"""Fail-closed prerequisites for full Ouro paper-benchmark validation runs.

These checks establish traceability and bounded parity evidence, not identical
author settings, authentic authorship of a checkpoint, or all-input parity.
"""
import hashlib
import math
from collections.abc import Mapping
import torch

from .export import validate_export_artifact
from .evaluation_provenance import source_paths
from .objective import KL_MODES


def source_digest(root) -> str:
    digest = hashlib.sha256()
    for path in source_paths(root):
        digest.update(str(path.relative_to(root)).encode() + b"\0")
        digest.update(hashlib.sha256(path.read_bytes()).digest())
    return digest.hexdigest()


def require_ouro_paper_calibration(artifact: dict, *, study: bool = False) -> None:
    validate_export_artifact(artifact)
    model, c = artifact["model"], artifact["calibration"]
    if model.get("architecture") != "ouro" or model.get("physical_layers") != 24 or model.get("loop_count") != 4:
        raise ValueError("paper readiness currently supports Ouro-1.4B, 24 layers / 4 loops")
    if c.get("completed") is not True or (not study and c.get("paper_calibration") is not True):
        raise ValueError("full paper evaluation requires completed full calibration")
    from .experiment_contract import STUDY_SAMPLES, SLT_BUDGETS
    study_info = c.get("study") or {}
    samples = study_info.get("samples") if study else 1024
    if study and (c.get("run_kind") != "study" or c.get("paper_calibration") is not False
                  or samples not in STUDY_SAMPLES or not study_info.get("axes")
                  or not set(study_info["axes"]) <= {"calibration_size", "slt_budget"}):
        raise ValueError("study evaluation requires explicit, non-paper study identity")
    if c.get("numerical_contract") != artifact["quantization"]["numerical_contract"]:
        raise ValueError("calibration must record the current numerical contract")
    data = c.get("data", {})
    expected = {"dataset": "mit-han-lab/pile-val-backup", "split": "validation",
                "text_field": "text", "samples": samples, "max_length": 256,
                "dataset_revision": "2f5e46ae6a69cf0dce4b12f78241c408936ca0e4"}
    if any(data.get(k) != v for k, v in expected.items()):
        raise ValueError(f"calibration must record Pile validation/text, {samples} samples, max length 256")
    if len(data.get("dataset_revision", "")) != 40:
        raise ValueError("calibration dataset revision must be pinned")
    records = c.get("token_records", [])
    if len(records) != samples:
        raise ValueError(f"full calibration must retain {samples} actual token records")
    for index, record in enumerate(records):
        ids, mask = record.get("input_ids", []), record.get("attention_mask", [])
        if (record.get("sample_index") != index or len(ids) != 1 or not 0 < len(ids[0]) <= 256
                or any(type(i) is not int or i < 0 for i in ids[0]) or mask != [[1] * len(ids[0])]):
            raise ValueError("invalid unpadded calibration token record")
    choices = c.get("algorithm_choices", {})
    if choices.get("kl_mode") not in KL_MODES[:2]:
        raise ValueError("paper Table 6 uses top-1000; full-vocabulary KL is diagnostic only")
    if choices.get("statistics_coordinate") not in {"svd_parameters", "effective_factors"}:
        raise ValueError("missing statistics coordinate")
    if choices.get("fisher_estimator") not in {"trajectory_gradient_square", "model_score_mc"}:
        raise ValueError("missing Fisher estimator")
    expected_budget = 0 if c.get("ablation") == "no_slt" else 4
    if study:
        expected_budget = study_info.get("slt_budget")
        if expected_budget not in SLT_BUDGETS:
            raise ValueError("invalid study SLT budget")
        from .experiment_contract import calibration_identity
        expected_identity = calibration_identity(smoke=False, samples=samples,
            study_samples="calibration_size" in study_info["axes"],
            budget=expected_budget, ablation=c.get("ablation"))
        if expected_identity["study"] != study_info:
            raise ValueError("inconsistent study identity")
    if choices.get("slt_budget") != expected_budget or not c.get("resolved_optimizer"):
        raise ValueError("paper SLT budget or resolved optimizer missing")
    optimizer = c["resolved_optimizer"]
    if any(not isinstance(v, (int, float)) or not math.isfinite(v) for key in ("lr", "weight_decay", "eps")
           for v in [optimizer.get(key)]) or optimizer["lr"] <= 0 or optimizer["eps"] <= 0 or optimizer["weight_decay"] < 0:
        raise ValueError("resolved optimizer requires finite lr, weight_decay and eps")
    betas = optimizer.get("betas", ())
    if len(betas) != 2 or any(not isinstance(b, (float, int)) or not math.isfinite(b) or not 0 <= b < 1 for b in betas):
        raise ValueError("resolved optimizer requires two finite betas")
    if type(c.get("global_optimization_steps")) is not int or c["global_optimization_steps"] <= 0:
        raise ValueError("completed optimizer updates missing")
    components = artifact["components"]
    def check_finite(value):
        if isinstance(value, torch.Tensor) and not torch.isfinite(value).all():
            raise ValueError("non-finite tensor in calibrated components")
        if isinstance(value, Mapping):
            for item in value.values():
                check_finite(item)
        elif isinstance(value, (list, tuple)):
            for item in value:
                check_finite(item)
    check_finite(components)
    from adapters.ouro import PAPER_GROUPS
    from .las import LoopAwareActivationScales
    from .cta import CrossLoopTransitionAdapter
    from .transforms import SharedKroneckerTransform
    expected_groups = {f"model.layers.{layer}.{group}" for layer in range(24) for group in PAPER_GROUPS}
    shared, selected = components["shared_transforms"], components["selected_loop_transforms"]
    las = LoopAwareActivationScales.from_export_state(components["las"])
    if set(shared) != expected_groups or set(las.module_names) != expected_groups:
        raise ValueError("paper artifact requires all 24 x 4 transform and LAS groups")
    if not las.dynamic_clip or las.loop_count != 4 or las.group_size != 32:
        raise ValueError("current full-calibration profile requires dynamic module-loop LAS")
    if sum(p.numel() for p in las.parameters()) != (96 if c.get("ablation") == "no_las" else 384):
        raise ValueError("unexpected LAS parameter count")
    for key in las.module_names:
        for loop in range(4):
            scale = las.scales_for(key, loop)
            if not torch.isfinite(scale).all() or (scale <= 0).any():
                raise ValueError("LAS exponentiation produced invalid clipping multiplier")
    if len(selected) != expected_budget or not set(selected) <= expected_groups:
        raise ValueError("selected transform groups do not match the paper budget")
    def checked_transform(state):
        transform = SharedKroneckerTransform.from_export_state(state)
        for factor in (transform.left, transform.right):
            inverse, info = torch.linalg.inv_ex(factor.detach().double())
            if info.any() or not torch.isfinite(inverse).all():
                raise ValueError("calibrated transform is not invertible")
        return transform
    for key, state in shared.items():
        transform = checked_transform(state)
        width = 5632 if key.endswith("mlp_down") else 2048
        if transform.feature_size != width:
            raise ValueError("shared transform shape does not match Ouro projection")
    for key, states in selected.items():
        if set(states) != {"0", "1", "2", "3"}:
            raise ValueError("selected group must contain all four transforms")
        for state in states.values():
            if (state["left_size"], state["right_size"]) != (shared[key]["left_size"], shared[key]["right_size"]):
                raise ValueError("selected/shared factor dimensions differ")
            checked_transform(state)
    cta = CrossLoopTransitionAdapter.from_export_state(components["cta"])
    if (cta.hidden_size, cta.rank, cta.transition_count) != (2048, 8, 3):
        raise ValueError("paper Ouro CTA must have hidden 2048, rank 8, three transitions")


# Established repository convention from the Track B parity work
# (docs/cowork/jun/0827_parity_gate_results.md): a reference top-2 gap at or
# below this is a near-tie that no backend can be required to break the same
# way, because the reference is not self-consistent there either.
PARITY_TIE_THRESHOLD = 0.25


def top1_verdict(row: dict, *, tie_threshold: float = PARITY_TIE_THRESHOLD) -> tuple[bool, bool]:
    """Top-1 equality, excusing only ties the reference itself cannot break.

    Returns (accepted, excused_as_tie). A row is excused only when the reference
    top-2 gap is within `tie_threshold` AND both backends propose the same
    unordered top-2 pair, i.e. they disagree on ordering, not on candidates.
    """
    if row.get("top1_agreement") is True:
        return True, False
    tokens = row.get("token_ids") or []
    reference = row.get("hf_logprobs") or []
    deployed = row.get("vllm_logprobs") or []
    if not (len(tokens) == len(reference) == len(deployed)) or len(tokens) < 2:
        return False, False
    reference_order = sorted(range(len(tokens)), key=lambda i: -reference[i])
    deployed_order = sorted(range(len(tokens)), key=lambda i: -deployed[i])
    gap = reference[reference_order[0]] - reference[reference_order[1]]
    same_pair = ({tokens[reference_order[0]], tokens[reference_order[1]]}
                 == {tokens[deployed_order[0]], tokens[deployed_order[1]]})
    excused = bool(gap <= tie_threshold and same_pair)
    return excused, excused


def parity_gate(report: dict, *, max_logprob_error: float, max_hidden_error: float) -> dict:
    """A bounded, unmodified six-prompt prefill gate; never an all-input proof."""
    reasons = []
    tie_excused = 0
    if any(not math.isfinite(x) or x < 0 for x in (max_logprob_error, max_hidden_error)):
        raise ValueError("parity tolerances must be finite and non-negative")
    interventions = ("<redacted-hf-token>", "hf_vllm_rope", "hf_vllm_attention", "hf_torch_flash_attention",
                     "hf_offline_weights", "hf_packed_linears", "attention_replay_artifact")
    if any(report.get(name) for name in interventions):
        reasons.append("diagnostic intervention is not production parity evidence")
    rows = report.get("rows", [])
    if len(rows) < 6:
        reasons.append("at least six prefill fixtures are required")
    if len({tuple(row.get("prompt_token_ids", [])) for row in rows}) != len(rows):
        reasons.append("parity fixtures must be distinct")
    for row in rows:
        error, hidden = row.get("max_abs_logprob_error"), row.get("loop_relative_hidden_error", [])
        accepted, excused = top1_verdict(row)
        tie_excused += excused
        if not accepted or row.get("compared_logprob_count", 0) < 1000:
            reasons.append("top1 or top-1000 comparison incomplete")
        if not isinstance(error, (int, float)) or not math.isfinite(error) or not 0 <= error <= max_logprob_error:
            reasons.append("logprob error exceeds tolerance")
        if len(hidden) != 4 or any(not isinstance(x, (int, float)) or not math.isfinite(x) or not 0 <= x <= max_hidden_error for x in hidden):
            reasons.append("four-loop hidden-state parity failed")
    if report.get("source_changed_during_run"):
        reasons.append("source changed during parity measurement")
    packed = report.get("packed_storage_diagnostic")
    if packed is not None:
        if packed.get('manifest_changed_during_run'):
            reasons.append("packed manifest changed during parity measurement")
        comparisons = packed.get("dense_vllm_comparison", [])
        if len(comparisons) != len(rows) or any(
            item.get("same_token") is not True or item.get("same_topk_indices") is not True
            or item.get("compared_logprobs", 0) < 1000 or item.get("max_abs_logprob_error") != 0.0
            for item in comparisons):
            reasons.append("packed/dense prefill mismatch")
    return dict(passed=not reasons, reasons=sorted(set(reasons)),
                max_logprob_error=max_logprob_error, max_hidden_error=max_hidden_error,
                tie_threshold=PARITY_TIE_THRESHOLD, rows_excused_as_reference_tie=tie_excused,
                scope="six_or_more_single_sequence_prefills; decode/batch/long_context still require A40 validation")


def require_parity_report(report: dict, *, artifact_sha256: str, current_source_digest: str) -> None:
    if report.get("artifact_sha256") != artifact_sha256 or report.get("source_digest") != current_source_digest:
        raise ValueError("parity evidence does not match this artifact and current code")
    gate = report.get("acceptance", {})
    if "max_logprob_error" not in gate or "max_hidden_error" not in gate:
        raise ValueError("parity acceptance thresholds missing")
    result = parity_gate(report, max_logprob_error=gate["max_logprob_error"], max_hidden_error=gate["max_hidden_error"])
    if not result["passed"]:
        raise ValueError(f"prefill parity gate failed: {result['reasons']}")