#!/usr/bin/env python
"""Transforms gml files to the tgf format

Author: Simon Willnauer (simonw@apache.org)
"""

# Licensed to the Apache Software Foundation (ASF) under one or more
#  contributor license agreements.  See the NOTICE file distributed with
#  this work for additional information regarding copyright ownership.
#  The ASF licenses this file to You under the Apache License, Version 2.0
#  (the "License"); you may not use this file except in compliance with
#  the License.  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.
#

# -*- coding: utf-8 -*-

import os
import re
import sys
from htmlentitydefs import name2codepoint

__author__= 'Simon Willnauer (simonw@apache.org)'
__version__= '1.0'


def decodeHtml(s):
  return re.sub('&(%s);' % '|'.join(name2codepoint), 
                lambda m: unichr(name2codepoint[m.group(1)]), s)


def transform(input, output):  
  """Transforms the input from the gml format into tgf
  
  Reads a GML (http://en.wikipedia.org/wiki/Graph_Modelling_Language) file from
  the input file and transforms the input graph into a TGF
  (http://en.wikipedia.org/wiki/Trivial_Graph_Format) file given as the output
  parameter.
  
    Argument: 
      input the input file stream to read the gml format from
      output the output file stream to write the tgf format to
  """
  nodePattern = re.compile(r'node\s*[[]\s*id\s*(\d+)\s*label\s*["](.+)["]',
                           re.MULTILINE)
  edgePattern = re.compile(r'edge\s*[[]\s*source\s*(\d+)\s*target\s*(\d+)'
                           '(\s*label\s*["](.+)["])?', re.MULTILINE)
  
  source = input.read()
  edgePrint = "%s %s %s\n"
  nodePrint = "%s %s\n"
  start = 0
  nodes = True
  while True:
    if nodes:
      matcher = nodePattern.search(source, start)
      if matcher:
        id = matcher.group(1)
        label = matcher.group(2)
        start = matcher.span()[1]
        output.write(nodePrint % (id, decodeHtml(label)))
      else:
        nodes = False
        output.write("#\n")
    else:
      matcher = edgePattern.search(source, start)
      if matcher:
        src = matcher.group(1)
        dest = matcher.group(2)
        label = ""
        if matcher.group(3):
          label = matcher.group(4)
        start = matcher.span()[1]
        output.write(edgePrint % (src, dest, decodeHtml(label)))
      else:
        break
      
if __name__ == "__main__":
  input = None
  output = None
  if len(sys.argv) < 2:
    print "Usage: %s INPUTFILE [OUTPUTFILE]" % (os.path.split(sys.argv[0])[1])
    sys.exit(- 1)
  if len(sys.argv) < 3:
    head, tail = os.path.split(sys.argv[1])
    outFileName = "%s.tgf" % (os.path.splitext(tail)[0])
  else:
    outFileName = sys.argv[2]
  
  try:
    input = open(sys.argv[1])
    
    output = open(outFileName, "w")    
    transform(input, output)
  finally:
    if input:
      input.close()
    if output:
      output.flush()
      output.close()