"""
Student progress page
"""
from common.test.acceptance.pages.lms.course_page import CoursePage


class ProgressPage(CoursePage):
    """
    Student progress page.
    """

    url_path = "progress"

    def is_browser_on_page(self):
        is_present = (
            self.q(css='.course-info').present and
            self.q(css='#grade-detail-graph').present
        )
        return is_present

    @property
    def grading_formats(self):
        return [label.replace(' Scores:', '') for label in self.q(css=".scores dt").text]

    def section_score(self, chapter, section):
        """
        Return a list of (points, max_points) tuples representing the
        aggregate score for the section.

        Example:
            page.section_score('Week 1', 'Lesson 1') --> (2, 5)

        Returns `None` if no such chapter and section can be found.
        """
        # Find the index of the section in the chapter
        chapter_index = self._chapter_index(chapter)
        if chapter_index is None:
            return None

        section_index = self._section_index(chapter_index, section)
        if section_index is None:
            return None

        # Retrieve the scores for the section
        return self._aggregate_section_score(chapter_index, section_index)

    def scores(self, chapter, section):
        """
        Return a list of (points, max_points) tuples representing the scores
        for the section.

        Example:
            page.scores('Week 1', 'Lesson 1') --> [(2, 4), (0, 1)]

        Returns `None` if no such chapter and section can be found.
        """

        # Find the index of the section in the chapter
        chapter_index = self._chapter_index(chapter)
        if chapter_index is None:
            return None

        section_index = self._section_index(chapter_index, section)
        if section_index is None:
            return None

        # Retrieve the scores for the section
        return self._section_scores(chapter_index, section_index)

    def text_on_page(self, text):
        """
        Return whether the given text appears
        on the page.
        """
        return text in self.q(css=".view-in-course").html[0]

    def _chapter_index(self, title):
        """
        Return the CSS index of the chapter with `title`.
        Returns `None` if it cannot find such a chapter.
        """
        chapter_css = '.chapters section .hd'
        chapter_titles = self.q(css=chapter_css).map(lambda el: el.text.lower().strip()).results

        try:
            # CSS indices are 1-indexed, so add one to the list index
            return chapter_titles.index(title.lower()) + 1
        except ValueError:
            self.warning("Could not find chapter '{0}'".format(title))
            return None

    def _section_index(self, chapter_index, title):
        """
        Return the CSS index of the section with `title` in the chapter at `chapter_index`.
        Returns `None` if it can't find such a section.
        """

        # This is a hideous CSS selector that means:
        # Get the links containing the section titles in `chapter_index`.
        # The link text is the section title.
        section_css = '.chapters>section:nth-of-type({0}) .sections div .hd a'.format(chapter_index)
        section_titles = self.q(css=section_css).map(lambda el: el.text.lower().strip()).results

        # The section titles also contain "n of m possible points" on the second line
        # We have to remove this to find the right title
        section_titles = [t.split('\n')[0] for t in section_titles]

        # Some links are blank, so remove them
        section_titles = [t for t in section_titles if t]

        try:
            # CSS indices are 1-indexed, so add one to the list index
            return section_titles.index(title.lower()) + 1
        except ValueError:
            self.warning("Could not find section '{0}'".format(title))
            return None

    def _aggregate_section_score(self, chapter_index, section_index):
        """
        Return a tuple of the form `(points, max_points)` representing
        the aggregate score for the specified chapter and section.
        """
        score_css = ".chapters>section:nth-of-type({0}) .sections>div:nth-of-type({1}) .hd>span".format(
            chapter_index, section_index

        )
        text_scores = self.q(css=score_css).text
        assert len(text_scores) == 1
        text_score = text_scores[0]
        text_score = text_score.split()[0]  # strip off percentage, if present

        assert (text_score[0], text_score[-1]) == ('(', ')')
        text_score = text_score.strip('()')

        assert '/' in text_score
        score = tuple(int(x) for x in text_score.split('/'))
        assert len(score) == 2
        return score

    def _section_scores(self, chapter_index, section_index):
        """
        Return a list of `(points, max_points)` tuples representing
        the scores in the specified chapter and section.

        `chapter_index` and `section_index` start at 1.
        """
        # This is CSS selector means:
        # Get the scores for the chapter at `chapter_index` and the section at `section_index`
        # Example text of the retrieved elements: "0/1"
        score_css = ".chapters>section:nth-of-type({0}) .sections>div:nth-of-type({1}) .scores>dd".format(
            chapter_index, section_index
        )

        text_scores = self.q(css=score_css).text

        # Convert text scores to tuples of (points, max_points)
        return [tuple(map(int, score.split('/'))) for score in text_scores]