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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 getopt, sys

##
def usage () :
    texte = """%(prog)s usage :
python %(prog)s [-d] [-i iodef.xml] [-o iodef_new.xml] -n <node in Xpath syntax> -k <key>  -v <value>
python %(prog)s [-d] [-i iodef.xml] [-o iodef_new.xml] -n <node in Xpath syntax> -t <value>
 -d         | --debug         : debug
 -i <file>  | --input=<file>  : input file  (default: iodef.xml)
 -o <file>  | --output=<file> : output file (default: overwrite input file)
 -n <node>  | --node=<node>   : node in Xpath syntax
 -f <field> | --field=<field> : xml field to update
 -v <value> | --value=<value> : new value for xml field
 -t <text>  | --text=<text>   : will replace the 'text' part of the Xpath by <text>
example :  
    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
    """
    #print ( texte % ( sys.argv[0], sys.argv[0], sys.argv[0], sys.argv[0] ) )
    #print ( texte %   ( 6*[sys.argv[0]] ))
    print ( texte % { 'prog':sys.argv[0] } )
    
# 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)
  
## Default input parameters
FileIn   = 'iodef.xml'
FileOut  = None
Node     = None 
Key      = None
Text     = None
Value    = None
Debug    = False

## Command line options
try:
    myopts, myargs = getopt.getopt ( sys.argv[1:], 'i:o:n:k:v:t:dh', [ 'input=', 'output=', 'node=', 'key=', 'value=', 'text=', 'debug=', '--help' ] )
except getopt.GetoptError as cmdle :
    print ( "Command line error : "+cmdle )
    usage ()
    sys.exit(1)

for myopt, myval in myopts :
    if myopt in [ '-h', '--help'   ] : usage () ; sys.exit (0) ; 
    if myopt in [ '-i', '--input'  ] : FileIn   = myval
    if myopt in [ '-o', '--output' ] : FileOut  = myval
    if myopt in [ '-n', '--node'   ] : Node     = myval
    if myopt in [ '-k', '--key'    ] : Key      = myval
    if myopt in [ '-t', '--text'   ] : Text     = myval
    if myopt in [ '-v', '--value'  ] : Value    = myval
    if myopt in [ '-d', '--debug'  ] : Debug    = True

## Some coherency checking of command line parameters
ErrorCount = 0

if FileIn == None :
    print ( "Error : please specify input file by -i <file>" )
    ErrorCount += 1

if Node == None :
    print ( "Error : please specify -n <node>" )
    ErrorCount += 1
    
if Key == None and Text == None :
    print ( "Error : please specify either -t <text> or -k <key> -v <value>" )
    ErrorCount += 1

if Key != None and Text != None :
    print ( "Error : please specify only one option between -t "+Text+" and -k "+Key )
    ErrorCount += 1

if Key != None and Value == None :
    print ( "Error : please specify -v <value> when -k "+Key+" is given")
    ErrorCount += 1
 
if ErrorCount > 0 :
    usage ()
    sys.exit (1)

if FileOut == None : FileOut = FileIn
    
## 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 (1)

## 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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