/autoconf'''

	'''Counter needs to increment as soon as any interface is set.'''


	if_count=0

	for v4 in v4names:
		ifname=basename
		suffix=""
		if if_count :
			ifname+=":" + str(if_count)
			suffix="_"+str(if_count)
		if not ifname in autolist:
			autolist += [ifname]
		output += [ "iface " + ifname + " inet static"]
		output += [ "\t" + "address " + kvp[v4]]
		if "NETMASK"+suffix in kvp.keys():
			output += ["\tnetmask " + kvp["NETMASK"+suffix]]
		if "GATEWAY"+suffix in kvp.keys():
			output += ["\tgateway " + kvp["GATEWAY"+suffix]]
		if not if_count :
			output += ["\tdns-nameservers " + ' '.join(dns)]
		output += [""]
		if_count+=1

	if6_count=0
	if6_used=0
	for v6 in v6names:
		ifname=basename
		suffix=""
		if if6_used :
			ifname+=":" + str(if6_used)
		if if6_count :
			suffix="_" + str(if6_count)
		if not ifname in autolist:
			autolist += [ifname]
		if "IPV6NETMASK"+suffix in kvp.keys():
			output += [ "iface " + ifname + " inet6 static"]
			output += [ "\taddress " + kvp[v6]]
			output += [ "\tnetmask " + kvp["IPV6NETMASK"+suffix]]
			if "IPV6_DEFAULTGW"+suffix in kvp.keys():
				output += [ "\tgateway " + kvp["IPV6_DEFAULTGW"+suffix] ]
			if not if_count :
				output += ["\tdns-nameservers " + ' '.join(dns)]
			output += [""]
			if_count += 1
			if6_used += 1
		if6_count += 1

	output = ["auto "+" ".join(autolist)] + output
print "==================================="
print output
print "==================================="


''' Time to clean out the existing interface file'''

# Markers.
start_mark = "# The following stanza(s) added by hv_set_ifconfig"
end_mark = "#End of hv_set_ifconfig stanzas"

f=open(if_filename,"r")
flines=f.readlines()
f.close()
newfile=[]
pitchstanza=0
inastanza=0
stanza=[]
prev_line=None
for line in flines:
	if line.startswith("auto"):
		if inastanza:
			if not pitchstanza:
				newfile.extend(stanza)
			stanza=[]
		inastanza=0
		newline=""
		autoline=line.strip().split(" ")
		for word in autoline:
			if (not word == basename) and (not word.startswith(basename+":")):
				newline+=word + " "
		newline = newline.strip()
		if not newline == "auto":
			newfile += [newline.strip()]
	elif line.startswith(("iface","mapping","source")):
		'''Read a stanza'''
		'''A Stanza can also start with allow- ie allow-hotplug'''
		if inastanza:
			if not pitchstanza:
				newfile.extend(stanza)
			stanza=[]
		inastanza=1
		pitchstanza=0
		autoline=line.strip().split(" ")
		for word in autoline:
			if (word == basename) or (word.startswith(basename+":")):
				pitchstanza=1
		if not pitchstanza:
			stanza+=[line.strip()]
        elif line.strip() in (start_mark, end_mark):
		if inastanza:
			if not pitchstanza:
				newfile.extend(stanza)
			stanza=[]
                inastanza = 0
                pitchstanza = 0
                # Deduplicate markers.
                if line != prev_line:
                    newfile += [line.strip()]
	else:
		if inastanza:
			if not pitchstanza:
				stanza+=[line.strip()]
		else:
			if not pitchstanza:
				newfile += [line.strip()]
        prev_line=line



def emit(line):
        print(line)
	os.write(fd, line + "\n")

# Insert the new output at the end and inside the existing markers if found.
emitted = False
fd, path = tempfile.mkstemp()
for line in newfile:
        if line == end_mark:
                emit("\n".join(output))
                emitted = True
        emit(line)
if not emitted:
        emit(start_mark)
        emit("\n".join(output))
        emit(end_mark)
os.close(fd)

shutil.copy(path,if_filename)
os.chmod(if_filename,0644)
#print "TMPFILE is at: " + path
#print "Copied file is at: " + if_filename


try:
    retcode = subprocess.call("ifdown "+basename , shell=True)
    if retcode < 0:
        print >>sys.stderr, "Child was terminated by signal", -retcode
    else:
        print >>sys.stderr, "Child returned", retcode
except OSError as e:
    print >>sys.stderr, "Execution failed:", e

try:
    retcode = subprocess.call("ifup "+basename , shell=True)
    if retcode < 0:
        print >>sys.stderr, "Child was terminated by signal", -retcode
    else:
        print >>sys.stderr, "Child returned", retcode
except OSError as e:
    print >>sys.stderr, "Execution failed:", e