#!/usr/bin/env python
# -*- coding: UTF-8 -*-
#
# writexml.py
#
# simple python script to demonstrate how to read xml
# files and walk though the elements and their children
# using the python lxml library directly.
#
# The five simple functions 
#    createADESTree
#    addElement
#    addDataElement
#    writeADESTree
#    freeADESTree
#
# are provided so that Fortran and C translations
# of this example can handle all the memory management
# in these functions.
#
#
# This script is designed to work with both
# python 2 and python 3
#
#
# This implementaiton uses lxml, which is not part of
# the default python installation and so must
# be installed separately. 
#
#
# __future__ imports for Python 3 compliance in Python 2
# 
from __future__ import absolute_import, division, print_function
from __future__ import unicode_literals
#
# end of __future__ imports
#


#
# Use the names XMLTree and XMLElement to easily find
# all references to the xml library object ctors
#

from lxml import etree as XMLTree
from lxml.etree import Element as XMLElement

import sys

#
# sys.argv[1]: output xml file
# sys.argv[2]: output xml encoding
# example: ./writexml <xml file>
# example: ./writexml <xml file> UTF-8
#

utf8 = "UTF-8";

def usage(name):
    print("Usage: %s <xml file> [<xml_encoding>]" % (name));

def createADESTree():
   """ createADESTree creates and returns
       a top-level ADES tree.  This returned
       pointer must be freed at the end
   """
   property = {}
   property["version"] = "2017"
   ades = XMLElement("ades", property)
   return ades
       

def addDataElement(branch, tag, text):
   """ addDataElement(branch, tag, text)
       makes a new element with tag and text
       extends branch with the new element (which now owns memory)
       and returns the new element for later extension itself
   """
   el = XMLElement(tag)
   el.text = text
   branch.extend([el])
   return el # so it can be extended itself

def addElement(branch, tag):
   """ addElement(branch, tag)
       makes a new element with tag
       extends branch with the new element (which now owns memory)
       and returns the new element for later extension itself
   """
   el = XMLElement(tag)
   branch.extend([el])
   return el # so it can be extended itself

def writeADESTree(filename, ades, xmlEncoding):
   """ writes the completed tree to filename
       with the requested encoding and returns
       the object to free.
   """
   mytree = XMLTree.ElementTree(ades)
   mytree.write(filename,
                pretty_print=True, 
                xml_declaration=True, 
                encoding=xmlEncoding)

def freeADESTree(tree):
   """ freeADESTree(tree) calls XMLFree on the
       input tree
   """
   pass # python does not need this since it collects garbage
   

def doit(argc, argv):
	xmlEncoding = utf8;

	if (argc <= 1):
		usage(argv[0])
		return(1)

	if (argc == 3):
		xmlEncoding = argv[2]

	if (argc > 3):
		usage(argv[0])
		return(1)

        ades = createADESTree()

        obsBlock = addElement(ades, "obsBlock")
        obsContext = addElement(obsBlock, "obsContext")

        item = addElement(obsContext, "observatory")
	addDataElement(item, "mpcCode", "F51")
	addDataElement(item, "name", "Pan-STARRS 1")

        item = addElement(obsContext, "submitter")
	addDataElement(item, "name", "P. Villa")
	addDataElement(item, "institution", "Ejército Constitutionalista")
 
	item = addElement(obsContext, "observers")
	addDataElement(item, "name", "P. Villa")
	addDataElement(item, "name", "F. Madero")

	item = addElement(obsContext, "measurers")
	addDataElement(item, "name", "P. Villa")
	addDataElement(item, "name", "F. Madero")

	item = addElement(obsContext, "telescope")
	addDataElement(item, "aperture", "1.5")
	addDataElement(item, "design", "Reflector")
	addDataElement(item, "detector", "CCD")

	item = addDataElement(obsContext, "fundingSource", "Your favorite funding agency")

	item = addElement(obsContext, "comment");
	addDataElement(item, "line", "A comment line with >stuff< in it")
	addDataElement(item, "line", "Another comment line")



	obsData = addElement(obsBlock, "obsData")

	optical = addElement(obsData, "optical")
	addDataElement(optical, "permID", "1234456")
	addDataElement(optical, "trkSub", "aa")
	addDataElement(optical, "mode", "CCD")
	addDataElement(optical, "stn", "F51")
	addDataElement(optical, "obsTime", "2016-08-29T12:32:34Z")
	addDataElement(optical, "ra", "10.21")
	addDataElement(optical, "dec", "21.21")
	addDataElement(optical, "astCat", "2MA")
	addDataElement(optical, "mag", "15.3")
	addDataElement(optical, "band", "w")
	addDataElement(optical, "notes", "klmn")
	addDataElement(optical, "remarks", "A free-form \"remark\" <with stuff>")

	optical = addElement(obsData, "optical")
	addDataElement(optical, "permID", "1334456")
	addDataElement(optical, "trkSub", "aa")
	addDataElement(optical, "mode", "CCD")
	addDataElement(optical, "stn", "F51")
	addDataElement(optical, "obsTime", "2016-08-29T12:32:34Z")
	addDataElement(optical, "ra", "10.21")
	addDataElement(optical, "dec", "21.21")
	addDataElement(optical, "astCat", "2MA")
	addDataElement(optical, "mag", "15.3")
	addDataElement(optical, "band", "w")
	addDataElement(optical, "notes", "klmn")
	addDataElement(optical, "remarks", "Another One")


        freeADESTree(writeADESTree(sys.argv[1], ades, xmlEncoding))


	
doit(len(sys.argv), sys.argv)


