#!/usr/bin/python -t
import  os, sys, string, time
import asynchat, asyncore, socket, httplib, urlparse
from heapq import heappush, heappop
try:
    import cStringIO as StringIO
except ImportError:
    import StringIO


ENDPOINTS = [
    ('10.2.2.11', 8888),
    ('10.3.1.2', 8888),
#    ('10.1.1.156', 8888),
]

kB = 1024
#minimum entity size to start a paralel fetch
THRESHOLD = 512 * kB
#first fetch-range blocksize
INIT_BLOCKSIZE = 512 * kB
#lower bound of fetch-range blocksize optimization
MIN_BLOCKSIZE = 512 * kB
#time each fetcher spent on his range, calculated using
#speed measured while using INIT_BLOCKSIZE
TIME_SLICE = 5
#start a new fetcher on a endpoint X-bytes before the
#old one finished
FETCHER_JUMPSTART = 32 * kB

#################

class Fetcher(asynchat.async_chat):
    def __init__(self, reader, proxy, url, headers, range):
        self.reader = reader
        self.proxy = proxy
        self.url = url
        self.headers = headers
        self.range = range

        self.pos = self.range[0]
        self.start_time = 0
        self.stop_time = 0
        self.http_status = ""
        self.http_header = StringIO.StringIO()
        self.state = 0 #0=status, 1=header, 2=body
 
        asynchat.async_chat.__init__(self)
        self.set_terminator("\r\n")
        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
        self.connect(self.proxy)

    def handle_connect (self):
        print self, "Start"
        self.send("GET http://%s:%s%s HTTP/1.0\r\n" % ( self.url.hostname, self.url.port or 80, self.url.path ))
        for key in filter(lambda k: k not in ("range"), self.headers.keys()): #send origin request headers
            self.send("%s: %s\r\n" % (key, self.headers[key]))
        self.send("Range: bytes=%s-%s\r\n" % (self.range[0], self.range[1]))
        self.send("\r\n")
        self.start_time = time.time()

    def time(self):
        if self.stop_time == 0:
            return time.time() - self.start_time
        else:
            return self.stop_time - self.start_time

    def speed(self):
        return (self.pos - self.range[0]) / self.time()

    def collect_incoming_data(self, data):
        if self.state==2: #body
            length = len(data)
            self.reader.handle_incoming_data(self, data, length)
            self.pos += length
            if self.pos >= self.range[1]: 
                self.stop_time = time.time()
                print self, "finished"
                #make sure the next fetcher will be started
                self.reader.handle_incoming_data(self)
                self.close()
        elif self.state ==1: #header
            self.http_header.write( data )
        else: #status
            self.http_status += data 

    def found_terminator(self):
        if self.state == 0: #got status-line
            self.state = 1
            self.set_terminator("\r\n\r\n")
        elif self.state == 1: #got headers
            self.state = 2
            self.set_terminator(None)
            self.reader.handle_incoming_http_header(self.http_header)

    def __str__(self):
        return "<Fetcher proxy=%s url=%s range=%s" % (self.proxy, urlparse.urlunparse(self.url), self.range)

class StringIOProducer(object):
    def __init__(self,buf, amt=1440):
        self.buf=buf
        self.amt = amt
        self.buf.seek(0)

    def more(self):
        return self.buf.read(self.amt)

class MultipleProxyReader(object):
    def __init__(self, channel, url, header, content_length):
        self.channel = channel
        self.url = url
        self.header = header
        self.content_length = content_length
        
        self.header_sent = False
        self.fetch_pos = 0
        self.write_pos = 0
        self.buffer = ""
        self.blocks = list()
        self.fetchers = list()

        for proxy in ENDPOINTS:
            self.fetchers.append( Fetcher(self, proxy, self.url, self.header, self.next_range(INIT_BLOCKSIZE)) )

    def handle_incoming_data(self, fetcher, data=None, length=0):
        if not data:
            self.fetchers = filter(lambda f: f != fetcher, self.fetchers)
        else:
            heappush(self.blocks, (fetcher.pos, data, length))

        if self.channel.is_closed:
            print self, "request side closed the connection"
            return

        if fetcher.range[1] - fetcher.pos < FETCHER_JUMPSTART \
                and self.fetch_pos + 1 < self.content_length and not self.channel.is_closed \
                and len( filter( (lambda f: f.proxy == fetcher.proxy), self.fetchers) ) < 2:
            #Start a new fetcher on this line if this fetchers is X-Bytes before  finishing his jobs
            blocksize = min(TIME_SLICE * int(fetcher.speed()), MIN_BLOCKSIZE)
            fetch_range = self.next_range(blocksize)
            print "Start new Fetcher, bs=%s range=%s" % (blocksize,fetch_range)
            self.fetchers.append( Fetcher(self, fetcher.proxy, self.url, self.header, fetch_range) )

        buf = StringIO.StringIO()
        while len(self.blocks)>0 and min(self.blocks)[0] == self.write_pos:
            item = heappop(self.blocks)
            buf.write(item[1])
            self.write_pos += item[2]

        if buf.tell() > 0:
            self.channel.push_with_producer(StringIOProducer(buf))

        if self.write_pos + 1 >= self.content_length:
            print self, "job done %s blocks left" % len(self.blocks)
            self.channel.is_closed = True
            self.channel.close_when_done()

    def next_range(self, suggested_blocksize):
        start = self.fetch_pos
        self.fetch_pos = min(self.fetch_pos + suggested_blocksize, self.content_length)
        return (start, self.fetch_pos-1)

    def handle_incoming_http_header(self, header):
        if self.header_sent:
            pass
        else:
            self.header_sent = True

            self.channel.push("HTTP/1.0 200 OK\r\n")
            # Sends header from first response
            header.seek(0)
            headers = httplib.HTTPMessage(header)
            for key in filter(lambda k: k not in ("content-range", "content-length"), headers.dict.keys()):
                self.channel.push("%s: %s\r\n" % (key, headers.dict[key]))
            self.channel.push("Content-Length: %s" % self.content_length)
            self.channel.push("X-Proxy: Magicproxy (superpower activated)\r\n")
            self.channel.push("\r\n")



    def __str__(self):
        return "<MultipleProxyReader url=%s content_length=%s>" % (urlparse.urlunparse(self.url), self.content_length)

class HTTPChannel(asynchat.async_chat):
    def __init__(self, server, sock, addr):
        self.server = server

        self.data = StringIO.StringIO()
        self.is_closed = False
        self.request = None

        asynchat.async_chat.__init__(self, sock)
        self.set_terminator("\r\n\r\n")

    def handle_close(self):
        self.is_closed = True

    def collect_incoming_data(self, data):
        self.data.write(data)
        if self.data.tell() > 16384:
            self.close_when_done()

    def found_terminator(self):
        if not self.request:
            # parse http header
            self.data.seek(0)
            self.request = string.split(self.data.readline(), None, 2)
            if len(self.request) != 3:
                # badly formed request; just shut down
                self.close_when_done()
            else:
                headers = httplib.HTTPMessage(self.data).dict
                self.server.handle_request(self, self.request[0], self.request[1], headers)
        else:
            pass # ignore body data, for now

class HTTPProxyServer(asyncore.dispatcher):
    def __init__(self):
        self.port = 8080

        asyncore.dispatcher.__init__(self)
        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
        self.set_reuse_addr()
        self.bind(("", 8080))
        self.listen(5)

    def handle_accept(self):
        conn, addr = self.accept()
        HTTPChannel(self, conn, addr)

    def handle_request(self, channel, method, path, headers):
        url = urlparse.urlparse(path)
        if method != "GET" or url.query != "":
            #do not handle non-GET or GET with Query (?foo=bla) requests
            return self._bypass_request(channel, method, url, headers)

        #check for content-length header with a HEAD request
        conn = httplib.HTTPConnection(url.hostname, url.port or 80)
        conn.request("HEAD", url.path)
        resp = conn.getresponse()
        content_length = filter(lambda it: it[0] == "content-length", resp.getheaders())
        if len( content_length ) == 0:
            # no content length given, bypass this request
            print "missing content-length, bypass"
            self._bypass_request(channel, "GET", url, headers)
        else:
            content_length = int(content_length[0][1])

        if content_length < THRESHOLD:
            self._bypass_request(channel, "GET", url, headers)
        else:
            MultipleProxyReader(channel, url, headers, content_length)
        
    def _bypass_request(self, channel, method, url, headers):
        print "_bypass request: %s %s" % (method, urlparse.urlunparse(url))
        #XXX hier sollte nicht proxy gespielt werden sondern
        #die daten 1-zu-1 durchgereicht werden.
        #Weiterhin sollte sichergestellt werden, dass die requests
        #zu Host X1 immer ueber Proxy Y1 geroutet werden
        # etwa proxy=proxies[ stuff(hostname) % len(proxies) ]
        conn = httplib.HTTPConnection(url.hostname, url.port or 80)
        conn.request(method, url.path, body="", headers=headers)
        resp = conn.getresponse()
        channel.push("HTTP/1.0 200 OK\r\nX-Proxy: Magicproxy (superpower disabled)\r\n")
        channel.push( "\r\n".join(map(lambda k: "%s: %s" % (k[0],k[1]), resp.getheaders())) )
        channel.push("\r\n\r\n")
        channel.push(resp.read())
        channel.close_when_done()

if __name__ == "__main__":
    proxy = HTTPProxyServer()
    asyncore.loop()