use actix_web::{
    dev::{forward_ready, Service, ServiceRequest, ServiceResponse, Transform},
    Error, HttpMessage, HttpRequest,
};
use dashmap::DashMap;
use futures_util::future::{ready, LocalBoxFuture, Ready};
use std::sync::Arc;
use uuid::Uuid;

const SESSION_HEADER: &str = "X-Session-Id";

#[derive(Clone)]
pub struct SessionManager {
    sessions: Arc<DashMap<Uuid, SessionRecord>>,
}

#[derive(Clone)]
pub struct SessionRecord {
    pub user_id: Uuid,
    pub username: String,
}

#[derive(Clone)]
pub struct SessionClaims {
    pub session_id: Uuid,
    pub user_id: Uuid,
    pub username: String,
}

impl SessionManager {
    pub fn new() -> Self {
        Self {
            sessions: Arc::new(DashMap::new()),
        }
    }

    pub fn create_session(&self, user_id: Uuid, username: String) -> Uuid {
        let session_id = Uuid::new_v4();
        self.sessions.insert(
            session_id,
            SessionRecord {
                user_id,
                username,
            },
        );
        session_id
    }

    pub fn get(&self, session_id: &Uuid) -> Option<SessionRecord> {
        self.sessions.get(session_id).map(|entry| entry.clone())
    }
}

#[derive(Clone)]
pub struct SessionLayer {
    manager: SessionManager,
}

impl SessionLayer {
    pub fn new(manager: SessionManager) -> Self {
        Self { manager }
    }

    pub fn claims(req: &HttpRequest) -> Option<SessionClaims> {
        req.extensions().get::<SessionClaims>().cloned()
    }
}

impl<S, B> Transform<S, ServiceRequest> for SessionLayer
where
    S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error> + 'static,
    S::Future: 'static,
{
    type Response = ServiceResponse<B>;
    type Error = Error;
    type InitError = ();
    type Transform = SessionMiddleware<S>;
    type Future = Ready<Result<Self::Transform, Self::InitError>>;

    fn new_transform(&self, service: S) -> Self::Future {
        ready(Ok(SessionMiddleware {
            service,
            manager: self.manager.clone(),
        }))
    }
}

pub struct SessionMiddleware<S> {
    service: S,
    manager: SessionManager,
}

impl<S, B> Service<ServiceRequest> for SessionMiddleware<S>
where
    S: Service<ServiceRequest, Response = ServiceResponse<B>, Error = Error> + 'static,
    S::Future: 'static,
{
    type Response = ServiceResponse<B>;
    type Error = Error;
    type Future = LocalBoxFuture<'static, Result<Self::Response, Self::Error>>;

    forward_ready!(service);

    fn call(&self, mut req: ServiceRequest) -> Self::Future {
        let manager = self.manager.clone();

        if let Some(claims) = extract_claims(&req, &manager) {
            req.extensions_mut().insert(claims);
        }

        let fut = self.service.call(req);

        Box::pin(async move {
            let res = fut.await?;
            Ok(res)
        })
    }
}

fn extract_claims(req: &ServiceRequest, manager: &SessionManager) -> Option<SessionClaims> {
    let session_id = req
        .headers()
        .get(SESSION_HEADER)
        .and_then(|value| value.to_str().ok())
        .and_then(|value| Uuid::parse_str(value).ok())?;

    manager.get(&session_id).map(|record| SessionClaims {
        session_id,
        user_id: record.user_id,
        username: record.username,
    })
}