"""Load or build one flat per-scene cache file for the selected model."""

from __future__ import annotations

import argparse
import gzip
import hashlib
import os
from pathlib import Path
import pickle
import sys

# Single-scene CLI runs (unlike launch.py's budgeted batch workers) otherwise inherit
# whatever thread defaults numpy/BLAS/scipy pick -- typically "use every core" -- which
# thrashes when geometric.py makes many small parallel-dispatched calls (cv2 ops per
# mask, KD-tree queries per class pair). setdefault() so launch.py's explicit
# per-worker budget (set before it imports this module via render.py) always wins.
for _var in ("OMP_NUM_THREADS", "MKL_NUM_THREADS", "OPENBLAS_NUM_THREADS"):
    os.environ.setdefault(_var, "1")
os.environ.setdefault("VSI_KD_WORKERS", "1")

WORKSPACE_ROOT = Path(__file__).resolve().parent.parent
if str(WORKSPACE_ROOT) not in sys.path:
    sys.path.insert(0, str(WORKSPACE_ROOT))

from encoder import adapters  # noqa: E402
from encoder import config  # noqa: E402


PROVENANCE_KEY = "source_provenance"
PROVENANCE_VERSION = 1


def _source_record(path):
    """Describe one native cache without copying its payload."""
    source = Path(path)
    size = source.stat().st_size
    digest = hashlib.sha256()
    with source.open("rb") as stream:
        for chunk in iter(lambda: stream.read(1024 * 1024), b""):
            digest.update(chunk)
    return {"path": str(source), "size": size, "sha256": digest.hexdigest()}


def _source_provenance(scene, mode, paths):
    """Record the exact native caches used to derive a combined cache."""
    return {
        "format_version": PROVENANCE_VERSION,
        "scene": scene,
        "mode": mode,
        "sources": {name: _source_record(path) for name, path in paths.items()},
    }


def _verify_source_provenance(provenance):
    """Ensure every referenced native cache still matches byte-for-byte."""
    if (
        not isinstance(provenance, dict)
        or provenance.get("format_version") != PROVENANCE_VERSION
    ):
        raise ValueError("combined cache has unsupported source provenance")
    sources = provenance.get("sources")
    if not isinstance(sources, dict) or set(sources) != {"sam3", "depth-anything-3"}:
        raise ValueError("combined cache source provenance is incomplete")
    for name, expected in sources.items():
        if not isinstance(expected, dict) or "path" not in expected:
            raise ValueError(f"combined cache source {name!r} has invalid provenance")
        try:
            actual = _source_record(expected["path"])
        except FileNotFoundError as exc:
            raise FileNotFoundError(
                f"combined cache source {name!r} is missing: {expected['path']}"
            ) from exc
        if (
            actual["size"] != expected.get("size")
            or actual["sha256"] != expected.get("sha256")
        ):
            raise ValueError(
                f"combined cache source {name!r} no longer matches its provenance"
            )


def cache_or_load(
    scene,
    depth,
    input_selection,
    tracking,
    frame_count=config.FRAMES_PER_VIDEO,
    rebuild=False,
):
    """Return canonical geometry for one specific set of input dimensions."""
    path = config.cache_file(
        scene, depth, input_selection, tracking, frame_count
    )
    if os.path.exists(path) and not rebuild:
        with gzip.open(path, "rb") as stream:
            cached = pickle.load(stream)
        provenance = cached.get(PROVENANCE_KEY) if isinstance(cached, dict) else None
        if provenance is not None:
            _verify_source_provenance(provenance)
            return adapters.validate(cached), "loaded"
        # Legacy combined caches are rebuilt to attach exact source provenance.

    raw_cache = {
        "scene": scene,
        "root": str(config.CACHE_ROOT),
        "rebuild": rebuild,
        "da3_path": config.da3_cache_file(
            scene, depth, input_selection, frame_count
        ),
        "sam3_path": config.sam3_cache_file(
            scene, input_selection, tracking, frame_count
        ),
    }
    geometry = adapters.adapt(config.MODEL, **raw_cache)
    mode = f"{input_selection}:{frame_count}:{tracking}"
    geometry[PROVENANCE_KEY] = _source_provenance(
        scene,
        mode,
        {
            "sam3": raw_cache["sam3_path"],
            "depth-anything-3": raw_cache["da3_path"],
        },
    )
    geometry[PROVENANCE_KEY].update(
        {
            "depth": depth,
            "input": input_selection,
            "tracking": tracking,
            "frames": frame_count,
        }
    )
    _verify_source_provenance(geometry[PROVENANCE_KEY])
    os.makedirs(os.path.dirname(path), exist_ok=True)
    with gzip.open(path, "wb") as stream:
        pickle.dump(geometry, stream, protocol=pickle.HIGHEST_PROTOCOL)
    return geometry, "built"


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("scene")
    parser.add_argument("--depth", required=True, choices=config.DEPTH_VARIANTS)
    parser.add_argument(
        "--input",
        required=True,
        choices=config.INPUT_SELECTIONS,
        dest="input_selection",
    )
    parser.add_argument("--frames", type=int, default=config.FRAMES_PER_VIDEO)
    parser.add_argument("--tracking", required=True, choices=config.TRACKING_MODES)
    parser.add_argument(
        "--format",
        choices=config.SPATIAL_CODE_FORMATS,
        default="explicit",
        dest="spatial_code_format",
    )
    parser.add_argument("--rebuild", action="store_true")
    args = parser.parse_args()
    if args.frames < 1:
        parser.error("--frames must be positive")
    from encoder import render

    import cv2

    cv2.setNumThreads(1)  # see thread-budget note near the top imports

    import torch  # torch ignores the OMP/MKL/OPENBLAS env vars set above

    torch.set_num_threads(1)
    try:
        torch.set_num_interop_threads(1)
    except RuntimeError:
        pass

    geometry, how = cache_or_load(
        args.scene,
        args.depth,
        args.input_selection,
        args.tracking,
        args.frames,
        args.rebuild,
    )
    count = sum(len(values) for values in geometry["instances"].values())
    print(
        f"[{args.scene}] depth={args.depth} input={args.input_selection} "
        f"frames={args.frames} tracking={args.tracking} cache={how} "
        f"classes={len(geometry['instances'])} instances={count}"
    )
    _, _, path = render.write_spatial_code_for(
        args.scene,
        args.depth,
        args.input_selection,
        args.tracking,
        args.frames,
        False,
        args.spatial_code_format,
    )
    print(f"[{args.scene}] spatial_code={path}")


if __name__ == "__main__":
    main()