#!/usr/bin/env python3
"""Tap Proxy — logs HTTP headers. Usage: python3 tap-proxy.py <port> <backend_host:port> <log_dir>"""
import http.server, urllib.request, sys, socket
from datetime import datetime

PORT = int(sys.argv[1]) if len(sys.argv) > 1 else 8081
BACKEND = sys.argv[2] if len(sys.argv) > 2 else "127.0.0.1:80"
LOG = (sys.argv[3] if len(sys.argv) > 3 else "/tmp") + "/tap-" + datetime.now().strftime("%Y%m%d-%H%M%S") + ".log"
BACKEND_URL = "http://" + BACKEND

# Don't follow redirects — preserve Set-Cookie
class NoRedirect(urllib.request.HTTPRedirectHandler):
    def http_error_302(self, req, fp, code, msg, headers):
        fp.status, fp.reason = code, msg
        return fp
    http_error_301 = http_error_302
    http_error_303 = http_error_302
    http_error_307 = http_error_302
    http_error_308 = http_error_302

_opener = urllib.request.build_opener(NoRedirect)

class Tap(http.server.BaseHTTPRequestHandler):
    def do_GET(self): self._tap('GET')
    def do_POST(self): self._tap('POST')
    def do_PUT(self): self._tap('PUT')
    def do_DELETE(self): self._tap('DELETE')
    
    def _tap(self, method):
        now = datetime.now().strftime('%H:%M:%S')
        msg = "\n" + "="*60 + "\n[" + now + "] " + method + " " + self.path
        msg += "\nClient: " + self.client_address[0] + "\n" + "-"*60 + "\n"
        for k, v in sorted(self.headers.items()):
            msg += "  " + k + ": " + v + "\n"
        
        # Handle chunked transfer-encoding
        body = None
        cl = self.headers.get('Content-Length')
        te = self.headers.get('Transfer-Encoding', '').lower()
        if cl:
            body = self.rfile.read(int(cl))
        elif 'chunked' in te:
            body = b''
            while True:
                line = self.rfile.readline().strip()
                if not line: continue
                size = int(line, 16)
                if size == 0: break
                body += self.rfile.read(size)
                self.rfile.readline()
            while True:
                line = self.rfile.readline().strip()
                if not line: break
        
        req = urllib.request.Request(BACKEND_URL + self.path, data=body, method=method)
        # Pass through all headers including Host
        for k, v in self.headers.items():
            if k.lower() not in ('connection',):
                req.add_header(k, v)
        
        try:
            resp = _opener.open(req, timeout=30)
            msg += "\nRESPONSE: " + str(resp.status) + " " + str(resp.reason) + "\n"
            for k, v in resp.getheaders():
                msg += "  " + k + ": " + v + "\n"
            self.send_response(resp.status)
            for k, v in resp.getheaders():
                if k.lower() not in ('transfer-encoding', 'connection'):
                    self.send_header(k, v)
            self.end_headers()
            self.wfile.write(resp.read())
        except Exception as e:
            msg += "\nBACKEND: " + str(e) + "\n"
            self.send_response(502)
            self.send_header('Content-Type', 'text/plain')
            self.end_headers()
            self.wfile.write(b"Backend unreachable: " + str(e).encode())
        
        with open(LOG, "a") as f:
            f.write(msg)
    
    def log_message(self, *args): pass

print("Tap proxy :{0} -> {1}\nLog: {2}\nCtrl+C to stop".format(PORT, BACKEND_URL, LOG))
http.server.HTTPServer(('0.0.0.0', PORT), Tap).serve_forever()