"""HuggingFace `datasets` loading script for the Panorama Depth Benchmark.

The data lives in sibling folders of this script (`stanford2d3d/`, …).
Non-parquet subsets expose `rgb`, `depth`, and optional `mask` as raw
bytes with the correct file extension; `zuripano` is already parquet
and keeps its native schema.

Usage:

    from datasets import load_dataset
    ds = load_dataset("/path/to/benchmark", "stanford2d3d", split="test")
    row = ds[0]
    # row["rgb"]        -> dict {"path": ..., "bytes": raw PNG/JPG}
    # row["depth"]      -> same (PNG u16 / RGB-encoded / EXR)
    # row["mask"]       -> same (JPG), or None if not available
    # row["stem"]       -> str
    # row["depth_scale"]-> str  recipe hint: "v / 512.0 -> meters", etc.
"""
from __future__ import annotations
from pathlib import Path

import datasets as hfds


_DESCRIPTION = (
    "Unified evaluation suite for equirectangular (360°) depth estimation,"
    " assembled from eight public panorama depth test splits."
)

_CITATION = """
If you use this benchmark please cite each original dataset's paper
(Stanford2D3D, Matterport3D, PanoSUNCG, Structured3D, Metropolis / DA360,
ZuriPano / PaGeR, Holo360D).
"""


# -- per-subset config ---------------------------------------------------
#   depth_fmt    : how depth maps to meters (string hint for consumers)
#   has_mask     : whether a per-sample mask file is present
#   min/max      : depth clamp range used for evaluation
#   scene        : indoor / outdoor / synthetic
_CONFIGS = {
    "stanford2d3d":    dict(fmt="png_u16", scale="v / 512.0",         has_mask=False, min=0.001, max=5.0,   scene="indoor",    n=373),
    "matterport3d":    dict(fmt="png_u16", scale="v / 4000.0",        has_mask=False, min=0.001, max=5.0,   scene="indoor",    n=2014),
    "panosuncg":       dict(fmt="png_u8_rgb", scale="v[...,0] * 10 / 255", has_mask=False, min=0.001, max=5.0, scene="synthetic", n=3944),
    "structured3d":    dict(fmt="png_u16", scale="v / 1000.0",        has_mask=False, min=0.001, max=5.0,   scene="synthetic", n=1691),
    "metropolis":      dict(fmt="png_u16", scale="v / 512.0",         has_mask=False, min=0.2,   max=128.0, scene="outdoor",   n=3000),
    "holo360d_indoor": dict(fmt="exr",     scale="EXR channel 0 is metric", has_mask=True,  min=0.01,  max=10.0,  scene="indoor",    n=360),
    "holo360d_outdoor":dict(fmt="exr",     scale="EXR channel 0 is metric", has_mask=True,  min=0.01,  max=75.0,  scene="outdoor",   n=90),
    "replica360_2k":   dict(fmt="dpt",     scale="Sintel .dpt float32 is metric", has_mask=False, min=0.001, max=10.0, scene="indoor", n=130),
    "panoinfinigen_indoor": dict(fmt="npy", scale="raw float16 meters", has_mask=False, min=0.001, max=10.0,  scene="indoor", n=4392),
    "panoinfinigen_nature": dict(fmt="npy", scale="raw float16 meters", has_mask=False, min=0.001, max=100.0, scene="nature", n=848),
    "panoinfinigen_urban":  dict(fmt="npy", scale="raw float32 meters", has_mask=False, min=0.001, max=500.0, scene="urban",  n=788),
}
# zuripano is handled via its own parquet shards; see the native dataset
# card for its schema.  Its entry lives in _loader.py CONFIG (min=0.01,
# max=75.0) — keep the two in sync.


class PanoDepthBenchmarkConfig(hfds.BuilderConfig):
    def __init__(self, scene: str = "", **kw):
        super().__init__(**kw)
        self.scene = scene


class PanoDepthBenchmark(hfds.GeneratorBasedBuilder):
    BUILDER_CONFIGS = [
        PanoDepthBenchmarkConfig(name=k, version=hfds.Version("1.0.0"),
                                 description=f"{k} test split", scene=v["scene"])
        for k, v in _CONFIGS.items()
    ]

    def _info(self):
        cfg = _CONFIGS[self.config.name]
        features = {
            "stem":        hfds.Value("string"),
            "rgb":         hfds.Image(decode=False),
            "depth":       hfds.Value("binary") if cfg["fmt"] in ("exr", "dpt", "npy")
                           else hfds.Image(decode=False),
            "depth_scale": hfds.Value("string"),
            "min_depth":   hfds.Value("float32"),
            "max_depth":   hfds.Value("float32"),
            "scene":       hfds.Value("string"),
        }
        if cfg["has_mask"]:
            features["mask"] = hfds.Image(decode=False)
        return hfds.DatasetInfo(
            description=_DESCRIPTION,
            features=hfds.Features(features),
            citation=_CITATION,
        )

    def _split_generators(self, dl_manager):
        root = Path(self.base_path or ".") / self.config.name
        return [hfds.SplitGenerator(name=hfds.Split.TEST,
                                     gen_kwargs={"root": str(root)})]

    def _generate_examples(self, root):
        cfg = _CONFIGS[self.config.name]
        root = Path(root)
        split_file = root / "test.txt"
        for idx, ln in enumerate(split_file.read_text().strip().splitlines()):
            parts = ln.split()
            if len(parts) < 2:
                continue
            rgb_rel, dep_rel = parts[0], parts[1]
            mask_rel = parts[2] if len(parts) >= 3 and parts[2] else None

            def _read_bytes(rel):
                with open(root / rel, "rb") as fp:
                    return fp.read()

            stem = Path(rgb_rel).stem
            if cfg["fmt"] in ("exr", "dpt", "npy"):
                depth_val = _read_bytes(dep_rel)
            else:
                depth_val = {"path": str(root / dep_rel), "bytes": _read_bytes(dep_rel)}

            row = {
                "stem":        stem,
                "rgb":         {"path": str(root / rgb_rel), "bytes": _read_bytes(rgb_rel)},
                "depth":       depth_val,
                "depth_scale": cfg["scale"],
                "min_depth":   float(cfg["min"]),
                "max_depth":   float(cfg["max"]),
                "scene":       cfg["scene"],
            }
            if cfg["has_mask"] and mask_rel:
                row["mask"] = {"path": str(root / mask_rel), "bytes": _read_bytes(mask_rel)}
            elif cfg["has_mask"]:
                row["mask"] = None
            yield idx, row