#!/usr/bin/env python3
"""
solve.py
Automates fetching observed outputs, recovering LCG params, computing next token,
and requesting /flag?token=<predicted>.
Usage: python3 solve.py http://127.0.0.1:9001
"""
import sys
import requests
from solve_lcg import recover_params, next_value

if len(sys.argv) < 2:
    print("Usage: python3 solve.py <base_url>")
    sys.exit(1)

base = sys.argv[1].rstrip("/")
api = base + "/api/observed"
r = requests.get(api, timeout=5)
r.raise_for_status()
j = r.json()
observed = j["observed"]
if len(observed) < 3:
    print("Need at least 3 observed outputs.")
    sys.exit(1)

x0, x1, x2 = [int(x) & 0xffffffff for x in observed[:3]]
a, c = recover_params(x0, x1, x2)
if a is None:
    print("Failed to recover parameters; difference was not invertible modulo 2^32.")
    sys.exit(1)
nxt = next_value(x2, a, c)
print("[*] Recovered a=0x%08x c=0x%08x" % (a, c))
print("[*] Predicted next token (dec):", nxt)
print("[*] Requesting flag...")
r2 = requests.get(base + "/flag", params={"token": str(nxt)}, timeout=5)
print("[*] Response:", r2.status_code)
print(r2.text)