scripts/compute_bestofn_with_selector.py

"""
Compute Best-of-N metrics with a TRAINED selector (binary YES/NO classifier).

For each question, run the selector on each of N candidates and pick the one
with the highest YES probability. Also compute greedy / pass@N for comparison.

Usage:
    python scripts/compute_bestofn_with_selector.py <rollout.jsonl> <selector_ckpt> <label> [--selector_host URL]

If --selector_host given (a vLLM endpoint), use it. Otherwise load model in-process.
"""
import argparse
import json
import os
import re
import sys
from collections import Counter
from concurrent.futures import ThreadPoolExecutor

# Bypass HTTP proxy for local vLLM endpoints
os.environ["NO_PROXY"] = "localhost,127.0.0.1"
os.environ["no_proxy"] = "localhost,127.0.0.1"

ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
os.chdir(ROOT)
sys.path.insert(0, ROOT)

from validator_data.validator import _execute_sql
from data_processing.planner import is_execution_correct
import requests


PROMPT_TEMPLATE = (
    "You are a SQL correctness judge.\n"
    "Schema:\n{schema}\n\n"
    "Question: {question}\n"
    "External knowledge: {evidence}\n\n"
    "Candidate SQL:\n{sql}\n\n"
    "Execution result:\n{exec_result}\n\n"
    "Is this SQL correct for the question? Answer YES or NO."
)


def qwen_chat(prompt: str) -> str:
    return f"<|im_start|>user\n{prompt}<|im_end|>\n<|im_start|>assistant\n"


def safe_truncate(s, n=400):
    if s is None:
        return "(empty)"
    s = str(s)
    return s if len(s) <= n else s[:n] + "..."


def safe_execute(db_path, sql):
    if not sql or sql.strip() == "":
        return ("", True)
    try:
        return _execute_sql("./" + db_path, sql)
    except Exception:
        return ("", True)


def score_via_vllm(host, prompt_chat, model_name="selector"):
    """Get P(YES) − P(NO) via vLLM completions with logprobs."""
    payload = {
        "model": model_name,
        "prompt": prompt_chat,
        "max_tokens": 1,
        "n": 1,
        "temperature": 0.0,
        "logprobs": 20,
    }
    try:
        r = requests.post(f"{host}/v1/completions", json=payload, timeout=60)
        r.raise_for_status()
        choice = r.json()["choices"][0]
        # Look at logprobs of top tokens; find YES vs NO
        if "logprobs" in choice and choice["logprobs"]:
            top = choice["logprobs"]["top_logprobs"][0]
            yes_lp = max((top[k] for k in (" YES", "YES", " yes", "yes", " Yes", "Yes") if k in top), default=-100.0)
            no_lp = max((top[k] for k in (" NO", "NO", " no", "no", " No", "No") if k in top), default=-100.0)
            return yes_lp - no_lp
        # Fallback: text match
        text = choice.get("text", "").strip().upper()
        return 1.0 if text.startswith("YES") else (-1.0 if text.startswith("NO") else -100.0)
    except Exception as e:
        sys.stderr.write(f"score_via_vllm err: {type(e).__name__}: {e}\n")
        return -100.0


def build_prompt_chat(sample, t, exec_result_str=None):
    """Build selector prompt.

    `exec_result_str` MUST be the actual SQL execution result preview (or error message).
    Do NOT pass the gold-graded label — that leaks the correctness label into the prompt
    and makes the selector trivially match the oracle.
    """
    schema = sample.get("schema", "")
    question = sample.get("question", "")
    evidence = sample.get("evidence", "") or "None"
    fixed_sql = t.get("fixed_sql") or t.get("planner_sql") or ""
    if exec_result_str is None:
        # Safe default at inference time: signal unknown (selector must judge from SQL alone)
        exec_result_str = "(execution result not available)"
    prompt = PROMPT_TEMPLATE.format(
        schema=safe_truncate(schema, 3000),
        question=question,
        evidence=evidence,
        sql=safe_truncate(fixed_sql, 800),
        exec_result=safe_truncate(exec_result_str, 300),
    )
    return qwen_chat(prompt)


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("rollout_jsonl")
    parser.add_argument("label")
    parser.add_argument("--selector_host", default="http://localhost:8103")
    args = parser.parse_args()

    n_q = 0
    n_greedy = 0
    n_pass_at_N = 0
    n_majority = 0  # rule-based majority (for compare)
    n_selector = 0  # trained selector pick
    K_used = None

    samples = []
    with open(args.rollout_jsonl) as f:
        for line in f:
            line = line.strip()
            if line:
                samples.append(json.loads(line))

    print(f"Loaded {len(samples)} samples")

    for sample in samples:
        traj = sample.get("trajectories", [])
        if not traj:
            continue
        n_q += 1
        if K_used is None:
            K_used = len(traj)

        # Greedy = first traj
        if traj[0].get("is_fixed_correct"):
            n_greedy += 1

        # pass@N = any correct
        if any(t.get("is_fixed_correct") for t in traj):
            n_pass_at_N += 1

        # Rule-based majority: pick most-common non-empty execution result
        db_path = sample["db_path"]
        gold_sql = sample["sql"]
        true_exec = safe_execute(db_path, gold_sql)
        if true_exec[1]:
            continue  # gold has error; skip

        # Execute all candidates' fixed SQLs once
        with ThreadPoolExecutor(max_workers=8) as exe:
            exec_results = list(exe.map(
                lambda t: safe_execute(db_path, t.get("fixed_sql") or t.get("planner_sql") or ""),
                traj
            ))

        # Rule-based majority
        majority_picks = []
        for i, (er, t) in enumerate(zip(exec_results, traj)):
            if er[1]:
                continue
            res_str = str(er[0]).strip()
            if not res_str or "(no rows)" in res_str or res_str == "[]":
                continue
            majority_picks.append((i, res_str))
        if majority_picks:
            counter = Counter(s for _, s in majority_picks)
            top_res, _ = counter.most_common(1)[0]
            for i, s in majority_picks:
                if s == top_res:
                    if traj[i].get("is_fixed_correct"):
                        n_majority += 1
                    break
        else:
            if traj[0].get("is_fixed_correct"):
                n_majority += 1

        # Trained selector: score each candidate using REAL execution result (no gold-label leak).
        # Re-use the exec_results computed above for rule-based majority.
        scores = []
        with ThreadPoolExecutor(max_workers=8) as exe:
            def _make_prompt(idx, t_):
                er = exec_results[idx]
                if er[1]:
                    exec_str = f"Error: {er[0]}"
                else:
                    rows_str = str(er[0])
                    if not rows_str.strip() or rows_str.strip() == "[]":
                        exec_str = "OK. Result rows (preview): (no rows)"
                    else:
                        exec_str = f"OK. Result rows (preview): {rows_str[:300]}"
                return build_prompt_chat(sample, t_, exec_result_str=exec_str)
            futs = [exe.submit(score_via_vllm, args.selector_host, _make_prompt(i, t)) for i, t in enumerate(traj)]
            for f in futs:
                scores.append(f.result())
        best_idx = max(range(len(scores)), key=lambda i: scores[i])
        if traj[best_idx].get("is_fixed_correct"):
            n_selector += 1

    if n_q == 0:
        print(f"{args.label}: no questions evaluated")
        return

    print()
    print(f"=== {args.label} ===")
    print(f"  questions evaluated: {n_q}")
    print(f"  K used per question: {K_used}")
    print(f"  greedy (1st traj):       {n_greedy}/{n_q} = {100*n_greedy/n_q:.2f}%")
    print(f"  rule-based majority:     {n_majority}/{n_q} = {100*n_majority/n_q:.2f}%")
    print(f"  trained selector:        {n_selector}/{n_q} = {100*n_selector/n_q:.2f}%")
    print(f"  pass@{K_used} (oracle):  {n_pass_at_N}/{n_q} = {100*n_pass_at_N/n_q:.2f}%")
    print()


if __name__ == "__main__":
    main()