#!/usr/bin/env python
#-*- encoding: utf-8 -*-
#
# captcha.py
# Library to simply use captchas.
#
# Copyright (c) 2008 Pierre "delroth" Bourdon <root@delroth.is-a-geek.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Original PHP code from coucou747, translated into Python.

import math
import random
import sys
import cgitb
from PIL import Image, ImageDraw

cgitb.enable()

class Captcha(object):
    """
    A captcha object is used to encapsulate a text and render the image
    with this text, which will generally be randomized.
    """

    def randomString(self):
        """
        Returns a random string to use in the captcha, with the most readable
        characters.
        """
        out = ''
        for i in xrange(self.len):
            out += random.choice(self.charset)
        return out

    def getMatrix(self):
        """
        Returns the deformation matrix.
        """
        lim_x = 16 * (len(self.text) + 1)
        array = []

        for k in xrange(20):
            array.append([])
            for i in xrange(lim_x):
                array[k].append(math.cos((i * self.cy + k * self.cx * math.pi)
                                         * self.cangle + self.phy) *
                                math.sin((i * self.cy + k * self.cx * math.pi)
                                         * self.cangle + self.phy) * self.h2 * 7)

        def e(x, y): array[x][y] -= 2 * self.h
        for k in xrange(1, len(self.text) + 1):
            for i in xrange(8):
                for j in xrange(7, -1, -1):
                    if ord(self.alphabet[i + 4 + ord(self.text[k - 1]) * 8]) & (1 << j):
                        e(i * 2 + 2, k * 16 + 9 - j * 2)
                        e(i * 2 + 3, k * 16 + 9 - j * 2)
                        e(i * 2 + 2, k * 16 + 10 - j * 2)
                        e(i * 2 + 3, k * 16 + 10 - j * 2)

        return array

    def getColor(self, matrix, color):
        return color * (10 - matrix / 3) / 10

    def drawMatrix(self, matrix, image):
        """
        Draws the matrix on the image.
        """
        drawer = ImageDraw.Draw(image)
        s, c = math.sin(self.angle), math.cos(self.angle)
        lx, ly = len(matrix[0]) - 1, len(matrix) - 1
        dx, dy, by = self.dx, self.dy, self.by
        a = matrix

        for y in xrange(ly):
            for x in xrange(lx):
                drawer.polygon([((x + y * c) * dx, by + a[y][x] + (y + x * s) * dy),
                                ((x + 1 + y * c) * dx, by + a[y + 1][x] + (y + 1 + x * s) * dy),
                                ((x + 1 + (y + 1) * c) * dx, by + a[y + 1][x + 1] + (y + 1 + (x + 1) * s) * dy),
                                ((x + (1 + y) * c) * dx, by + a[y][x + 1] + (y + (x + 1) * s) * dy)],
                                outline=self.color, fill=self.background)
        del drawer

    def getImage(self):
        sizex = self.width
        sizey = self.height
        img = Image.new("RGBA", (sizex, sizey), self.background)
        self.drawMatrix(self.matrix, img)
        return img
    
    def loadAlphabet(self):
        return file(self.alphaf).read()
    
    def __init__(self, alphaf, charset="bcdefghijklmnopqrstuvwxyz", len=5, width=450, height=160, color=(0, 0, 0, 255), background=(255, 255, 255, 0), angle=-5*3.1415/200, dx=4, dy=6, by=40, h=5, h2=0, cangle=0.055, cx=0.5, cy=1, phy=0):
        l = locals()
        for k in l:
            if k == 'self': continue
            setattr(self, k, l[k])
        self.alphabet = self.loadAlphabet()
        self.text = self.randomString()
        self.matrix = self.getMatrix()

print 'Content-Type: image/png'
print

if __name__ == '__main__':
    c = Captcha('alt-8x8.psf', color=(0, 0, 255, 255), background=(255, 255, 255, 255))
    c.getImage().save(sys.stdout, 'png')