#!/usr/bin/env python3
"""Build one train-ready T-Rex Track-Force demo with fresh statistics."""

from __future__ import annotations

import argparse
import copy
import hashlib
import json
import os
import shutil
import sys
from pathlib import Path
from typing import Sequence

_ROOT = Path(__file__).resolve().parents[2]
_DATA_SCRIPTS = _ROOT / "scripts" / "data"
if str(_DATA_SCRIPTS) not in sys.path:
    sys.path.insert(0, str(_DATA_SCRIPTS))

import build_trex_track_force_v2 as force_builder  # noqa: E402
import check_trex_dataset_ready as ready_check  # noqa: E402
import rebuild_trex_dataset_variants as variants  # noqa: E402


def _read_json(path: Path) -> dict:
    return json.loads(path.read_text())


def _read_jsonl(path: Path) -> list[dict]:
    return [
        json.loads(line)
        for line in path.read_text().splitlines()
        if line.strip()
    ]


def _sha256_or_empty(path: Path) -> str:
    if path.is_file():
        return variants._sha256(path)
    return hashlib.sha256(b"[]\n").hexdigest()


def build_mini_dataset(
    *,
    source_root: Path,
    output_root: Path,
    source_episode: int,
    workers: int,
) -> dict:
    source_root = source_root.expanduser().resolve()
    output_root = output_root.expanduser().resolve()
    if source_root == output_root:
        raise ValueError("source and output dataset roots must differ")

    ready_check.check_dataset(source_root, require_force=True)
    if output_root.exists():
        result = ready_check.check_dataset(output_root, require_force=True)
        variant = _read_json(output_root / "meta" / "dataset_variant.json")
        if int(variant.get("source_episode", -1)) != source_episode:
            raise ValueError(
                f"{output_root} already uses source episode "
                f"{variant.get('source_episode')}, not {source_episode}"
            )
        return result

    source_info = _read_json(source_root / "meta" / "info.json")
    source_modality = _read_json(source_root / "meta" / "modality.json")
    source_embodiment = _read_json(source_root / "meta" / "embodiment.json")
    source_episodes = _read_jsonl(source_root / "meta" / "episodes.jsonl")
    source_tasks = _read_jsonl(source_root / "meta" / "tasks.jsonl")
    selected = [
        episode
        for episode in source_episodes
        if int(episode["episode_index"]) == source_episode
    ]
    if len(selected) != 1:
        raise ValueError(
            f"source episode {source_episode} was not found exactly once"
        )
    registry, tasks = variants._build_registry(
        selected,
        source_tasks,
        excluded=set(),
        source_limit=None,
    )
    if len(registry) != 1 or registry[0].episode_index != 0:
        raise AssertionError("mini dataset must contain dense episode 0")

    stage_root = output_root.parent / f".{output_root.name}.staging"
    if stage_root.exists():
        shutil.rmtree(stage_root)
    video_keys = variants._video_keys(source_info)
    blacklist = source_root / "meta" / "excluded_source_episode_indices.json"
    variants._write_variant_metadata_skeleton(
        variant_root=stage_root,
        final_root=output_root,
        source_info=source_info,
        source_modality=source_modality,
        source_embodiment=source_embodiment,
        registry=registry,
        tasks=tasks,
        video_keys=video_keys,
        excluded_source_indices=[],
        force=True,
        source_dataset=source_root,
        blacklist_sha256=_sha256_or_empty(blacklist),
    )
    variant_path = stage_root / "meta" / "dataset_variant.json"
    variant = _read_json(variant_path)
    variant["source_episode"] = source_episode
    variants._atomic_write_json(variant_path, variant)

    variants._rewrite_parquets(
        source_root=source_root,
        destination_root=stage_root,
        registry=registry,
        workers=workers,
        force=True,
    )
    variants._link_videos(
        source_root=source_root,
        destination_root=stage_root,
        registry=registry,
        video_keys=video_keys,
        source_uses_new_indices=False,
        workers=workers,
    )
    track_hashes = variants._rewrite_tracks(
        source_root=source_root,
        destination_root=stage_root,
        registry=registry,
        workers=workers,
    )

    source_manifest = _read_json(
        source_root / "meta" / "trex_track_force_manifest.json"
    )
    source_entries = {
        int(index): copy.deepcopy(entry)
        for index, entry in source_manifest["episodes"].items()
    }
    variants._build_force_manifest(
        variant_root=stage_root,
        final_root=output_root,
        registry=registry,
        source_entries=source_entries,
        track_hashes=track_hashes,
    )

    variants._atomic_write_json(
        stage_root / "meta" / "stats.json",
        variants._compute_base_stats(stage_root, registry),
    )
    metadata_result = force_builder.update_metadata(
        stage_root,
        assume_all_converted=True,
    )
    manifest_path = stage_root / "meta" / "trex_track_force_manifest.json"
    manifest = _read_json(manifest_path)
    manifest["metadata"] = metadata_result
    manifest["updated_at"] = variants._utc_now()
    variants._atomic_write_json(manifest_path, manifest)
    force_builder.validate_metadata(stage_root)
    for backup in (stage_root / "meta").glob("*.trex_track_force.bak"):
        backup.unlink()

    variants._validate_variant(
        root=stage_root,
        expected_registry=registry,
        video_keys=video_keys,
        force=True,
    )
    os.replace(stage_root, output_root)
    variants._validate_variant(
        root=output_root,
        expected_registry=registry,
        video_keys=video_keys,
        force=True,
    )
    return ready_check.check_dataset(output_root, require_force=True)


def _parse_args(argv: Sequence[str] | None = None) -> argparse.Namespace:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument(
        "--source-root",
        type=Path,
        default=_ROOT / "data" / "trex_full_force",
    )
    parser.add_argument(
        "--output-root",
        type=Path,
        default=_ROOT / "data" / "trex_mini_force",
    )
    parser.add_argument("--source-episode", type=int, default=49)
    parser.add_argument("--workers", type=int, default=4)
    return parser.parse_args(argv)


def main(argv: Sequence[str] | None = None) -> int:
    args = _parse_args(argv)
    result = build_mini_dataset(
        source_root=args.source_root,
        output_root=args.output_root,
        source_episode=args.source_episode,
        workers=max(1, int(args.workers)),
    )
    print(json.dumps(result))
    return 0


if __name__ == "__main__":
    raise SystemExit(main())