import logging
import re

from lxml.html import document_fromstring
from lxml.html import HTMLParser
from lxml.html import tostring

from cleaners import clean_attributes
from cleaners import normalize_spaces
from encoding import get_encoding

logging.getLogger().setLevel(logging.DEBUG)
utf8_parser = HTMLParser(encoding='utf-8')


LOG = logging.getLogger()


def build_doc(page):
    """Requires that the `page` not be None"""
    if page is None:
        LOG.error("Page content is None, can't build_doc")
        return ''
    if isinstance(page, unicode):
        page_unicode = page
    else:
        enc = get_encoding(page)
        page_unicode = page.decode(enc, 'replace')
    doc = document_fromstring(
        page_unicode.encode('utf-8', 'replace'),
        parser=utf8_parser)
    return doc


def js_re(src, pattern, flags, repl):
    return re.compile(pattern, flags).sub(src, repl.replace('$', '\\'))


def normalize_entities(cur_title):
    entities = {
        u'\u2014': '-',
        u'\u2013': '-',
        u'—': '-',
        u'–': '-',
        u'\u00A0': ' ',
        u'\u00AB': '"',
        u'\u00BB': '"',
        u'"': '"',
    }
    for c, r in entities.iteritems():
        if c in cur_title:
            cur_title = cur_title.replace(c, r)

    return cur_title


def norm_title(title):
    return normalize_entities(normalize_spaces(title))


def get_title(doc):
    title_node = doc.find('.//title')

    if not title_node:
        return '[no-title]'
    title = title_node.text
    return norm_title(title)


def add_match(collection, text, orig):
    text = norm_title(text)
    if len(text.split()) >= 2 and len(text) >= 15:
        if text.replace('"', '') in orig.replace('"', ''):
            collection.add(text)


def shorten_title(doc):
    title_node = doc.find('.//title')
    if not title_node:
        return ''

    title = title_node.text
    title = orig = norm_title(title)

    candidates = set()

    for item in ['.//h1', './/h2', './/h3']:
        for e in list(doc.iterfind(item)):
            if e.text:
                add_match(candidates, e.text, orig)
            if e.text_content():
                add_match(candidates, e.text_content(), orig)

    for item in ['#title', '#head', '#heading', '.pageTitle', '.news_title',
        '.title', '.head', '.heading', '.contentheading', '.small_header_red']:
        for e in doc.cssselect(item):
            if e.text:
                add_match(candidates, e.text, orig)
            if e.text_content():
                add_match(candidates, e.text_content(), orig)

    if candidates:
        title = sorted(candidates, key=len)[-1]
    else:
        for delimiter in [' | ', ' - ', ' :: ', ' / ']:
            if delimiter in title:
                parts = orig.split(delimiter)
                if len(parts[0].split()) >= 4:
                    title = parts[0]
                    break
                elif len(parts[-1].split()) >= 4:
                    title = parts[-1]
                    break
        else:
            if ': ' in title:
                parts = orig.split(': ')
                if len(parts[-1].split()) >= 4:
                    title = parts[-1]
                else:
                    title = orig.split(': ', 1)[1]

    if not 15 < len(title) < 150:
        return orig

    return title


def get_body(doc):
    [elem.drop_tree() for elem in doc.xpath('.//script | .//link | .//style')]
    raw_html = unicode(tostring(doc.body or doc))
    cleaned = clean_attributes(raw_html)
    try:
        #BeautifulSoup(cleaned) #FIXME do we really need to try loading it?
        return cleaned
    except Exception:  # FIXME find the equivalent lxml error
        logging.error("cleansing broke html content: %s\n---------\n%s" % (
            raw_html,
            cleaned))
        return raw_html