#!/usr/bin/env python3
"""Fetch the lab page and report the circuit that carried this request."""

import re
import socket
import subprocess
import sys
import time


def reply(reader):
    """Read one control reply, including GETINFO's dot-terminated data."""
    rows = []
    while True:
        line = reader.readline().rstrip("\r\n")
        if not line:
            raise RuntimeError("Tor closed its control connection")
        if line.startswith("650 "):
            continue
        rows.append(line)
        if line.startswith("250+"):
            while True:
                line = reader.readline().rstrip("\r\n")
                if line == ".":
                    break
                if not line:
                    raise RuntimeError("Incomplete circuit list")
                rows.append(line)
        elif line.startswith("250 "):
            return rows
        elif not line.startswith("250-"):
            raise RuntimeError(line)


def main():
    marker = sys.argv[1] if len(sys.argv) == 2 else "tor-lab-01"
    if len(sys.argv) > 2 or not re.fullmatch(r"[A-Za-z0-9-]{1,64}", marker):
        raise RuntimeError("Use: request [word-with-letters-numbers-or-hyphens]")
    with socket.create_connection(("127.0.0.1", 9051), timeout=5) as control:
        control.settimeout(5)
        reader = control.makefile("r", encoding="utf-8", newline="")
        for command in ("AUTHENTICATE", "SETEVENTS STREAM"):
            control.sendall((command + "\r\n").encode())
            reply(reader)
        for attempt in range(2):
            result = subprocess.run(
                ["curl", "--fail", "--silent", "--show-error", "--max-time", "30",
                 "--socks5-hostname", "127.0.0.1:9050", f"http://10.77.0.80/?{marker}"],
                capture_output=True, text=True, timeout=35, check=False,
            )
            # A failed SOCKS handshake never established a successful stream.
            # Retry it once while the private network finishes starting.
            if result.returncode != 97 or attempt == 1:
                break
            print("SOCKS connection failed; retrying once in 3 seconds.", file=sys.stderr)
            time.sleep(3)
        if result.returncode:
            raise RuntimeError(result.stderr.strip() + "; check the client bootstrap log and retry")
        while True:
            line = reader.readline().strip()
            if not line:
                raise RuntimeError("No stream event received")
            fields = line.split()
            if (len(fields) >= 6 and fields[:2] == ["650", "STREAM"]
                    and fields[3] == "SUCCEEDED" and fields[5] == "10.77.0.80:80"):
                stream_id, circuit_id = fields[2], fields[4]
                break
        control.sendall(b"SETEVENTS\r\n")
        reply(reader)
        control.sendall(b"GETINFO circuit-status\r\n")
        for line in reply(reader):
            fields = line.split()
            if len(fields) >= 3 and fields[:2] == [circuit_id, "BUILT"]:
                names = [hop.replace("~", "=").split("=")[-1] for hop in fields[2].split(",")]
                print(result.stdout.strip())
                print(f"Marker: {marker}")
                print(f"Stream {stream_id} used circuit {circuit_id}: " + " -> ".join(names))
                print("Positions: guard -> middle -> exit")
                return
        raise RuntimeError("The used circuit closed before it could be listed; retry")


if __name__ == "__main__":
    try:
        main()
    except (OSError, RuntimeError, subprocess.TimeoutExpired) as error:
        print(f"request: {error}", file=sys.stderr)
        sys.exit(1)