#encoding:utf-8

"""
Copyright 2013 TY<tianyu0915@gmail.com>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

"""

from django.http import HttpResponse
from PIL import Image,ImageDraw,ImageFont
import random,StringIO
import os
from math import ceil

__version__ = '0.2.9',  

current_path = os.path.normpath(os.path.dirname(__file__))

class Captcha(object):

    def __init__(self,request):
        """   初始化,设置各种属性

        """
        self.django_request = request
        self.session_key = '_django_captcha_key'
        self.words = self._get_words()

        # 验证码图片尺寸
        self.img_width = 150
        self.img_height = 30
        self.type = 'number'

    def _get_font_size(self):
        """  将图片高度的80%作为字体大小

        """
        s1 = int(self.img_height * 0.8)
        s2 = int(self.img_width/len(self.code))
        return int(min((s1,s2)) + max((s1,s2))*0.05)

    def _get_words(self):
        """   读取默认的单词表

        """
        #TODO  扩充单词表

        file_path = os.path.join(current_path,'words.list')
        f = open(file_path,'r')
        return [line.replace('\n','') for line in f.readlines()]

    def _set_answer(self,answer):
        """  设置答案
        
        """
        self.django_request.session[self.session_key] = str(answer)

    def _yield_code(self):
        """  生成验证码文字,以及答案
        
        """

        # 英文单词验证码
        def word():
            code = random.sample(self.words,1)[0]
            self._set_answer(code)
            return code


        # 数字公式验证码
        def number():
            m,n = 1,50
            x = random.randrange(m,n)
            y = random.randrange(m,n)

            r = random.randrange(0,2)
            if r == 0:
                code = "%s - %s = ?" %(x,y)
                z = x - y
            else:
                code = "%s + %s = ?" %(x,y)
                z = x + y
            self._set_answer(z)
            return code

        fun = eval(self.type.lower())
        return fun()

    def display(self):
        """  生成验证码图片
        """

        # font color
        self.font_color = ['black','darkblue','darkred']

        # background color
        self.background = (random.randrange(230,255),random.randrange(230,255),random.randrange(230,255))

        # font path
        self.font_path = os.path.join(current_path,'timesbi.ttf')
        #self.font_path = os.path.join(current_path,'Menlo.ttc')

        # the words list maxlength = 8
        self.django_request.session[self.session_key] = '' 

        # creat a image
        im = Image.new('RGB',(self.img_width,self.img_height),self.background)
        self.code = self._yield_code()

        # set font size automaticly
        self.font_size = self._get_font_size()

        # creat a pen
        draw = ImageDraw.Draw(im)

        # draw noisy point/line
        if self.type == 'word':
            c = int(8/len(self.code)*3) or 3
        elif self.type == 'number':
            c = 4

        for i in range(random.randrange(c-2,c)):
            line_color = (random.randrange(0,255),random.randrange(0,255),random.randrange(0,255))
            xy = (
                    random.randrange(0,int(self.img_width*0.2)),
                    random.randrange(0,self.img_height),
                    random.randrange(3*self.img_width/4,self.img_width),
                    random.randrange(0,self.img_height)
                )
            draw.line(xy,fill=line_color,width=int(self.font_size*0.1))
            #draw.arc(xy,fill=line_color,width=int(self.font_size*0.1))
        #draw.arc(xy,0,1400,fill=line_color)

        # draw code
        j = int(self.font_size*0.3)
        k = int(self.font_size*0.5)
        x = random.randrange(j,k) #starts point
        for i in self.code:
            # 上下抖动量,字数越多,上下抖动越大
            m = int(len(self.code))
            y = random.randrange(1,3)

            if i in ('+','=','?'):
                # 对计算符号等特殊字符放大处理
                m = ceil(self.font_size*0.8)
            else:
                # 字体大小变化量,字数越少,字体大小变化越多
                m = random.randrange(0,int( 45 / self.font_size) + int(self.font_size/5))

            self.font = ImageFont.truetype(self.font_path.replace('\\','/'),self.font_size + int(ceil(m)))
            draw.text((x,y), i, font=self.font, fill=random.choice(self.font_color))
            x += self.font_size*0.9

        del x
        del draw
        buf = StringIO.StringIO()
        im.save(buf,'gif')
        buf.closed
        return HttpResponse(buf.getvalue(),'image/gif')

    def check(self,code):
        """ 
        检查用户输入的验证码是否正确 
        """
        _code = self.django_request.session.get(self.session_key) or ''
        if not _code:
            return False
        return _code.lower() == str(code).lower()

class Code(Captcha):
    """
    compatibility for less than v2.0.6 
    """
    pass

if __name__ == '__main__':
    import mock
    request = mock.Mock()
    c = Captcha(request)

