#!/usr/bin/python

import sys
import os
import jinja2
try:
    import json
except ImportError:
    import simplejson as json

source   = sys.argv[1]
dest     = sys.argv[2]
metadata = sys.argv[3]
 
# raise an error if there is no template metadata
if not os.path.exists(metadata):
    print json.dumps({
        "failed" : 1,
        "msg"    : "Missing %s, did you run the setup module yet?" % metadata
    })
    sys.exit(1)

# raise an error if we can't parse the template metadata
try:
   f = open(metadata)
   data = json.loads(f.read())
   f.close()
except:
   print json.dumps({
       "failed" : 1,
       "msg"    : "Failed to parse/load %s, rerun the setup module?" % metadata
   })
   sys.exit(1)

if not os.path.exists(source):
    print json.dumps({
        "failed" : 1,
        "msg"    : "Source template could not be read: %s" % source
    })
    sys.exit(1)

source = file(source).read()

# record md5sum of original source file so we can report if it changed
changed = False
md5sum = None
if os.path.exists(dest):
    md5sum = os.popen("md5sum %s" % dest).read().split()[0]

# call Jinja2 here and save the new template file
template = jinja2.Template(source)
data_out = template.render(data)
f = open(dest, "w+")
f.write(data_out)
f.close()

# TODO: catch templating errors and do not clobber the file on the
# other end unless things were successful

# record m5sum and return success and whether things have changed
md5sum2 = os.popen("md5sum %s" % dest).read().split()[0]

if md5sum != md5sum2:
    changed = True

# mission accomplished
print json.dumps({
   "md5sum"   : md5sum2,
   "changed"  : changed 
})