import logging
from ipaddress import IPv4Address
from typing import Any, Dict

import rapidjson
import uvicorn
from fastapi import Depends, FastAPI
from fastapi.middleware.cors import CORSMiddleware
from starlette.responses import JSONResponse

from freqtrade.exceptions import OperationalException
from freqtrade.rpc.api_server.uvicorn_threaded import UvicornServer
from freqtrade.rpc.rpc import RPC, RPCException, RPCHandler


logger = logging.getLogger(__name__)


class FTJSONResponse(JSONResponse):
    media_type = "application/json"

    def render(self, content: Any) -> bytes:
        """
        Use rapidjson for responses
        Handles NaN and Inf / -Inf in a javascript way by default.
        """
        return rapidjson.dumps(content).encode("utf-8")


class ApiServer(RPCHandler):

    __instance = None
    __initialized = False

    _rpc: RPC
    # Backtesting type: Backtesting
    _bt = None
    _bt_data = None
    _bt_timerange = None
    _bt_last_config: Dict[str, Any] = {}
    _has_rpc: bool = False
    _bgtask_running: bool = False
    _config: Dict[str, Any] = {}
    # Exchange - only available in webserver mode.
    _exchange = None

    def __new__(cls, *args, **kwargs):
        """
        This class is a singleton.
        We'll only have one instance of it around.
        """
        if ApiServer.__instance is None:
            ApiServer.__instance = object.__new__(cls)
            ApiServer.__initialized = False
        return ApiServer.__instance

    def __init__(self, config: Dict[str, Any], standalone: bool = False) -> None:
        ApiServer._config = config
        if self.__initialized and (standalone or self._standalone):
            return
        self._standalone: bool = standalone
        self._server = None
        ApiServer.__initialized = True

        api_config = self._config['api_server']

        self.app = FastAPI(title="Freqtrade API",
                           docs_url='/docs' if api_config.get('enable_openapi', False) else None,
                           redoc_url=None,
                           default_response_class=FTJSONResponse,
                           )
        self.configure_app(self.app, self._config)

        self.start_api()

    def add_rpc_handler(self, rpc: RPC):
        """
        Attach rpc handler
        """
        if not self._has_rpc:
            ApiServer._rpc = rpc
            ApiServer._has_rpc = True
        else:
            # This should not happen assuming we didn't mess up.
            raise OperationalException('RPC Handler already attached.')

    def cleanup(self) -> None:
        """ Cleanup pending module resources """
        ApiServer._has_rpc = False
        del ApiServer._rpc
        if self._server and not self._standalone:
            logger.info("Stopping API Server")
            self._server.cleanup()

    @classmethod
    def shutdown(cls):
        cls.__initialized = False
        del cls.__instance
        cls.__instance = None
        cls._has_rpc = False
        cls._rpc = None

    def send_msg(self, msg: Dict[str, str]) -> None:
        pass

    def handle_rpc_exception(self, request, exc):
        logger.exception(f"API Error calling: {exc}")
        return JSONResponse(
            status_code=502,
            content={'error': f"Error querying {request.url.path}: {exc.message}"}
        )

    def configure_app(self, app: FastAPI, config):
        from freqtrade.rpc.api_server.api_auth import http_basic_or_jwt_token, router_login
        from freqtrade.rpc.api_server.api_backtest import router as api_backtest
        from freqtrade.rpc.api_server.api_v1 import router as api_v1
        from freqtrade.rpc.api_server.api_v1 import router_public as api_v1_public
        from freqtrade.rpc.api_server.web_ui import router_ui

        app.include_router(api_v1_public, prefix="/api/v1")

        app.include_router(api_v1, prefix="/api/v1",
                           dependencies=[Depends(http_basic_or_jwt_token)],
                           )
        app.include_router(api_backtest, prefix="/api/v1",
                           dependencies=[Depends(http_basic_or_jwt_token)],
                           )
        app.include_router(router_login, prefix="/api/v1", tags=["auth"])
        # UI Router MUST be last!
        app.include_router(router_ui, prefix='')

        app.add_middleware(
            CORSMiddleware,
            allow_origins=config['api_server'].get('CORS_origins', []),
            allow_credentials=True,
            allow_methods=["*"],
            allow_headers=["*"],
        )

        app.add_exception_handler(RPCException, self.handle_rpc_exception)

    def start_api(self):
        """
        Start API ... should be run in thread.
        """
        rest_ip = self._config['api_server']['listen_ip_address']
        rest_port = self._config['api_server']['listen_port']

        logger.info(f'Starting HTTP Server at {rest_ip}:{rest_port}')
        if not IPv4Address(rest_ip).is_loopback:
            logger.warning("SECURITY WARNING - Local Rest Server listening to external connections")
            logger.warning("SECURITY WARNING - This is insecure please set to your loopback,"
                           "e.g 127.0.0.1 in config.json")

        if not self._config['api_server'].get('password'):
            logger.warning("SECURITY WARNING - No password for local REST Server defined. "
                           "Please make sure that this is intentional!")

        if (self._config['api_server'].get('jwt_secret_key', 'super-secret')
                in ('super-secret, somethingrandom')):
            logger.warning("SECURITY WARNING - `jwt_secret_key` seems to be default."
                           "Others may be able to log into your bot.")

        logger.info('Starting Local Rest Server.')
        verbosity = self._config['api_server'].get('verbosity', 'error')

        uvconfig = uvicorn.Config(self.app,
                                  port=rest_port,
                                  host=rest_ip,
                                  use_colors=False,
                                  log_config=None,
                                  access_log=True if verbosity != 'error' else False,
                                  )
        try:
            self._server = UvicornServer(uvconfig)
            if self._standalone:
                self._server.run()
            else:
                self._server.run_in_thread()
        except Exception:
            logger.exception("Api server failed to start.")
