"""CLI: diff two engine-surface snapshots.

    python -m ams OLD.snapshot.json NEW.snapshot.json [--owner CMC_Animo] [--only types,methods] [--json]
"""

from __future__ import annotations

import argparse
import json
import sys

from .diff import compute_diff, filter_by_owner
from .render import render_text
from .snapshot import Snapshot

_AXES = ["types", "methods", "events", "fields", "layout", "dispatch"]


def main(argv: list[str] | None = None) -> int:
    p = argparse.ArgumentParser(prog="ams", description="Diff two engine-surface snapshots.")
    p.add_argument("old", help="older snapshot.json")
    p.add_argument("new", help="newer snapshot.json")
    p.add_argument("--owner", help="restrict to one class, e.g. CMC_Animo")
    p.add_argument("--only", help="comma-separated axes to show: " + ",".join(_AXES))
    p.add_argument("--json", action="store_true", help="emit machine-readable JSON")
    args = p.parse_args(argv)

    old = Snapshot.load(args.old)
    new = Snapshot.load(args.new)
    diff = compute_diff(old, new)
    if args.owner:
        diff = filter_by_owner(diff, args.owner)

    if args.json:
        print(json.dumps(diff, indent=2, sort_keys=True))
        return 0

    only = None
    if args.only:
        only = {a.strip() for a in args.only.split(",") if a.strip()}
        bad = only - set(_AXES)
        if bad:
            p.error("unknown axis: {0} (choose from {1})".format(",".join(sorted(bad)), ",".join(_AXES)))
    print(render_text(diff, only=only))
    return 0


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