#!/usr/bin/env python3
"""Delete the USD files listed by ``usd_models_cleaner.py --unused``.

Takes the JSON list written by ``usd_models_cleaner.py --out`` and removes each
file from ``assets/usd_models``. Afterwards any directory left holding no USD
file at all is removed whole (its leftover textures/materials went with the
model that referenced them).

Destructive. Preview with --dry-run first; the real run asks for confirmation
unless --yes is given.

Usage:
    python scripts/usd_cleaner/usd_models_cleaner.py --unused --out unused_usds.json
    python scripts/usd_cleaner/usd_models_delete.py unused_usds.json --dry-run   # found in scripts/
    python scripts/usd_cleaner/usd_models_delete.py unused_usds.json
"""

from __future__ import annotations

import argparse
import json
import shutil
from pathlib import Path

SCRIPT_DIR = Path(__file__).resolve().parent
REPO_ROOT = SCRIPT_DIR.parent.parent
USD_SUFFIXES = {".usd", ".usda", ".usdc", ".usdz"}
# Never sweep VCS/metadata dirs: they hold no USD, so the "USD-less" rule would
# otherwise eat assets/usd_models/.git wholesale.
PROTECTED = {".git", ".svn", ".hg", ".datasets", "__pycache__"}


def human(nbytes: int) -> str:
    size = float(nbytes)
    for unit in ("B", "K", "M", "G", "T"):
        if size < 1024 or unit == "T":
            return f"{size:.1f}{unit}"
        size /= 1024


def resolve(value: str) -> Path:
    path = Path(value)
    return path if path.is_absolute() else REPO_ROOT / path


def is_protected(path: Path, root: Path) -> bool:
    """True if ``path`` is, or sits inside, a protected directory."""
    return any(
        part in PROTECTED or part.startswith(".")
        for part in path.relative_to(root).parts
    )


def usd_census(directory: Path, doomed: set):
    """(had a USD beneath, keeps one after ``doomed`` is deleted)."""
    had = keeps = False
    for f in directory.rglob("*"):
        if f.is_file() and f.suffix.lower() in USD_SUFFIXES:
            had = True
            if f not in doomed:
                return True, True
    return had, keeps


def main() -> None:
    parser = argparse.ArgumentParser(
        description="Delete unreferenced USD files and the folders left without any USD"
    )
    parser.add_argument(
        "usd_delete_list",
        help="JSON list of paths to delete (from usd_models_cleaner.py --out)",
    )
    parser.add_argument(
        "--models_dir",
        default="assets/usd_models",
        help="Deletion is confined to this directory",
    )
    parser.add_argument(
        "--dry-run",
        action="store_true",
        help="Report what would be removed without touching anything",
    )
    parser.add_argument(
        "--yes", action="store_true", help="Skip the confirmation prompt"
    )
    parser.add_argument(
        "--keep_empty_dirs",
        action="store_true",
        help="Delete only the files; leave USD-less directories in place",
    )
    args = parser.parse_args()

    models_dir = resolve(args.models_dir).resolve()
    if not models_dir.is_dir():
        raise SystemExit(f"Models directory not found: {models_dir}")

    # Accept the list as given, or by bare name from scripts/ or the repo root.
    for candidate in (
        Path(args.usd_delete_list),
        SCRIPT_DIR / args.usd_delete_list,
        REPO_ROOT / args.usd_delete_list,
    ):
        if candidate.is_file():
            list_path = candidate.resolve()
            break
    else:
        raise SystemExit(f"Delete list not found: {args.usd_delete_list}")
    entries = json.loads(list_path.read_text())
    if not isinstance(entries, list):
        raise SystemExit(f"{list_path} must contain a JSON list of paths")

    targets, missing, outside = [], [], []
    for entry in entries:
        path = resolve(entry).resolve()
        # Containment check: a stray "../" in the list must never escape the tree.
        if not path.is_relative_to(models_dir):
            outside.append(entry)
        elif not path.is_file():
            missing.append(entry)
        else:
            targets.append(path)

    if outside:
        raise SystemExit(
            f"Refusing to run: {len(outside)} path(s) fall outside {models_dir}, "
            f"e.g. {outside[0]}"
        )

    doomed = set(targets)

    # Plan the directory sweep before deleting anything, so the dry-run and the
    # real run agree. Keep only the top-most doomed dirs: rmtree takes the rest.
    doomed_dirs = []
    if not args.keep_empty_dirs:
        # A dir is swept only if it HELD a USD and now holds none. A dir that never
        # held one (textures/, materials/) belongs to its parent model — deleting it
        # standalone would strip a surviving model of its assets.
        candidates = []
        for d in models_dir.rglob("*"):
            if not d.is_dir() or is_protected(d, models_dir):
                continue
            had, keeps = usd_census(d, doomed)
            if had and not keeps:
                candidates.append(d)
        candidates.sort(key=lambda d: len(d.parts))
        for directory in candidates:
            if not any(directory.is_relative_to(kept) for kept in doomed_dirs):
                doomed_dirs.append(directory)

    # Every file that actually disappears, counted exactly once.
    going = set(doomed)
    for directory in doomed_dirs:
        going.update(f for f in directory.rglob("*") if f.is_file())
    freed = sum(f.stat().st_size for f in going if f.exists())

    print(f"[delete] list      : {list_path}")
    print(f"[delete] confined  : {models_dir}")
    print(f"[delete] to delete : {len(targets)} listed USD files")
    if doomed_dirs:
        print(
            f"[delete] plus      : {len(doomed_dirs)} USD-less directories "
            f"({len(going) - len(doomed)} further files)"
        )
    if missing:
        print(f"[delete] skipping  : {len(missing)} already absent")
    print(f"[delete] frees     : {human(freed)}")
    if not targets:
        print("[delete] nothing to do")
        return

    if args.dry_run:
        for path in sorted(going):
            print(f"  would delete {path.relative_to(REPO_ROOT)}")
        for directory in sorted(doomed_dirs):
            print(f"  would remove dir {directory.relative_to(REPO_ROOT)}")
        print(f"\n[delete] dry run — nothing was touched, would free {human(freed)}")
        return

    if not args.yes:
        answer = input(f"Delete {len(going)} files under {models_dir}? [y/N] ")
        if answer.strip().lower() not in ("y", "yes"):
            raise SystemExit("[delete] aborted")

    removed = 0
    for path in targets:
        if path.exists():
            path.unlink()
            removed += 1
    for directory in doomed_dirs:
        if directory.exists():
            shutil.rmtree(directory)

    print(
        f"\n[delete] deleted {removed} listed files, "
        f"removed {len(doomed_dirs)} USD-less directories"
    )
    print(f"[delete] freed {human(freed)}")


if __name__ == "__main__":
    main()