use std::ops::Add;
use std::sync::Arc;

use actix_http::body::MessageBody;
use actix_jwt_authc::*;
use actix_web::web::{Data, ServiceConfig};
use actix_web::{get, HttpResponse};
use dashmap::DashSet;
use futures::channel::{mpsc, mpsc::Sender};
use futures::stream::Stream;
use futures::SinkExt;
use jsonwebtoken::*;
use ring::rand::SystemRandom;
use ring::signature::{Ed25519KeyPair, KeyPair};
use serde::{Deserialize, Serialize};
use time::ext::*;
use time::OffsetDateTime;
use tokio::sync::Mutex;
use uuid::Uuid;

pub type UserSession = Authenticated<Claims>;

#[derive(Clone, Copy)]
pub struct JWTTtl(time::Duration);

#[derive(Debug, Serialize, Deserialize, Clone, Eq, PartialEq)]
pub struct Claims {
    exp: usize,
    iat: usize,
    sub: String,
}

#[derive(Serialize, Deserialize)]
pub struct EmptyResponse {}

#[derive(Debug, Serialize, Deserialize)]
pub struct LoginResponse {
    bearer_token: String,
    claims: Claims,
}

const JWT_SIGNING_ALGO: Algorithm = Algorithm::EdDSA;

#[derive(Clone)]
pub struct SessionConfigurator {
    jwt_ttl: Data<JWTTtl>,
    invalidated_jwts_store: Data<InvalidatedJWTStore>,
    encoding_key: Data<EncodingKey>,
    factory: AuthenticateMiddlewareFactory<Claims>,
}

impl SessionConfigurator {
    pub fn app_data(self, config: &mut ServiceConfig) {
        config
            .app_data(self.invalidated_jwts_store)
            .app_data(self.encoding_key)
            .app_data(self.jwt_ttl)
            .service(login)
            .service(logout)
            .service(session_info);
    }

    pub fn factory(&self) ->
     AuthenticateMiddlewareFactory<Claims> {
         self.factory.clone()
     }

    pub fn new() -> Self {
        let jwt_ttl = JWTTtl(31.days());
        let jwt_signing_keys = JwtSigningKeys::generate().unwrap();
        let validator = Validation::new(JWT_SIGNING_ALGO);
        let auth_middleware_settings = AuthenticateMiddlewareSettings {
            jwt_decoding_key: jwt_signing_keys.decoding_key,
            jwt_authorization_header_prefixes: Some(vec!["Bearer".to_string()]),
            jwt_validator: validator,
            jwt_session_key: None,
        };
        let (invalidated_jwts_store, stream) = InvalidatedJWTStore::new_with_stream();
        let auth_middleware_factory =
            AuthenticateMiddlewareFactory::<Claims>::new(stream, auth_middleware_settings.clone());

        Self {
            invalidated_jwts_store: Data::new(invalidated_jwts_store.clone()),
            encoding_key: Data::new(jwt_signing_keys.encoding_key.clone()),
            jwt_ttl: Data::new(jwt_ttl.clone()),
            factory: auth_middleware_factory,
        }
    }
}

#[get("/login")]
async fn login(
    jwt_encoding_key: Data<EncodingKey>,
    jwt_ttl: Data<JWTTtl>,
) -> Result<HttpResponse, Error> {
    let sub = format!("{}", Uuid::new_v4().as_u128());
    let iat = OffsetDateTime::now_utc().unix_timestamp() as usize;
    let expires_at = OffsetDateTime::now_utc().add(jwt_ttl.0);
    let exp = expires_at.unix_timestamp() as usize;

    let jwt_claims = Claims { iat, exp, sub };
    let jwt_token = encode(
        &Header::new(JWT_SIGNING_ALGO),
        &jwt_claims,
        &jwt_encoding_key,
    )
    .map_err(|_| Error::InternalError)?;
    let login_response = LoginResponse {
        bearer_token: jwt_token,
        claims: jwt_claims,
    };

    Ok(HttpResponse::Ok().json(login_response))
}

#[get("/session")]
async fn session_info(authenticated: UserSession) -> Result<HttpResponse, Error> {
    Ok(HttpResponse::Ok().json(authenticated))
}

#[get("/logout")]
async fn logout(
    invalidated_jwts: Data<InvalidatedJWTStore>,
    authenticated: Authenticated<Claims>,
) -> Result<HttpResponse, Error> {
    invalidated_jwts.add_to_invalidated(authenticated).await;
    Ok(HttpResponse::Ok().json(EmptyResponse {}))
}

#[derive(Clone)]
struct InvalidatedJWTStore {
    store: Arc<DashSet<JWT>>,
    tx: Arc<Mutex<Sender<InvalidatedTokensEvent>>>,
}

impl InvalidatedJWTStore {
    /// Returns a [InvalidatedJWTStore] with a Stream of [InvalidatedTokensEvent]s
    fn new_with_stream() -> (
        InvalidatedJWTStore,
        impl Stream<Item = InvalidatedTokensEvent>,
    ) {
        let invalidated = Arc::new(DashSet::new());
        let (tx, rx) = mpsc::channel(100);
        let tx_to_hold = Arc::new(Mutex::new(tx));
        (
            InvalidatedJWTStore {
                store: invalidated,
                tx: tx_to_hold,
            },
            rx,
        )
    }

    async fn add_to_invalidated(&self, authenticated: Authenticated<Claims>) {
        self.store.insert(authenticated.jwt.clone());
        let mut tx = self.tx.lock().await;
        if let Err(_e) = tx
            .send(InvalidatedTokensEvent::Add(authenticated.jwt))
            .await
        {
            #[cfg(feature = "tracing")]
            error!(error = ?_e, "Failed to send update on adding to invalidated")
        }
    }
}

struct JwtSigningKeys {
    encoding_key: EncodingKey,
    decoding_key: DecodingKey,
}

impl JwtSigningKeys {
    fn generate() -> Result<Self, Box<dyn std::error::Error>> {
        let doc = Ed25519KeyPair::generate_pkcs8(&SystemRandom::new())?;
        let keypair = Ed25519KeyPair::from_pkcs8(doc.as_ref())?;
        let encoding_key = EncodingKey::from_ed_der(doc.as_ref());
        let decoding_key = DecodingKey::from_ed_der(keypair.public_key().as_ref());
        Ok(JwtSigningKeys {
            encoding_key,
            decoding_key,
        })
    }
}