"""FlowDeck — CSRF protection middleware."""
from __future__ import annotations

import secrets

from starlette.middleware.base import BaseHTTPMiddleware
from starlette.responses import JSONResponse
from starlette.requests import Request


class CSRFMiddleware(BaseHTTPMiddleware):
    """Lightweight CSRF protection for state-changing requests.

    All POST/PUT/PATCH/DELETE requests must include X-CSRF-Token
    header matching the csrf_token cookie.
    """

    SAFE_METHODS = {"GET", "HEAD", "OPTIONS"}
    EXCLUDED_PATHS = {"/api/webhook", "/api/v1", "/auth/callback", "/auth/register", "/auth/local-login", "/api/user", "/board/api/pages", "/board/api/favorites", "/api/workspace", "/api/local-workspace", "/api/settings", "/db/", "/workspace", "/api/frontend-error", "/api/admin", "/api/gitea", "/api/github", "/api/pages", "/api/recents", "/api/csrf-token"}

    async def dispatch(self, request: Request, call_next):
        # Webhook receiver, OAuth callback, and internal API are exempt
        if any(request.url.path.startswith(p) for p in self.EXCLUDED_PATHS):
            return await call_next(request)

        if request.method in self.SAFE_METHODS:
            response = await call_next(request)
            # Set CSRF cookie if not present
            if "csrf_token" not in request.cookies:
                response.set_cookie(
                    "csrf_token",
                    secrets.token_hex(32),
                    httponly=False,  # Must be readable by JS
                    samesite="lax",
                    max_age=86400,
                    path="/",
                )
            return response

        # Validate CSRF for state-changing methods
        csrf_cookie = request.cookies.get("csrf_token", "")
        csrf_header = request.headers.get("X-CSRF-Token", "")

        if not csrf_cookie or not csrf_header or not secrets.compare_digest(csrf_cookie, csrf_header):
            return JSONResponse(
                {"detail": "CSRF validation failed"},
                status_code=403,
            )

        return await call_next(request)