from typing import Any, Callable, Optional
from urllib.parse import unquote

from fastapi import Request
from fastapi.responses import JSONResponse
from sqlmodel import Session

from models.bot import BotInstance


class DashboardAuthService:
    AUTH_TOKEN_HEADER = "authorization"
    AUTH_TOKEN_FALLBACK_HEADER = "x-auth-token"

    def __init__(self, *, engine: Any) -> None:
        self._engine = engine

    def extract_bot_id_from_api_path(self, path: str) -> Optional[str]:
        raw = str(path or "").strip()
        if not raw.startswith("/api/bots/"):
            return None
        rest = raw[len("/api/bots/") :]
        if not rest:
            return None
        bot_id_segment = rest.split("/", 1)[0].strip()
        if not bot_id_segment:
            return None
        try:
            decoded = unquote(bot_id_segment)
        except Exception:
            decoded = bot_id_segment
        return str(decoded).strip() or None

    def get_supplied_auth_token_http(self, request: Request) -> str:
        auth_header = str(request.headers.get(self.AUTH_TOKEN_HEADER) or "").strip()
        if auth_header.lower().startswith("bearer "):
            token = auth_header[7:].strip()
            if token:
                return token
        header_value = str(request.headers.get(self.AUTH_TOKEN_FALLBACK_HEADER) or "").strip()
        if header_value:
            return header_value
        return str(request.query_params.get("auth_token") or "").strip()

    @staticmethod
    def is_public_api_path(path: str, method: str = "GET") -> bool:
        raw = str(path or "").strip()
        if not raw.startswith("/api/"):
            return False
        return raw in {
            "/api/sys/auth/status",
            "/api/sys/auth/login",
            "/api/sys/auth/logout",
            "/api/health",
            "/api/health/cache",
        }

    def is_bot_enable_api_path(self, path: str, method: str = "GET") -> bool:
        raw = str(path or "").strip()
        verb = str(method or "GET").strip().upper()
        if verb != "POST":
            return False
        bot_id = self.extract_bot_id_from_api_path(raw)
        if not bot_id:
            return False
        return raw == f"/api/bots/{bot_id}/enable"

    def validate_dashboard_auth(self, request: Request, session: Session) -> Optional[str]:
        token = self.get_supplied_auth_token_http(request)
        if not token:
            return "Authentication required"

        from services.sys_auth_service import resolve_user_by_token

        user = resolve_user_by_token(session, token)
        if user is None:
            return "Session expired or invalid"

        request.state.sys_auth_mode = "session_token"
        request.state.sys_user_id = int(user.id or 0)
        request.state.sys_username = str(user.username or "")
        return None

    @staticmethod
    def _json_error(request: Request, *, status_code: int, detail: str) -> JSONResponse:
        headers = {"Access-Control-Allow-Origin": "*"}
        origin = str(request.headers.get("origin") or "").strip()
        if origin:
            headers["Vary"] = "Origin"
        return JSONResponse(status_code=status_code, content={"detail": detail}, headers=headers)

    async def guard(self, request: Request, call_next: Callable[..., Any]):
        if request.method.upper() == "OPTIONS":
            return await call_next(request)

        if self.is_public_api_path(request.url.path, request.method):
            return await call_next(request)

        current_user_id = 0
        with Session(self._engine) as session:
            auth_error = self.validate_dashboard_auth(request, session)
            if auth_error:
                return self._json_error(request, status_code=401, detail=auth_error)
            current_user_id = int(getattr(request.state, "sys_user_id", 0) or 0)

        bot_id = self.extract_bot_id_from_api_path(request.url.path)
        if not bot_id:
            return await call_next(request)

        with Session(self._engine) as session:
            from models.sys_auth import SysUser
            from services.sys_auth_service import user_can_access_bot

            current_user = session.get(SysUser, current_user_id) if current_user_id > 0 else None
            if current_user is None:
                return self._json_error(request, status_code=401, detail="Authentication required")
            if not user_can_access_bot(session, current_user, bot_id):
                return self._json_error(request, status_code=403, detail="You do not have access to this bot")
            bot = session.get(BotInstance, bot_id)
            if not bot:
                return self._json_error(request, status_code=404, detail="Bot not found")

            enabled = bool(getattr(bot, "enabled", True))
            if not enabled:
                is_enable_api = self.is_bot_enable_api_path(request.url.path, request.method)
                is_read_api = request.method.upper() == "GET"
                if not (is_enable_api or is_read_api):
                    return self._json_error(request, status_code=403, detail="Bot is disabled. Enable it first.")
        return await call_next(request)