"""CLI: detect green→red regressions between the published matrix and a
freshly built one, so `run_daily.sh` can decide whether to enable
auto-merge on the daily docs PR.

All real logic lives in `claude_code.matrix_builder.find_regressions`;
this file only does the I/O and maps the result onto an exit code the
bash caller can branch on.

Exit codes (the bash gate depends on these exact values):

  0  no green→red regressions          -> safe to auto-merge
  3  one or more green→red regressions  -> do NOT auto-merge (human review)
  2  argparse/usage error (argparse default)

The `--old` file is allowed to be missing: on the first-ever publish there
is no baseline to regress against, so we exit 0.

Imports resolve with `tests/e2e/` on sys.path, mirroring build_matrix.py.
"""

from __future__ import annotations

import argparse
import json
import sys
from pathlib import Path

sys.path.insert(0, str(Path(__file__).resolve().parents[2]))

from claude_code.matrix_builder import (
    find_regressions,
)  # noqa: E402  # needs the sys.path bootstrap above

REGRESSION_EXIT = 3


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument(
        "--old",
        type=Path,
        required=True,
        help="currently published matrix JSON (may be absent on first publish)",
    )
    parser.add_argument(
        "--new",
        type=Path,
        required=True,
        help="freshly built matrix JSON",
    )
    args = parser.parse_args()

    if not args.old.exists():
        print(  # noqa: T201  # CLI output read by run_daily.sh
            "no published matrix to compare against "
            "(first publish); treating as no regressions"
        )
        return 0

    old_matrix = json.loads(args.old.read_text())
    new_matrix = json.loads(args.new.read_text())

    regressions = find_regressions(old_matrix, new_matrix)
    if not regressions:
        print("no green->red regressions detected")  # noqa: T201  # CLI output
        return 0

    print(  # noqa: T201  # CLI output read by run_daily.sh
        f"detected {len(regressions)} green->red regression(s):"
    )
    for r in regressions:
        line = f"  - {r['feature_name']} [{r['provider']}]: pass -> fail"
        if r["error"]:
            line += f" ({r['error'][:160]})"
        print(line)  # noqa: T201  # CLI output read by run_daily.sh
    return REGRESSION_EXIT


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