"""E1 eval (PLAN_SELFPACED): halting-gate MBPP eval.

Per item: deploy-time halting picks k* (1..kmax); generation then uses the
frozen-prompt path at that k (items grouped by k* for batching). Reports
pass@1 by label, the k* distribution by label, mean compute, and the
gate-difficulty point-biserial correlation.
"""

import argparse
import json
import os
import sys
import time
from concurrent.futures import ThreadPoolExecutor
from pathlib import Path

import torch

from halting_common import HaltingMergeAdapter, halted_k_per_item
from loop_common import BandLooper
from prep_mbpp import DIRECT_SUFFIX, extract_code, mbpp_prompt, run_tests

sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
from jlens.core import load_model  # noqa: E402

OUT = Path(os.environ.get("LOOP_OUT",
    Path(__file__).resolve().parent.parent / "results-loop"))


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--adapter", required=True)
    ap.add_argument("--tag", required=True)
    ap.add_argument("--kmax", type=int, default=4)
    ap.add_argument("--n", type=int, default=250)
    ap.add_argument("--batch", type=int, default=8)
    args = ap.parse_args()

    model, tok = load_model(dtype=torch.bfloat16)
    tok.padding_side = "left"
    looper = BandLooper(model)
    adapter = HaltingMergeAdapter(
        d=model.config.get_text_config().hidden_size).cuda()
    adapter.load_state_dict(torch.load(args.adapter, map_location="cuda"))
    adapter.eval()

    items = [it for it in json.load(open(OUT / "mbpp_data.json"))
             if it["split"] == "test"][: args.n]
    print(f"[{args.tag}] gated MBPP eval on {len(items)}, kmax={args.kmax}",
          flush=True)

    # phase 1: per-item k*
    kstars = []
    with torch.no_grad():
        for i in range(0, len(items), args.batch):
            chunk = items[i : i + args.batch]
            enc = tok([mbpp_prompt(tok, it, DIRECT_SUFFIX) for it in chunk],
                      return_tensors="pt", padding=True,
                      add_special_tokens=False).to("cuda")
            pl = enc["attention_mask"].sum(-1) - 1  # left-pad: last position
            pl = torch.full_like(pl, enc["input_ids"].shape[1] - 1)
            ks = halted_k_per_item(looper, adapter, enc["input_ids"],
                                   args.kmax, enc["attention_mask"], pl)
            kstars.extend(ks.tolist())
    t0 = time.time()

    # phase 2: generate grouped by k*
    codes = [None] * len(items)
    for kval in sorted(set(kstars)):
        idxs = [i for i, kk in enumerate(kstars) if kk == kval]
        for j in range(0, len(idxs), args.batch):
            grp = idxs[j : j + args.batch]
            enc = tok([mbpp_prompt(tok, items[i], DIRECT_SUFFIX) for i in grp],
                      return_tensors="pt", padding=True,
                      add_special_tokens=False).to("cuda")
            gen = looper.generate_frozen_prompt(
                adapter, tok, enc["input_ids"], kval, max_new_tokens=220,
                attention_mask=enc["attention_mask"])
            for gi, i in enumerate(grp):
                txt = tok.decode(gen[gi, enc["input_ids"].shape[1]:],
                                 skip_special_tokens=True)
                codes[i] = extract_code(txt)
    with ThreadPoolExecutor(8) as ex:
        oks = list(ex.map(lambda ci: run_tests(ci[0], ci[1]),
                          zip(codes, items)))

    per_label, kdist = {}, {}
    for it, ok, kk in zip(items, oks, kstars):
        d = per_label.setdefault(it["label"], [0, 0, 0.0])
        d[0] += ok; d[1] += 1; d[2] += kk
        kdist.setdefault(it["label"], []).append(kk)
    acc = sum(oks) / len(items)
    by_label = {l: c / n for l, (c, n, _) in per_label.items()}
    mean_k = {l: sum(v) / len(v) for l, v in kdist.items()}
    hard = torch.tensor([it["label"] == "hard" for it in items], dtype=torch.float)
    kk = torch.tensor(kstars, dtype=torch.float)
    r = ((kk - kk.mean()) * (hard - hard.mean())).mean() / (kk.std() * hard.std() + 1e-9)
    print(f"pass@1={acc:.3f} by_label={ {l: round(v,3) for l,v in by_label.items()} }")
    print(f"mean k* by label: { {l: round(v,2) for l,v in mean_k.items()} }  "
          f"overall E[k]={sum(kstars)/len(kstars):.2f}  "
          f"gate-difficulty r={r:.3f}  ({time.time()-t0:.0f}s)", flush=True)

    json.dump({"tag": args.tag, "acc": acc, "by_label": by_label,
               "mean_kstar": mean_k, "corr_hard": r.item(),
               "kstars": kstars,
               "per_item": [{"task_id": it["task_id"], "ok": bool(o),
                             "kstar": kk_} for it, o, kk_ in
                            zip(items, oks, kstars)]},
              open(OUT / f"eval_code_{args.tag}.json", "w"), indent=1)
    print("wrote", OUT / f"eval_code_{args.tag}.json")


if __name__ == "__main__":
    main()