"""Download and extract ring-data.

Downloads whole shard tars from allenai/ring-data, decompresses each
inner .tar.zst archive, and extracts its contents into:

    <target_dir>/<task_config>

Per-config scene metadata (asset lists and annotation excerpts) is fetched
from the repo into:

    <target_dir>/<task_config>/metadata/

A local JSON manifest tracks progress per-shard so that interrupted
downloads can be resumed without re-extracting already-completed shards.
"""

import argparse
import io
import json
import os
import tarfile
import tempfile
from collections import defaultdict
from pathlib import Path

try:
    import datasets
    import zstandard as zstd
    from datasets import load_dataset
    from huggingface_hub import hf_hub_download
    from tqdm import tqdm
except ImportError:
    print(
        "Please install dependencies with e.g.\n"
        "  pip install zstandard datasets huggingface_hub tqdm"
    )
    raise

datasets.logging.set_verbosity_error()
datasets.disable_progress_bars()

REPO = "allenai/ring-data"
REPO_TYPE = "dataset"

TASK_CONFIGS = [
    "ObjectNavType",
]

MANIFEST_FILENAME = "download_manifest.json"

METADATA_FILES = [
    "annotations_used.json.gz",
    "train_assets.jsonl.gz",
    "val_assets.jsonl.gz",
]


def _format_size(size_bytes: int) -> str:
    if size_bytes >= 1024**4:
        return f"{size_bytes / 1024**4:.2f} TiB"
    if size_bytes >= 1024**3:
        return f"{size_bytes / 1024**3:.2f} GiB"
    if size_bytes >= 1024**2:
        return f"{size_bytes / 1024**2:.2f} MiB"
    if size_bytes >= 1024:
        return f"{size_bytes / 1024:.2f} KiB"
    return f"{size_bytes} B"


def _manifest_path(target_dir: str) -> Path:
    return Path(target_dir) / MANIFEST_FILENAME


def _load_manifest(target_dir: str) -> dict:
    """Load the local progress manifest.

    Structure::

        {
            "<config_name>": {
                "num_completed_entries": [700, 500, ...]
                "completed_shards": [0, 1, ...]
            },
            ...
        }
    """
    if target_dir is None:
        return {}

    p = _manifest_path(target_dir)
    if p.is_file():
        with open(p) as f:
            return json.load(f)
    return {}


def _save_manifest(target_dir: str, manifest: dict) -> None:
    p = _manifest_path(target_dir)
    os.makedirs(p.parent, exist_ok=True)
    tmp = p.with_suffix(".tmp")
    with open(tmp, "w") as f:
        json.dump(manifest, f, indent=2)
    tmp.replace(p)


def load_entries(config_name: str) -> list[dict]:
    """Load the parquet arrow table for a task config as a list of dicts."""
    try:
        ds = load_dataset(REPO, name=config_name, split=f"pkgs")
        return [row for row in ds]
    except ValueError as e:
        print(f"No pkgs for {config_name}")
        return []


def summarize_config(config_name: str, entries: list[dict]) -> dict:
    """Return a summary dict with sizes, shard/part counts."""
    compressed = sum(e["size"] for e in entries)
    inflated = sum(e.get("inflated_size", 0) for e in entries)
    has_inflated = entries and "inflated_size" in entries[0]
    shards = sorted(set(e["shard_id"] for e in entries))

    return {
        "config": config_name,
        "entries": len(entries),
        "compressed": compressed,
        "inflated": inflated if has_inflated else None,
        "shards": shards,
    }


def print_summary(summary: dict) -> None:
    print(f"  Task config:   {summary['config']}")
    print(f"  Entries:       {summary['entries']}")
    print(f"  Shards:        {len(summary['shards'])}")
    print(f"  Download size: {_format_size(summary['compressed'])}")
    if summary["inflated"] is not None:
        print(f"  Extracted size: {_format_size(summary['inflated'])}")
    else:
        print(f"  Extracted size: (unknown)")


def download_metadata(config_name: str, target_dir: str) -> None:
    """Download scene metadata files into <target_dir>/<config_name>/metadata/."""
    missing: list[str] = []
    for filename in METADATA_FILES:
        local_path = os.path.join(target_dir, config_name, "metadata", filename)
        if not os.path.isfile(local_path):
            missing.append(filename)

    if not missing:
        return

    print(f"Downloading metadata for {config_name}...")
    for filename in missing:
        repo_path = f"{config_name}/metadata/{filename}"
        hf_hub_download(
            repo_id=REPO,
            filename=repo_path,
            repo_type=REPO_TYPE,
            revision="main",
            local_dir=target_dir,
        )
        local_path = os.path.join(target_dir, repo_path)
        print(f"  {local_path}")


def _extract_tar_zst_bytes(data: bytes, output_dir: str) -> None:
    """Decompress a .tar.zst payload and stream-extract into *output_dir*."""
    dctx = zstd.ZstdDecompressor()
    with dctx.stream_reader(io.BytesIO(data)) as reader:
        with tarfile.open(fileobj=reader, mode="r|") as tar:
            tar.extractall(path=output_dir)


def download_and_extract_config(
    config_name: str,
    target_dir: str,
    entries: list[dict] | None = None,
) -> None:
    """Download and extract all shards for a single task config.

    Whole shard tars are downloaded via ``hf_hub_download`` into a
    temporary directory (avoiding HF's symlink cache).  Each inner
    ``.tar.zst`` member is decompressed and extracted
    into ``<target_dir>/<config_name>``.

    Progress is tracked per-shard in a local manifest so that interrupted
    runs can be resumed.
    """
    if entries is None:
        print(f"Loading entry table for {config_name}...")
        entries = load_entries(config_name)

    # Build lookup: path -> entry (for part resolution)
    path_to_entry = {e["path"]: e for e in entries}

    # Group entries by shard
    shard_to_paths: dict[int, list[str]] = defaultdict(list)
    for e in entries:
        shard_to_paths[e["shard_id"]].append(e["path"])
    all_shard_ids = sorted(shard_to_paths.keys())

    # Load manifest for resume
    manifest = _load_manifest(target_dir)
    cfg_manifest = manifest.setdefault(config_name, {})
    completed_shards: set[int] = set(cfg_manifest.get("completed_shards", []))
    num_completed_entries: list[int] = cfg_manifest.get("num_completed_entries", [])

    remaining_shards = [s for s in all_shard_ids if s not in completed_shards]
    if completed_shards:
        print(
            f"Resuming: {len(completed_shards)} shard(s) already done, "
            f"{len(remaining_shards)} remaining"
        )

    if not remaining_shards:
        print(f"All shards for {config_name} already extracted.")
        return

    print(
        f"Downloading & extracting {len(remaining_shards)} shard(s) for {config_name}..."
    )

    for shard_id in tqdm(remaining_shards, desc=f"{config_name} shards"):
        entries_count = 0

        shard_filename = f"{config_name}/shards/{shard_id:05d}.tar"

        with tempfile.TemporaryDirectory(prefix="bulk-shards-") as shard_dl_dir:
            shard_local = hf_hub_download(
                repo_id=REPO,
                filename=shard_filename,
                repo_type=REPO_TYPE,
                revision="main",
                local_dir=shard_dl_dir,
            )

            with tarfile.open(shard_local, "r:") as shard_tar:
                members = [m for m in shard_tar.getmembers() if m.isfile()]
                for member in tqdm(
                    members,
                    desc=f"  extracting shard {shard_id:05d}",
                    leave=False,
                ):
                    archive_path = member.name

                    entry = path_to_entry.get(archive_path)
                    if entry is None:
                        continue

                    extract_dir = os.path.join(target_dir, config_name)
                    os.makedirs(extract_dir, exist_ok=True)

                    fobj = shard_tar.extractfile(member)
                    if fobj is None:
                        continue
                    data = fobj.read()
                    _extract_tar_zst_bytes(data, extract_dir)
                    entries_count += 1

        completed_shards.add(shard_id)
        num_completed_entries.append(entries_count)

        # Persist progress after each shard
        cfg_manifest["completed_shards"] = sorted(completed_shards)
        cfg_manifest["num_completed_entries"] = num_completed_entries
        _save_manifest(target_dir, manifest)

    print(
        f"Done extracting {config_name} ({sum(num_completed_entries)} entries, {len(completed_shards)} shards)."
    )


def main() -> None:
    parser = argparse.ArgumentParser(
        description="Download RING training data from Hugging Face.",
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog=(
            "Available task configs:\n" + "\n".join(f"  - {c}" for c in TASK_CONFIGS)
        ),
    )
    parser.add_argument(
        "target_dir",
        nargs="?",
        default=None,
        help="Local root directory to extract data into.",
    )
    parser.add_argument(
        "--config",
        choices=TASK_CONFIGS,
        default=None,
        help="Download a single task config. Omit to see --list or use --all.",
    )
    parser.add_argument(
        "--all",
        action="store_true",
        dest="download_all",
        help="Download all task configs.",
    )
    parser.add_argument(
        "--list",
        action="store_true",
        dest="list_only",
        help="List available task configs and their sizes, then exit.",
    )
    parser.add_argument(
        "-y",
        "--yes",
        action="store_true",
        help="Skip confirmation prompts.",
    )
    parser.add_argument(
        "--max_shards",
        type=int,
        default=None,
        help="Extract only the given number of shards per config.",
    )
    args = parser.parse_args()

    if not args.list_only and args.target_dir is None:
        parser.error("target_dir is required.")

    configs_to_process: list[str] = []
    if args.config:
        configs_to_process = [args.config]
    elif args.download_all or args.list_only:
        configs_to_process = list(TASK_CONFIGS)
    else:
        parser.error("Specify --config <NAME>, --all, or --list.")

    requested_configs = list(configs_to_process)

    # Load entries and compute summaries
    all_entries: dict[str, list[dict]] = {}
    total_compressed = 0
    total_inflated = 0
    has_all_inflated = True

    print(f"Loading metadata for {len(configs_to_process)} config(s)...\n")

    manifest = _load_manifest(args.target_dir)

    configs_to_skip = set()
    for config_name in configs_to_process:
        shard_to_entries: dict[int, list[dict]] = defaultdict(list)
        entries = load_entries(config_name)

        if not entries:
            configs_to_skip.add(config_name)
            continue

        for e in entries:
            shard_to_entries[e["shard_id"]].append(e)

        if args.max_shards is not None:
            shards = sorted(shard_to_entries.keys())[: args.max_shards]
            shard_to_entries = {s: shard_to_entries[s] for s in shards}

        # Show resume status and filter out fully-completed configs
        cfg_m = manifest.get(config_name, {})
        done_shards = set(cfg_m.get("completed_shards", []))
        if done_shards:
            required_shards = set(shard_to_entries.keys())
            missing_shards = required_shards - done_shards
            if not missing_shards:
                print(f"  {config_name}: already fully extracted, skipping")
                configs_to_skip.add(config_name)
                continue
            else:
                print(
                    f"  {config_name}: {len(missing_shards)}/{len(required_shards)} "
                    f"shards pending extraction (will resume)"
                )

        entries = [
            e
            for shard, entries in shard_to_entries.items()
            for e in entries
            if shard not in done_shards
        ]

        all_entries[config_name] = entries
        summary = summarize_config(config_name, entries)

        print_summary(summary)
        total_compressed += summary["compressed"]
        if summary["inflated"] is not None:
            total_inflated += summary["inflated"]
        else:
            has_all_inflated = False
        print()

    configs_to_process = [
        config_name
        for config_name in configs_to_process
        if config_name not in configs_to_skip
    ]

    if len(configs_to_process) > 1:
        print(f"Total across {len(configs_to_process)} configs:")
        print(f"  Download size:  {_format_size(total_compressed)}")
        if has_all_inflated:
            print(f"  Extracted size: {_format_size(total_inflated)}")
        else:
            print(f"  Extracted size: (partially unknown)")
        print()

    if args.list_only:
        return

    for config_name in requested_configs:
        try:
            download_metadata(config_name, args.target_dir)
        except Exception as e:
            print(f"FAILED metadata for {config_name} — {e}")

    if not configs_to_process:
        print("\nNothing to download — all configs are fully extracted.")
        print("\nAll done.")
        return

    if not args.yes:
        answer = input("\nProceed with download? [Y/n] ").strip().lower()
        if answer and answer not in ("y", "yes"):
            print("Aborted.")
            return

    for config_name in configs_to_process:
        print(f"\n{'=' * 60}")
        print(f"  {config_name}")
        print(f"{'=' * 60}")
        try:
            download_and_extract_config(
                config_name,
                args.target_dir,
                entries=all_entries[config_name],
            )
        except KeyboardInterrupt:
            print("\nInterrupted. Progress has been saved; re-run to resume.")
            raise SystemExit(1)
        except Exception as e:
            print(f"FAILED: {config_name} — {e}")

    print("\nAll done.")


if __name__ == "__main__":
    main()