#!/usr/bin/env python3
"""Fail if client/project.godot's baked version has drifted from project.yaml.

project.yaml is the version source of truth (CLAUDE.md). The client cannot read
it at runtime — an exported build has no repo root — so the value is mirrored
into `application/config/version` in client/project.godot, which Godot bakes
into the PCK (T-1241).

A mirror nobody checks is worse than the bug it replaced: the old code failed
LOUDLY in an export ("?.?.?" everywhere, no cache invalidation ever), whereas a
stale mirror fails SILENTLY — the Atlas disk cache would keep serving canvases
under a version that stopped matching the build. That is precisely the T-1239
failure, which cost eight days of a map drawn from a canvas whose generating
code no longer existed. Hence this check, wired into the pre-push hook.

Exit: 0 = in sync, 1 = drifted or unreadable.
"""

import re
import sys
from pathlib import Path

ROOT = Path(__file__).resolve().parent.parent
PROJECT_YAML = ROOT / "project.yaml"
PROJECT_GODOT = ROOT / "client" / "project.godot"

# Anchored to line start so the commentary above `version:` (which mentions
# earlier versions by number) can never be mistaken for the field itself.
YAML_VERSION = re.compile(r"^version:\s*(\S+)\s*$", re.MULTILINE)
GODOT_VERSION = re.compile(r'^config/version\s*=\s*"([^"]*)"\s*$', re.MULTILINE)


def read(path: Path, pattern: re.Pattern, label: str) -> str | None:
    if not path.exists():
        print(f"check-client-version: {path} not found", file=sys.stderr)
        return None
    match = pattern.search(path.read_text(encoding="utf-8"))
    if not match:
        print(f"check-client-version: no {label} in {path}", file=sys.stderr)
        return None
    return match.group(1)


def main() -> int:
    yaml_version = read(PROJECT_YAML, YAML_VERSION, "`version:` line")
    godot_version = read(PROJECT_GODOT, GODOT_VERSION, "`config/version=` line")
    if yaml_version is None or godot_version is None:
        return 1

    if yaml_version != godot_version:
        print(
            "check-client-version: version drift\n"
            f"  project.yaml          {yaml_version}\n"
            f"  client/project.godot  {godot_version}\n"
            "\n"
            "project.yaml is the source of truth. Set config/version in\n"
            "client/project.godot's [application] section to match it.\n"
            "\n"
            "This matters beyond cosmetics: the Atlas disk cache keys its\n"
            "invalidation on this version, so a stale mirror makes a shipped\n"
            "build serve canvases generated by code it no longer runs (T-1239).",
            file=sys.stderr,
        )
        return 1

    print(f"check-client-version: OK — {yaml_version}")
    return 0


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