#!/usr/bin/env python
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### Modifies or add an element in an XML file
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##
##  Warning, to install, configure, run, use any of Olivier Marti's
##  software or to read the associated documentation you'll need at least
##  one (1) brain in a reasonably working order. Lack of this implement
##  will void any warranties (either express or implied).
##  O. Marti assumes no responsability for errors, omissions,
##  data loss, or any other consequences caused directly or indirectly by
##  the usage of his software by incorrectly or partially configured
##  personal.
##
## SVN information
__Author__   = "$Author$"
__Date__     = "$Date$"
__Revision__ = "$Revision$"
__Id__       = "$Id$"
__HeadURL    = "$HeadURL$"

# 
# Tested with python/2.7.12 and python/3.6.4
#
import xml.etree.ElementTree
import argparse, sys, textwrap
    
# Check version of Python
Version = sys.version_info
if Version < (2,7,0) :
  sys.stderr.write ( "You need python 2.7 or later to run this script\n" )
  sys.stderr.write ( "Present version is: " + str(Version[0]) + "." + str(Version[1]) + "." + str(Version[2]) + "\n" )
  sys.exit (1)
  
# Creating a parser to read the command line arguments
# The first step in using the argparse is creating an ArgumentParser object:
parser = argparse.ArgumentParser (description = """
examples : 
     python %(prog)s -i iodef.xml -n 'context[@id="interpol_run"]/file_definition/file[@id="file_src"]/field[@id="mask_source"]' -k name -v maskutil_T
     python %(prog)s -i iodef.xml -n 'context[@id="interpol_run"]/file_definition/file[@id="dia"]/variable[@name="dest_grid"]'   -t dstDomainType
     python %(prog)s -i iodef.xml -e commands.txt (not implemented yet)
   """ + "\n" + "SVN : " + __Revision__, formatter_class=argparse.RawDescriptionHelpFormatter, epilog='-------- This is the end of the help message --------')

# Adding arguments
group1 = parser.add_mutually_exclusive_group (required=True)

parser.add_argument ( '-i', '--input'  , help="input file"            , default='iodef.xml', type=str, metavar='<input_file>' )
parser.add_argument ( '-o', '--output' , help="output file"           , default=None       , type=str, metavar='<output_file>'  )
parser.add_argument ( '-n', '--node'   , help="xml node in Xpath syntax", default=None, required=True, type=str, metavar='<xml_node>')
group1.add_argument ( '-k', '--key'    , help="xml key to update"     , default=None , type=str , metavar='<xml_key>' )
group1.add_argument ( '-t', '--text'   , help="will replace the 'text' part of the Xpath by <text>", default=None, type=str, metavar='<text>' )
parser.add_argument ( '-v', '--value'  , help="new value for xml key", default=None, type=str, metavar='<value>' )
parser.add_argument ( '-d', '--debug'  , action="store_true", default=False )
parser.add_argument ( '-V', '--verbose', action="store_true", default=False )

# Parse command line
myargs = parser.parse_args()
Verbose  = myargs.verbose

if Verbose : print ( "Command line arguments : " , myargs )

FileIn   = myargs.input
FileOut  = myargs.output
Node     = myargs.node
Key      = myargs.key
Text     = myargs.text
Value    = myargs.value
Debug    = myargs.debug

# Error handling not dealed by argparse
if Key != None and Value == None :
    print ( "Error. When -k|--key=<key> is specified, you must specify -v|--value=<xml_value>" )
    sys.exit (-1)

if FileOut == None : FileOut = FileIn

# Remove whitespaces at both ends
Node = Node.rstrip().lstrip()

## Get XML tree from input file
iodef = xml.etree.ElementTree.parse ( FileIn )

## Find node
nodeList = iodef.findall ( Node )

## Check that one and only one node is found
if len (nodeList) == 0 :
    print ( "Error : node not found" )
    print ( "Node  : " + Node )
    sys.exit (1)
    
if len (nodeList) > 1 :
    print ( "Error : " + len (nodeList)+" occurences of node found" )
    print ( "Node  : " + Node )
    sys.exit (2)

## Update element
elem = nodeList[0]

if Debug :
    print ( 'Node  : ' + Node  )
    print ( 'Key   : ' + Key   )
    print ( 'Value : ' + Value )

if Text != None :
    if Debug :
        print ( 'Attributes of node: ' + str (elem.attrib) )
        print ( 'Text              : ' + str (elem.text)   )
    elem.text = Text

if Key != None :
    # To do : check that Key exist (it is added if not : do we want that ?)
    if Debug :
        print ( 'Attributes of node: ' + str (elem.attrib) )
    elem.attrib.update ( { Key:Value } )
    
## Writes XML tree to file
iodef.write ( FileOut )

## This is the end
sys.exit (0)
    
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###
###                               That's all folk's !!!
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