# /// script
# requires-python = ">=3.11"
# dependencies = [
#   "torch>=2.1,<2.7",
#   "transformers>=4.46,<4.50",
#   "datasets",
#   "hqq>=0.2.8",
#   "accelerate",
#   "tqdm",
#   "huggingface_hub",
# ]
# ///
"""
Phase-3a drift-inversion transfer test → microsoft/phi-4 (14B, MHA)
====================================================================
Question: does the granite-8B drift-inversion finding (forcing o_proj layers
from 3-bit to 4-bit improves PPL despite worse drift scores) reproduce on
a different architecture and model family?

Design (single-job two-pass):
  1. Load phi-4 bf16 → cuda
  2. HSAQ profile + assign (no floor) → baseline name_to_bits
  3. Identify any `o_proj` layers landing at 3-bit in baseline
  4. Save bf16 weights of those o_proj layers
  5. HQQ everything except those o_proj layers per baseline assignment
  6. HQQ those o_proj layers at 3-bit
  7. Full-set wikitext-2 PPL → ppl_baseline
  8. Reinstall bf16 on those o_proj layers, HQQ them at 4-bit (floor)
  9. Full-set wikitext-2 PPL → ppl_floor
 10. Report delta. Positive delta = drift-inversion confirmed on phi-4.

If no o_proj layers land at 3-bit in baseline, the test is moot — report
that as the outcome (transfer-not-applicable).

Cost: ~$3, ~50 min on A100 80GB.
"""
from __future__ import annotations
import json, logging, os, statistics, subprocess, sys, time
from datetime import UTC, datetime
from pathlib import Path
import torch

if not torch.cuda.is_available():
    subprocess.check_call([sys.executable, "-m", "pip", "install", "torch", "--force-reinstall",
                            "--index-url", "https://download.pytorch.org/whl/cu124"])
    import importlib; importlib.reload(torch)
    if not torch.cuda.is_available(): sys.exit(1)

logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(name)s | %(message)s")
logger = logging.getLogger("Phi4Transfer")

sys.path.insert(0, "/opt/hsaq")
from quantization.hsaq.config import HSAQConfig
from quantization.hsaq.pipeline import HSAQPipeline

MODEL_ID = "microsoft/phi-4"
HF_TOKEN = os.environ.get("HF_TOKEN")
RUN_TAG = datetime.now(UTC).strftime("%Y%m%d_%H%M%S")
OUT = Path("/tmp/phi4_transfer"); OUT.mkdir(parents=True, exist_ok=True)
HQQ_GROUP_SIZE = 64


def evaluate_ppl(model, tokenizer, ctx_len: int = 2048) -> tuple[float, int, list[float]]:
    from datasets import load_dataset
    ds = load_dataset("wikitext", "wikitext-2-raw-v1", split="test")
    text = "\n\n".join(ds["text"])
    enc = tokenizer(text, return_tensors="pt", truncation=False)
    input_ids = enc.input_ids.to("cuda:0")
    nlls = []
    per_window = []
    stride = ctx_len
    prev_end = 0
    n = 0
    for i in range(0, input_ids.size(1), stride):
        begin = max(i + stride - ctx_len, 0)
        end = min(i + stride, input_ids.size(1))
        trg_len = end - prev_end
        ids = input_ids[:, begin:end]
        target = ids.clone()
        target[:, :-trg_len] = -100
        with torch.no_grad():
            out = model(ids, labels=target)
        nlls.append(out.loss.float() * trg_len)
        per_window.append(float(torch.exp(out.loss.float()).item()))
        prev_end = end
        n += 1
    return float(torch.exp(torch.stack(nlls).sum() / end).item()), n, per_window


def _set_submodule(model, name, new_mod):
    if "." in name:
        parent_name, attr = name.rsplit(".", 1)
        parent = model.get_submodule(parent_name)
    else:
        parent, attr = model, name
    setattr(parent, attr, new_mod)


def apply_hqq_one(model, name, nbits):
    from hqq.core.quantize import BaseQuantizeConfig, HQQLinear
    mod = model.get_submodule(name)
    cfg = BaseQuantizeConfig(nbits=nbits, group_size=HQQ_GROUP_SIZE, axis=0)
    hqq = HQQLinear(mod, cfg, compute_dtype=torch.bfloat16, device="cuda:0", del_orig=True)
    _set_submodule(model, name, hqq)


def reinstall_bf16(model, name, W_bf16, bias_or_none, in_f, out_f):
    new_linear = torch.nn.Linear(in_f, out_f, bias=bias_or_none is not None, dtype=torch.bfloat16)
    new_linear = new_linear.to("cuda:0")
    with torch.no_grad():
        new_linear.weight.copy_(W_bf16.to(torch.bfloat16).to("cuda:0"))
        if bias_or_none is not None:
            new_linear.bias.copy_(bias_or_none.to(torch.bfloat16).to("cuda:0"))
    _set_submodule(model, name, new_linear)


def upload_report(report):
    from huggingface_hub import HfApi
    repo_id = f"mxguru1/phi4-drift-transfer-{RUN_TAG}"
    api = HfApi(token=HF_TOKEN)
    api.create_repo(repo_id=repo_id, repo_type="dataset", exist_ok=True)
    p = OUT / "report.json"; p.write_text(json.dumps(report, indent=2))
    api.upload_file(path_or_fileobj=str(p), path_in_repo="report.json",
                    repo_id=repo_id, repo_type="dataset")
    logger.info("Report uploaded: https://huggingface.co/datasets/%s", repo_id)


def main():
    start = time.time()
    report = {
        "run_tag": RUN_TAG,
        "approach": "phase3a_drift_inversion_transfer_to_phi4",
        "model_id": MODEL_ID,
        "intervention": "force o_proj layers at 3-bit to 4-bit",
        "eval_protocol": "wikitext-2-raw-v1/test, full set, ctx=2048, stride=2048",
    }
    try:
        cfg = HSAQConfig(
            model_id=MODEL_ID,
            output_dir=str(OUT.parent),
            hf_token=HF_TOKEN,
            gpu_budget_gb=11.2,
            enable_2bit=False,
            enable_pruning=False,
            train_lora=False,
            calibration_samples=128,
        )
        pipe = HSAQPipeline(cfg)
        logger.info("Stage 1: load + profile phi-4")
        model, tokenizer = pipe._load_model()
        model = model.to("cuda:0")
        if tokenizer.pad_token is None:
            tokenizer.pad_token = tokenizer.eos_token

        sensitivity = pipe.profiler.profile(model)
        candidates = pipe._build_layer_candidates(sensitivity, model)
        from quantization.hsaq.assignment import assign_bit_widths
        weight_budget_gb = pipe._compute_weight_budget()
        baseline_assignment = assign_bit_widths(candidates, weight_budget_gb)
        name_to_bits = {a.component: a.chosen.bits for a in baseline_assignment.assignments}

        # Identify o_proj layers in 3-bit residue
        o_proj_3bit = sorted([n for n, b in name_to_bits.items() if b == 3 and "o_proj" in n])
        logger.info("o_proj layers at 3-bit in baseline assignment: %d", len(o_proj_3bit))
        for n in o_proj_3bit:
            logger.info("  %s", n)
        report["o_proj_3bit_count"] = len(o_proj_3bit)
        report["o_proj_3bit_layers"] = o_proj_3bit

        # Three-bit residue summary
        residue = sorted([n for n, b in name_to_bits.items() if b == 3])
        report["full_3bit_residue_count"] = len(residue)
        report["full_3bit_residue"] = residue

        if not o_proj_3bit:
            logger.info("No o_proj at 3-bit — transfer test not applicable on phi-4")
            report["status"] = "transfer_not_applicable"
            report["reason"] = "No o_proj layers landed at 3-bit in baseline assignment"
            # Still do a single baseline eval for the record
            n_hqq = pipe._apply_per_module_hqq(model, name_to_bits, device="cuda:0")
            logger.info("HQQ applied to %d Linears", n_hqq)
            ppl, n_w, pw = evaluate_ppl(model, tokenizer)
            report["ppl_baseline_no_floor"] = ppl
            report["n_windows"] = n_w
            return

        # Save bf16 weights for the o_proj layers we'll re-quantize twice
        o_proj_bf16, o_proj_bias, o_proj_shape = {}, {}, {}
        for name in o_proj_3bit:
            mod = model.get_submodule(name)
            o_proj_bf16[name] = mod.weight.detach().clone().cpu()
            o_proj_bias[name] = None if mod.bias is None else mod.bias.detach().clone().cpu()
            o_proj_shape[name] = (mod.in_features, mod.out_features)

        # Apply HQQ to all non-target layers
        non_target_bits = {n: b for n, b in name_to_bits.items() if n not in o_proj_3bit}
        n_hqq = pipe._apply_per_module_hqq(model, non_target_bits, device="cuda:0")
        logger.info("HQQ applied to %d non-target Linears", n_hqq)

        # Pass 1 — baseline: target o_proj layers HQQ at 3-bit
        logger.info("=== PASS 1: baseline (o_proj at 3-bit) ===")
        for name in o_proj_3bit:
            apply_hqq_one(model, name, nbits=3)
        ppl_baseline, n_w, pw_baseline = evaluate_ppl(model, tokenizer)
        logger.info("Pass 1 PPL: %.4f", ppl_baseline)

        # Pass 2 — floor: reinstall bf16 on o_proj layers, HQQ at 4-bit
        logger.info("=== PASS 2: floor (o_proj at 4-bit) ===")
        for name in o_proj_3bit:
            in_f, out_f = o_proj_shape[name]
            reinstall_bf16(model, name, o_proj_bf16[name], o_proj_bias[name], in_f, out_f)
            apply_hqq_one(model, name, nbits=4)
        ppl_floor, _, pw_floor = evaluate_ppl(model, tokenizer)
        logger.info("Pass 2 PPL: %.4f", ppl_floor)

        delta_abs = ppl_baseline - ppl_floor
        delta_pct = (ppl_baseline - ppl_floor) / ppl_baseline * 100
        report["result"] = {
            "ppl_baseline": ppl_baseline,
            "ppl_floor": ppl_floor,
            "delta_abs": delta_abs,
            "delta_pct": delta_pct,
            "n_windows": n_w,
            "per_window_baseline": pw_baseline,
            "per_window_floor": pw_floor,
        }
        report["status"] = "success"
        logger.info("=" * 60)
        logger.info("PHI-4 DRIFT-INVERSION TRANSFER:")
        logger.info("  baseline (o_proj@3): %.4f", ppl_baseline)
        logger.info("  floor    (o_proj@4): %.4f", ppl_floor)
        logger.info("  delta:               %.4f (%+.3f%%)  %s", delta_abs, -delta_pct,
                    "← drift-inversion confirmed" if delta_abs > 0 else "← does not transfer")
        logger.info("=" * 60)
    except Exception as e:
        logger.exception("Run failed")
        report["status"] = "failed"
        report["error"] = repr(e)
    finally:
        report["elapsed_s"] = round(time.time() - start, 1)
        upload_report(report)


if __name__ == "__main__":
    main()