"""Simple captcha library, based on PIL. Monkey patch functions in this module

if you want something better...

:organization: Logilab

:copyright: 2009-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.

:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr

:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses

"""

__docformat__ = "restructuredtext en"

from random import randint, choice

from cStringIO import StringIO

import Image, ImageFont, ImageDraw, ImageFilter

from time import time

from cubicweb import tags

def pil_captcha(text, fontfile, fontsize):

    """Generate a captcha image. Return a PIL image object.

    adapted from http://code.activestate.com/recipes/440588/

    """

    # randomly select the foreground color

    fgcolor = randint(0, 0xffff00)

    # make the background color the opposite of fgcolor

    bgcolor = fgcolor ^ 0xffffff

    # create a font object

    font = ImageFont.truetype(fontfile, fontsize)

    # determine dimensions of the text

    dim = font.getsize(text)

    # create a new image slightly larger that the text

    img = Image.new('RGB', (dim[0]+5, dim[1]+5), bgcolor)

    draw = ImageDraw.Draw(img)

    # draw 100 random colored boxes on the background

    x, y = img.size

    for num in range(100):

        draw.rectangle((randint(0, x), randint(0, y),

                        randint(0, x), randint(0, y)),

                       fill=randint(0, 0xffffff))

    # add the text to the image

    draw.text((3, 3), text, font=font, fill=fgcolor)

    img = img.filter(ImageFilter.EDGE_ENHANCE_MORE)

    return img

def captcha(fontfile, fontsize, size=5, format='JPEG'):

    """Generate an arbitrary text, return it together with a buffer containing

    the captcha image for the text

    """

    text = u''.join(choice('QWERTYUOPASDFGHJKLZXCVBNM') for i in range(size))

    img = pil_captcha(text, fontfile, fontsize)

    out = StringIO()

    img.save(out, format)

    out.seek(0)

    return text, out

class CaptchaWidget(fw.TextInput):

    def render(self, form, field, renderer=None):

        # t=int(time()*100) to make sure img is not cached

        src = form._cw.build_url('view', vid='captcha', t=int(time()*100))

        img = tags.img(src=src, alt=u'captcha')

        img = u'<div class="captcha">%s</div>' % img

        return img + super(CaptchaWidget, self).render(form, field, renderer)