#!/usr/bin/env python
# /// script
# requires-python = ">=3.10"
# dependencies = [
#   "torch>=2.4",
#   "transformers>=4.56",
#   "accelerate>=1.2",
#   "safetensors>=0.5",
#   "huggingface_hub>=0.34",
#   "trackio>=0.3",
# ]
# ///
"""Run one provenance-bound, non-routing Fable donor-bank structural smoke.

This is deliberately not a quality training run.  It validates all 2,880
bank tensors but attaches only the final host layer, keeping a real gradient
and counterfactual test feasible on a free 16 GiB GPU.
"""
from __future__ import annotations

import argparse
import json
import os
import platform
import shutil
import sys
import time
import traceback
from datetime import datetime, timezone
from pathlib import Path
from typing import Any

import torch
import torch.nn.functional as F
from huggingface_hub import HfApi, hf_hub_download
from safetensors.torch import load_file, save_file
from transformers import AutoModelForCausalLM, AutoTokenizer

HERE = Path(__file__).resolve().parent
if str(HERE) not in sys.path:
    sys.path.insert(0, str(HERE))

from fable_router_common import (  # noqa: E402
    iter_jsonl,
    read_json,
    selected_expert_ids,
    sha256,
    validate_bank_header,
    validate_curriculum_row,
    verify_file,
)
from fable_router_hybrid import (  # noqa: E402
    FrozenExpertRouterBlock,
    assert_trainable_isolation,
    attach_router_block,
    benefit_targets,
    benefit_weighted_router_loss,
    freeze_except_routers,
    load_router_state_dict,
    router_state_dict,
)


def now() -> str:
    return datetime.now(timezone.utc).isoformat()


def download(repo: str, revision: str, filename: str, repo_type: str, token: str | None) -> Path:
    return Path(
        hf_hub_download(
            repo_id=repo,
            revision=revision,
            filename=filename,
            repo_type=repo_type,
            token=token,
        )
    )


def render_and_tokenize(tokenizer: Any, messages: list[dict[str, Any]]) -> list[int]:
    # Transformers 5 can return a BatchEncoding from apply_chat_template with
    # tokenize=True, whose len() is the number of fields rather than tokens.
    rendered = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=False)
    return list(tokenizer(rendered, add_special_tokens=False)["input_ids"])


def select_complete_rows(path: Path, tokenizer: Any, maximum_tokens: int) -> list[dict[str, Any]]:
    wanted = ("host_preservation", "verified_expert")
    best: dict[str, tuple[int, dict[str, Any], list[int]]] = {}
    for row in iter_jsonl(path):
        validate_curriculum_row(row, "train")
        lane = str(row["lane"])
        if lane not in wanted:
            continue
        ids = render_and_tokenize(tokenizer, row["messages"])
        if len(ids) > maximum_tokens:
            continue
        previous = best.get(lane)
        if previous is None or len(ids) < previous[0]:
            best[lane] = (len(ids), row, ids)
    missing = sorted(set(wanted) - set(best))
    if missing:
        raise RuntimeError(f"no complete <= {maximum_tokens}-token rows for lanes {missing}")
    return [
        {"id": best[lane][1]["id"], "lane": lane, "inputIds": best[lane][2]}
        for lane in wanted
    ]


def batch_rows(rows: list[dict[str, Any]], pad_token_id: int, device: torch.device) -> dict[str, torch.Tensor]:
    maximum = max(len(row["inputIds"]) for row in rows)
    input_ids, attention_mask, labels = [], [], []
    for row in rows:
        ids = list(row["inputIds"])
        padding = maximum - len(ids)
        input_ids.append(ids + [pad_token_id] * padding)
        attention_mask.append([1] * len(ids) + [0] * padding)
        labels.append(ids + [-100] * padding)
    return {
        "input_ids": torch.tensor(input_ids, dtype=torch.long, device=device),
        "attention_mask": torch.tensor(attention_mask, dtype=torch.long, device=device),
        "labels": torch.tensor(labels, dtype=torch.long, device=device),
    }


def token_nll(logits: torch.Tensor, labels: torch.Tensor) -> torch.Tensor:
    shifted_logits = logits[:, :-1, :].float()
    shifted_labels = labels[:, 1:]
    losses = F.cross_entropy(
        shifted_logits.reshape(-1, shifted_logits.shape[-1]),
        shifted_labels.reshape(-1),
        reduction="none",
        ignore_index=-100,
    ).reshape(shifted_labels.shape)
    return losses


def gpu_facts(minimum_vram_gib: float) -> dict[str, Any]:
    if not torch.cuda.is_available():
        raise RuntimeError("a CUDA GPU is required for the structural smoke")
    properties = torch.cuda.get_device_properties(0)
    total_gib = properties.total_memory / 2**30
    if total_gib < minimum_vram_gib:
        raise RuntimeError(f"GPU has {total_gib:.2f} GiB, requires at least {minimum_vram_gib:.2f} GiB")
    capability = torch.cuda.get_device_capability(0)
    native_bf16 = capability[0] >= 8 and bool(torch.cuda.is_bf16_supported())
    return {
        "name": properties.name,
        "totalVramGiB": total_gib,
        "capability": list(capability),
        "torchBf16Reported": bool(torch.cuda.is_bf16_supported()),
        "nativeBf16Admitted": native_bf16,
    }


def compute_dtype(gpu: dict[str, Any]) -> torch.dtype:
    return torch.bfloat16 if gpu["nativeBf16Admitted"] else torch.float16


def upload_evidence(output: Path, repo_id: str, token: str) -> dict[str, Any]:
    api = HfApi(token=token)
    api.create_repo(repo_id, repo_type="dataset", private=True, exist_ok=True)
    info = api.repo_info(repo_id, repo_type="dataset")
    if not bool(info.private):
        raise RuntimeError(f"refusing to upload smoke evidence to public repo {repo_id}")
    prefix = output.name
    for item in output.iterdir():
        if item.is_file():
            api.upload_file(
                path_or_fileobj=str(item),
                path_in_repo=f"runs/{prefix}/{item.name}",
                repo_id=repo_id,
                repo_type="dataset",
                commit_message=f"Persist non-routing structural smoke {prefix}",
            )
    return {"repo": repo_id, "private": True, "path": f"runs/{prefix}"}


def upload_final_result(output: Path, repo_id: str, token: str) -> None:
    HfApi(token=token).upload_file(
        path_or_fileobj=str(output / "result.json"),
        path_in_repo=f"runs/{output.name}/result.json",
        repo_id=repo_id,
        repo_type="dataset",
        commit_message=f"Finalize non-routing structural smoke {output.name}",
    )


def run(args: argparse.Namespace, result: dict[str, Any]) -> None:
    config_path = args.config.resolve()
    config = read_json(config_path)
    if config.get("trainingAuthorized") is not False or config.get("nonRouting") is not True:
        raise RuntimeError("cloud smoke config is not explicitly non-routing/training-disabled")
    smoke = config["smoke"]
    bank_config = config["banks"]["artifacts"].get(args.bank)
    if not bank_config:
        raise RuntimeError(f"unknown bank {args.bank}")
    token = os.environ.get("HF_TOKEN")
    curriculum_override = getattr(args, "curriculum_path", None)
    if not token and not curriculum_override:
        raise RuntimeError(
            "either HF_TOKEN or --curriculum-path is required for the private curriculum"
        )

    result["config"] = {"path": str(config_path), "sha256": sha256(config_path)}
    result["bank"] = args.bank
    result["platform"] = args.platform
    result["gpu"] = gpu_facts(14.0)
    free_disk_gib = shutil.disk_usage(args.work_dir).free / 2**30
    result["freeDiskGiBBeforeDownloads"] = free_disk_gib
    if free_disk_gib < float(smoke["minimumFreeDiskGiBBeforeBankDownload"]):
        raise RuntimeError(
            f"only {free_disk_gib:.2f} GiB free; requires "
            f"{smoke['minimumFreeDiskGiBBeforeBankDownload']} GiB before downloads"
        )

    bank_repo = config["banks"]
    curriculum = config["curriculum"]
    bank_manifest = download(
        bank_repo["repo"], bank_repo["revision"], bank_repo["manifestPath"], "model", token
    )
    if sha256(bank_manifest) != bank_repo["manifestSha256"]:
        raise RuntimeError("frozen selected-bank manifest hash mismatch")
    manifest = read_json(bank_manifest)
    banks = {row["id"]: row for row in manifest["banks"]}
    bank_definition = banks[args.bank]

    warm_config = bank_repo["routerWarmstart"]
    warmstart = download(bank_repo["repo"], bank_repo["revision"], warm_config["path"], "model", token)
    verify_file(warmstart, int(warm_config["bytes"]), warm_config["sha256"])
    bank_path = download(bank_repo["repo"], bank_repo["revision"], bank_config["path"], "model", token)
    bank_artifact = verify_file(bank_path, int(bank_config["bytes"]), bank_config["sha256"])
    bank_validation = validate_bank_header(bank_path, bank_definition)
    result["bankArtifact"] = bank_artifact
    result["bankValidation"] = bank_validation.as_dict()

    train_config = curriculum["sftTrain"]
    train_path = (
        Path(curriculum_override).resolve()
        if curriculum_override
        else download(
            curriculum["repo"], curriculum["revision"], train_config["path"], "dataset", token
        )
    )
    result["curriculumArtifact"] = verify_file(
        train_path, int(train_config["bytes"]), train_config["sha256"]
    )

    host = config["host"]
    tokenizer = AutoTokenizer.from_pretrained(
        host["repo"], revision=host["revision"], token=token, trust_remote_code=True,
        fix_mistral_regex=True,
    )
    rows = select_complete_rows(train_path, tokenizer, int(smoke["maximumTokens"]))
    result["retokenization"] = {
        "maximumTokens": int(smoke["maximumTokens"]),
        "truncated": False,
        "rows": [{"id": row["id"], "lane": row["lane"], "tokens": len(row["inputIds"])} for row in rows],
    }

    device = torch.device("cuda:0")
    dtype = compute_dtype(result["gpu"])
    torch.cuda.reset_peak_memory_stats(device)
    load_started = time.perf_counter()
    model = AutoModelForCausalLM.from_pretrained(
        host["repo"], revision=host["revision"], token=token, trust_remote_code=True,
        torch_dtype=dtype, low_cpu_mem_usage=True, attn_implementation="sdpa",
    ).to(device)
    model.config.use_cache = False
    model.eval()
    batch = batch_rows(rows, int(tokenizer.pad_token_id), device)

    with torch.inference_mode():
        baseline_logits = model(
            input_ids=batch["input_ids"], attention_mask=batch["attention_mask"], use_cache=False
        ).logits.detach().cpu()

    layer = int(smoke["attachedLayer"])
    block = FrozenExpertRouterBlock(
        selected_expert_ids(bank_definition, layer),
        top_k=int(smoke["topK"]),
        initial_scale=float(smoke["initialExpertScale"]),
        maximum_scale=float(smoke["maximumExpertScale"]),
    )
    wrapper = attach_router_block(model, layer, block)
    block.router.to(device=device, dtype=torch.float32)
    block.expert_scale.data = block.expert_scale.data.to(device=device)
    block.materialize_experts(bank_path, layer, device=device, dtype=dtype)
    warm_tensors = load_file(str(warmstart), device="cpu")
    block.load_router_warmstart(warm_tensors[f"layers.{layer}.router.gate.weight"])
    block.enabled = False
    with torch.inference_mode():
        wrapped_disabled = model(
            input_ids=batch["input_ids"], attention_mask=batch["attention_mask"], use_cache=False
        ).logits.detach().cpu()
    identity_equal = torch.equal(baseline_logits, wrapped_disabled)
    identity_max_difference = (baseline_logits.float() - wrapped_disabled.float()).abs().max().item()
    result["hostDisabledIdentity"] = {
        "exact": identity_equal,
        "maximumAbsoluteDifference": identity_max_difference,
    }
    if not identity_equal:
        raise RuntimeError(f"host-disabled identity failed: max difference {identity_max_difference}")
    del baseline_logits, wrapped_disabled

    counts = freeze_except_routers(model)
    trainable_names = assert_trainable_isolation(model)
    result["trainableIsolation"] = {"counts": counts, "names": trainable_names}
    block.enabled = True
    model.zero_grad(set_to_none=True)
    gradient_output = model(**batch, use_cache=False)
    gradient_loss_scale = float(smoke["gradientLossScale"])
    (gradient_output.loss * gradient_loss_scale).backward()
    router_gradient = block.router.gate.weight.grad
    scale_gradient = block.expert_scale.grad
    gradient_gate = {
        "routerFinite": bool(router_gradient is not None and torch.isfinite(router_gradient).all()),
        "routerL1Scaled": float(router_gradient.float().abs().sum()) if router_gradient is not None else 0.0,
        "routerL1Unscaled": (
            float(router_gradient.float().abs().sum() / gradient_loss_scale)
            if router_gradient is not None else 0.0
        ),
        "scaleFinite": bool(scale_gradient is not None and torch.isfinite(scale_gradient).all()),
        "scaleAbsoluteScaled": float(scale_gradient.float().abs()) if scale_gradient is not None else 0.0,
        "scaleAbsoluteUnscaled": (
            float(scale_gradient.float().abs() / gradient_loss_scale)
            if scale_gradient is not None else 0.0
        ),
        "lossScale": gradient_loss_scale,
        "routerDtype": str(block.router.gate.weight.dtype),
    }
    result["gradientGate"] = gradient_gate
    if not all((gradient_gate["routerFinite"], gradient_gate["scaleFinite"])) or min(
        gradient_gate["routerL1Scaled"], gradient_gate["scaleAbsoluteScaled"]
    ) <= 0:
        raise RuntimeError(f"router gradient gate failed: {gradient_gate}")

    expert_row = next(row for row in rows if row["lane"] == "verified_expert")
    oracle_batch = batch_rows([expert_row], int(tokenizer.pad_token_id), device)
    block.enabled = False
    with torch.inference_mode():
        host_logits = model(
            input_ids=oracle_batch["input_ids"], attention_mask=oracle_batch["attention_mask"], use_cache=False
        ).logits
        host_nll = token_nll(host_logits, oracle_batch["labels"])[0]
    valid_tokens = oracle_batch["labels"][0, 1:] != -100
    host_nll = host_nll[valid_tokens].detach().cpu()

    candidate_indices = list(range(0, 32, max(1, 32 // int(smoke["oracleCandidateExperts"]))))[
        : int(smoke["oracleCandidateExperts"])
    ]
    best_candidate_nll = []
    oracle_rows = []
    block.enabled = True
    for candidate in candidate_indices:
        scale_losses = []
        for scale in smoke["oracleProbeScales"]:
            with block.forced_route(candidate, float(scale)), torch.inference_mode():
                logits = model(
                    input_ids=oracle_batch["input_ids"],
                    attention_mask=oracle_batch["attention_mask"],
                    use_cache=False,
                ).logits
                losses = token_nll(logits, oracle_batch["labels"])[0][valid_tokens].detach().cpu()
            scale_losses.append(losses)
            oracle_rows.append(
                {
                    "localExpert": candidate,
                    "globalExpert": block.expert_ids[candidate],
                    "scale": float(scale),
                    "meanNll": float(losses.mean()),
                    "improvedTokenCount": int((losses < host_nll).sum()),
                }
            )
        best_candidate_nll.append(torch.stack(scale_losses).min(dim=0).values)
    candidate_matrix = torch.stack(best_candidate_nll, dim=-1)
    targets = benefit_targets(host_nll, candidate_matrix, float(smoke["benefitMarginNats"]))
    positive = targets != candidate_matrix.shape[-1]

    block.enabled = True
    with torch.no_grad():
        _ = model(
            input_ids=oracle_batch["input_ids"], attention_mask=oracle_batch["attention_mask"], use_cache=False
        )
    if block.last_trace is None:
        raise RuntimeError("router did not retain a main-path trace")
    router_logits = block.last_trace.logits[: targets.numel()].float()
    ranking_loss = benefit_weighted_router_loss(router_logits, targets.to(device), host_nll.to(device), candidate_matrix.to(device))
    result["counterfactualDiscovery"] = {
        "hostOnlyClass": block.off_class_index,
        "candidateLocalExperts": candidate_indices,
        "probes": oracle_rows,
        "eligibleTokens": int(targets.numel()),
        "positiveBenefitTokens": int(positive.sum()),
        "hostOnlyTargets": int((~positive).sum()),
        "rankingLossFinite": bool(torch.isfinite(ranking_loss)),
    }
    if not torch.isfinite(ranking_loss) or int(positive.sum()) == 0 or int((~positive).sum()) == 0:
        raise RuntimeError("counterfactual smoke did not exercise both positive expert and host-only targets")

    output = Path(result["output"])
    checkpoint = output / "router-checkpoint.safetensors"
    saved_state = router_state_dict(model)
    save_file(saved_state, str(checkpoint), metadata={"autonoma": "non-routing-structural-smoke"})
    with torch.inference_mode():
        before_reload = model(
            input_ids=oracle_batch["input_ids"], attention_mask=oracle_batch["attention_mask"], use_cache=False
        ).logits.detach().cpu()
    with torch.no_grad():
        block.router.gate.weight.zero_()
    load_router_state_dict(model, load_file(str(checkpoint), device="cpu"))
    with torch.inference_mode():
        after_reload = model(
            input_ids=oracle_batch["input_ids"], attention_mask=oracle_batch["attention_mask"], use_cache=False
        ).logits.detach().cpu()
    reload_equal = torch.equal(before_reload, after_reload)
    result["checkpointParity"] = {
        "exact": reload_equal,
        "path": str(checkpoint),
        "bytes": checkpoint.stat().st_size,
        "sha256": sha256(checkpoint),
    }
    if not reload_equal:
        raise RuntimeError("router checkpoint save/reload parity failed")

    result["runtime"] = {
        "loadAndSmokeSeconds": time.perf_counter() - load_started,
        "peakAllocatedVramMiB": torch.cuda.max_memory_allocated(device) / 2**20,
        "peakReservedVramMiB": torch.cuda.max_memory_reserved(device) / 2**20,
        "computeDtype": str(dtype),
        "torch": torch.__version__,
    }
    result["gates"] = {gate: True for gate in smoke["requiredGates"]}


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--owner-execute", action="store_true")
    parser.add_argument("--config", type=Path, required=True)
    parser.add_argument("--bank", required=True)
    parser.add_argument("--platform", choices=("colab", "kaggle", "other"), default="other")
    parser.add_argument("--work-dir", type=Path, default=Path("/content/autonoma-fable-smoke"))
    parser.add_argument(
        "--curriculum-path",
        type=Path,
        help="Verified local sft-train.jsonl override for credential-free cloud execution",
    )
    args = parser.parse_args()
    if not args.owner_execute:
        raise SystemExit("refusing GPU/model execution without --owner-execute")
    args.work_dir.mkdir(parents=True, exist_ok=True)
    stamp = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
    output = args.work_dir / f"fable-router-structural-smoke-{args.bank}-{stamp}"
    output.mkdir(parents=True, exist_ok=False)
    result: dict[str, Any] = {
        "schema": "AutonomaFableRouterStructuralSmoke.v1",
        "status": "running_nonrouting",
        "nonRouting": True,
        "trainingAuthorized": False,
        "startedAt": now(),
        "output": str(output),
        "system": {"python": sys.version, "platform": platform.platform()},
    }
    tracking: dict[str, Any] = {"status": "not_started"}
    try:
        import trackio

        # Structural-smoke evidence is persisted directly to the private Hub
        # dataset.  Keep Trackio local here: Trackio's Space mode configures a
        # Hub Bucket/Xet write context, which can leak into a subsequent large
        # model download in the same process.  Full training uses a dedicated
        # remote Trackio process after acquisition instead.
        os.environ["TRACKIO_DIR"] = str(output / "trackio")
        trackio.init(
            project="autonoma-fable-router-smoke",
            name=f"{args.bank}-{stamp}",
            config={"bank": args.bank, "platform": args.platform, "mode": "structural-smoke"},
        )
        tracking = {"status": "started_local", "directory": str(output / "trackio")}
        run(args, result)
        result["status"] = "structural_smoke_passed_nonrouting"
        result["passed"] = True
        trackio.log(
            {
                "peak_vram_mib": result["runtime"]["peakAllocatedVramMiB"],
                "positive_oracle_tokens": result["counterfactualDiscovery"]["positiveBenefitTokens"],
                "router_gradient_l1_unscaled": result["gradientGate"]["routerL1Unscaled"],
            }
        )
    except BaseException as exc:
        result["status"] = "structural_smoke_failed_nonrouting"
        result["passed"] = False
        result["error"] = {"type": type(exc).__name__, "message": str(exc), "traceback": traceback.format_exc()}
    finally:
        result["finishedAt"] = now()
        result["tracking"] = tracking
        result_path = output / "result.json"
        result_path.write_text(json.dumps(result, indent=2) + "\n", encoding="utf-8")
        try:
            if tracking["status"] == "started_local":
                import trackio

                trackio.finish()
                tracking["status"] = "finished"
                result_path.write_text(json.dumps(result, indent=2) + "\n", encoding="utf-8")
        except BaseException as exc:
            tracking["finishError"] = str(exc)
            result_path.write_text(json.dumps(result, indent=2) + "\n", encoding="utf-8")
        token = os.environ.get("HF_TOKEN")
        try:
            config = read_json(args.config.resolve())
            if token:
                result["evidenceUpload"] = upload_evidence(output, config["smoke"]["resultRepo"], token)
                result_path.write_text(json.dumps(result, indent=2) + "\n", encoding="utf-8")
                upload_final_result(output, config["smoke"]["resultRepo"], token)
            else:
                result["evidenceUpload"] = {
                    "status": "local_only_pending_authenticated_download",
                    "privateRemoteCredentialUsed": False,
                }
                result_path.write_text(json.dumps(result, indent=2) + "\n", encoding="utf-8")
        except BaseException as exc:
            result["evidenceUpload"] = {"status": "failed", "error": str(exc)}
            result_path.write_text(json.dumps(result, indent=2) + "\n", encoding="utf-8")
        print(result_path.resolve())
    return 0 if result.get("passed") else 1


if __name__ == "__main__":
    raise SystemExit(main())