# backend/middleware/lockfile_guard.py
# This middleware is the backend half of the Crime 2 causal chain.
# Without this, the Python backend keeps serving requests even during lockdown.
# JARVIS would still respond to API calls even with the lockfile present.
# That means lockdown is cosmetic only. That is Crime 2.
#
# REGISTRATION REQUIREMENT:
# This middleware MUST be registered in EVERY FastAPI/Flask app in this codebase.
# Check every app's startup file. If this middleware is missing from any server,
# that server violates Crime 2. No exceptions.

import os
import json
from pathlib import Path
from fastapi import Request
from fastapi.responses import JSONResponse

def get_lock_path():
    data_dir = os.environ.get("JARVIS_APP_DATA_DIR")
    if not data_dir:
        return None
    return Path(data_dir) / "jarvis.lock"

async def lockfile_middleware(request: Request, call_next):
    # Exempt the unlock endpoint — otherwise the user can never unlock
    if request.url.path == "/api/unlock":
        return await call_next(request)

    lock_path = get_lock_path()
    if lock_path and lock_path.exists():
        try:
            lock_data = json.loads(lock_path.read_text())
        except Exception:
            lock_data = {}
        return JSONResponse(
            status_code=423,
            content={
                "error": "SYSTEM_LOCKED",
                "reason": "Unauthorized device detected. Authenticate to resume.",
                "device_serial": lock_data.get("device_serial", "unknown"),
                "locked_at": lock_data.get("timestamp", 0),
            }
        )
    return await call_next(request)

# ── REGISTRATION TEMPLATE ────────────────────────────────────────────────────
# Copy this into every FastAPI app's main startup file:
#
# from backend.middleware.lockfile_guard import lockfile_middleware
# app = FastAPI()
# app.middleware("http")(lockfile_middleware)
#
# For Flask apps:
# from backend.middleware.lockfile_guard import flask_lockfile_guard
# app.before_request(flask_lockfile_guard)
# ─────────────────────────────────────────────────────────────────────────────

def flask_lockfile_guard():
    from flask import request, jsonify
    if request.path == "/api/unlock":
        return None
    lock_path = get_lock_path()
    if lock_path and lock_path.exists():
        try:
            lock_data = json.loads(lock_path.read_text())
        except Exception:
            lock_data = {}
        return jsonify({
            "error": "SYSTEM_LOCKED",
            "reason": "Unauthorized device detected. Authenticate to resume.",
            "device_serial": lock_data.get("device_serial", "unknown"),
            "locked_at": lock_data.get("timestamp", 0),
        }), 423