text: # This file is part of EbookLib.
  # Copyright (c) 2013 Aleksandar Erkalovic <aerkalov@gmail.com>
  #
  # EbookLib is free software: you can redistribute it and/or modify
  # it under the terms of the GNU Affero General Public License as published by
  # the Free Software Foundation, either version 3 of the License, or
  # (at your option) any later version.
  #
  # EbookLib is distributed in the hope that it will be useful,
  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  # GNU Affero General Public License for more details.
  #
  # You should have received a copy of the GNU Affero General Public License
  # along with EbookLib.  If not, see <http://www.gnu.org/licenses/>.
  
  import io
  import mimetypes
  
  from lxml import etree
  
  
  mimetype_initialised = False
  
  
  def debug(obj):
      import pprint
  
      pp = pprint.PrettyPrinter(indent=4)
      pp.pprint(obj)
  
  
  def parse_string(s):
      try:
          tree = etree.parse(io.BytesIO(s.encode('utf-8')))
      except:
          tree = etree.parse(io.BytesIO(s))
  
      return tree
  
  
  def parse_html_string(s):
      from lxml import html
  
      utf8_parser = html.HTMLParser(encoding='utf-8')
  
      html_tree = html.document_fromstring(s, parser=utf8_parser)
  
      return html_tree
  
  
  def guess_type(extenstion):
      global mimetype_initialised
  
      if not mimetype_initialised:
          mimetypes.init()
          mimetypes.add_type('application/xhtml+xml', '.xhtml')
          mimetype_initialised = True
  
      return mimetypes.guess_type(extenstion)
  
  
  def create_pagebreak(pageref, label=None, html=True):
      from ebooklib.epub import NAMESPACES
  
      pageref_attributes = {
          '{%s}type' % NAMESPACES['EPUB']: 'pagebreak',
          'title': u'{}'.format(pageref),
          'id': u'{}'.format(pageref),
       }
  
      pageref_elem = etree.Element('span', pageref_attributes, nsmap={'epub': NAMESPACES['EPUB']})
  
      if label:
          pageref_elem.text = label
  
      if html:
          return etree.tostring(pageref_elem, encoding='unicode')
  
      return pageref_elem
  
  
  def get_headers(elem):
      for n in range(1, 7):
          headers = elem.xpath('./h{}'.format(n))
  
          if len(headers) > 0:
              text = headers[0].text_content().strip()
              if len(text) > 0:
                  return text
      return None
  
  
  def get_pages(item):
      body = parse_html_string(item.get_body_content())
      pages = []
  
      for elem in body.iter():
          if 'epub:type' in elem.attrib:
              if elem.get('id') is not None:
                  _text = None
                  
                  if elem.text is not None and elem.text.strip() != '':
                      _text = elem.text.strip()
  
                  if _text is None:
                      _text = elem.get('aria-label')
  
                  if _text is None:
                      _text = get_headers(elem)
  
                  pages.append((item.get_name(), elem.get('id'), _text or elem.get('id')))
  
      return pages
  
  
  def get_pages_for_items(items):
      pages_from_docs = [get_pages(item) for item in items]
  
      return [item for pages in pages_from_docs for item in pages]
  