#!/usr/bin/env python3
"""Check a sentence-helper directory before a site build ships it.

  python3 tools/ai/check_packs.py DIR

DIR must hold what tools/ai/build_ai.py built for the committed catalogue
(data/ai/index.json): its index.json points at index.<sha12>.json, whose
bytes are the committed catalogue's, and every part and licence file that
catalogue names is there with its exact size and SHA-256. Otherwise this exits
non-zero and says what is wrong, so a build never ships a model that
disagrees with the catalogue, or that is incomplete.

Standard library only; Python 3.9 or later (macOS's own python3).
"""

import hashlib
import json
import sys
from pathlib import Path

HERE = Path(__file__).resolve().parent
COMMITTED = HERE.parents[1] / "data" / "ai" / "index.json"
SHOW = 10


def sha256(path):
    h = hashlib.sha256()
    with open(path, "rb") as f:
        for chunk in iter(lambda: f.read(1 << 22), b""):
            h.update(chunk)
    return h.hexdigest()


def main(argv):
    if len(argv) != 2:
        print(__doc__, file=sys.stderr)
        return 2
    root = Path(argv[1])
    problems = []
    try:
        pointer = json.loads((root / "index.json").read_text(encoding="utf-8"))
        name = pointer["current"]
        cat_bytes = (root / name).read_bytes()
    except (OSError, ValueError, KeyError) as e:
        print(f"✗ {root}: no readable index.json and catalogue ({e})", file=sys.stderr)
        return 1
    if cat_bytes != COMMITTED.read_bytes():
        problems.append(f"{name} is not the committed catalogue ({COMMITTED})")
    if name != f"index.{hashlib.sha256(cat_bytes).hexdigest()[:12]}.json":
        problems.append(f"{name} is not named by its contents")
    cat = json.loads(cat_bytes)
    refs = []
    for model in cat.get("models", {}).values():
        refs += [(p["url"], p["bytes"], p["sha256"]) for p in model.get("parts", [])]
        lf = model.get("licence_file")
        if lf:
            data = (root / lf).read_bytes() if (root / lf).is_file() else b""
            refs.append((lf, len(data) if data else -1, hashlib.sha256(data).hexdigest() if data else ""))
    if not (root / "LICENSES.md").is_file():
        problems.append("LICENSES.md is missing")
    for rel, size, digest in refs:
        f = root / rel
        if not f.is_file():
            problems.append(f"missing {rel}")
        elif f.stat().st_size != size:
            problems.append(f"{rel} is {f.stat().st_size} bytes, the catalogue says {size}")
        elif sha256(f) != digest:
            problems.append(f"{rel} does not match its SHA-256")
    if problems:
        for p in problems[:SHOW]:
            print(f"✗ {p}", file=sys.stderr)
        if len(problems) > SHOW:
            print(f"  … and {len(problems) - SHOW} more", file=sys.stderr)
        return 1
    print(f"✓ {root}: {len(refs)} files match {name}")
    return 0


if __name__ == "__main__":
    sys.exit(main(sys.argv))