"""05 AGENT IN THE BOX. The payoff. A tiny "agent" writes code for a task, and that code
runs ONLY inside a throwaway container, never on your host. No API key needed. The
"agent" here is a canned code-writing step, so you can see the full loop with nothing
to configure. Swap in a real coding agent later; the box stays the same.

Run:  python 05_agent_in_the_box.py
Needs: Docker installed and running. If Docker is missing, this prints what it WOULD
       do and exits 0. It never fakes output.
"""
import shutil
import subprocess
import sys

IMAGE = "python:3.11-slim"
TASK = "compute the sum of the first 10 square numbers"


def have_docker() -> bool:
    return shutil.which("docker") is not None


def fake_agent_writes_code(task: str) -> str:
    """Stand-in for a real coding agent. No LLM call, no API key. Just enough to prove
    the loop: TASK IN -> CODE OUT -> CODE RUNS IN THE BOX, NEVER ON YOUR HOST."""
    return (
        "total = sum(n * n for n in range(1, 11))\n"
        f"print('{task}:', total)"
    )


def run_in_sandbox(code: str) -> str:
    cmd = [
        "docker", "run", "--rm",
        "--network", "none",
        "--memory", "256m",
        "--cpus", "0.5",
        IMAGE,
        "python3", "-c", code,
    ]
    result = subprocess.run(cmd, capture_output=True, text=True, timeout=60)
    return result.stdout.strip() or result.stderr.strip()


def main():
    print(f"== TASK ==\n{TASK}\n")

    code = fake_agent_writes_code(TASK)
    print("== AGENT WROTE THIS CODE ==")
    print(code)

    if not have_docker():
        print("\nDocker not found on this machine.")
        print("What happens next, if Docker were here: that code runs ONLY inside a")
        print("throwaway container (--network none, --memory 256m), never on your host.")
        print("Install Docker Desktop (or the docker CLI) and re-run to see it live.")
        sys.exit(0)

    print("\n== RUNNING THE AGENT'S CODE, ONLY INSIDE THE BOX ==")
    try:
        output = run_in_sandbox(code)
        print(output)
    except subprocess.TimeoutExpired:
        print("Sandbox timed out after 60s (that's the timeout working as intended).")
        sys.exit(1)

    print("\nThe agent wrote code and ran it, and your host never saw a single line execute.")
    print("That's the pattern you leave with: task in, code out, code runs in the box.")


if __name__ == "__main__":
    main()