# -*- coding: utf-8 -*-

# Copyright(C) 2010-2011 Christophe Benz
#
# This file is part of weboob.
#
# weboob 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.
#
# weboob 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 weboob. If not, see <http://www.gnu.org/licenses/>.


import re
import lxml.html

from .iparser import IParser
from ..browser import BrokenPageError


__all__ = ['LxmlHtmlParser']


class LxmlHtmlParser(IParser):
    """
    Parser using lxml.

    Note that it is not available on every systems.
    """

    def parse(self, data, encoding=None):
        if encoding is None:
            parser = None
        else:
            parser = lxml.html.HTMLParser(encoding=encoding)
        return lxml.html.parse(data, parser)

    def tostring(self, element):
        return lxml.html.tostring(element, encoding=unicode)

    def tocleanstring(self, element):
        txt = element.xpath('text()')   # ['foo ', ' bar']
        txt = ' '.join(txt)             # 'foo   bar'
        txt = re.sub('\s+', ' ', txt)   # 'foo bar'
        return txt.strip()

    def strip(self, s):
        doc = lxml.html.fromstring(s)   # parse html string
        return self.tocleanstring(doc)

    @classmethod
    def select(cls, element, selector, nb=None, method='cssselect'):
        """
        Select one or many elements from an element, using lxml cssselect by default.

        Raises BrokenPageError if not found.

        @param element [obj]  element on which to apply selector
        @param selector [str]  CSS or XPath expression
        @param method [str]  (cssselect|xpath)
        @param nb [int]  number of elements expected to be found.
                         Use None for undefined number, and 'many' for 1 to infinite.
        @return  one or many Element
        """
        if method == 'cssselect':
            results = element.cssselect(selector)
        elif method == 'xpath':
            results = element.xpath(selector)
        else:
            raise NotImplementedError('Only the cssselect and xpath methods are supported')
        if nb is None:
            return results
        elif isinstance(nb, basestring) and nb == 'many':
            if results is None or len(results) == 0:
                raise BrokenPageError('Element not found with selector "%s"' % selector)
            elif len(results) == 1:
                raise BrokenPageError('Only one element found with selector "%s"' % selector)
            else:
                return results
        elif isinstance(nb, int) and nb > 0:
            if results is None:
                raise BrokenPageError('Element not found with selector "%s"' % selector)
            elif len(results) < nb:
                raise BrokenPageError('Not enough elements found (%d expected) with selector "%s"' % (nb, selector))
            else:
                return results[0] if nb == 1 else results
        else:
            raise Exception('Unhandled value for kwarg "nb": %s' % nb)
