# Copyright (c) 2011 Google Inc. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Applies a fix to CR LF TAB handling in xml.dom.

Fixes this: http://code.google.com/p/chromium/issues/detail?id=76293
Working around this: http://bugs.python.org/issue5752
TODO(bradnelson): Consider dropping this when we drop XP support.
"""


import xml.dom.minidom


def _Replacement_write_data(writer, data, is_attrib=False):
    """Writes datachars to writer."""
    data = data.replace("&", "&amp;").replace("<", "&lt;")
    data = data.replace('"', "&quot;").replace(">", "&gt;")
    if is_attrib:
        data = data.replace("\r", "&#xD;").replace("\n", "&#xA;").replace("\t", "&#x9;")
    writer.write(data)


def _Replacement_writexml(self, writer, indent="", addindent="", newl=""):
    # indent = current indentation
    # addindent = indentation to add to higher levels
    # newl = newline string
    writer.write(indent + "<" + self.tagName)

    attrs = self._get_attributes()
    a_names = sorted(attrs.keys())

    for a_name in a_names:
        writer.write(' %s="' % a_name)
        _Replacement_write_data(writer, attrs[a_name].value, is_attrib=True)
        writer.write('"')
    if self.childNodes:
        writer.write(">%s" % newl)
        for node in self.childNodes:
            node.writexml(writer, indent + addindent, addindent, newl)
        writer.write("%s</%s>%s" % (indent, self.tagName, newl))
    else:
        writer.write("/>%s" % newl)


class XmlFix(object):
    """Object to manage temporary patching of xml.dom.minidom."""

    def __init__(self):
        # Preserve current xml.dom.minidom functions.
        self.write_data = xml.dom.minidom._write_data
        self.writexml = xml.dom.minidom.Element.writexml
        # Inject replacement versions of a function and a method.
        xml.dom.minidom._write_data = _Replacement_write_data
        xml.dom.minidom.Element.writexml = _Replacement_writexml

    def Cleanup(self):
        if self.write_data:
            xml.dom.minidom._write_data = self.write_data
            xml.dom.minidom.Element.writexml = self.writexml
            self.write_data = None

    def __del__(self):
        self.Cleanup()
