"""
xml_test1.py -- V.1.1 by leonardo maffi, Feb 7 2007

This is just a little exercise of managing SML from Python. This the first
time I manage XML with Python, so in this code there can be various problems.

This is the Python version of the Perl code of the article:
  "XML for Perl developers, Part 1: XML plus Perl -- simply magic
  Integrate XML into a Perl application using XML::Simple"
  By Jim Dixon, 30 Jan 2007:
  http://www-128.ibm.com/developerworks/xml/library/x-xmlperl1.html?ca=dgr-lnxw01XML-Simple


REQUIREMENTS to run this code:
- Python V.2.5 (but with little changes it works with Python 2.3 too).
- cElementTree, that is built-in in Python 2.5, but can be installed for older
  versions of Python too free: http://effbot.org/zone/element-index.htm
- mx.DateTime, to manage dates better than the built-ins of CPython.
  Can be found free:  http://www.egenix.com/files/python/mxDateTime.html


THINGS TO BE DONE FOR THIS EXERCISE:
 - To save space, change all of the subelements to attributes
 - Increase prices by 20%
 - Make all prices look the same, so all will show two decimal places
 - Sort the list [I sort it according to pet name]
 - Replace dates of birth with ages
"""

import xml.etree.cElementTree as cet
from time import strptime
from mx import DateTime


def plural(n):
    return "s" if n>1 else ""

def manage_dob(pet_attr_text):
    dob = strptime(pet_attr_text, "%d %B %Y")
    dob2 = DateTime.Date(*dob[0:3])
    diff = DateTime.RelativeDateDiff(DateTime.now(), dob2)
    if diff.years > 0:
        age = str(diff.years) + " year" + plural(diff.years)
    elif diff.months > 0:
        age = str(diff.months) + " month" + plural(diff.months)
    else:
        age = str(diff.days) + " day" + plural(diff.days)
    return "age", age

def manage_price(pet_attr_text):
    return "price", "%.02f" % (1.2 * float(pet_attr_text))


def et_prettify(elem, level=0):
    "Indents an Element and its subelements, recursively, to produce a pretty print"
    # From: http://effbot.org/zone/element-lib.htm#prettyprint
    i = "\n" + level * "  "
    if len(elem):
        if not elem.text or not elem.text.strip():
            elem.text = i + "  "
        for elem in elem:
            et_prettify(elem, level+1)
        if not elem.tail or not elem.tail.strip():
            elem.tail = i
    else:
        if level and (not elem.tail or not elem.tail.strip()):
            elem.tail = i


def process_xml(input_xml, declaration=True, prettify=True):
    root = cet.fromstring(input_xml)

    # sort according to names, I don't know if there is a better way to sort
    sorted_tree = sorted(root, key=lambda el:el.find("name").text)
    for i in xrange(len(sorted_tree)):
        root[i] = sorted_tree[i]

    root2 = cet.Element("pets")

    # Compute on the fly the dispatch table dict, it equals to:
    # {"dob":manage_dob(), "price":manage_price(), ...}
    pr = "manage_"
    dispatch = dict((name[len(pr):], globals()[name]) for name in globals() if name.startswith(pr))

    for pet in root:
        attributes = {}
        for pet_attr in pet:
            if pet_attr.tag in dispatch:
                key, val = dispatch[pet_attr.tag](pet_attr.text)
            else:
                key, val = pet_attr.tag, pet_attr.text
            attributes[key] = val

        # Attributes are unsorted, it seems there's no way to put 'name' first
        cet.SubElement(root2, pet.tag, attributes)

    if prettify: # optional
        et_prettify(root2)

    result = cet.tostring(root2)

    if declaration:
        xml_declaration = input_xml.split(">", 1)[0] + ">\n"
        result = xml_declaration + result

    return result


input_xml = """\
<?xml version='1.0'?>
<pets>
  <cat>
    <name>Madness</name>
    <dob>1 February 2004</dob>
    <price>150</price>
  </cat>
  <dog>
    <name>Maggie</name>
    <dob>12 October 2006</dob>
    <price>75</price>
    <owner>Rosie</owner>
  </dog>
  <cat>
    <name>Little</name>
    <dob>28 January 2007</dob>
    <price>25</price>
  </cat>
</pets>"""

# If used with a file on disk:
# tree = cet.parse("xml_test2.xml")
# root = tree.getroot()

print process_xml(input_xml, declaration=True, prettify=True)


"""
OUTPUT XML:

<?xml version='1.0'?>
<pets>
  <cat age="10 days" name="Little" price="30.00" />
  <cat age="3 years" name="Madness" price="180.00" />
  <dog age="3 months" name="Maggie" owner="Rosie" price="90.00" />
</pets>

"""