import json
import os
import pathlib
import re

task_dir = pathlib.Path(os.environ.get("LOOM_TASK_DIR", "/workspace"))
output_path = pathlib.Path(
    os.environ.get("LOOM_AGENT_OUTPUT", str(task_dir / "final_answer.txt"))
)
answer_key = json.loads((task_dir / "answer_key.json").read_text())
valid_letters = answer_key["letters"]
pattern = r"\b([" + re.escape(valid_letters) + r"])\b"
text = output_path.read_text() if output_path.is_file() else ""
matches = re.findall(pattern, text.upper())
got = matches[-1] if matches else ""
expected = answer_key["answer"]
passed = got == expected
score = 1.0 if passed else 0.0
result = {
    "rewards": {"score": score},
    "checks": [
        {
            "name": "multiple_choice_letter",
            "passed": passed,
            "score": score,
            "message": f"expected {expected}, got {got or '<none>'}",
        }
    ],
    "structured": {"got": got, "expected": expected},
    "confidence": 1.0,
}
pathlib.Path(os.environ["LOOM_VERIFIER_OUTPUT"]).write_text(json.dumps(result))