"""RunPod diagnostic — did TransUNet's ViT encoder actually train, or stay at ImageNet init?

Run on the pod (where the .npz, the TransUNet repo, and the trained best.pt all exist):

  python check_encoder_moved.py \
      --repo   /workspace/TransUNet \
      --npz    /workspace/model/vit_checkpoint/imagenet21k/R50+ViT-B_16.npz \
      --ckpt   /workspace/runs/TransUNet_Phase1/repeated_holdout/stratified_holdout_v1/phase_001/pct_100/repeat_01/strategy_2/final/checkpoints/best.pt \
      --img    128

Prints, per encoder tensor and overall, the relative change  ||trained - imagenet_init|| / ||imagenet_init||.
If the mean change is a meaningful fraction (>~1%) and most tensors moved, the 105M encoder trained.
If it's ~0 everywhere, the encoder was effectively frozen (that would explain parity with small models).
"""
import argparse, sys, os, copy, numpy as np, torch

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--repo", required=True)
    ap.add_argument("--npz", required=True)
    ap.add_argument("--ckpt", required=True)
    ap.add_argument("--img", type=int, default=128)
    a = ap.parse_args()

    sys.path.insert(0, a.repo)
    from networks.vit_seg_modeling import VisionTransformer, CONFIGS

    cfg = copy.deepcopy(CONFIGS["R50-ViT-B_16"])
    cfg.n_classes = 1; cfg.n_skip = 3; cfg.classifier = "seg"
    cfg.patches.grid = (a.img // 16, a.img // 16)
    vit = VisionTransformer(cfg, img_size=a.img, num_classes=1)

    # (1) ImageNet init
    vit.load_from(weights=np.load(a.npz, allow_pickle=False))
    init = {k: v.detach().float().clone() for k, v in vit.transformer.state_dict().items()}

    # (2) trained weights from best.pt -> map "smp_model.encoder.transformer.*" -> "transformer.*"
    ck = torch.load(a.ckpt, map_location="cpu", weights_only=False)
    sd = ck["model_state_dict"] if "model_state_dict" in ck else ck
    trained_transformer = {}
    for k, v in sd.items():
        if k.startswith("smp_model.encoder.transformer."):
            trained_transformer[k.replace("smp_model.encoder.transformer.", "")] = v
    if not trained_transformer:
        print("!! No 'smp_model.encoder.transformer.*' keys in checkpoint. Keys sample:")
        print([k for k in list(sd)[:10]]); return
    missing, unexpected = vit.transformer.load_state_dict(trained_transformer, strict=False)
    print(f"loaded trained transformer tensors={len(trained_transformer)} (missing={len(missing)} unexpected={len(unexpected)})")
    trained = {k: v.detach().float().clone() for k, v in vit.transformer.state_dict().items()}

    # (3) compare
    rows = []
    for k in init:
        if init[k].numel() == 0 or "num_batches_tracked" in k:
            continue
        num = (trained[k] - init[k]).norm().item()
        den = init[k].norm().item() + 1e-12
        rows.append((k, num / den, init[k].numel()))
    rel = np.array([r[1] for r in rows]); npar = np.array([r[2] for r in rows])
    wmean = float((rel * npar).sum() / npar.sum())   # param-weighted mean rel change
    print("\n=== ENCODER MOVEMENT (relative change from ImageNet init) ===")
    print(f"tensors compared      : {len(rows)}")
    print(f"param-weighted mean   : {wmean*100:.3f}%")
    print(f"median tensor change  : {np.median(rel)*100:.3f}%")
    print(f"max tensor change     : {rel.max()*100:.3f}%")
    print(f"tensors moved >1%     : {int((rel>0.01).sum())}/{len(rows)}")
    print(f"tensors basically 0   : {int((rel<1e-4).sum())}/{len(rows)}  (<0.01% change)")
    print("\nexamples:")
    for name in ["embeddings.position_embeddings",
                 "embeddings.hybrid_model.root.conv.weight",
                 "encoder.layer.0.attn.query.weight",
                 "encoder.layer.11.ffn.fc1.weight"]:
        m = {r[0]: r[1] for r in rows}.get(name)
        if m is not None: print(f"  {name:52s} {m*100:7.3f}%")
    print("\nVERDICT:", "ENCODER TRAINED (capacity used)" if wmean > 0.005
          else "ENCODER BARELY MOVED (effectively frozen -> tuning target)")

if __name__ == "__main__":
    main()