#!/usr/bin/env python3
"""Hydrate and verify Xet-backed assets in the single Nanobrush Git checkout."""
import argparse
import hashlib
from pathlib import Path
import subprocess
import sys

import storage_policy as policy

ROOT = Path(__file__).resolve().parents[1]


def run(*args, capture=False):
    return subprocess.run(args, cwd=ROOT, check=True, stdout=subprocess.PIPE if capture else None).stdout


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("command", choices=("check", "fetch"))
    args = parser.parse_args()
    policy.check_setup()
    policy.check_index()
    if args.command == "fetch":
        run("git", "lfs", "pull", "hf")
    # A fresh clone's cache starts empty; verify hydrated working bytes directly.
    count = 0
    paths = policy.git("ls-files", "-z").split(b"\0")
    for raw in paths:
        if not raw:
            continue
        path = raw.decode("utf-8")
        if not policy.is_asset(path):
            continue
        pointer = policy.git("show", ":" + path)
        policy.check_asset(path, pointer)
        if not pointer:
            expected_hash, size = hashlib.sha256(b"").hexdigest(), 0
        else:
            lines = pointer.decode().splitlines()
            expected_hash, size = lines[1].split(":", 1)[1], int(lines[2].split()[1])
        payload = ROOT / path
        if payload.is_symlink() or not payload.is_file() or payload.stat().st_size != size:
            raise ValueError(f"Missing/unhydrated asset: {path}; run assets-fetch")
        digest = hashlib.sha256()
        with payload.open("rb") as stream:
            for chunk in iter(lambda: stream.read(1024 * 1024), b""):
                digest.update(chunk)
        if digest.hexdigest() != expected_hash:
            raise ValueError(f"Modified/unhydrated asset: {path}; preserve edits before fetching")
        count += 1
    print(f"Verified {count} hydrated Xet/LFS assets against staged pointer identities.")


if __name__ == "__main__":
    try:
        main()
    except (ValueError, OSError, subprocess.CalledProcessError) as error:
        print(f"Assets: {error}", file=sys.stderr)
        sys.exit(1)