text.py

__copyright__ = "Copyright (C) 2014 Andreas Kloeckner"

__license__ = """
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""


import re
import sys
from typing import Any, Tuple

import django.forms as forms
from django.utils.translation import gettext, gettext_lazy as _

from course.page.base import (
    AnswerFeedback,
    PageBaseWithCorrectAnswer,
    PageBaseWithHumanTextFeedback,
    PageBaseWithTitle,
    PageBaseWithValue,
    get_editor_interaction_mode,
    markup_to_html,
)
from course.validation import ValidationError, validate_struct
from relate.utils import Struct, StyledForm, string_concat


CORRECT_ANSWER_PATTERN = string_concat(_("A correct answer is"), ": '%s'.")


class TextAnswerForm(StyledForm):
    # prevents form submission with codemirror's empty textarea
    use_required_attribute = False

    @staticmethod
    def get_text_widget(widget_type, check_only=False,
            interaction_mode=None, initial_text=None):
        """Returns None if no widget found."""

        if widget_type in [None, "text_input"]:
            if check_only:
                return True

            widget = forms.TextInput()
            widget.attrs["autofocus"] = None
            return widget, None

        elif widget_type == "textarea":
            if check_only:
                return True

            widget = forms.Textarea()
            widget.attrs["autofocus"] = None
            return widget, None

        elif widget_type.startswith("editor:"):
            if check_only:
                return True

            from course.utils import get_codemirror_widget
            cm_widget, cm_help_text = get_codemirror_widget(
                    language_mode=widget_type[widget_type.find(":")+1:],
                    interaction_mode=interaction_mode)

            return cm_widget, cm_help_text

        else:
            return None, None

    def __init__(self, read_only, interaction_mode, validators, *args, **kwargs):
        widget_type = kwargs.pop("widget_type", "text_input")
        initial_text = kwargs.pop("initial_text", None)

        super().__init__(*args, **kwargs)
        widget, help_text = self.get_text_widget(
                    widget_type,
                    interaction_mode=interaction_mode)
        self.validators = validators
        self.fields["answer"] = forms.CharField(
                required=True,
                initial=initial_text,
                disabled=read_only,
                widget=widget,
                help_text=help_text,
                label=_("Answer"))

    def clean(self):
        cleaned_data = super().clean()

        answer = cleaned_data.get("answer", "")
        for i, validator in enumerate(self.validators):
            try:
                validator.validate(answer)
            except forms.ValidationError:
                if i + 1 == len(self.validators):
                    # last one, and we flunked -> not valid
                    raise
            else:
                # Found one that will take the input. Good enough.
                break


# {{{ validators

class RELATEPageValidator:
    type = "relate_page"

    def __init__(self, vctx, location, validator_desc):
        self.validator_desc = validator_desc

        validate_struct(
                vctx,
                location,
                validator_desc,
                required_attrs=(
                    ("type", str),
                    ),
                allowed_attrs=(
                    ("page_type", str),
                    ),
                )

    def validate(self, new_page_source):
        import yaml

        from relate.utils import dict_to_struct

        try:
            page_desc = dict_to_struct(yaml.safe_load(new_page_source))

            from course.validation import ValidationContext, validate_flow_page
            vctx = ValidationContext(
                    # FIXME
                    repo=None,
                    commit_sha=None)

            validate_flow_page(vctx, "submitted page", page_desc)

            if page_desc.type != self.validator_desc.page_type:
                raise ValidationError(gettext("page must be of type '%s'")
                        % self.validator_desc.page_type)

        except Exception:
            tp, e, _ = sys.exc_info()

            raise forms.ValidationError("%(err_type)s: %(err_str)s"
                    % {"err_type": tp.__name__, "err_str": str(e)})


TEXT_ANSWER_VALIDATOR_CLASSES = [
        RELATEPageValidator,
        ]


def get_validator_class(location, validator_type):
    for validator_class in TEXT_ANSWER_VALIDATOR_CLASSES:
        if validator_class.type == validator_type:
            return validator_class

    raise ValidationError(
            string_concat(
                "%(location)s: ",
                _("unknown validator type"),
                "'%(type)s'")
            % {"location": location, "type": validator_type})


def parse_validator(vctx, location, validator_desc):
    if not isinstance(validator_desc, Struct):
        raise ValidationError(
                string_concat(
                    "%s: ",
                    _("must be struct"))
                % location)

    if not hasattr(validator_desc, "type"):
        raise ValidationError(
                string_concat(
                    "%s: ",
                    "matcher must supply 'type'")
                % location)

    return (get_validator_class(location, validator_desc.type)
        (vctx, location, validator_desc))