"""Objects interacting together to provides the external page embeding

functionality.

"""

__docformat__ = "restructuredtext en"

import re

from urlparse import urljoin

from urllib2 import urlopen, Request, HTTPError

from urllib import quote as urlquote # XXX should use view.url_quote method

from logilab.mtconverter import guess_encoding

from cubicweb.selectors import (one_line_rset, score_entity,

                                match_search_state, implements)

from cubicweb.interfaces import IEmbedable

from cubicweb.view import NOINDEX, NOFOLLOW

from cubicweb.uilib import soup2xhtml

from cubicweb.web.controller import Controller

from cubicweb.web.action import Action

from cubicweb.web.views import basetemplates

class ExternalTemplate(basetemplates.TheMainTemplate):

    """template embeding an external web pages into CubicWeb web interface

    """

    __regid__ = 'external'

    def call(self, body):

        # XXX fallback to HTML 4 mode when embeding ?

        self.set_request_content_type()

        self._cw.search_state = ('normal',)

        self.template_header(self.content_type, None, self._cw._('external page'),

                             [NOINDEX, NOFOLLOW])

        self.content_header()

        self.w(body)

        self.content_footer()

        self.template_footer()

class EmbedController(Controller):

    __regid__ = 'embed'

    template = 'external'

    def publish(self, rset=None):

        req = self._cw

        if 'custom_css' in req.form:

            req.add_css(req.form['custom_css'])

        embedded_url = req.form['url']

        allowed = self._cw.vreg.config['embed-allowed']

        _ = req._

        if allowed is None or not allowed.match(embedded_url):

            body = '<h2>%s</h2><h3>%s</h3>' % (

                _('error while embedding page'),

                _('embedding this url is forbidden'))

        else:

            prefix = req.build_url(self.__regid__, url='')

            authorization = req.get_header('Authorization')

            if authorization:

                headers = {'Authorization' : authorization}

            else:

                headers = {}

            try:

                body = embed_external_page(embedded_url, prefix,

                                           headers, req.form.get('custom_css'))

                body = soup2xhtml(body, self._cw.encoding)

            except HTTPError, err:

                body = '<h2>%s</h2><h3>%s</h3>' % (

                    _('error while embedding page'), err)

        self.process_rql(req.form.get('rql'))

        return self._cw.vreg['views'].main_template(req, self.template,

                                                rset=self.cw_rset, body=body)

def entity_has_embedable_url(entity):

    """return 1 if the entity provides an allowed embedable url"""

    url = entity.embeded_url()

    if not url or not url.strip():

        return 0

    allowed = entity._cw.vreg.config['embed-allowed']

    if allowed is None or not allowed.match(url):

        return 0

    return 1

class EmbedAction(Action):

    """display an 'embed' link on entity implementing `embeded_url` method

    if the returned url match embeding configuration

    """

    __regid__ = 'embed'

    __select__ = (one_line_rset() & match_search_state('normal')

                  & implements(IEmbedable)

                  & score_entity(entity_has_embedable_url))

    title = _('embed')

    def url(self, row=0):

        entity = self.cw_rset.get_entity(row, 0)

        url = urljoin(self._cw.base_url(), entity.embeded_url())

        if self._cw.form.has_key('rql'):

            return self._cw.build_url('embed', url=url, rql=self._cw.form['rql'])

        return self._cw.build_url('embed', url=url)

# functions doing necessary substitutions to embed an external html page ######

BODY_RGX = re.compile('<body.*?>(.*?)</body>', re.I | re.S | re.U)

HREF_RGX = re.compile('<a\s+href="([^"]*)"', re.I | re.S | re.U)

SRC_RGX = re.compile('<img\s+src="([^"]*)"', re.I | re.S | re.U)

class replace_href:

    def __init__(self, prefix, custom_css=None):

        self.prefix = prefix

        self.custom_css = custom_css

    def __call__(self, match):

        original_url = match.group(1)

        url = self.prefix + urlquote(original_url, safe='')

        if self.custom_css is not None:

            if '?' in url:

                url = '%s&custom_css=%s' % (url, self.custom_css)

            else:

                url = '%s?custom_css=%s' % (url, self.custom_css)

        return '<a href="%s"' % url

class absolutize_links:

    def __init__(self, embedded_url, tag, custom_css=None):

        self.embedded_url = embedded_url

        self.tag = tag

        self.custom_css = custom_css

    def __call__(self, match):

        original_url = match.group(1)

        if '://' in original_url:

            return match.group(0) # leave it unchanged

        return '%s="%s"' % (self.tag, urljoin(self.embedded_url, original_url))

def prefix_links(body, prefix, embedded_url, custom_css=None):

    filters = ((HREF_RGX, absolutize_links(embedded_url, '<a href', custom_css)),

               (SRC_RGX, absolutize_links(embedded_url, '<img src')),

               (HREF_RGX, replace_href(prefix, custom_css)))

    for rgx, repl in filters:

        body = rgx.sub(repl, body)

    return body

def embed_external_page(url, prefix, headers=None, custom_css=None):

    req = Request(url, headers=(headers or {}))

    content = urlopen(req).read()

    page_source = unicode(content, guess_encoding(content), 'replace')

    page_source = page_source

    match = BODY_RGX.search(page_source)

    if match is None:

        return page_source

    return prefix_links(match.group(1), prefix, url, custom_css)