#!/usr/bin/python -t
#TODO: ignore non-functional endpoints
#TODO: support Range: ... in requests

import  os, sys, string, time, md5, random
import asynchat, asyncore, socket, httplib, urlparse
from heapq import heappush, heappop
import cStringIO as StringIO

kB = 1024
class DefaultConfiguration:
    """bind to that"""
    listen=("",8080)

    """available http-proxies"""
    endpoints=[ 
        ('10.2.2.11', 8888),
        #('10.3.1.2',8888)
        ]

    """minimum entity size to start parallelize fetch"""
    threshold = 512*kB
    
    """initial size/range for a fetcher-job"""
    initial_blocksize=512*kB

    """minimal size/range for a fetcher-job"""
    minimal_blocksize=512*kB
    
    """(sec) #time each fetcher spent on his range,
    calculated using speed measured while using initial_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, fetch_range):
        self.reader = reader
        self.proxy = proxy
        self.url = url
        self.headers = headers
        self.range = fetch_range

        self.pos = (self.range[0] != -1) and self.range[0] or 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 __str__(self):
        return "<Fetcher proxy=%s host=%s path=%s range=%s" % (self.proxy, self.url.hostname, self.url.path, self.range)

    def handle_connect (self):
        print self, "connected"
        buf = "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
            buf += "%s: %s\r\n" % (key, self.headers[key])
        if self.range != (-1,-1):
            buf += "Range: bytes=%s-%s\r\n" % (self.range[0], self.range[1])
        buf += "\r\n"
        self.push(buf)
        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)
            if self.range != (-1,-1) and self.pos + length >= self.range[1] + 1:
                #if this request is the first one (whithout Range: ...) then the server
                # dont send us our expected range, we must cut it at some point (here)
                bytes_remaining = self.range[1] - ( self.pos )
                data=data[:bytes_remaining+1]
                print self,"cut: pos=%s length=%s => %s" % (self.pos, length, len(data))
                length = len(data)
                if length == 0:
                    self.reader.handle_incoming_data(self)
                    self.close()
                    return
            if not self.reader.handle_incoming_data(self, data, length):
                self.close()
                return
            self.pos += length
            if self.range != (-1,-1) and self.pos >= self.range[1]:
                self.stop_time = time.time()
                print self, "finished with %s kB/s" % (self.speed() / 1024)
                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
            status = self.http_status.split(" ")
            if len(status) > 1:
                try:
                    self.http_status_code = int(status[1])
                except:
                    self.http_status_code = 520 #Bad Gateway
            else:
                self.http_status_code = 520 #Bad Gateway
            self.state = 1
            self.set_terminator("\r\n\r\n") #end of header
        elif self.state == 1: #got headers
            self.state = 2
            self.set_terminator(None)
            self.reader.handle_incoming_http_header(self, self.http_status_code, self.http_header)

class MagicHTTPProxyClient(object):
    def __init__(self, channel, url, header):
        self.channel = channel
        self.config = self.channel.server.config
        self.url = url
        self.header = header

        self.content_length = -1
        self.header_sent = False
        self.fetch_pos = 0
        self.write_pos = 0
        self.buffer = ""
        self.blocks = list()
        self.fetchers = list()

        proxy = self.config.endpoints[ random.randint(0, len(self.config.endpoints)-1) ]
        self.fetchers.append( Fetcher(self, proxy, self.url, self.header, (-1,-1)) )

    def __str__(self):
        return "<MagicHTTPProxyClient host=%s path=%s content_length=%s>" % (self.url.hostname, self.url.path, self.content_length)

    def handle_incoming_data(self, fetcher, data=None, length=0):
        if not data:
            #fetcher is done, remove from list
            self.fetchers = filter(lambda f: f != fetcher, self.fetchers)
            print "Remove: %s" % fetcher
        else:
            assert fetcher.pos < fetcher.range[1] or fetcher.range == (-1,-1)
            heappush(self.blocks, (fetcher.pos, data, length))

        if not self.channel.connected:
            print self, "request side closed the connection"
            return False

        if fetcher.range != (-1,-1) \
                and fetcher.range[1] - (fetcher.pos+length) < self.config.fetcher_jumpstart \
                and self.fetch_pos + 1 < self.content_length \
                and len( filter(lambda f: f.proxy == fetcher.proxy, self.fetchers) ) < 2:
            #Start a new fetcher if this fetcher is X-Bytes before finished his job
            blocksize = max(int(self.config.time_slice * fetcher.speed()), self.config.minimal_blocksize)
            fetch_range = self.next_range(blocksize)
            self.fetchers.append( Fetcher(self, fetcher.proxy, self.url, self.header, fetch_range) )

        #if len(self.blocks)>0:
            #print self,"fetch_pos=%s write_pos=%s get=%s with length=%s pending=%s" % (self.fetch_pos, self.write_pos, min(self.blocks)[0],min(self.blocks)[2], len(self.blocks))
 
        buf = ""
        while len(self.blocks)>0 and min(self.blocks)[0] == self.write_pos:
            item = heappop(self.blocks)
            buf += item[1]
            self.write_pos += item[2]

        if buf != "":
            self.channel.push(buf)

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

    def next_range(self, suggested_blocksize):
        assert self.content_length != -1
        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, fetcher, status_code, header):
        if not self.channel.connected:
            return
        if self.header_sent:
            if status_code < 200 or status_code >= 300:
                print self, "Error: got error code %s in %s. Giving up" % (status_code, fetcher)
                self.channel.close()
        else:
            self.header_sent = True

            # Sends header from first response
            header.seek(0)
            headers = httplib.HTTPMessage(header)

            content_length = filter(lambda i: i == "content-length", headers.dict.keys())
            #if there are content-length headers decide if entity size is
            #bigger then threshold, if true then start n proxies (n=#endpoints)
            if len(content_length) == 1:
                content_length = int(headers.dict["content-length"])
                if content_length >= self.config.threshold:
                    self.content_length = content_length
                    fetcher.range = self.next_range(self.config.initial_blocksize)
                    for proxy in filter(lambda p: fetcher.proxy != p, self.config.endpoints):
                        if self.fetch_pos == self.content_length -1:
                            break
                        self.fetchers.append(Fetcher( self, proxy, self.url, self.header, self.next_range(self.config.initial_blocksize)))

            else:
                content_length = None

            buf = "HTTP/1.1 %s OK\r\n" % (status_code)
            buf += "".join(map(lambda key: "%s: %s\r\n" % (key, headers.dict[key]),
                               filter(lambda k: k not in ("content-range", "content-length"),
                                      headers.dict.keys())))
            if content_length:
                buf += "Content-Length: %s\r\n" % content_length
                buf += "Content-Range: bytes 0-%s/%s\r\n" % (content_length-1, content_length)
            buf += "X-Proxy: Magicproxy; using proxies %s\r\n" % ", ".join(map(lambda host: "%s:%s"%host, self.config.endpoints))
            buf += "\r\n"
            self.channel.push(buf)

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

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

    def handle_close(self):
        self.connected = False
        self.close()

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

    def found_terminator(self):
        # 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:
            self.set_terminator(None)
            headers = httplib.HTTPMessage(self.data).dict
            self.handle_request(self.request[0], self.request[1], headers)

    def handle_request(self, 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
            proxy = self.server.config.endpoints[ int( md5.md5(url.hostname).hexdigest(),16 ) % len(self.server.config.endpoints) ]
            print Fetcher(self, proxy, url, headers, (-1,-1))
        else:
            MagicHTTPProxyClient(self, url, headers)

    def handle_incoming_http_header(self,fetcher, status_code, header):
        header.seek(0)
        headers = httplib.HTTPMessage(header)
        buf = "HTTP/1.1 %s OK\r\n" % status_code
        buf += "\r\n".join(map(lambda hdr: "%s: %s" % (hdr,headers.dict[hdr]), headers.dict.keys()))
        buf += "\r\n\r\n"
        self.push(buf)


    def handle_incoming_data(self, fetcher, data=None, length=0):
        if data:
            self.push(data)
        return True

class HTTPProxyServer(asyncore.dispatcher):
    def __init__(self,config):
        self.config = config
        asyncore.dispatcher.__init__(self)
        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
        self.set_reuse_addr()
        self.bind(self.config.listen)
        self.listen(5)

    def __str__(self):
        return "<HTTPProxyServer listen=%s:%s>" % self.config.listen

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

def main():
    proxy = HTTPProxyServer(DefaultConfiguration)
    print proxy
    asyncore.loop()