#!/usr/bin/env python3
"""Sketch B YAQA calibration for lalamo language models.

Universal part of the pipeline (Layer 2 in YAQA_CALIBRATION_DESIGN.md):

  forward  -> pseudo target sampling from the model's own logits
  backward -> per-sample weight gradient G_b for every selected Linear
  H_I = mean_b G_b^T G_b
  H_O = mean_b G_b G_b^T
  damping + PSD checks -> preconditioners.npz

Per-model work is limited to selecting LinearSite entries.

Usage:
  JAX_PLATFORM_NAME=cpu python scripts/yaqa_calibration.py \
    --model-dir /tmp/qwen35_0.8b_bf16_lalamo_lalamo_origcfg \
    --corpus experiments/qwen35-0.8b/data/calibration.txt \
    --output experiments/qwen35-0.8b/yaqa-hin/calibration.npz \
    --samples 32 --max-tokens 128 --output-block none
"""

from __future__ import annotations

import argparse
import json
import time
import os
import sys
from dataclasses import dataclass
from pathlib import Path

os.environ.setdefault("JAX_PLATFORM_NAME", "cpu")


@dataclass(frozen=True)
class LinearSite:
    path: tuple[str, ...]
    linear: object
    out_dim: int
    in_dim: int
    components: tuple[int, ...]

    @property
    def key(self) -> str:
        return "/".join(self.path)


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser()
    parser.add_argument("--model-dir", type=Path, default=None, help="saved lalamo model directory")
    parser.add_argument("--spec-name", default="Qwen3.5-0.8B", help="built-in lalamo spec for direct HF import")
    parser.add_argument("--hf-repo", default=None, help="load directly from this Hugging Face repo (no save)")
    parser.add_argument("--hf-dir", default=None, help="load directly from a local HF snapshot directory")
    parser.add_argument("--corpus", type=Path, required=True)
    parser.add_argument("--output", type=Path, required=True)
    parser.add_argument("--lalamo-path", default=os.environ.get("LALAMO_PATH", "/tmp/lalamo-direct"))
    parser.add_argument(
        "--parallel",
        choices=("replicated", "tensor", "fsdp", "data"),
        default="replicated",
        help="JAX device sharding: tensor/fsdp use all visible GPUs as one memory pool",
    )
    parser.add_argument("--samples", type=int, default=32)
    parser.add_argument("--max-tokens", type=int, default=128)
    parser.add_argument("--min-tokens", type=int, default=32, help="drop shorter trailing chunks")
    parser.add_argument("--layer-filter", default="", help="only paths containing this substring")
    parser.add_argument("--output-block", choices=("none", "small", "all"), default="none")
    parser.add_argument("--output-block-limit", type=int, default=2048)
    parser.add_argument("--raw-output", action="store_true", help="save raw H before normalization/damping (for language-balanced merge)")
    parser.add_argument("--damping", type=float, default=1e-2, help="initial sigma_reg after mean-diagonal normalization")
    parser.add_argument("--seed", type=int, default=0)
    parser.add_argument(
        "--calib-dtype",
        choices=("float32", "bfloat16"),
        default="float32",
        help="model dtype during calibration; bfloat16 halves memory for 4B/9B",
    )
    parser.add_argument("--json-out", type=Path, default=None)
    parser.add_argument("--eval-corpus", type=Path, action="append", default=[], help="evaluation corpus to keep disjoint")
    parser.add_argument("--allow-overlap", action="store_true", help="allow calibration/eval overlap for analysis only")
    parser.add_argument("--progress-jsonl", type=Path, default=None, help="default: <output>.progress.jsonl")
    parser.add_argument("--checkpoint-every", type=int, default=0, help="save partial accumulators every N samples; 0=off")
    parser.add_argument("--checkpoint-path", type=Path, default=None, help="default: <output>.partial.npz")
    parser.add_argument("--resume", default=None, help="'auto' or a partial npz path")
    return parser.parse_args()


def main() -> None:
    args = parse_args()
    from corpus_guard import assert_disjoint
    from lalamo_forward import bf16_block_reason, gpu_capabilities

    reason = bf16_block_reason(args.calib_dtype, gpu_capabilities())
    if reason:
        raise SystemExit(reason)
    assert_disjoint(args.corpus, args.eval_corpus, allow_overlap=args.allow_overlap)
    progress_path = args.progress_jsonl or args.output.with_suffix(".progress.jsonl")
    progress_path.parent.mkdir(parents=True, exist_ok=True)
    checkpoint_path = args.checkpoint_path or args.output.with_suffix(".partial.npz")
    if checkpoint_path.suffix != ".npz":
        checkpoint_path = checkpoint_path.with_suffix(".npz")
    if checkpoint_path.resolve() == args.output.resolve():
        raise SystemExit("--checkpoint-path must differ from --output")
    run_id = time.strftime("%Y%m%d-%H%M%S")
    if not args.resume:
        progress_path.write_text("", encoding="utf-8")

    def progress(record: dict) -> None:
        record = {"run_id": run_id, **record}
        with open(progress_path, "a", encoding="utf-8") as file:
            file.write(json.dumps(record) + "\n")

    sys.path.insert(0, args.lalamo_path)

    import equinox as eqx
    import jax
    import jax.numpy as jnp
    import numpy as np

    from lalamo.model import Model
    from lalamo_forward import apply_attention_env, describe, enter_mesh, force_float32_activations
    from lalamo.module import Keychain
    from lalamo.modules import DecoderForwardPassConfig, ForwardPassMode
    from lalamo.modules.linear import Linear
    from lalamo.utils.sharding import ShardingConfig
    from lalamo.utils.surgery import select_nodes_of_type
    from tokenizers import Tokenizer

    if args.parallel == "tensor":
        sharding = ShardingConfig.tensor_parallel()
    elif args.parallel == "fsdp":
        sharding = ShardingConfig.fully_sharded_data_parallel()
    elif args.parallel == "data":
        sharding = ShardingConfig.data_parallel()
    else:
        sharding = ShardingConfig.replicated()
    _mesh = enter_mesh(sharding)
    keychain = Keychain.init(seed=args.seed, sharding_config=sharding)
    forward_pass_config = DecoderForwardPassConfig.for_inference(mode=ForwardPassMode.MULTI_TOKEN)
    forward_pass_config = force_float32_activations(apply_attention_env(forward_pass_config))
    print(f"attention: {describe()}", flush=True)

    dtype = jnp.dtype(args.calib_dtype)
    if args.hf_repo or args.hf_dir:
        from dataclasses import replace as dataclass_replace
        from pathlib import Path as _Path

        from lalamo.model_import.common import import_model
        from lalamo.model_import.model_specs.qwen import QWEN_MODELS

        spec = next((item for item in QWEN_MODELS if item.name == args.spec_name), None)
        if spec is None:
            raise SystemExit(f"lalamo spec {args.spec_name!r} not found")
        if args.hf_dir:
            from lalamo.model_import.origins import LocalOrigin

            weight_files = tuple(sorted(path.name for path in _Path(args.hf_dir).glob("*.safetensors")))
            if not weight_files:
                raise SystemExit(f"no safetensors in {args.hf_dir}")
            origin = LocalOrigin(root=args.hf_dir, weight_files=weight_files)
        else:
            from lalamo.model_import.origins import HuggingFaceOrigin

            origin = HuggingFaceOrigin(repo=args.hf_repo)
        print(f"importing {args.spec_name} from {origin.description} ({args.calib_dtype})...")
        results = import_model(dataclass_replace(spec, origin=origin), sharding_config=sharding, dtype=dtype)
        model = results.model
        tokenizer = model.token_codec.tokenizer
    else:
        if args.model_dir is None:
            raise SystemExit("provide --model-dir, --hf-repo, or --hf-dir")
        print(f"loading model ({args.calib_dtype})...")
        model = Model.load(args.model_dir, sharding, dtype=dtype)
        tokenizer = Tokenizer.from_file(str(args.model_dir / "tokenizer.json"))
    print("loaded")

    def module_at(root, attribute_path):
        node = root
        for part in attribute_path:
            if part.startswith("["):
                node = node[int(part[1:-1])]
            else:
                node = getattr(node, part.lstrip("."))
        return node

    layer_filters = [item for item in args.layer_filter.split(",") if item]
    sites: list[LinearSite] = []
    for path, linear in select_nodes_of_type(Linear, model):
        joined = "/".join(path)
        if layer_filters and not any(item in joined for item in layer_filters):
            continue
        shape = tuple(int(x) for x in linear.weights.shape)
        if len(shape) < 2:
            continue
        components = shape[:-2]
        out_dim, in_dim = shape[-2], shape[-1]
        sites.append(LinearSite(path=path, linear=linear, out_dim=out_dim, in_dim=in_dim, components=components))
    if not sites:
        raise SystemExit("no LinearSite selected")
    print(f"sites: {len(sites)}")

    def logits_for(m, ids):
        token_ids = jnp.asarray([ids], dtype=jnp.int32)
        positions = jnp.arange(len(ids), dtype=jnp.int32)[None, :]
        result = m.decoder(
            token_ids=token_ids,
            token_positions=positions,
            state=None,
            return_updated_state=False,
            lengths_without_padding=None,
            forward_pass_config=forward_pass_config,
            keychain=keychain.split(1)[0],
        )
        return result.logits[0]

    def cross_entropy(logits, targets):
        log_probs = jax.nn.log_softmax(logits.astype(jnp.float32), axis=-1)
        # Official get_hess_llama.py uses F.cross_entropy(..., reduction="mean")
        # over all tokens of the batch. Per-sample mean keeps the same scale
        # independently of sequence length.
        return -jnp.mean(jnp.take_along_axis(log_probs, targets[:, None], axis=-1))

    base_arrays = tuple(site.linear.weights.weights for site in sites)

    def model_with_weights(arrays):
        updated = model
        for site, array in zip(sites, arrays):
            current = module_at(updated, site.path)
            new_weights = eqx.tree_at(lambda wm: wm.weights, current.weights, array)
            new_linear = eqx.tree_at(lambda linear: linear.weights, current, new_weights)
            updated = eqx.tree_at(lambda root, path=site.path: module_at(root, path), updated, new_linear)
        return updated

    current_ids: list[int] = []
    current_targets = None

    def per_sample_loss(arrays):
        m = model_with_weights(arrays)
        logits = logits_for(m, current_ids)
        return cross_entropy(logits, current_targets)

    texts = [line.strip() for line in args.corpus.read_text(encoding="utf-8").splitlines() if line.strip()]
    if not texts:
        raise SystemExit("empty calibration corpus")

    def build_chunks() -> list[list[int]]:
        # Concatenate documents and cut into full-context windows, matching the
        # official calibration flow (continuous sequences instead of single lines).
        joined = "\n\n".join(texts)
        ids = tokenizer.encode(joined, add_special_tokens=True).ids
        chunks = [ids[start : start + args.max_tokens] for start in range(0, len(ids), args.max_tokens)]
        chunks = [chunk for chunk in chunks if len(chunk) >= args.min_tokens]
        if not chunks:
            raise SystemExit("no usable calibration chunks")
        rng = np.random.default_rng(args.seed)
        rng.shuffle(chunks)
        return chunks

    chunks = build_chunks()
    if len(chunks) < args.samples:
        print(f"warning: only {len(chunks)} calibration chunks available, using all")
        args.samples = len(chunks)

    accumulators = []
    for site in sites:
        components = site.components or ()
        input_shape = (*components, site.in_dim, site.in_dim)
        accumulators.append(
            {
                "input": np.zeros(input_shape, dtype=np.float32),
                "output": np.zeros((*components, site.out_dim, site.out_dim), dtype=np.float32)
                if args.output_block == "all"
                or (args.output_block == "small" and site.out_dim <= args.output_block_limit)
                else None,
                "samples": 0,
            }
        )

    meta = {
        "site_keys": [site.key for site in sites],
        "site_shapes": [[site.in_dim, site.out_dim] for site in sites],
        "output_block": args.output_block,
        "output_block_limit": args.output_block_limit,
        "corpus": str(args.corpus),
        "seed": args.seed,
        "samples": args.samples,
        "model_dir": str(args.model_dir) if args.model_dir else None,
        "calib_dtype": args.calib_dtype,
        "parallel": args.parallel,
    }

    def save_partial() -> None:
        arrays: dict[str, np.ndarray] = {}
        for site, accumulator in zip(sites, accumulators):
            arrays[f"{site.key}/input"] = accumulator["input"]
            if accumulator["output"] is not None:
                arrays[f"{site.key}/output"] = accumulator["output"]
            arrays[f"{site.key}/samples"] = np.asarray([accumulator["samples"]], dtype=np.int64)
        arrays["processed"] = np.asarray([processed], dtype=np.int64)
        arrays["sample_index"] = np.asarray([sample_index], dtype=np.int64)
        arrays["__meta__"] = np.asarray(json.dumps(meta, sort_keys=True))
        checkpoint_path.parent.mkdir(parents=True, exist_ok=True)
        tmp_path = checkpoint_path.with_name(checkpoint_path.name + ".tmp.npz")
        np.savez(tmp_path, **arrays)
        os.replace(tmp_path, checkpoint_path)
        print(f"  checkpoint -> {checkpoint_path}", flush=True)

    def peak_rss_mb() -> float:
        """Peak RSS, so bf16 vs f32 calibration can be compared on memory.

        XLA CPU may upcast bf16 internally, so a bf16 run does not necessarily
        halve the peak; this is the number that decides whether q512 fits.
        """
        import resource

        usage = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
        return usage / (1024 * 1024) if sys.platform == "darwin" else usage / 1024

    print(f"start peak_rss={peak_rss_mb():.0f}MB", flush=True)

    processed = 0
    sample_index = 0
    if args.resume:
        if args.resume == "auto":
            resume_path = checkpoint_path if checkpoint_path.exists() else None
        else:
            resume_path = Path(args.resume)
        if resume_path is None:
            print("resume: no partial checkpoint found; starting from 0", flush=True)
        elif not resume_path.exists():
            raise SystemExit(f"checkpoint not found: {resume_path}")
        else:
            with np.load(resume_path) as saved:
                if "__meta__" not in saved:
                    raise SystemExit("partial checkpoint missing __meta__; refusing to resume")
                saved_meta = json.loads(str(saved["__meta__"]))
                if saved_meta != meta:
                    raise SystemExit(
                        "partial checkpoint metadata mismatch; refusing to mix runs\n"
                        f"saved={saved_meta}\ncurrent={meta}"
                    )
                for site, accumulator in zip(sites, accumulators):
                    accumulator["input"] = saved[f"{site.key}/input"]
                    if accumulator["output"] is not None and f"{site.key}/output" in saved:
                        accumulator["output"] = saved[f"{site.key}/output"]
                    accumulator["samples"] = int(saved[f"{site.key}/samples"][0])
                processed = int(saved["processed"][0])
                sample_index = int(saved["sample_index"][0])
            print(f"resumed from {resume_path}: processed={processed} sample_index={sample_index}", flush=True)

    grad_fn = jax.grad(per_sample_loss)
    rng = np.random.default_rng(args.seed)
    started_at = time.time()
    while processed < args.samples:
        ids = chunks[sample_index]
        sample_index += 1
        current_ids = ids
        logits = logits_for(model, ids)
        current_targets = jax.random.categorical(
            jax.random.key(args.seed + processed), logits, axis=-1
        )
        grads = grad_fn(base_arrays)
        for site, accumulator, gradient in zip(sites, accumulators, grads):
            G = np.asarray(gradient, dtype=np.float64)
            if G.ndim == 2:
                accumulator["input"] += G.T @ G
                if accumulator["output"] is not None:
                    accumulator["output"] += G @ G.T
            else:
                # MoE-style leading component axes: one Hessian per component.
                for component in np.ndindex(*site.components):
                    g = G[component]
                    accumulator["input"][component] += g.T @ g
                    if accumulator["output"] is not None:
                        accumulator["output"][component] += g @ g.T
            accumulator["samples"] += 1
        processed += 1
        progress(
            {
                "sample": processed,
                "samples": args.samples,
                "sample_index": sample_index,
                "elapsed_s": time.time() - started_at,
            }
        )
        if args.checkpoint_every and processed % args.checkpoint_every == 0:
            save_partial()
        if processed % 4 == 0:
            print(f"  sample {processed}/{args.samples} peak_rss={peak_rss_mb():.0f}MB", flush=True)

    print(f"calibration done peak_rss={peak_rss_mb():.0f}MB", flush=True)

    records = []
    arrays: dict[str, np.ndarray] = {}

    def regularize(matrix: np.ndarray, name: str):
        # Official pipeline: H /= mean(diag), then add sigma_reg (1e-2) until
        # Cholesky succeeds. Fall back to eigenvalue clipping if needed.
        scale = float(np.mean(np.diagonal(matrix, axis1=-2, axis2=-1)))
        normalized = matrix / max(scale, 1e-30)
        sigma = args.damping
        for _ in range(8):
            candidate = normalized + np.eye(normalized.shape[-1]) * sigma
            try:
                np.linalg.cholesky(candidate)
                return candidate.astype(np.float32), sigma
            except np.linalg.LinAlgError:
                sigma *= 10.0
        eigenvalues, eigenvectors = np.linalg.eigh(normalized)
        eigenvalues = np.clip(eigenvalues, 1e-6, None)
        rebuilt = (eigenvectors * eigenvalues[..., None, :]) @ np.swapaxes(eigenvectors, -1, -2)
        print(f"warning: {name} needed eigenvalue clipping")
        return rebuilt.astype(np.float32), None

    for site, accumulator in zip(sites, accumulators):
        count = max(accumulator["samples"], 1)
        H_I = accumulator["input"] / count
        H_O = None if accumulator["output"] is None else accumulator["output"] / count
        if args.raw_output:
            damping_input = None
        else:
            H_I, damping_input = regularize(H_I, f"{site.key}/input_block")
        record = {
            "path": site.key,
            "in_dim": site.in_dim,
            "out_dim": site.out_dim,
            "components": list(site.components),
            "samples": accumulator["samples"],
            "input_trace": float(np.trace(H_I, axis1=-2, axis2=-1).sum()),
            "input_min_eig": None,
            "input_max_eig": None,
            "input_condition": None,
            "input_damping": damping_input,
            "output_block": H_O is not None,
        }
        try:
            eigenvalues = np.linalg.eigvalsh(H_I)
            record["input_min_eig"] = float(eigenvalues.min())
            record["input_max_eig"] = float(eigenvalues.max())
            record["input_condition"] = float(eigenvalues.max() / max(eigenvalues.min(), 1e-30))
        except np.linalg.LinAlgError:
            record["input_condition"] = float("inf")
        arrays[f"{site.key}/input_block"] = H_I
        if H_O is not None:
            if args.raw_output:
                damping_output = None
            else:
                H_O, damping_output = regularize(H_O, f"{site.key}/output_block")
            arrays[f"{site.key}/output_block"] = H_O
            record["output_damping"] = damping_output
            try:
                eigenvalues = np.linalg.eigvalsh(H_O)
                record["output_min_eig"] = float(eigenvalues.min())
                record["output_max_eig"] = float(eigenvalues.max())
                record["output_condition"] = float(eigenvalues.max() / max(eigenvalues.min(), 1e-30))
            except np.linalg.LinAlgError:
                record["output_condition"] = float("inf")
        records.append(record)

    args.output.parent.mkdir(parents=True, exist_ok=True)
    np.savez(args.output, **arrays)
    if checkpoint_path.exists():
        checkpoint_path.unlink()
    print(f"saved {args.output} ({len(arrays)} arrays)")

    summary = {
        "model_dir": str(args.model_dir),
        "corpus": str(args.corpus),
        "eval_corpora": [str(path) for path in args.eval_corpus],
        "overlap_checked": bool(args.eval_corpus),
        "raw_output": bool(args.raw_output),
        "samples": args.samples,
        "max_tokens": args.max_tokens,
        "output_block": args.output_block,
        "damping": args.damping,
        "layers": records,
    }
    if args.json_out:
        args.json_out.parent.mkdir(parents=True, exist_ok=True)
        args.json_out.write_text(json.dumps(summary, indent=2) + "\n")
        print(f"saved {args.json_out}")
    for record in records:
        print(
            f"  {record['path']} in={record['in_dim']} out={record['out_dim']} "
            f"cond={record['input_condition']:.3e} out_block={record['output_block']}"
        )


if __name__ == "__main__":
    main()