"""This module implements API"""

import asyncio
import traceback
import time
import html

from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse

from mab import MatrixBot
import uvicorn

from datatypes import AppConfig, ObjectToken
from database import Database

class Web:
    #
    # PRIVATE
    #
    @staticmethod
    def _get_client_ip(request: Request) -> str | None:
        """Returns IP address of the client"""
        x_forwarded_for = request.headers.get("x-forwarded-for")
        if x_forwarded_for:
            return x_forwarded_for.split(",")[0].strip()
        else:
            x_real_ip = request.headers.get("x-real-ip")
            if x_real_ip:
                return x_real_ip
            else:
                return request.client.host if request.client else None

    def _is_banned(self, request: Request) -> bool:
        # get IP
        ip = self._get_client_ip(request)
        if ip is None:
            # treat requests without source IP as banned
            return True
        # check if banned in database
        return self._db.ban_check(ip)

    async def _handle_failed_request(self, request: Request, possible_ban_reason: str) -> None:
        """Adds the request to list of failed."""
        ip: str = self._get_client_ip(request) # type: ignore
        fails_total = self._db.fail_create(
            ip,
            time.time() + 60
        )
        if fails_total >= self._app_config.fails_to_ban:
            await self._db.ban_create(
                ip,
                time.time() + self._app_config.ban_duration,
                possible_ban_reason
            )
            self._db.fail_clear(ip)
        return None

    async def _middleware_banned(self, request: Request, call_next):
        if self._is_banned(request):
            return JSONResponse(
                status_code=403,
                content={"detail": "Try again later"}
            )
        return await call_next(request)

    async def _middleware_auth(self, request: Request, call_next):
        # ignore favicon
        if request.url.path.endswith("favicon.ico"):
            return JSONResponse(
                status_code=404,
                content={"detail": "Not found"}
            )
        # token that will be used
        token: str | None = None
        # check if token is provided via header
        auth_header = request.headers.get("Authorization")
        if auth_header and auth_header.lower().startswith("bearer"):
            parts = auth_header.split(" ")
            if len(parts) >= 2:
                token = auth_header.split(" ")[1]
        # get token from URL if not found in headers
        if not token:
            params = dict(request.query_params)
            if "token" in params:
                token = params["token"]
        # still no token
        if not token:
            await self._handle_failed_request(request, "Banned by the web server")
            return JSONResponse(
                status_code=403,
                content={"detail": "No token provided"}
            )
        # try to authorize
        auth_data = await self._db.token_get(token)
        if not auth_data:
            await self._handle_failed_request(request, "Banned by the web server")
            return JSONResponse(
                status_code=403,
                content={"detail": "Invalid token"}
            )
        # authorized
        request.state.user = auth_data
        return await call_next(request)

    async def _cb_get_notify(self, request: Request) -> dict:
        params = dict(request.query_params)
        token: ObjectToken = request.state.user
        if "channel" not in params or len(params["channel"]) < 1:
            return { "detail": "Missing `channel`" }
        if params["channel"][0] != "q":
            return { "detail": "Invalid `channel`" }
        if "text" not in params:
            return { "detail": "Missing `text`" }
        if not token.name:
            service_name = params["service"] if "service" in params else "Unnamed"
        else:
            service_name = token.name
        # get the room
        room = await self._db.room_get(params["channel"])
        if not room:
            return { "detail": "Unknown `channel`" }
        # send the notification
        full_text = f"<strong>Уведомление от службы <code>{html.escape(service_name)}</code></strong>"
        full_text += "<br><br>"
        full_text += html.escape(params["text"])
        try:
            notification_id = await self._bot.send_text_to_room(room.matrix_id, full_text, is_html=True)
        except:
            traceback.print_exc()
            return { "detail": "Failed to send the notification" }
        return { "notification_id": notification_id }


    async def _cb_exception(self, request: Request, exc: Exception):
        traceback.print_exception(exc)
        return JSONResponse(
            status_code=500,
            content={"detail": "Internal Server Error"}
        )

    #
    # PUBLIC
    #
    def __init__(self, app_config: AppConfig, bot: MatrixBot, db: Database):
        self._bot = bot
        self._db = db
        self._app_config = app_config

        self._api = FastAPI(docs_url=None, redoc_url=None, openapi_url=None)
        self._api.add_api_route("/notify", self._cb_get_notify, methods=["GET"])

        self._api.middleware("http")(self._middleware_auth)
        self._api.middleware("http")(self._middleware_banned)
        self._api.add_exception_handler(Exception, self._cb_exception)
        self._server_config = uvicorn.Config(
            self._api,
            host=app_config.web_ip,
            port=app_config.web_port
        )
        self._server: uvicorn.Server | None = None
        self._server_task: asyncio.Task | None = None

    async def start(self) -> None:
        """Start the API."""
        if self._server is not None or self._server_task is not None:
            raise RuntimeError("The server is already started")
        self._server = uvicorn.Server(self._server_config)
        self._server_task = asyncio.create_task(self._server.serve())

    async def stop(self) -> None:
        """Stop the API server."""
        if self._server is None or self._server_task is None:
            raise RuntimeError("The server is not started yet")
        self._server_task.cancel()
        try:
            await self._server_task
        except asyncio.CancelledError:
            pass
        except:
            traceback.print_exc()
        self._server_task = None
        self._server = None