# -*- coding: utf-8 -*-
"""Shared plumbing for the BCS/BES/ISS/KTS metric stack.

Everything here is deliberately read-only with respect to data/: the fact set
and the query bank are frozen artefacts (protocol 2.1), and this package only
consumes them.

Path resolution has one rule: entries under `paths:` in configs/metrics.yaml
are taken relative to the repository root unless they are absolute, and each is
overridable by an environment variable so nobody has to edit a tracked config
to run on their own filesystem.
"""
import os, json, math, functools

import numpy as np
import yaml

HERE = os.path.dirname(os.path.abspath(__file__))
ROOT = os.path.dirname(HERE)
CONFIGS = os.path.join(ROOT, "configs")


@functools.lru_cache(maxsize=None)
def cfg():
    with open(os.path.join(CONFIGS, "metrics.yaml")) as f:
        return yaml.safe_load(f)


def _root(key, env):
    p = os.environ.get(env) or cfg()["paths"][key]
    return p if os.path.isabs(p) else os.path.join(ROOT, p)


def data_file(name):
    """A frozen input artefact: the fact set or the query bank."""
    return os.path.join(_root("data", "FKS_DATA"), name)


def runner_dir():
    """Where eval_run.py lives; imported so the prompt format has one owner."""
    return os.path.join(ROOT, "runner")


@functools.lru_cache(maxsize=None)
def models_cfg():
    with open(os.path.join(CONFIGS, "models.yaml")) as f:
        return yaml.safe_load(f)


def model_entry(name):
    for m in models_cfg()["evaluated_models"]:
        if m["name"] == name:
            return m
    aux = models_cfg().get("auxiliary_models", {})
    for m in aux.values():
        if m["name"] == name:
            return m
    raise KeyError(f"{name} is not in configs/models.yaml")


def model_path(name):
    """Local weights if we have them, otherwise the hub id.

    Resolution order: $FKS_MODELS/<path>, then configs/models.yaml:model_root
    (absent by default), then the entry's `hf` id, which transformers resolves
    against the hub. A model that is in neither the config nor the hub has to be
    passed explicitly by the caller.
    """
    entry = model_entry(name)
    root = os.environ.get("FKS_MODELS") or models_cfg().get("model_root")
    if root:
        local = os.path.join(root, entry.get("path", name))
        if os.path.isdir(local):
            return local
    if entry.get("hf"):
        return entry["hf"]
    raise SystemExit(
        f"cannot locate weights for {name}: set FKS_MODELS to a directory "
        f"containing '{entry.get('path', name)}', or add an `hf:` id to "
        f"configs/models.yaml")


def out(kind, *parts):
    """kind in {evaluation, hidden, jlens, metrics}."""
    p = os.path.join(_root("outputs", "FKS_OUTPUTS"), kind, *parts)
    os.makedirs(os.path.dirname(p) if os.path.splitext(p)[1] else p, exist_ok=True)
    return p


def generations(model):
    """Where eval_run.py put this model's raw generations."""
    return out("evaluation", f"{model}.jsonl")


def read_jsonl(path):
    with open(path) as f:
        for line in f:
            line = line.strip()
            if line:
                yield json.loads(line)


def write_jsonl(path, rows):
    os.makedirs(os.path.dirname(path), exist_ok=True)
    n = 0
    with open(path, "w") as f:
        for r in rows:
            f.write(json.dumps(r, ensure_ascii=False, default=_jsonable) + "\n")
            n += 1
    return n


def write_json(path, obj):
    os.makedirs(os.path.dirname(path), exist_ok=True)
    with open(path, "w") as f:
        json.dump(obj, f, indent=2, ensure_ascii=False, default=_jsonable)


def _jsonable(o):
    if isinstance(o, (np.floating, np.integer)):
        return o.item()
    if isinstance(o, np.ndarray):
        return o.tolist()
    raise TypeError(type(o))


# ------------------------------------------------------------------- queries
QUERY_BANK = "evaluation_queries_44416.jsonl"


@functools.lru_cache(maxsize=None)
def main_forward_queries():
    """The 39,260 queries that protocol 1.1 admits to the main analysis.

    The filter reads each row's own `use_for_main_forward` flag rather than
    testing `condition_family in main_families`: the flags are derived from
    eval_conditions.yaml and are what the build-time validator checks, so trusting
    them keeps one definition of the split instead of two that can drift.
    """
    rows = []
    for r in read_jsonl(data_file(QUERY_BANK)):
        if r.get("use_for_main_forward"):
            rows.append(r)
    fams = set(cfg()["main_families"])
    bad = {r["condition_family"] for r in rows} - fams
    if bad:
        raise SystemExit(f"main_forward rows carry unexpected families: {bad}")
    return rows


@functools.lru_cache(maxsize=None)
def facts():
    """fact_id -> record, plus the relation of each fact."""
    return {r["fact_id"]: r for r in read_jsonl(data_file("benchmark_facts_2592.jsonl"))}


@functools.lru_cache(maxsize=None)
def fact_relation():
    return {fid: r["relation"]["relation_id"] for fid, r in facts().items()}


@functools.lru_cache(maxsize=None)
def coverage():
    """fact_id -> set of main families that actually contain it.

    Protocol 1.3: coverage is ragged (multilingual 2,402, context 2,591), and
    the two reporting modes below are both mandatory.
    """
    cov = {}
    for r in main_forward_queries():
        cov.setdefault(r["fact_id"], set()).add(r["condition_family"])
    return cov


@functools.lru_cache(maxsize=None)
def complete_family_facts():
    """D_cap: the facts carrying all five main families (protocol 1.3).

    This set is a property of the query bank, not of any model, so every model
    is scored on exactly the same facts -- which is the point of protocol 1.3's
    prohibition on per-model effective sets.
    """
    need = set(cfg()["main_families"])
    return sorted(f for f, c in coverage().items() if c >= need)


def eval_fact_set(mode):
    if mode == "complete_family":
        return complete_family_facts()
    if mode == "full_set":
        return sorted(coverage())
    raise ValueError(mode)


# -------------------------------------------------------------- layer window
def layer_window(n_layers, min_depth=None):
    """Protocol 7.10: {l : d_l >= min_depth}, d_l = l / (L - 1).

    `l` indexes decoder blocks 0..L-1, so l = L-1 is the final residual stream
    that J-Lens transports to. In HF terms the state is hidden_states[l+1],
    because hidden_states[0] is the embedding output.
    """
    if min_depth is None:
        min_depth = cfg()["extraction"]["window_min_depth"]
    return [l for l in range(n_layers) if l / max(n_layers - 1, 1) >= min_depth - 1e-9]


def late_window(n_layers):
    return layer_window(n_layers, cfg()["extraction"]["late_min_depth"])


# --------------------------------------------------------------- linear alg
def l2_normalize(x, axis=-1, eps=1e-12):
    n = np.linalg.norm(x, axis=axis, keepdims=True)
    return x / np.maximum(n, eps)


def pca_whiten(X, dim, shrinkage, eps=1e-12):
    """Return the whitened matrix and the fitted transform.

    Protocol 7.5 forbids fitting a separate transform per condition family, so
    this is called once per (model, layer) on the pooled matrix and the same
    components are then applied to every family.
    """
    mu = X.mean(axis=0, keepdims=True)
    Xc = X - mu
    # Economy SVD on the centred matrix is the covariance eigendecomposition
    # without ever forming a d x d matrix -- d can be 5120 and n is ~39k.
    k = min(dim, Xc.shape[0], Xc.shape[1])
    U, S, Vt = np.linalg.svd(Xc, full_matrices=False)
    U, S, Vt = U[:, :k], S[:k], Vt[:k]
    var = (S ** 2) / max(Xc.shape[0] - 1, 1)
    # lambda is expressed as a fraction of the mean retained variance so that
    # one config value behaves the same across models with different scales.
    lam = shrinkage * float(var.mean())
    Z = (Xc @ Vt.T) / np.sqrt(var + lam + eps)
    return Z.astype(np.float32), {"mean": mu, "components": Vt, "scale": np.sqrt(var + lam + eps)}


# ------------------------------------------------------------------ negatives
def negative_sample(fact_ids, relation_of, max_negatives, seed):
    """Protocol 7.8: for each fact, up to `max_negatives` same-relation others.

    Drawn ONCE from the fixed fact set and reused for every model. If each model
    drew its own, a model could score well merely by having been handed more
    distant negatives.
    """
    rng = np.random.default_rng(seed)
    by_rel = {}
    for f in fact_ids:
        by_rel.setdefault(relation_of[f], []).append(f)
    for r in by_rel:
        by_rel[r].sort()
    negs = {}
    for f in fact_ids:
        pool = [g for g in by_rel[relation_of[f]] if g != f]
        if len(pool) > max_negatives:
            idx = rng.choice(len(pool), size=max_negatives, replace=False)
            pool = [pool[i] for i in sorted(idx)]
        negs[f] = pool
    return negs


# ----------------------------------------------------------------- bootstrap
def relation_clustered_bootstrap(values, relation_of, n_resamples, seed, ci=0.95):
    """Protocol 14.1: resample relations, then facts within each drawn relation.

    A plain per-fact bootstrap would understate the interval because the 21
    relations are very unevenly sized and facts inside one relation are far from
    independent.
    """
    fact_ids = [f for f in values if values[f] == values[f]]  # drop NaN
    if not fact_ids:
        return {"mean": float("nan"), "lo": float("nan"), "hi": float("nan"), "n": 0}
    by_rel = {}
    for f in fact_ids:
        by_rel.setdefault(relation_of[f], []).append(f)
    rels = sorted(by_rel)
    arr = {r: np.array([values[f] for f in by_rel[r]], dtype=np.float64) for r in rels}
    rng = np.random.default_rng(seed)
    draws = np.empty(n_resamples, dtype=np.float64)
    for b in range(n_resamples):
        picked = rng.integers(0, len(rels), size=len(rels))
        pool = []
        for i in picked:
            a = arr[rels[i]]
            pool.append(a[rng.integers(0, len(a), size=len(a))])
        draws[b] = np.concatenate(pool).mean()
    lo, hi = np.percentile(draws, [(1 - ci) / 2 * 100, (1 + ci) / 2 * 100])
    point = float(np.mean([values[f] for f in fact_ids]))
    return {"mean": point, "lo": float(lo), "hi": float(hi), "n": len(fact_ids)}