#!/usr/bin/env python
# coding:utf-8

__version__ = '3.1.11'
__password__ = ''
__hostsdeny__ = ()  # __hostsdeny__ = ('.youtube.com', '.youku.com')
__content_type__ = 'image/gif'
__mirror_userjs__ = ()  # __mirror_userjs__ = '//www.example.com/user.js'

import os
import re
import time
import struct
import zlib
import base64
import logging
import urlparse
import io
import string

from google.appengine.api import urlfetch
from google.appengine.api.taskqueue.taskqueue import MAX_URL_LENGTH
from google.appengine.runtime import apiproxy_errors

URLFETCH_MAX = 2
URLFETCH_MAXSIZE = 4*1024*1024
URLFETCH_DEFLATE_MAXSIZE = 4*1024*1024
URLFETCH_TIMEOUT = 60

def message_html(title, banner, detail=''):
    MESSAGE_TEMPLATE = '''
    <html><head>
    <meta http-equiv="content-type" content="text/html;charset=utf-8">
    <title>$title</title>
    <style><!--
    body {font-family: arial,sans-serif}
    div.nav {margin-top: 1ex}
    div.nav A {font-size: 10pt; font-family: arial,sans-serif}
    span.nav {font-size: 10pt; font-family: arial,sans-serif; font-weight: bold}
    div.nav A,span.big {font-size: 12pt; color: #0000cc}
    div.nav A {font-size: 10pt; color: black}
    A.l:link {color: #6f6f6f}
    A.u:link {color: green}
    //--></style>
    </head>
    <body text=#000000 bgcolor=#ffffff>
    <table border=0 cellpadding=2 cellspacing=0 width=100%>
    <tr><td bgcolor=#3366cc><font face=arial,sans-serif color=#ffffff><b>Message From FetchServer</b></td></tr>
    <tr><td> </td></tr></table>
    <blockquote>
    <H1>$banner</H1>
    $detail
    <p>
    </blockquote>
    <table width=100% cellpadding=0 cellspacing=0><tr><td bgcolor=#3366cc><img alt="" width=1 height=4></td></tr></table>
    </body></html>
    '''
    return string.Template(MESSAGE_TEMPLATE).substitute(title=title, banner=banner, detail=detail)


try:
    from Crypto.Cipher.ARC4 import new as RC4Cipher
except ImportError:
    logging.warn('Load Crypto.Cipher.ARC4 Failed, Use Pure Python Instead.')
    class RC4Cipher(object):
        def __init__(self, key):
            x = 0
            box = range(256)
            for i, y in enumerate(box):
                x = (x + y + ord(key[i % len(key)])) & 0xff
                box[i], box[x] = box[x], y
            self.__box = box
            self.__x = 0
            self.__y = 0
        def encrypt(self, data):
            out = []
            out_append = out.append
            x = self.__x
            y = self.__y
            box = self.__box
            for char in data:
                x = (x + 1) & 0xff
                y = (y + box[x]) & 0xff
                box[x], box[y] = box[y], box[x]
                out_append(chr(ord(char) ^ box[(box[x] + box[y]) & 0xff]))
            self.__x = x
            self.__y = y
            return ''.join(out)


def application(environ, start_response):
    cookie = environ.get('HTTP_COOKIE', '')
    options = environ.get('HTTP_X_GOA_OPTIONS', '')
    if environ['REQUEST_METHOD'] == 'GET' and not cookie:
        if '204' in environ['QUERY_STRING']:
            start_response('204 No Content', [])
            yield ''
        else:
            timestamp = long(os.environ['CURRENT_VERSION_ID'].split('.')[1])/2**28
            ctime = time.strftime('%Y-%m-%d %H:%M:%S', time.gmtime(timestamp+8*3600))
            html = u'GoAgent Python Server %s \u5df2\u7ecf\u5728\u5de5\u4f5c\u4e86\uff0c\u90e8\u7f72\u65f6\u95f4 %s\n' % (__version__, ctime)
            start_response('200 OK', [('Content-Type', 'text/plain; charset=utf-8')])
            yield html.encode('utf8')
        raise StopIteration

    inflate = lambda x: zlib.decompress(x, -zlib.MAX_WBITS)
    deflate = lambda x: zlib.compress(x)[2:-4]
    rc4crypt = lambda s, k: RC4Cipher(k).encrypt(s) if k else s

    wsgi_input = environ['wsgi.input']
    input_data = wsgi_input.read()

    try:
        if cookie:
            if 'rc4' not in options:
                metadata = inflate(base64.b64decode(cookie))
                payload = input_data or ''
            else:
                metadata = inflate(rc4crypt(base64.b64decode(cookie), __password__))
                payload = rc4crypt(input_data, __password__) if input_data else ''
        else:
            if 'rc4' in options:
                input_data = rc4crypt(input_data, __password__)
            metadata_length, = struct.unpack('!h', input_data[:2])
            metadata = inflate(input_data[2:2+metadata_length])
            payload = input_data[2+metadata_length:]
        headers = dict(x.split(':', 1) for x in metadata.splitlines() if x)
        method = headers.pop('G-Method')
        url = headers.pop('G-Url')
    except (zlib.error, KeyError, ValueError):
        import traceback
        start_response('500 Internal Server Error', [('Content-Type', 'text/html')])
        yield message_html('500 Internal Server Error', 'Bad Request (metadata) - Possible Wrong Password', '<pre>%s</pre>' % traceback.format_exc())
        raise StopIteration

    kwargs = {}
    any(kwargs.__setitem__(x[2:].lower(), headers.pop(x)) for x in headers.keys() if x.startswith('G-'))

    if 'Content-Encoding' in headers:
        if headers['Content-Encoding'] == 'deflate':
            payload = inflate(payload)
            headers['Content-Length'] = str(len(payload))
            del headers['Content-Encoding']

    logging.info('%s "%s %s %s" - -', environ['REMOTE_ADDR'], method, url, 'HTTP/1.1')
    #logging.info('request headers=%s', headers)

    if __password__ and __password__ != kwargs.get('password', ''):
        start_response('403 Forbidden', [('Content-Type', 'text/html')])
        yield message_html('403 Wrong password', 'Wrong password(%r)' % kwargs.get('password', ''), 'GoAgent proxy.ini password is wrong!')
        raise StopIteration

    netloc = urlparse.urlparse(url).netloc

    if __hostsdeny__ and netloc.endswith(__hostsdeny__):
        start_response('403 Forbidden', [('Content-Type', 'text/html')])
        yield message_html('403 Hosts Deny', 'Hosts Deny(%r)' % netloc, detail='url=%r' % url)
        raise StopIteration

    if len(url) > MAX_URL_LENGTH:
        start_response('400 Bad Request', [('Content-Type', 'text/html')])
        yield message_html('400 Bad Request', 'length of URL too long(greater than %r)' % MAX_URL_LENGTH, detail='url=%r' % url)
        raise StopIteration

    if netloc.startswith(('127.0.0.', '::1', 'localhost')):
        start_response('400 Bad Request', [('Content-Type', 'text/html')])
        html = ''.join('<a href="https://%s/">%s</a><br/>' % (x, x) for x in ('google.com', 'mail.google.com'))
        yield message_html('GoAgent %s is Running' % __version__, 'Now you can visit some websites', html)
        raise StopIteration

    fetchmethod = getattr(urlfetch, method, None)
    if not fetchmethod:
        start_response('405 Method Not Allowed', [('Content-Type', 'text/html')])
        yield message_html('405 Method Not Allowed', 'Method Not Allowed: %r' % method, detail='Method Not Allowed URL=%r' % url)
        raise StopIteration

    deadline = URLFETCH_TIMEOUT
    validate_certificate = bool(int(kwargs.get('validate', 0)))
    # https://www.freebsdchina.org/forum/viewtopic.php?t=54269
    accept_encoding = headers.get('Accept-Encoding', '') or headers.get('Bccept-Encoding', '')
    errors = []
    for i in xrange(int(kwargs.get('fetchmax', URLFETCH_MAX))):
        try:
            response = urlfetch.fetch(url, payload, fetchmethod, headers, allow_truncated=False, follow_redirects=False, deadline=deadline, validate_certificate=validate_certificate)
            break
        except apiproxy_errors.OverQuotaError as e:
            time.sleep(5)
        except urlfetch.DeadlineExceededError as e:
            errors.append('%r, deadline=%s' % (e, deadline))
            logging.error('DeadlineExceededError(deadline=%s, url=%r)', deadline, url)
            time.sleep(1)
            deadline = URLFETCH_TIMEOUT * 2
        except urlfetch.DownloadError as e:
            errors.append('%r, deadline=%s' % (e, deadline))
            logging.error('DownloadError(deadline=%s, url=%r)', deadline, url)
            time.sleep(1)
            deadline = URLFETCH_TIMEOUT * 2
        except urlfetch.ResponseTooLargeError as e:
            errors.append('%r, deadline=%s' % (e, deadline))
            response = e.response
            logging.error('ResponseTooLargeError(deadline=%s, url=%r) response(%r)', deadline, url, response)
            m = re.search(r'=\s*(\d+)-', headers.get('Range') or headers.get('range') or '')
            if m is None:
                headers['Range'] = 'bytes=0-%d' % int(kwargs.get('fetchmaxsize', URLFETCH_MAXSIZE))
            else:
                headers.pop('Range', '')
                headers.pop('range', '')
                start = int(m.group(1))
                headers['Range'] = 'bytes=%s-%d' % (start, start+int(kwargs.get('fetchmaxsize', URLFETCH_MAXSIZE)))
            deadline = URLFETCH_TIMEOUT * 2
        except urlfetch.SSLCertificateError as e:
            errors.append('%r, should validate=0 ?' % e)
            logging.error('%r, deadline=%s', e, deadline)
        except Exception as e:
            errors.append(str(e))
            if i == 0 and method == 'GET':
                deadline = URLFETCH_TIMEOUT * 2
    else:
        start_response('500 Internal Server Error', [('Content-Type', 'text/html')])
        error_string = '<br />\n'.join(errors)
        if not error_string:
            logurl = 'https://appengine.google.com/logs?&app_id=%s' % os.environ['APPLICATION_ID']
            error_string = 'Internal Server Error. <p/>try <a href="javascript:window.location.reload(true);">refresh</a> or goto <a href="%s" target="_blank">appengine.google.com</a> for details' % logurl
        yield message_html('502 Urlfetch Error', 'Python Urlfetch Error: %r' % method,  error_string)
        raise StopIteration

    #logging.debug('url=%r response.status_code=%r response.headers=%r response.content[:1024]=%r', url, response.status_code, dict(response.headers), response.content[:1024])

    data = response.content
    response_headers = response.headers
    content_type = response_headers.get('content-type', '')
    if 'content-encoding' not in response_headers and 512 < len(response.content) < URLFETCH_DEFLATE_MAXSIZE and content_type.startswith(('text/', 'application/json', 'application/javascript')):
        if 'gzip' in accept_encoding:
            response_headers['Content-Encoding'] = 'gzip'
            compressobj = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION, zlib.DEFLATED, -zlib.MAX_WBITS, zlib.DEF_MEM_LEVEL, 0)
            dataio = io.BytesIO()
            dataio.write('\x1f\x8b\x08\x00\x00\x00\x00\x00\x02\xff')
            dataio.write(compressobj.compress(data))
            dataio.write(compressobj.flush())
            dataio.write(struct.pack('<LL', zlib.crc32(data) & 0xFFFFFFFFL, len(data) & 0xFFFFFFFFL))
            data = dataio.getvalue()
        elif 'deflate' in accept_encoding:
            response_headers['Content-Encoding'] = 'deflate'
            data = deflate(data)
    response_headers['Content-Length'] = str(len(data))
    response_headers_data = deflate('\n'.join('%s:%s' % (k.title(), v) for k, v in response_headers.items() if not k.startswith('x-google-')))
    if 'rc4' not in options or content_type.startswith(('audio/', 'image/', 'video/')):
        start_response('200 OK', [('Content-Type', __content_type__)])
        yield struct.pack('!hh', int(response.status_code), len(response_headers_data))+response_headers_data
        yield data
    else:
        start_response('200 OK', [('Content-Type', __content_type__), ('X-GOA-Options', 'rc4')])
        yield struct.pack('!hh', int(response.status_code), len(response_headers_data))
        yield rc4crypt(response_headers_data, __password__)
        yield rc4crypt(data, __password__)


class LegacyHandler(object):
    """GoAgent 1.x GAE Fetch Server"""
    @classmethod
    def application(cls, environ, start_response):
        return cls()(environ, start_response)

    def __call__(self, environ, start_response):
        self.environ = environ
        self.start_response = start_response
        return self.process_request()

    def send_response(self, status, headers, content, content_type=__content_type__):
        headers['Content-Length'] = str(len(content))
        strheaders = '&'.join('%s=%s' % (k, v.encode('hex')) for k, v in headers.iteritems() if v)
        #logging.debug('response status=%s, headers=%s, content length=%d', status, headers, len(content))
        if headers.get('content-type', '').startswith(('text/', 'application/json', 'application/javascript')):
            data = '1' + zlib.compress('%s%s%s' % (struct.pack('>3I', status, len(strheaders), len(content)), strheaders, content))
        else:
            data = '0%s%s%s' % (struct.pack('>3I', status, len(strheaders), len(content)), strheaders, content)
        self.start_response('200 OK', [('Content-type', content_type)])
        return [data]

    def send_notify(self, method, url, status, content):
        logging.warning('%r Failed: url=%r, status=%r', method, url, status)
        content = '<h2>Python Server Fetch Info</h2><hr noshade="noshade"><p>%s %r</p><p>Return Code: %d</p><p>Message: %s</p>' % (method, url, status, content)
        return self.send_response(status, {'content-type': 'text/html'}, content)

    def process_request(self):
        environ = self.environ
        if environ['REQUEST_METHOD'] == 'GET':
            redirect_url = 'https://%s/2' % environ['HTTP_HOST']
            self.start_response('302 Redirect', [('Location', redirect_url)])
            return [redirect_url]

        data = zlib.decompress(environ['wsgi.input'].read(int(environ['CONTENT_LENGTH'])))
        request = dict((k, v.decode('hex')) for k, _, v in (x.partition('=') for x in data.split('&')))

        method = request['method']
        url = request['url']
        payload = request['payload']

        if __password__ and __password__ != request.get('password', ''):
            return self.send_notify(method, url, 403, 'Wrong password.')

        if __hostsdeny__ and urlparse.urlparse(url).netloc.endswith(__hostsdeny__):
            return self.send_notify(method, url, 403, 'Hosts Deny: url=%r' % url)

        fetchmethod = getattr(urlfetch, method, '')
        if not fetchmethod:
            return self.send_notify(method, url, 501, 'Invalid Method')

        deadline = URLFETCH_TIMEOUT

        headers = dict((k.title(), v.lstrip()) for k, _, v in (line.partition(':') for line in request['headers'].splitlines()))
        headers['Connection'] = 'close'

        errors = []
        for _ in xrange(URLFETCH_MAX if 'fetchmax' not in request else int(request['fetchmax'])):
            try:
                response = urlfetch.fetch(url, payload, fetchmethod, headers, False, False, deadline, False)
                break
            except apiproxy_errors.OverQuotaError as e:
                time.sleep(4)
            except urlfetch.DeadlineExceededError as e:
                errors.append('DeadlineExceededError %s(deadline=%s)' % (e, deadline))
                logging.error('DeadlineExceededError(deadline=%s, url=%r)', deadline, url)
                time.sleep(1)
            except urlfetch.DownloadError as e:
                errors.append('DownloadError %s(deadline=%s)' % (e, deadline))
                logging.error('DownloadError(deadline=%s, url=%r)', deadline, url)
                time.sleep(1)
            except urlfetch.InvalidURLError as e:
                return self.send_notify(method, url, 501, 'Invalid URL: %s' % e)
            except urlfetch.ResponseTooLargeError as e:
                response = e.response
                logging.error('ResponseTooLargeError(deadline=%s, url=%r) response(%r)', deadline, url, response)
                m = re.search(r'=\s*(\d+)-', headers.get('Range') or headers.get('range') or '')
                if m is None:
                    headers['Range'] = 'bytes=0-%d' % URLFETCH_MAXSIZE
                else:
                    headers.pop('Range', '')
                    headers.pop('range', '')
                    start = int(m.group(1))
                    headers['Range'] = 'bytes=%s-%d' % (start, start+URLFETCH_MAXSIZE)
                deadline = URLFETCH_TIMEOUT * 2
            except Exception as e:
                errors.append('Exception %s(deadline=%s)' % (e, deadline))
        else:
            return self.send_notify(method, url, 500, 'Python Server: Urlfetch error: %s' % errors)

        headers = response.headers
        if 'content-length' not in headers:
            headers['content-length'] = str(len(response.content))
        headers['connection'] = 'close'
        return self.send_response(response.status_code, headers, response.content)
