"""Local verification of the converted WebDataset shards (Step 5 of the plan):

  1. Decode a sample of each tier through both `webdataset` and HF `datasets` loaders.
  2. Build the FLAME-params in-memory dict and confirm it joins to every view-tier scene via
     ENV = EXPR_ENV[5:] (not a prefix match).
  3. Confirm scene-mesh key is a true prefix of the corresponding view-tier keys.
  4. Test itertools.groupby scene (30-view) and subject assembly, single-process/no-shuffle.
"""
import glob
import io
import itertools
import sys

import numpy as np
import trimesh
import webdataset as wds
from datasets import load_dataset

SHARD_DIR = sys.argv[1] if len(sys.argv) > 1 else "./data/shards_single_subject"


def view_key_parts(key):
    subject, expr_env, cam = key.split("/")
    expr, env = expr_env.split("_")
    return subject, expr, env, cam


def check_decode_both_loaders():
    print("=" * 60)
    print("1. Decode check (webdataset lib + HF datasets) per tier")
    print("=" * 60)

    view_shards = sorted(glob.glob(f"{SHARD_DIR}/views/*.tar"))
    mesh_shards = sorted(glob.glob(f"{SHARD_DIR}/scene_mesh/*.tar"))
    flame_shards = sorted(glob.glob(f"{SHARD_DIR}/flame_params/*.tar"))

    print(f"\n--- view tier: webdataset lib, first 3 samples ---")
    ds = wds.WebDataset(view_shards, shardshuffle=False).decode()
    for i, s in enumerate(ds):
        rgb = np.array(s["rgb.png"]) if hasattr(s["rgb.png"], "shape") else None
        print(f"  key={s['__key__']} cam.json keys={list(s['cam.json'].keys())[:3]} "
              f"landmark keys={list(s['landmark.npz'].keys())}")
        if i >= 2:
            break

    print(f"\n--- view tier: HF datasets, first sample features ---")
    hf_ds = load_dataset("webdataset", data_files=view_shards, split="train")
    print("  features:", {k: str(v)[:60] for k, v in hf_ds.features.items()})
    sample = hf_ds[0]
    print(f"  seg.png mode={sample['seg.png'].mode} size={sample['seg.png'].size}")
    print(f"  rgb.png mode={sample['rgb.png'].mode} size={sample['rgb.png'].size}")
    assert sample["seg.png"].mode == "I;16", "segmentation did not decode as 16-bit!"

    print(f"\n--- scene-mesh tier: webdataset lib ---")
    ds = wds.WebDataset(mesh_shards, shardshuffle=False).decode()
    for i, s in enumerate(ds):
        mesh = trimesh.load(io.BytesIO(s["mesh.obj"] if isinstance(s["mesh.obj"], bytes) else s["mesh.obj"]), file_type="obj")
        print(f"  key={s['__key__']} mesh vertices={mesh.vertices.shape}")
        if i >= 1:
            break

    print(f"\n--- flame-params tier: HF datasets ---")
    hf_flame = load_dataset("webdataset", data_files=flame_shards, split="train")
    print("  count:", len(hf_flame))
    for row in hf_flame:
        shape = np.array(row["flame.npz"]["expr"]).shape
        print(f"  key={row['__key__']} expr shape={shape}")

    return view_shards, mesh_shards, flame_shards


def check_flame_join(view_shards, flame_shards):
    print("\n" + "=" * 60)
    print("2. FLAME-params join via ENV = EXPR_ENV[5:] (dict lookup, not prefix)")
    print("=" * 60)

    flame_ds = wds.WebDataset(flame_shards, shardshuffle=False).decode()
    flame_by_key = {s["__key__"]: s["flame.npz"] for s in flame_ds}
    print(f"  loaded {len(flame_by_key)} flame-params entries: {list(flame_by_key.keys())}")

    view_ds = wds.WebDataset(view_shards, shardshuffle=False)
    scenes_seen = set()
    missing = []
    for s in view_ds:
        subject, expr, env, cam = view_key_parts(s["__key__"])
        expr_env = f"{expr}_{env}"
        scene_key = f"{subject}/{expr_env}"
        if scene_key in scenes_seen:
            continue
        scenes_seen.add(scene_key)
        flame_key = f"{subject}/{env}"
        if flame_key not in flame_by_key:
            missing.append((scene_key, flame_key))

    print(f"  checked {len(scenes_seen)} distinct scenes")
    if missing:
        print(f"  MISSING flame entries for: {missing}")
    else:
        print("  OK: every scene's FLAME-params entry found via env slice")


def check_scene_mesh_prefix(view_shards, mesh_shards):
    print("\n" + "=" * 60)
    print("3. Scene-mesh key is a true prefix of view-tier keys")
    print("=" * 60)

    mesh_keys = {s["__key__"] for s in wds.WebDataset(mesh_shards, shardshuffle=False)}
    view_ds = wds.WebDataset(view_shards, shardshuffle=False)
    bad = []
    checked = 0
    for s in view_ds:
        subject, expr, env, cam = view_key_parts(s["__key__"])
        scene_key = f"{subject}/{expr}_{env}"
        checked += 1
        if not s["__key__"].startswith(scene_key + "/"):
            bad.append(s["__key__"])
        if scene_key not in mesh_keys:
            bad.append((s["__key__"], "no matching mesh key"))
    print(f"  checked {checked} view samples against {len(mesh_keys)} mesh keys")
    print("  OK: prefix relationship holds" if not bad else f"  FAILURES: {bad[:10]}")


def check_groupby(view_shards):
    print("\n" + "=" * 60)
    print("4. itertools.groupby scene (30-view) and subject assembly")
    print("   (single-process, no shuffle, sequential read)")
    print("=" * 60)

    ds = wds.WebDataset(view_shards, shardshuffle=False)

    def scene_key(sample):
        subject, expr, env, cam = view_key_parts(sample["__key__"])
        return f"{subject}/{expr}_{env}"

    def subject_key(sample):
        subject, expr, env, cam = view_key_parts(sample["__key__"])
        return subject

    scene_sizes = []
    for key, group in itertools.groupby(ds, key=scene_key):
        scene_sizes.append((key, len(list(group))))

    print(f"  found {len(scene_sizes)} scene groups")
    bad_scenes = [(k, n) for k, n in scene_sizes if n != 30]
    print("  OK: every scene has exactly 30 views" if not bad_scenes
          else f"  FAILURES (expected 30 views each): {bad_scenes}")

    ds2 = wds.WebDataset(view_shards, shardshuffle=False)
    subject_sizes = []
    for key, group in itertools.groupby(ds2, key=subject_key):
        subject_sizes.append((key, len(list(group))))
    print(f"  found {len(subject_sizes)} subject groups: {[(k, n) for k, n in subject_sizes]}")


if __name__ == "__main__":
    view_shards, mesh_shards, flame_shards = check_decode_both_loaders()
    check_flame_join(view_shards, flame_shards)
    check_scene_mesh_prefix(view_shards, mesh_shards)
    check_groupby(view_shards)
    print("\nAll checks completed.")