#!/usr/bin/env python
# -*- tab-width: 4; indent-tabs-mode: nil; py-indent-offset: 4 -*-
#
# This file is part of the LibreOffice project.
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#
# This file incorporates work covered by the following license notice:
#
#   Copyright (c) 2018 Martin Pieuchot
#   Copyright (c) 2018 Samuel Thibault <sthibault@hypra.fr>
#
#   Permission to use, copy, modify, and distribute this software for any
#   purpose with or without fee is hereby granted, provided that the above
#   copyright notice and this permission notice appear in all copies.
#
#   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
#   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
#   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
#   ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
#   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
#   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
#   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
# vim: set shiftwidth=4 softtabstop=4 expandtab:

# Take LibreOffice (glade) .ui files and check for non accessible widgets

from __future__ import print_function

import os
import sys
import getopt
import lxml.etree as ET

progname = os.path.basename(sys.argv[0])
Werror = False
Wnone = False
errors = 0
warnings = 0


def errstr(elm):
    """
    Print the line number of the element
    """

    return str(elm.sourceline)

def err(filename, elm, msg):
    global errors

    if elm == None:
        prefix = "%s:" % filename
    else:
        prefix = "%s:%s" % (filename, errstr(elm))

    errors += 1
    msg = "%s ERROR: %s" % (prefix, msg)
    print(msg.encode('ascii', 'ignore'))


def warn(filename, elm, msg):
    global Werror, Wnone, errors, warnings

    if Wnone:
        return

    prefix = "%s:%s" % (filename, errstr(elm))

    if Werror:
        errors += 1
    else:
        warnings += 1

    msg = "%s WARNING: %s" % (prefix,  msg)
    print(msg.encode('ascii', 'ignore'))


def check_objects(filename, elm, objects, target):
    """
    Check that objects contains exactly one object
    """
    length = len(list(objects))
    if length == 0:
        err(filename, elm, "use of undeclared target '%s'" % target)
    elif length > 1:
        err(filename, elm, "sevral targets are named '%s'" % target)

def check_props(filename, root, props):
    """
    Check the given list of relation properties
    """
    for prop in props:
        objects = root.iterfind(".//object[@id='%s']" % prop.text)
        check_objects(filename, prop, objects, prop.text)

def check_rels(filename, root, rels):
    """
    Check the given list of relations
    """
    for rel in rels:
        target = rel.attrib['target']
        targets = root.iterfind(".//object[@id='%s']" % target)
        check_objects(filename, rel, targets, target)

def check_a11y_relation(filename, root):
    """
    Emit an error message if any of the 'object' elements of the XML
    document represented by `root' doesn't comply with Accessibility
    rules.
    """

    for obj in root.iter('object'):

        label_for = obj.findall("accessibility/relation[@type='label-for']")
        check_rels(filename, root, label_for)

        labelled_by = obj.findall("accessibility/relation[@type='labelled-by']")
        check_rels(filename, root, labelled_by)

        member_of = obj.findall("accessibility/relation[@type='member-of']")
        check_rels(filename, root, member_of)

        if obj.attrib['class'] == 'GtkLabel':
            # Case 0: A 'GtkLabel' must contain one or more "label-for"
            # pointing to existing elements or...
            if len(label_for) > 0:
                continue

            # ...a single "mnemonic_widget"
            properties = obj.findall("property[@name='mnemonic_widget']")
            check_props(filename, root, properties)
            if len(properties) > 1:
                # It does not make sense for a label to be a mnemonic for
                # several actions.
                lines = ', '.join([str(p.sourceline) for p in properties])
                err(filename, obj, "too many sub-elements"
                    ", expected single <property name='mnemonic_widgets'>"
                    ": lines %s" % lines)
                continue
            if len(properties) == 1:
                continue
            # TODO: warn that it is a label for nothing
            continue

        # Case 1: has a <child internal-child="accessible"> sub-element
        children = obj.findall("child[@internal-child='accessible']")
        if children:
            if len(children) > 1:
                lines = ', '.join([str(c.sourceline) for c in children])
                err(filename, obj, "too many sub-elements"
                    ", expected single <child internal-child='accessible'>"
                    ": lines %s" % lines)
            continue

        # Case 2: has an <accessibility> sub-element with a "labelled-by"
        # <relation> pointing to an existing element.
        if len(labelled_by) > 0:
            continue

        # TODO: after a few more checks and false-positives filtering, warn
        # that this does not have a label


def usage():
    print("%s [-W error|none] [file ...]" % progname,
          file=sys.stderr)
    sys.exit(2)


def main():
    global Werror, Wnone, errors

    try:
        opts, args = getopt.getopt(sys.argv[1:], "pW:")
    except getopt.GetoptError:
        usage()

    for o, a in opts:
        if o == "-W":
            if a == "error":
                Werror = True
            elif a == "none":
                Wnone = True

    for filename in args:
        try:
            tree = ET.parse(filename)
        except ET.ParseError:
            err(filename, None, "malformatted xml file")
        except IOError:
            err(filename, None, "unable to read file")

        try:
            check_a11y_relation(filename, tree.getroot())
        except Exception as error:
            import traceback
            traceback.print_exc()
            err(filename, None, "error parsing file")


    if errors > 0:
        sys.exit(1)


if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        pass