import argparse
from xml.dom import minidom

# fuzzy compare XML tree from XML strings
def isFuzzyEqualXml(xml1, xml2, absolute, relative):
    dom1 = minidom.parseString(xml1)
    dom2 = minidom.parseString(xml2)
    return isFuzzyEqualNode(dom1.documentElement, dom2.documentElement, absolute, relative)

# fuzzy compare of XML nodes
def isFuzzyEqualNode(node1, node2, absolute, relative):
    noError = True
    if node1.tagName != node2.tagName:
        print 'The name of the node differs in ', node1.tagName, ' and ', node2.tagName
        return False
    if sorted(node1.attributes.items()) != sorted(node2.attributes.items()):
        print 'Attributes differ in node ', node1.tagName
        return False
    if len(node1.childNodes) != len(node2.childNodes):
        print 'Number of children differs in node ', node1.tagName
        return False
    for node1child, node2child in zip(node1.childNodes, node2.childNodes):
        if node1child.nodeType != node2child.nodeType:
            print 'Node type differs in ', node1.tagName
            return False
        if node1child.nodeType == node1child.TEXT_NODE and not isFuzzyEqualText(node1child.data, node2child.data, absolute, relative):
            print 'Data differs in parameter ', node2.attributes.items(), ' at node ', node2child.nodeType
            noError = False
            continue
        if node1child.nodeType == node1child.ELEMENT_NODE and not isFuzzyEqualNode(node1child, node2child, absolute, relative):
            noError = False
            continue
    return noError

# fuzzy compare of text consisting of whitespace separated numbers
def isFuzzyEqualText(text1, text2, absolute, relative):
    list1 = text1.split()
    list2 = text2.split()
    # difference only in whitespace?
    if (list1 == list2):
        return True
    # compare number by number
    maximum1 = 0.0
    maximum2 = 0.0
    for number1, number2 in zip(list1, list2):
        number1 = float(number1)
        number2 = float(number2)
        if (abs(number1 - number2) > absolute 
            and (number2 == 0.0 or abs(abs(number1 / number2) - 1.0) > relative)):
            if (abs(number1 - number2) > abs(maximum1 - maximum2)):
                maximum1 = float(number1)
                maximum2 = float(number2)
    if (abs(maximum1 - maximum2) > 0.0):
        print 'Difference is too large between', maximum1, ' and ', maximum2
        return False
    return True

# main program
# handle arguments and print help message
parser = argparse.ArgumentParser(description='Fuzzy compare of two VTK\
    (Visualization Toolkit) files. The files are accepted if for every\
    value the difference is below the absolute error or below the\
    relative error or below both.')
parser.add_argument('vtu_file_1', type=open,
    help='first file to compare')
parser.add_argument('vtu_file_2', type=open,
    help='second file to compare')
parser.add_argument('-r', '--relative', type=float, default=1e-2,
    help='maximum relative error (default=1e-2)')
parser.add_argument('-a', '--absolute', type=float, default=1e-9,
    help='maximum relative error (default=1e-9)')
args = parser.parse_args()

# fuzzy compare
if (isFuzzyEqualXml(args.vtu_file_1.read(), args.vtu_file_2.read(), args.absolute, args.relative)):
    exit
else:
    exit(1)