#!/usr/bin/env python3
"""tracker.py [port] — a minimal HTTP BitTorrent tracker for the night's R-1261 rig (stdlib only). It records every
peer that announces (by source address and the announced port) and answers the others in compact form."""
import http.server, socket, struct, sys, time, urllib.parse

PEERS = {}  # info_hash -> {(ip, port): last_seen}

def benc(d):
    out = b"d"
    for k in sorted(d):
        v = d[k]
        out += b"%d:%s" % (len(k), k.encode())
        out += (b"i%de" % v) if isinstance(v, int) else (b"%d:%s" % (len(v), v))
    return out + b"e"

class H(http.server.BaseHTTPRequestHandler):
    def do_GET(self):
        u = urllib.parse.urlsplit(self.path)
        q = urllib.parse.parse_qs(u.query, keep_blank_values=True, encoding="latin-1")
        ih = q.get("info_hash", [""])[0].encode("latin-1")
        port = int(q.get("port", ["0"])[0] or 0)
        ip = self.client_address[0]
        now = time.time()
        peers = PEERS.setdefault(ih, {})
        if q.get("event", [""])[0] == "stopped":
            peers.pop((ip, port), None)
        else:
            peers[(ip, port)] = now
        others = [p for p, t in peers.items() if p != (ip, port) and now - t < 600]
        compact = b"".join(socket.inet_aton(a) + struct.pack(">H", pt) for a, pt in others)
        body = benc({"interval": 30, "peers": compact})
        self.send_response(200)
        self.send_header("Content-Type", "text/plain")
        self.send_header("Content-Length", str(len(body)))
        self.end_headers()
        self.wfile.write(body)
        sys.stdout.write("%s announce %s:%d -> %d peer(s)\n" % (time.strftime("%H:%M:%S"), ip, port, len(others)))
        sys.stdout.flush()

    def log_message(self, *a):
        pass

http.server.ThreadingHTTPServer(("0.0.0.0", int(sys.argv[1]) if len(sys.argv) > 1 else 6969), H).serve_forever()