use std::fs;

use tonic::codegen::InterceptedService;
use tonic::transport::{Certificate, Channel, ClientTlsConfig};
use tonic::Request;

use crate::auth::AuthInterceptor;
use crate::error::{ensure_command_success, ensure_protocol_success, Error};
use crate::generated::mxaccess_gateway::v1::mx_access_gateway_client::MxAccessGatewayClient;
use crate::generated::mxaccess_gateway::v1::{
    CloseSessionReply, CloseSessionRequest, MxCommandReply, MxCommandRequest, MxEvent,
    OpenSessionReply, OpenSessionRequest, StreamEventsRequest,
};
use crate::options::ClientOptions;
use crate::session::Session;

pub type RawGatewayClient = MxAccessGatewayClient<InterceptedService<Channel, AuthInterceptor>>;
pub type EventStream =
    std::pin::Pin<Box<dyn futures_core::Stream<Item = Result<MxEvent, Error>> + Send + 'static>>;

/// Thin owner for the generated gateway client.
#[derive(Clone)]
pub struct GatewayClient {
    inner: RawGatewayClient,
    call_timeout: std::time::Duration,
    stream_timeout: Option<std::time::Duration>,
}

impl GatewayClient {
    pub async fn connect(options: ClientOptions) -> Result<Self, Error> {
        let mut endpoint =
            Channel::from_shared(options.endpoint().to_owned()).map_err(|source| {
                Error::InvalidEndpoint {
                    endpoint: options.endpoint().to_owned(),
                    detail: source.to_string(),
                }
            })?;
        endpoint = endpoint.connect_timeout(options.connect_timeout());

        if !options.plaintext() {
            let mut tls = ClientTlsConfig::new();
            if let Some(server_name) = options.server_name_override() {
                tls = tls.domain_name(server_name.to_owned());
            }
            if let Some(ca_file) = options.ca_file() {
                let certificate = fs::read(ca_file).map_err(|source| Error::InvalidEndpoint {
                    endpoint: options.endpoint().to_owned(),
                    detail: format!("failed to read CA file {}: {source}", ca_file.display()),
                })?;
                tls = tls.ca_certificate(Certificate::from_pem(certificate));
            }
            endpoint = endpoint.tls_config(tls)?;
        }

        let channel = endpoint.connect().await?;
        let interceptor = AuthInterceptor::new(options.api_key().cloned());

        Ok(Self {
            inner: MxAccessGatewayClient::with_interceptor(channel, interceptor),
            call_timeout: options.call_timeout(),
            stream_timeout: options.stream_timeout(),
        })
    }

    pub fn raw_client(&mut self) -> &mut RawGatewayClient {
        &mut self.inner
    }

    pub fn into_inner(self) -> RawGatewayClient {
        self.inner
    }

    pub fn session(&self, session_id: impl Into<String>) -> Session {
        Session::new(session_id, self.clone())
    }

    pub async fn open_session_raw(
        &self,
        request: OpenSessionRequest,
    ) -> Result<OpenSessionReply, Error> {
        let mut client = self.inner.clone();
        let response = client.open_session(self.unary_request(request)).await?;
        Ok(response.into_inner())
    }

    pub async fn open_session(&self, request: OpenSessionRequest) -> Result<Session, Error> {
        let reply = self.open_session_raw(request).await?;
        ensure_protocol_success("open session", reply.protocol_status.as_ref())?;
        Ok(Session::new(reply.session_id, self.clone()))
    }

    pub async fn close_session_raw(
        &self,
        request: CloseSessionRequest,
    ) -> Result<CloseSessionReply, Error> {
        let mut client = self.inner.clone();
        let response = client.close_session(self.unary_request(request)).await?;
        Ok(response.into_inner())
    }

    pub async fn invoke_raw(&self, request: MxCommandRequest) -> Result<MxCommandReply, Error> {
        let mut client = self.inner.clone();
        let response = client.invoke(self.unary_request(request)).await?;
        Ok(response.into_inner())
    }

    pub async fn invoke(&self, request: MxCommandRequest) -> Result<MxCommandReply, Error> {
        ensure_command_success(self.invoke_raw(request).await?)
    }

    pub async fn stream_events(&self, request: StreamEventsRequest) -> Result<EventStream, Error> {
        let mut client = self.inner.clone();
        let response = client.stream_events(self.stream_request(request)).await?;
        let stream = futures_util::StreamExt::map(response.into_inner(), |result| {
            result.map_err(Error::from)
        });

        Ok(Box::pin(stream))
    }

    fn unary_request<T>(&self, message: T) -> Request<T> {
        let mut request = Request::new(message);
        request.set_timeout(self.call_timeout);
        request
    }

    fn stream_request<T>(&self, message: T) -> Request<T> {
        let mut request = Request::new(message);
        if let Some(timeout) = self.stream_timeout {
            request.set_timeout(timeout);
        }

        request
    }
}