#!/usr/bin/env python3
"""Installed-skill entry point for the fail-closed BLUN Language Gateway."""

from __future__ import annotations

import argparse
import importlib.util
import json
import sys
from pathlib import Path


GUARD_PATH = Path(__file__).with_name("blun_language_guard.py")
SPEC = importlib.util.spec_from_file_location("blun_installed_gateway_guard", GUARD_PATH)
assert SPEC and SPEC.loader
GUARD = importlib.util.module_from_spec(SPEC)
sys.modules[SPEC.name] = GUARD
SPEC.loader.exec_module(GUARD)


def gate(request: dict) -> dict:
    required = ("task_kind", "target_text", "language")
    missing = [
        key for key in required
        if not isinstance(request.get(key), str) or not request[key].strip()
    ]
    if missing:
        return {"status": "BLOCK", "release_allowed": False, "reason": "missing-fields", "fields": missing}
    task_kind = request["task_kind"]
    source = request.get("source_text", "")
    if not isinstance(source, str):
        return {"status": "BLOCK", "release_allowed": False, "reason": "invalid-source-type"}
    if task_kind == "translation":
        if not source.strip():
            return {"status": "BLOCK", "release_allowed": False, "reason": "translation-source-required"}
        result = GUARD.release_translation(request)
    elif task_kind == "response":
        if source.strip():
            return {"status": "BLOCK", "release_allowed": False, "reason": "response-cannot-carry-source"}
        result = GUARD.release_response(request)
    else:
        return {"status": "BLOCK", "release_allowed": False, "reason": "invalid-task-kind"}
    result["gateway"] = f"blun-language-gateway/{GUARD.VERSION}"
    result["task_kind"] = task_kind
    return result


def main() -> int:
    parser = argparse.ArgumentParser(description="BLUN fail-closed language output gateway")
    parser.add_argument("--input", type=Path)
    args = parser.parse_args()
    try:
        request = json.loads(args.input.read_text(encoding="utf-8-sig") if args.input else sys.stdin.read().lstrip("\ufeff"))
        result = gate(request)
    except (OSError, json.JSONDecodeError) as error:
        result = {"status": "BLOCK", "release_allowed": False, "reason": "invalid-input", "error": str(error)}
    print(json.dumps(result, ensure_ascii=False, indent=2))
    return 0 if result.get("release_allowed") else 1


if __name__ == "__main__":
    raise SystemExit(main())