import os

import cache
import helper
import slides as slides_helper

root = ""
lang = ""

# Compiles a presentation's chapters (the content without the wrapper)
# according to slides.yml and returns them as one string of <section>s.
def compile_chapters(root_directory, language, force_recompile=False):
    global root
    root = root_directory

    global lang
    lang = language

    structure = helper.read_yaml(root, 'slides.yml')
    no_cache = cache.is_recompile_obligatory(root, lang) or force_recompile

    chapters = ""
    for chapter in structure:
        chapters += '<section>' + os.linesep + compile_chapter(chapter, no_cache) + os.linesep + '</section>'

    cache.save_compile_timestamp(root, lang)
    return chapters # string

# Compiles a presentation's chapter (given its name) by splitting it into
# slides, compiling those, and returning them as a string of <article>s.
def compile_chapter(chapter, no_cache):
    global root
    if type(chapter) != str:
        raise Exception('Chapters with attributes are not supported yet.\n' +
                str(chapter))

    chapter_file_name = 'slides/' + chapter + '.' + lang + '.md'
    chapter_path = os.path.join(root, chapter_file_name)

    can_use_cache = not (
        no_cache or
        cache.not_cached_before(root, lang, chapter) or
        cache.file_touched_since_last_compile(root, lang, chapter_file_name))

    if can_use_cache:
        print("Using cached version of chapter " + chapter + " (" + lang + ").")
        return cache.get_cached_chapter(root, lang, chapter)

    print("Recompiling chapter " + chapter + " (" + lang + ").")
    chapter_file = open(chapter_path, 'r', encoding='utf-8')
    delimiter = '\n@slide'
    chapter_input = ('\n' + chapter_file.read()).split(delimiter)
    slides = [delimiter + slide for slide in chapter_input][1:]
    chapter_content = ''
    for slide in slides:
        chapter_content +=\
            '<article>\n' +\
            slides_helper.compile_slide(slide, root) + '\n' +\
            '</article>\n'

    cache.store_cached_chapter(root, lang, chapter, chapter_content)
    return chapter_content