"""Zero-training check of the fine-tuning pipeline: same weights, compare predictions.

Checkpoints made by `lerobot-train` with --steps=1 and --policy.optimizer_lr=0.0 keep
the original weights but carry the processors the training pipeline built, in
particular the state/action normalization it takes from the training dataset
(lerobot_train.py overrides the saved statistics when fine-tuning from a checkpoint).

1. Weights: every tensor of each variant against the reference (max abs difference).
2. Normalization: the saved state/action statistics of each variant against the reference.
3. Predictions: identical observations (the settings profile's scenes from --seed; the
   first frame and frames along the reference policy's own approach) and identical
   sampling noise (torch seed per observation). For each observation the whole 50-step
   action chunk is read (50 calls on a fresh queue) and compared with the reference:
   joint differences in degrees and the shift of the `gripperframe` site (forward
   kinematics of the commanded joints) in mm.

Writes pipeline_check.md and pipeline_check.json to --out.

Run:  MUJOCO_GL=egl PHASE2_PROFILE=baseline .venv/bin/python sim/pipeline_check.py \
          --reference models/baseline --variant P0=ckpt/p0 --variant M0=ckpt/m0 --out sim/reports/pipeline_check
"""
from __future__ import annotations

import argparse
import json
import sys
from pathlib import Path

HERE = Path(__file__).resolve().parent
sys.path.insert(0, str(HERE))


def weight_diff(ref: Path, other: Path) -> dict:
    from safetensors.torch import load_file

    a, b = load_file(str(ref / "model.safetensors")), load_file(str(other / "model.safetensors"))
    diffs = {k: float((a[k].float() - b[k].float()).abs().max()) for k in a if k in b}
    return dict(tensors=len(a), missing=len(set(a) ^ set(b)), max_abs=max(diffs.values(), default=None),
                differing=sum(v > 0 for v in diffs.values()))


def norm_stats(path: Path) -> dict:
    from safetensors.torch import load_file

    out = {}
    for f in sorted(path.glob("policy_*processor*normalizer*.safetensors")):
        for k, v in load_file(str(f)).items():
            if k.startswith(("observation.state", "action")):
                out[f"{f.name.split('_step')[0]}:{k}"] = v.float().numpy().tolist()
    return out


def main():
    ap = argparse.ArgumentParser(description=__doc__)
    ap.add_argument("--reference", required=True)
    ap.add_argument("--variant", action="append", default=[], help="NAME=path, repeatable")
    ap.add_argument("--seed", type=int, default=1_000_003)
    ap.add_argument("--scenes", type=int, default=8)
    ap.add_argument("--frames", default="0,20,40,60,80", help="frames along the reference rollout to sample")
    ap.add_argument("--out", required=True)
    args = ap.parse_args()
    import mujoco
    import numpy as np
    import torch
    from lerobot.utils.control_utils import predict_action

    from camera_effects import training_look
    from episode import EpisodeRunner, load_config
    from eval_policy import load_policy
    from lerobot_export import Recorder, video_settings
    from piece_sets import sample_piece_set

    out = Path(args.out)
    out.mkdir(parents=True, exist_ok=True)
    cfg = load_config()
    crf, pix_fmt = video_settings(cfg)
    ref = Path(args.reference)
    variants = dict(v.split("=", 1) for v in args.variant)
    report = dict(reference=str(ref), variants=variants, seed=args.seed)
    report["weights"] = {n: weight_diff(ref, Path(p)) for n, p in variants.items()}
    ref_stats = norm_stats(ref)
    report["normalization"] = {}
    for n, p in variants.items():
        st = norm_stats(Path(p))
        report["normalization"][n] = {k: float(np.max(np.abs(np.array(st[k]) - np.array(v)))) if k in st else None
                                      for k, v in ref_stats.items()}

    # Observations: frames of the reference policy's own rollouts.
    runner = EpisodeRunner(cfg, sample_piece_set(np.random.default_rng([args.seed, 10**9]), cfg, "check"), render=True)
    policy, pre, post, device = load_policy(str(ref))
    frames = [int(x) for x in args.frames.split(",")]
    obs_list = []
    lo, hi = runner.grip_range
    for i in range(args.scenes):
        erng = np.random.default_rng([args.seed, i])
        ep_seed = int(erng.integers(2**62))
        task = runner.setup(np.random.default_rng(ep_seed))
        rec = Recorder(cfg, None)
        rec.begin(runner, task, np.random.default_rng(ep_seed ^ 0x5EED))
        policy.reset()
        torch.manual_seed(int(erng.integers(2**31)))
        d = runner.d
        for f in range(max(frames) + 1):
            obs = {"observation.images.overhead": training_look(rec.observe(runner, "overhead"), crf, pix_fmt),
                   "observation.images.wrist": training_look(rec.observe(runner, "wrist"), crf, pix_fmt),
                   "observation.state": runner.to_lerobot(d.qpos[runner.qadr])}
            if f in frames:
                obs_list.append(dict(scene=i, frame=f, move=f"{task.source}-{task.dest.square}",
                                     obs={k: np.array(v, copy=True) for k, v in obs.items()}))
            a = predict_action(obs, policy, device, pre, post, use_amp=False, task=cfg["dataset"]["instruction"],
                               robot_type="so101_follower").squeeze().float().cpu().numpy()
            d.ctrl[:5] = np.radians(a[:5])
            d.ctrl[5] = lo + np.clip(a[5], 0, 100) / 100 * (hi - lo)
            for _ in range(runner.n_sub):
                mujoco.mj_step(runner.m, d)
    del policy
    torch.cuda.empty_cache()

    m = runner.m
    dk = mujoco.MjData(m)
    site = m.site("gripperframe").id
    arm = runner.expert.kin.qadr

    def fingertips(chunk):
        pts = []
        for a in chunk:
            dk.qpos[arm] = np.radians(a[:5])
            mujoco.mj_kinematics(m, dk)
            pts.append(dk.site_xpos[site].copy())
        return np.array(pts)

    def chunks(path):
        pol, pre_, post_, dev = load_policy(path)
        res = []
        for j, o in enumerate(obs_list):
            pol.reset()
            torch.manual_seed(12345 + j)                     # identical sampling noise for every model
            res.append(np.array([predict_action(dict(o["obs"]), pol, dev, pre_, post_, use_amp=False,
                                                task=cfg["dataset"]["instruction"], robot_type="so101_follower")
                                 .squeeze().float().cpu().numpy() for _ in range(50)]))
        del pol
        torch.cuda.empty_cache()
        return res

    ref_chunks = chunks(str(ref))
    again = chunks(str(ref))                                  # the reference against itself: determinism floor
    report["predictions"] = {}
    for name, path in [("reference_again", str(ref))] + list(variants.items()):
        ch = again if name == "reference_again" else chunks(path)
        dj = np.array([np.abs(c - r) for c, r in zip(ch, ref_chunks)])            # obs x 50 x 6
        tip = np.array([np.linalg.norm(fingertips(c) - fingertips(r), axis=1) for c, r in zip(ch, ref_chunks)])
        report["predictions"][name] = dict(
            joint_deg_max=round(float(dj[..., :5].max()), 4), joint_deg_median=round(float(np.median(dj[..., :5])), 4),
            first_action_joint_deg_median=round(float(np.median(dj[:, 0, :5])), 4),
            gripper_cmd_max=round(float(dj[..., 5].max()), 3),
            fingertip_mm_median=round(1000 * float(np.median(tip)), 3), fingertip_mm_p95=round(1000 * float(np.percentile(tip, 95)), 3),
            fingertip_mm_max=round(1000 * float(tip.max()), 3),
            per_joint_deg_median=[round(float(np.median(dj[..., k])), 3) for k in range(6)])
    report["observations"] = [dict(scene=o["scene"], frame=o["frame"], move=o["move"]) for o in obs_list]
    (out / "pipeline_check.json").write_text(json.dumps(report, indent=1))
    lines = ["# Fine-tuning pipeline check (zero updates)", "",
             f"Reference `{ref}`. Variants: " + ", ".join(f"{n} = `{p}`" for n, p in variants.items()) + ".",
             f"{len(obs_list)} observations ({args.scenes} scenes from seed {args.seed}, frames {args.frames} of the "
             "reference policy's own rollout), each with identical sampling noise; the whole 50-step chunk compared.", "",
             "## Weights", "", "| variant | tensors | differing | max abs difference |", "|---|---|---|---|"]
    lines += [f"| {n} | {w['tensors']} | {w['differing']} | {w['max_abs']} |" for n, w in report["weights"].items()]
    lines += ["", "## Saved state/action normalization (max abs difference from the reference)", "",
              "| variant | " + " | ".join(report["normalization"][next(iter(variants))].keys()) + " |" if variants else "",
              "|---|" + "---|" * len(ref_stats)]
    lines += [f"| {n} | " + " | ".join(f"{v:.3g}" if v is not None else "-" for v in d.values()) + " |"
              for n, d in report["normalization"].items()]
    lines += ["", "## Predictions against the reference", "",
              "| model | joint deg median | joint deg max | first action deg median | gripper cmd max | "
              "fingertip mm median | fingertip mm p95 | fingertip mm max |", "|---|---|---|---|---|---|---|---|"]
    lines += [f"| {n} | {p['joint_deg_median']} | {p['joint_deg_max']} | {p['first_action_joint_deg_median']} | "
              f"{p['gripper_cmd_max']} | {p['fingertip_mm_median']} | {p['fingertip_mm_p95']} | {p['fingertip_mm_max']} |"
              for n, p in report["predictions"].items()]
    lines += ["", "`reference_again` is the reference model loaded a second time: the numerical floor (GPU "
              "non-determinism) any difference must be judged against."]
    (out / "pipeline_check.md").write_text("\n".join(lines) + "\n")
    print("\n".join(lines))


if __name__ == "__main__":
    main()